[yocto-autobuilder2,2/2] README-Guide: wrap lines at 80 characters

Submitted by Trevor Gamblin on June 22, 2020, 2:18 p.m. | Patch ID: 173787

Details

Message ID 20200622141848.3461211-3-trevor.gamblin@windriver.com
State New
Headers show

Commit Message

Trevor Gamblin June 22, 2020, 2:18 p.m.
Signed-off-by: Trevor Gamblin <trevor.gamblin@windriver.com>
---
 README-Guide.md | 454 ++++++++++++++++++++++++++++++++++++------------
 1 file changed, 341 insertions(+), 113 deletions(-)

Patch hide | download patch | download mbox

diff --git a/README-Guide.md b/README-Guide.md
index 83e30d0..aaefd02 100644
--- a/README-Guide.md
+++ b/README-Guide.md
@@ -1,14 +1,20 @@ 
 # Installing and Maintaining the Yocto Autobuilder 2
 
-This guide will walk through how to install a stand-alone autobuilder controller and worker, and then reconfigure it with new builds, etc.  The guide was written with the help of Richard Purdie under the context of a headless Ubuntu 18.04.02 Server installation.
+This guide will walk through how to install a stand-alone autobuilder controller
+and worker, and then reconfigure it with new builds, etc.  The guide was written
+with the help of Richard Purdie under the context of a headless Ubuntu 18.04.02
+Server installation.
 
 ## 1) Stand-alone Installation
 
 ### 1.1) Basic Requirements
 
-The final outputs of this section are a controller and worker installed in the same server, ready for trimming back to an individual organization's needs.
+The final outputs of this section are a controller and worker installed in the
+same server, ready for trimming back to an individual organization's needs.
 
- > NOTE: The guide assumes that your host OS has the packages installed to support BitBake for the release(s) you are targeting.  Please refer to the Yocto manual for those packages.
+ > NOTE: The guide assumes that your host OS has the packages installed to
+ > support BitBake for the release(s) you are targeting.  Please refer to the
+ > Yocto manual for those packages.
 
 The latest version of BuildBot is written in Python 3, so installation via pip3:
 
@@ -17,11 +23,15 @@  apt install git build-essential python3-pip virtualenv enchant npm
 sudo pip3 install buildbot buildbot-www buildbot-waterfall-view buildbot-console-view buildbot-grid-view buildbot-worker
 ```
 
-It is recommended to also install `testtools` and `libccpunit-subunit-dev` (via apt, in this case) on the worker in order for certain image tests to work correctly (e.g., `core-image-sato-sdk:do_testimage`).
+It is recommended to also install `testtools` and `libccpunit-subunit-dev` (via
+apt, in this case) on the worker in order for certain image tests to work
+correctly (e.g., `core-image-sato-sdk:do_testimage`).
 
 ### 1.2) Creating the Autobuilder User's Directory
 
-For a new installation you will need a system user that can run Autobuilder2 as well as a couple of repositories: Autobuilder2 itself and a helper plugin.  As root:
+For a new installation you will need a system user that can run Autobuilder2 as
+well as a couple of repositories: Autobuilder2 itself and a helper plugin.  As
+root:
 
 ```
 useradd -m --system pokybuild3
@@ -39,9 +49,13 @@  chown -R pokybuild3:nogroup /home/pokybuild3
 Note: depending on the configuration of your system, you may need to
 replace "nogroup" with "pokybuild3" for the last command to work.
 
- > **IMPORTANT:** In the above command you created a controller and a worker, which will attempt to join the controller using `pass` as the password.  Feel free to change this, knowing that if you do, you must change the controller's master configuration file to match.
+ > **IMPORTANT:** In the above command you created a controller and a worker,
+ > which will attempt to join the controller using `pass` as the password.  Feel
+ > free to change this, knowing that if you do, you must change the controller's
+ > master configuration file to match.
 
-At the end of this, your build user's home directory (e.g., `/home/pokybuild3`) should look like this:
+At the end of this, your build user's home directory (e.g., `/home/pokybuild3`)
+should look like this:
 
 ```
 yocto-autobuilder-helper
@@ -52,23 +66,50 @@  yocto-worker
 
 ### 1.3) Customizing the Autobuilder Configuration
 
-Next, we need to update the `yocto-controller/yoctoabb/master.cfg` towards the bottom where the `title`, `titleURL`, and `buildbotURL` are all set.  This is also where you would specify a different password for binding workers to the master.
+Next, we need to update the `yocto-controller/yoctoabb/master.cfg` towards the
+bottom where the `title`, `titleURL`, and `buildbotURL` are all set.  This is
+also where you would specify a different password for binding workers to the
+master.
 
-Then, we need to update the `yocto-controller/yoctoabb/config.py` to include our worker.  In that file, find the line where `workers` is set and add: ["example-worker"].  _NOTE:_ if your worker's name is different, use that here.  Section 3.1 discusses how to further refine this list of workers.
+Then, we need to update the `yocto-controller/yoctoabb/config.py` to include our
+worker.  In that file, find the line where `workers` is set and
+add: ["example-worker"].  _NOTE:_ if your worker's name is different, use that
+here.  Section 3.1 discusses how to further refine this list of workers.
 
- > **IMPORTANT:** You should also take this time to edit the `sharedrepodir` and `publish_dest` variables to be in your build user's home as well.  You will need to create these directories since the related code that will check for if they exist _will not_ also attempt to create them (and the server will crash on start).
+ > **IMPORTANT:** You should also take this time to edit the `sharedrepodir`
+ > and `publish_dest` variables to be in your build user's home as well.  You
+ > will need to create these directories since the related code that will check
+ > for if they exist _will not_ also attempt to create them (and the server will
+ > crash on start).
 
-Next, if you do not want to edit the original `yocto-autobuilder-helper/config.json`, you can overlay your own by creating, for instance, `yocto-autobuilder-helper/config-local.json`.  _NOTE:_ there is no way for your overlay to _remove_ builders or other attributes, so this route is really more about extenending the original set of builders.
+Next, if you do not want to edit the original
+`yocto-autobuilder-helper/config.json`, you can overlay your own by creating,
+for instance, `yocto-autobuilder-helper/config-local.json`.  _NOTE:_ there is no
+way for your overlay to _remove_ builders or other attributes, so this route is
+really more about extenending the original set of builders.
 
 Here are some suggestions for the sake of :
 
- 1. In the original `config.json`, find all instances of whatever `BASE_HOMEDIR` was set to, for example `/home/pokybuild3`.  Copy those variables to your `config-local.json` replace `/home/pokybuild3` with `${BASE_HOMEDIR}`.  These will be variables like `BUILDPERF_STATEDIR` and `EXTRAPLAINCMDS`.
-Set `BASE_HOMEDIR` should be your build user's home directory.  (There are shell scripts where this is assumed.)
- 2. Add `BASE_SHAREDDIR` and `BASE_PUBLISHDIR` such that they are subtrees of your `BASE_HOMEDIR`, e.g., `${BASE_HOMEDIR}/srv/autobuilder.yoursite.com`.
- 3. Change your `WEBPUBLISH_URL` to match your `config.py` definition for `buildbotURL`.
- 4. In order for this to work, you must export `ABHELPER_JSON="config.json config-local.json"` into the environment of the controller and janitor services (the example service scripts included below already have this).
-
- > NOTE: The way the build step is written, the worker will pull a fresh copy of the helper from the server.  Therefore these configuration files must be committed to the `yocto-autobuilder-helper` repo location you have specified in `yoctoabb/config.py` because the worker is given a build step that pulls from that repo (see `yoctoabb/builders.py`).
+ 1. In the original `config.json`, find all instances of whatever
+    `BASE_HOMEDIR` was set to, for example `/home/pokybuild3`.  Copy those
+    variables to your `config-local.json` replace `/home/pokybuild3`
+    with `${BASE_HOMEDIR}`.  These will be variables
+    like `BUILDPERF_STATEDIR` and `EXTRAPLAINCMDS`.  Set `BASE_HOMEDIR` should
+    be your build user's home directory.  (There are shell scripts where this is
+    assumed.)
+ 2. Add `BASE_SHAREDDIR` and `BASE_PUBLISHDIR` such that they are subtrees of
+    your `BASE_HOMEDIR`, e.g., `${BASE_HOMEDIR}/srv/autobuilder.yoursite.com`.
+ 3. Change your `WEBPUBLISH_URL` to match your `config.py` definition
+    for `buildbotURL`.
+ 4. In order for this to work, you must export `ABHELPER_JSON="config.json
+    config-local.json"` into the environment of the controller and janitor
+    services (the example service scripts included below already have this).
+
+ > NOTE: The way the build step is written, the worker will pull a fresh copy of
+ > the helper from the server.  Therefore these configuration files must be
+ > committed to the `yocto-autobuilder-helper` repo location you have specified
+ > in `yoctoabb/config.py` because the worker is given a build step that pulls
+ > from that repo (see `yoctoabb/builders.py`).
 
 ### 1.4) Starting the Autobuilder
 
@@ -86,21 +127,23 @@  Run the following from the pokybuild3 directory:
 
 #### 1.4.2) Creating Service Files
 
- 1. As root, add the `yocto-*.service` files to `/lib/systemd/system` (See Appendix A).  
+ 1. As root, add the `yocto-*.service` files to `/lib/systemd/system` (See
+    Appendix A).  
  2. Run: `systemctl daemon-reload`.  
- 3. You should now be able to successfully start these services (e.g., `sudo systemctl start yocto-*`). The controller may take up to 15 seconds to start.
+ 3. You should now be able to successfully start these services (e.g., `sudo
+    systemctl start yocto-*`). The controller may take up to 15 seconds to
+    start.
 
 ### 1.5) Configuring the Worker's Hash Equivalency Server
 
-A key part of the autobuilder setup is the use of a hash equivalency
-server, which is started manually on the Yocto hosts. By default, the 
-config.json file that is pulled along with yocto-autobuilder-helper 
-contains "BB_HASHSERVE = 'typhoon.yocto.io:8686'", which will likely 
-cause a custom autobuilder instance to hang while trying to communicate 
-with the hash equivalency server. As mentioned in the previous section, 
-any configuration changes made need to be committed to the 
-yocto-autobuilder-helper repo that your worker will pull from. A simple
-way to start the hash equivalency server and properly configure your
+A key part of the autobuilder setup is the use of a hash equivalency server,
+which is started manually on the Yocto hosts. By default, the config.json file
+that is pulled along with yocto-autobuilder-helper contains "BB_HASHSERVE =
+'typhoon.yocto.io:8686'", which will likely cause a custom autobuilder instance
+to hang while trying to communicate with the hash equivalency server. As
+mentioned in the previous section, any configuration changes made need to be
+committed to the yocto-autobuilder-helper repo that your worker will pull from.
+A simple way to start the hash equivalency server and properly configure your
 workers is done with the following steps:
 
 1. Clone a copy of the poky distribution repo from
@@ -108,27 +151,32 @@  workers is done with the following steps:
 2. Source the oe-init-build-env script into your build directory
 3. Run "bitbake-hashserv --bind <PORT>:<IP>" from the build directory
 4. Clone a copy of
-   https://git.yoctoproject.org/cgit/cgit.cgi/yocto-autobuilder-helper/,
-   then create config-local.json by copying config.json (and removing 
-   sections that aren't required). Since the contents of config-local.json 
-   are an overlay for those in config.json, this will preserve as much of 
-   the initial configuration as possible.
-5. Change the BB_HASHSERVE value in config-local.json to point to the IP 
-   and port you specified in step 3
+   https://git.yoctoproject.org/cgit/cgit.cgi/yocto-autobuilder-helper/, then
+   create config-local.json by copying config.json (and removing sections that
+   aren't required). Since the contents of config-local.json are an overlay for
+   those in config.json, this will preserve as much of the initial configuration
+   as possible.
+5. Change the BB_HASHSERVE value in config-local.json to point to the IP and
+   port you specified in step 3
 6. Commit the changes in the local yocto-autobuilder-helper repository
-7. In <autobuilderpath>/yocto-controller/yoctoabb/config.py, change the
-   entry for "yocto-autobuilder-helper" under "repos" to point at your
-   local copy of the yocto-autobuilder-helper repository.
+7. In <autobuilderpath>/yocto-controller/yoctoabb/config.py, change the entry
+   for "yocto-autobuilder-helper" under "repos" to point at your local copy of
+   the yocto-autobuilder-helper repository.
 
-After these steps have been taken, the workers that you start should
-attach to your local hash equivalency server and be able to complete a
-target build.
+After these steps have been taken, the workers that you start should attach to
+your local hash equivalency server and be able to complete a target build.
 
-### 1.2) Special Notes for the Worker Environment
+### 1.6) Special Notes for the Worker Environment
 
-The QEMU tap interfaces also need to be generated and owned by the worker's user (created above).  One way to this is to compile the `meta/recipes-devtools/qemu/qemu-helper/tunctl.c` file and run it _N_ times on the worker's host.  See the related `qemu-helper-native` recipe for instructions.  The resulting executable would be run _N_ times (e.g., 8), so for example: `sudo tunctl -u $(id -u pokybuild3) -g $(id -g pokybuild3) -t tun0`.
+The QEMU tap interfaces also need to be generated and owned by the worker's user
+(created above).  One way to this is to compile the
+`meta/recipes-devtools/qemu/qemu-helper/tunctl.c` file and run it _N_ times on
+the worker's host.  See the related `qemu-helper-native` recipe for
+instructions.  The resulting executable would be run _N_ times (e.g., 8), so for
+example: `sudo tunctl -u $(id -u pokybuild3) -g $(id -g pokybuild3) -t tun0`.
 
-Another way to create these interface is to let the build fail once, then issue a command like this from a user with sudo permissions on the worker:
+Another way to create these interface is to let the build fail once, then issue
+a command like this from a user with sudo permissions on the worker:
 
 ```
 sudo /home/pokybuild3/yocto-worker/qemuarm/build/scripts/runqemu-gen-tapdevs \
@@ -137,37 +185,77 @@  sudo /home/pokybuild3/yocto-worker/qemuarm/build/scripts/runqemu-gen-tapdevs \
     /home/pokybuild3/yocto-worker/qemuarm/build/build/tmp/sysroots-components/x86_64/qemu-helper-native/usr/bin
 ```
 
-In the above command, we assume the a build named qemuarm failed.  The value of 8 is the number of tap interfaces to create on the worker.
+In the above command, we assume the a build named qemuarm failed.  The value
+of 8 is the number of tap interfaces to create on the worker.
 
 ## 2) Basics
 
-This section is an overview of operation and a few basic configuration file relationships.  See Section 3 for more detailed instructions.
+This section is an overview of operation and a few basic configuration file
+relationships.  See Section 3 for more detailed instructions.
 
 ### 2.1) Start / Stop the Master and Worker Services
 
-Per the installation in Section 1, both the Master and Worker are running on the same host and the service files (Appendix A) maintain that assumption.  To start all services:
+Per the installation in Section 1, both the Master and Worker are running on the
+same host and the service files (Appendix A) maintain that assumption.  To start
+all services:
 
 ```
 sudo systemctl start yocto-controller yocto-worker yocto-janitor
 ```
 
-Depending on your web front-end setup (reverse proxy, etc.), you should now be able to access the BuildBot web UI at the address you specified in `yoctoabb/master.cfg` during the installation (e.g., https://localhost:8010).
+Depending on your web front-end setup (reverse proxy, etc.), you should now be
+able to access the BuildBot web UI at the address you specified
+in `yoctoabb/master.cfg` during the installation (e.g., https://localhost:8010).
 
 ### 2.2) Build Schedule Types
 
-The `yoctoabb/schedulers.py` defines three main types of build schedules: triggerable, force, and nightly.  The `wait-quick` and `wait-full` schedules are triggerable, and each has a specific list of builders that are defined in the `yoctoabb/config.py` variables: `trigger_builders_wait_quick` and `trigger_builders_wait_full`, respectively.  Each of the builders in those lists also have a force schedule for manual runs.  To run all of them, the `a-quick` and `a-full` schedules exist; those names are also the names of the builders.  Finally, there is one nightly build defined which runs the a-quick builder against the `HEAD` of the various master branches to help maintain freshness of the shared state and downloads caches.
+The `yoctoabb/schedulers.py` defines three main types of build schedules:
+triggerable, force, and nightly.  The `wait-quick` and `wait-full` schedules are
+triggerable, and each has a specific list of builders that are defined in the
+`yoctoabb/config.py` variables:
+`trigger_builders_wait_quick` and `trigger_builders_wait_full`, respectively. 
+Each of the builders in those lists also have a force schedule for manual runs. 
+To run all of them, the `a-quick` and `a-full` schedules exist; those names are
+also the names of the builders.  Finally, there is one nightly build defined
+which runs the a-quick builder against the `HEAD` of the various master branches
+to help maintain freshness of the shared state and downloads caches.
 
 ### 2.3) Running a Triggered Build Manually
 
-Assuming you have the controller and worker running, log into the BuildBot web server on port 8010.  Click on the Builds, Builders left menu.  It should populate the main panel (right) with a table showing all builders defined between the `yoctoabb/config.py` and the combination of any config JSON files loaded for `yocto-autobuilder-helper` (e.g., `config.json`).  The status of associated workers is shown with a bubble graph on the far right of this panel.  One should be green,  yours, because it's associated in `yoctoabb/config.py`, `builder_to_workers` map to that build by being one of the default builders.
-
-Select one of the builders, for example `beaglebone`.  At the top right, you will see _Force Build_ (this is a force because all builders in the `yoctoabb/config.py` `subbuilders` list get a _Force Scheduler_, per `yoctoabb/schedulers.py`).  Click that button and fill in your name (as _you <your@email.com>_) and a reason for forcing a build.  Scroll to the bottom, setting branches and revisions you want along the way, and press _Start Build_.
-
-Your browser will automatically navigate to the builder's status as the worker begins executing the build.
+Assuming you have the controller and worker running, log into the BuildBot web
+server on port 8010.  Click on the Builds, Builders left menu.  It should
+populate the main panel (right) with a table showing all builders defined
+between the `yoctoabb/config.py` and the combination of any config JSON files
+loaded for `yocto-autobuilder-helper` (e.g., `config.json`).  The status of
+associated workers is shown with a bubble graph on the far right of this panel. 
+One should be green,  yours, because it's associated
+in `yoctoabb/config.py`, `builder_to_workers` map to that build by being one of
+the default builders.
+
+Select one of the builders, for example `beaglebone`.  At the top right, you
+will see _Force Build_ (this is a force because all builders in the
+`yoctoabb/config.py` `subbuilders` list get a _Force Scheduler_,
+per `yoctoabb/schedulers.py`).  Click that button and fill in your name (as _you
+<your@email.com>_) and a reason for forcing a build.  Scroll to the bottom,
+setting branches and revisions you want along the way, and press _Start Build_.
+
+Your browser will automatically navigate to the builder's status as the worker
+begins executing the build.
 
 ### 2.4) Shared State and Downloads Mirrors
 
-One of the main useful features of having this build server is to speed up builds at development workstations.  Both of these are defined by the `yocto-autobuilder-json/config.json` (or your extra configuration if following the standalone installation instructions above).  The main variables are `BASE_SHAREDIR` and `BASE_PUBLISHDIR`.  These two are re-used in the bitbake configuration variables DLDIR and SSTATEDIR to help individual builds re-use prior work.  The default is to append `BASE_SHAREDDIR` with `current_sources` and `pub/sstate`, respectively.  These paths can be shared by NFS, HTTPS, etc.  In the example below, we're using https and assuming that a static file server has been configured to share the former under `yocto_downloads` and the latter as `yocto_sstate`.  To use these at a developer's station, set the following in the `build/conf/local.conf`:
+One of the main useful features of having this build server is to speed up
+builds at development workstations.  Both of these are defined by
+the `yocto-autobuilder-json/config.json` (or your extra configuration if
+following the standalone installation instructions above).  The main variables
+are `BASE_SHAREDIR` and `BASE_PUBLISHDIR`.  These two are re-used in the bitbake
+configuration variables DLDIR and SSTATEDIR to help individual builds re-use
+prior work.  The default is to append `BASE_SHAREDDIR` with `current_sources`
+and `pub/sstate`, respectively.  These paths can be shared by NFS, HTTPS, etc.
+In the example below, we're using https and assuming that a static file server
+has been configured to share the former under `yocto_downloads` and the latter
+as `yocto_sstate`.  To use these at a developer's station, set the following in
+the `build/conf/local.conf`:
 
 ```
 SSTATE_MIRRORS ?= "file://.* http://your.site.com/yocto_sstate/PATH;downloadfilename=PATH \n"
@@ -179,99 +267,239 @@  PREMIRRORS_prepend = "\
 "
 ```
 
-The developers have stated that this single shared state and downloads cache can be shared across multiple tagged versions of Poky, so there is no need to maintain separate paths for different releases.
+The developers have stated that this single shared state and downloads cache can
+be shared across multiple tagged versions of Poky, so there is no need to
+maintain separate paths for different releases.
 
- > Full Disclosure: In practice, the author has not seen a single successful cache query from the shared state mirror, as seen through the web server logs, despite using the same revision of branches at the server and desktop.  YMMV.  The downloads mirror however worked as expected.
+ > Full Disclosure: In practice, the author has not seen a single successful
+ > cache query from the shared state mirror, as seen through the web server
+ > logs, despite using the same revision of branches at the server and desktop.
+ > YMMV.  The downloads mirror however worked as expected.
 
 ### 2.5) Clearing Build History, Old Workers
 
- > _TODO:_ This is really heavy-handed; it removes all history.  You could try your luck at directly editing the state.sqlite file.
+ > _TODO:_ This is really heavy-handed; it removes all history.  You could try
+ > your luck at directly editing the state.sqlite file.
 
-All of the build history and worker related information is stored in a database, `yocto-controller/state.sqlite`.  From the `yocto-controller` directory, while it isn't runnign, delete the database and recreate it: `buildbot upgrade-master`.  Then restart the controller.
+All of the build history and worker related information is stored in a
+database, `yocto-controller/state.sqlite`.  From the `yocto-controller`
+directory, while it isn't runnign, delete the database and recreate
+it: `buildbot upgrade-master`.  Then restart the controller.
 
 # 3) Configuration
 
-As mentioned before, BuildBot is the underlying tool that Autobuilder2 uses.  It's a python3-based framework that consists of a master and multiple workers that may be remotely connected.  Per this guide, both are installed on the same host under `/home/pokybuild3`.
-
-The configuration for the controller is in `/home/pokybuild3/yocto-controller`.  This directory also contains the Yocto Project's Autobuilder source code (in `yoctoabb`) and master configuration file, `master.cfg`.  The `master.cfg` is a python file that pulls in other configuration data from the Autobuilder source code directory.  Based on comments in the `yoctoabb/master.cfg`, provisions have been made so that you can run `buildbot sighup` from this directory, which would cause the configuration to reload without taking down the controller.  This configuration data file primarily controls the web server and what port(s) are open for workers.  It also controls authentication and notification services (by way of importing `services.py` and `www.py`, see BuildBot's own documentation for answers).
-
-The main `yoctoabb/config.py` pairs up with the `yocto-autobuilder-helper/config.json` to define the relationship between what builds exist and what those builds _do_ in terms of steps to run.  There is a lot of duplication between these two scripts that must be managed manually, especially as it pertains to builders, the layer repositories each needs, and the locations of those layer repositories.
-
-Another interesting thing about this configuration is that only one branch of the `yocto-autobuilder-helper` is ever pulled even if you manually specify a different branch for a non-triggered build.  For example, manually Force Building `beaglebone` does not give you a chance to change yocto-autobuilder-helper branches but doing the same for `a-quick` would.  So if you have a repository that contains multiple layers and for `rocko` you need one of them, but for `thud` you need 2, your builder will fail if you run the build on `rocko` because the worker will try to use the `thud` build instructions...the only ones it knows unless you are using multiple branches of `yocto-autobuilder-helper` (`thud`, `warrior`, etc.) and running `a-quick` forced builds or configured additional `nightly` builds for different branchs.  There is also no way, from a single configuration JSON stack, to specify a builder being only compatible with a specific layer branch other than having multiple branches and omitting that builder from the incompatible branches, then forcing a trigger build.  This is controlled by `schedulers.py`, so it's not a limitation; instead consider this a _flag_ of something you probably want to change if you have to maintain multiple branches in regression.
-
-The remaining portion of this section will focus on the changes required to the various configuration files to accomplish specific tasks, which will hopefully provide some guardrails and sign posts along the way for when you do something wrong.
+As mentioned before, BuildBot is the underlying tool that Autobuilder2 uses. 
+It's a python3-based framework that consists of a master and multiple workers
+that may be remotely connected.  Per this guide, both are installed on the same
+host under `/home/pokybuild3`.
+
+The configuration for the controller is in `/home/pokybuild3/yocto-controller`. 
+This directory also contains the Yocto Project's Autobuilder source code
+(in `yoctoabb`) and master configuration file, `master.cfg`.  The `master.cfg`
+is a python file that pulls in other configuration data from the Autobuilder
+source code directory.  Based on comments in the `yoctoabb/master.cfg`,
+provisions have been made so that you can run `buildbot sighup` from this
+directory, which would cause the configuration to reload without taking down the
+controller.  This configuration data file primarily controls the web server and
+what port(s) are open for workers.  It also controls authentication and
+notification services (by way of importing `services.py` and `www.py`,
+see BuildBot's own documentation for answers).
+
+The main `yoctoabb/config.py` pairs up with
+the `yocto-autobuilder-helper/config.json` to define the relationship between
+what builds exist and what those builds _do_ in terms of steps to run.  There is
+a lot of duplication between these two scripts that must be managed manually,
+especially as it pertains to builders, the layer repositories each needs, and
+the locations of those layer repositories.
+
+Another interesting thing about this configuration is that only one branch of
+the `yocto-autobuilder-helper` is ever pulled even if you manually specify a
+different branch for a non-triggered build.  For example, manually Force
+Building `beaglebone` does not give you a chance to change
+yocto-autobuilder-helper branches but doing the same for `a-quick` would.  So if
+you have a repository that contains multiple layers and for `rocko` you need one
+of them, but for `thud` you need 2, your builder will fail if you run the build
+on `rocko` because the worker will try to use the `thud` build
+instructions...the only ones it knows unless you are using multiple branches of
+`yocto-autobuilder-helper` (`thud`, `warrior`, etc.) and running `a-quick`
+forced builds or configured additional `nightly` builds for different branchs.
+There is also no way, from a single configuration JSON stack, to specify a
+builder being only compatible with a specific layer branch other than having
+multiple branches and omitting that builder from the incompatible branches, then
+forcing a trigger build.  This is controlled by `schedulers.py`, so it's not a
+limitation; instead consider this a _flag_ of something you probably want to
+change if you have to maintain multiple branches in regression.
+
+The remaining portion of this section will focus on the changes required to the
+various configuration files to accomplish specific tasks, which will hopefully
+provide some guardrails and sign posts along the way for when you do something
+wrong.
 
 ## 3.1) Repositories
 
-There are two main areas where repositories are defined.  The first is in `yoctoabb/config.py`, which provides builders with a default set of repositories stored locally at the worker.  The second place is more nuanced, in your `config.json` stack of the `yocto-autobuilder-helper` under the `repo-defaults`.  This map defines a duplicate of that information, which is consumed by the layer-config and run-config scripts by way of the `NEEDREPOS` and `ADDLAYER` lists on a given template or override.
-
-The `NEEDREPOS` behavior ensures that the copies of your meta layers are organized in the `BUILDDIR/../` correctly, and then if `no-layer-add` is set to `false` (or omitted), will automatically call `bitbake-layers add-layer...` to update your build's `bblayers.conf` file.  This process goes in order of build dependencies.  The content of `NEEDREPOS` can be either a repo that is a layer, or a repo that contains multiple layers.  In the latter case, specifying `meta-openembedded/meta-oe` will copy the whole repo `meta-openembedded` and then call `bitbake-layers add-layer...` for only the sub-layer, `meta-oe` (assuming you've set `no-layer-add` to `false` for that repo; the default is `true`).
-
-The `ADDLAYER` behavior is similar but is processed during the `run-config` step that executes all of your steps.  You can add this variable at the _step_ level (it does not work at the builder level; `run-config` doesn't pick it up).  Each list item in this variable takes the form: `${BUILDDIR}/../path/to/layer`.
-
- > **IMPORTANT:** The order of these two lists matter!  If you add a layer that has unmet dependencies on other layers (i.e., they're not in `bblayers.conf` yet), the next repo/layer in the list will fail to add because you've technically broken your layer configuration (bitbake cannot parse it because dependencies are missing).
-
- > **IMPORTANT:** If you allowed `NEEDREPOS` to update your `bblayers.conf` file, then you do not need to use `ADDLAYER` as it'll be redundant.
+There are two main areas where repositories are defined.  The first is
+in `yoctoabb/config.py`, which provides builders with a default set of
+repositories stored locally at the worker.  The second place is more nuanced, in
+your `config.json` stack of the `yocto-autobuilder-helper` under
+the `repo-defaults`.  This map defines a duplicate of that information, which is
+consumed by the layer-config and run-config scripts by way of the `NEEDREPOS`
+and `ADDLAYER` lists on a given template or override.
+
+The `NEEDREPOS` behavior ensures that the copies of your meta layers are
+organized in the `BUILDDIR/../` correctly, and then if `no-layer-add` is set
+to `false` (or omitted), will automatically call `bitbake-layers add-layer...`
+to update your build's `bblayers.conf` file.  This process goes in order of
+build dependencies.  The content of `NEEDREPOS` can be either a repo that is a
+layer, or a repo that contains multiple layers.  In the latter case,
+specifying `meta-openembedded/meta-oe` will copy the whole
+repo `meta-openembedded` and then call `bitbake-layers add-layer...` for only
+the sub-layer, `meta-oe` (assuming you've set `no-layer-add` to `false` for that
+repo; the default is `true`).
+
+The `ADDLAYER` behavior is similar but is processed during the `run-config` step
+that executes all of your steps.  You can add this variable at the _step_ level
+(it does not work at the builder level; `run-config` doesn't pick it up).  Each
+list item in this variable takes the form: `${BUILDDIR}/../path/to/layer`.
+
+ > **IMPORTANT:** The order of these two lists matter!  If you add a layer that
+ > has unmet dependencies on other layers (i.e., they're not in `bblayers.conf`
+ > yet), the next repo/layer in the list will fail to add because you've
+ > technically broken your layer configuration (bitbake cannot parse it because
+ > dependencies are missing).
+
+ > **IMPORTANT:** If you allowed `NEEDREPOS` to update your `bblayers.conf`
+ > file, then you do not need to use `ADDLAYER` as it'll be redundant.
 
 ## 3.2) Workers
 
-As stated previously, this is exclusively defined by the `yoctoabb/config.py` file.  In it, there is a section of workers that culminate into a final map that defines build names vs. compatible workers, with default carrying the generic meaning that it should be applicable to any build.  Ultimately the list of workers defined in this configuration can be also thought of as _users_ of the system because a worker will fail to join the master if it's not in this list or provides an incorrect password (variable: `worker_password`).
+As stated previously, this is exclusively defined by the `yoctoabb/config.py`
+file.  In it, there is a section of workers that culminate into a final map that
+defines build names vs. compatible workers, with default carrying the generic
+meaning that it should be applicable to any build.  Ultimately the list of
+workers defined in this configuration can be also thought of as _users_ of the
+system because a worker will fail to join the master if it's not in this list or
+provides an incorrect password (variable: `worker_password`).
 
-You will also notice in the standard configuration file that there are workers in the cluster for CentOS and Ubuntu, etc. since they're testing build host OS -specific things.
+You will also notice in the standard configuration file that there are workers
+in the cluster for CentOS and Ubuntu, etc. since they're testing build host OS
+-specific things.
 
-If you would like to trim this list down to just the workers you have at your site:
+If you would like to trim this list down to just the workers you have at your
+site:
 
- 1. You can safely remove any of the `workers_*` lists since they're only used locally to the `config.py`.
- 2. Retain the following related variables: `workers`, `all_workers`, `builder_to_workers`.  They're used elsewhere.
+ 1. You can safely remove any of the `workers_*` lists since they're only used
+    locally to the `config.py`.
+ 2. Retain the following related
+    variables: `workers`, `all_workers`, `builder_to_workers`.  They're used
+    elsewhere.
 
 ## 3.3) Builds and Builders
 
-This section details how to configure new builds, and thus, new builders.  There are two main files involved in this relationship: `yoctoabb/config.py` and the configuration JSON files you specified for `yocto-autobuilder-helper`.  Only builds that exist in both places will actually be visible and usable at the UI.  The remaining subsections below are general guidelines for how these various files interact.
+This section details how to configure new builds, and thus, new builders.  There
+are two main files involved in this relationship: `yoctoabb/config.py` and the
+configuration JSON files you specified for `yocto-autobuilder-helper`.  Only
+builds that exist in both places will actually be visible and usable at the UI. 
+The remaining subsections below are general guidelines for how these various
+files interact.
 
 **Removing Builders:**
 
- 1. You must keep the `buildertorepos` and `repos` maps.  The former provides a top-level set of builders and must include a key for default.  This map indicates which source code repositories to install for a given builder by way of a repository name.  The compliment to this map is `repos`, the list of repository locations and revisions. 
- 2. You must keep the `subbuilders` list because it is used by `yoctoabb/builders.py` and `yoctoabb/schedulers.py`.
- 3. You must keep the `a-quick` and `a-full` builds unless you are also modifying `yoctoabb/builders.py`, `generate-test-result-index.py`, and `schedulers.py` to remove those references as well.
- 4. For any build you remove from `yoctoabb/config.py`, you should also remove in your `yocto-autobuilder-helper/config.json` file (if not purely for the sake of being tidy).
+ 1. You must keep the `buildertorepos` and `repos` maps.  The former provides a
+    top-level set of builders and must include a key for default.  This map
+    indicates which source code repositories to install for a given builder by
+    way of a repository name.  The compliment to this map is `repos`, the list
+    of repository locations and revisions. 
+ 2. You must keep the `subbuilders` list because it is used
+    by `yoctoabb/builders.py` and `yoctoabb/schedulers.py`.
+ 3. You must keep the `a-quick` and `a-full` builds unless you are also
+    modifying `yoctoabb/builders.py`, `generate-test-result-index.py`, and
+    `schedulers.py` to remove those references as well.
+ 4. For any build you remove from `yoctoabb/config.py`, you should also remove
+    in your `yocto-autobuilder-helper/config.json` file (if not purely for the
+    sake of being tidy).
 
 **Adding Builders:**
 
- 1. If the build will only be manually run: add it to the `yoctoabb/config.py` subbuilders list.
- 2. If the build will be run by either of the default `a-quick` or `a-full` builds, add the name instead to the `trigger_builders_wait_[quick|full]` list of your choice.  If you want both, add it to `the trigger_builders_wait_shared` list.
- 3. If you have added a build that has requirements differing from the `yocto-autobuilder-helper/config.json` `defaults` map, create an entry for the builder in `the overrides` map fill in the details (see below for more suggestions).
- 4. If the build has a set of layer repositories that differs from the `default` list in the `yoctoabb/config.py` `buildertorepos` map, you need to add a reference to its needs in that map.
- 5. If the the repositories the builder requires are not listed in the `yoctoabb/config.py` `repos` map, add it under the same name with its default branch.
- 6. If you have added repositories, you should also add it to the `yocto-autobuilder-helper/config.json` `repo-defaults` map.
- 7. You should create `an overrides` for the builder that specifies `NEEDSREPOS` to identify those layers and `ADDLAYER` for any layers that have the `no-layer-add` flag set to `false` in the `repo-defaults` map.
- 8. If these needs are shared among multiple builders, consider adding these changes instead to a new, named template in the `templates` map and then for each affected builder, set the value of its `overrides` `TEMPLATE` to that named template.
+ 1. If the build will only be manually run: add it to the
+    `yoctoabb/config.py` subbuilders list.
+ 2. If the build will be run by either of the default `a-quick` or `a-full`
+    builds, add the name instead to the `trigger_builders_wait_[quick|full]`
+    list of your choice.  If you want both, add it to
+    `the trigger_builders_wait_shared` list.
+ 3. If you have added a build that has requirements differing from
+    the `yocto-autobuilder-helper/config.json` `defaults` map, create an entry
+    for the builder in `the overrides` map fill in the details (see below for
+    more suggestions).
+ 4. If the build has a set of layer repositories that differs from the `default`
+    list in the `yoctoabb/config.py` `buildertorepos` map, you need to add a
+    reference to its needs in that map.
+ 5. If the the repositories the builder requires are not listed in
+    the `yoctoabb/config.py` `repos` map, add it under the same name with its
+    default branch.
+ 6. If you have added repositories, you should also add it to
+    the `yocto-autobuilder-helper/config.json` `repo-defaults` map.
+ 7. You should create `an overrides` for the builder that specifies `NEEDSREPOS`
+    to identify those layers and `ADDLAYER` for any layers that have
+    the `no-layer-add` flag set to `false` in the `repo-defaults` map.
+ 8. If these needs are shared among multiple builders, consider adding these
+    changes instead to a new, named template in the `templates` map and then for
+    each affected builder, set the value of its `overrides` `TEMPLATE` to that
+    named template.
 
 **Anatomy: _overrides_ and _templates_**
 
-All of these guidelines pertain to the `yocto-autobuilder-helper/config.json` file (and any overlay configurations you have).  The main difference between these two items is that an `overrides` entry can specify the `TEMPLATE` variable, the value of which must exist in the `templates` map.  There is no provision for template stacking (i.e., adding `TEMPLATE` to a template has no effect).  Otherwise as the names imply the `overrides` values will take precedence over any named template and the `defaults`.
+All of these guidelines pertain to the `yocto-autobuilder-helper/config.json`
+file (and any overlay configurations you have).  The main difference between
+these two items is that an `overrides` entry can specify the `TEMPLATE`
+variable, the value of which must exist in the `templates` map.  There is no
+provision for template stacking (i.e., adding `TEMPLATE` to a template has no
+effect).  Otherwise as the names imply the `overrides` values will take
+precedence over any named template and the `defaults`.
 
  > NOTE: This is not a comprehensive list.
 
  1. Top-level variables:
-   1. `BUILDINFO` – boolean – If enabled, the values of `BUILDINFOVARS` are added to the list of variables in the build environment.
-   2. `BUILDHISTORY` – boolean – Enables `INHERIT += 'buildhistory'` BitBake behavior.
-   3. `BUILDINFOVARS` – list – For inheriting from `image-buildinfo` to save off additional build variables.
+   1. `BUILDINFO` – boolean – If enabled, the values of `BUILDINFOVARS` are
+      added to the list of variables in the build environment.
+   2. `BUILDHISTORY` – boolean – Enables `INHERIT += 'buildhistory'` BitBake
+      behavior.
+   3. `BUILDINFOVARS` – list – For inheriting from `image-buildinfo` to save off
+      additional build variables.
    4. `DISTRO` – string – Distro conf to use from the layer in the build.
-   5. `DLDIR` – string – Set the bitbake `DL_DIR` to where downloads should be stored (e.g., `"DL_DIR = 'some_path'"`).
-   6. `PACKAGE_CLASSES` – string – Set to the value of the Yocto `PACKAGE_CLASSES` variable
-   7. `SDKEXTRAS` – list – Unknown.  To some end, the example appends `SSTATE_MIRRORS` with the Yocto Project's shared state release mirror.
+   5. `DLDIR` – string – Set the bitbake `DL_DIR` to where downloads should be
+      stored (e.g., `"DL_DIR = 'some_path'"`).
+   6. `PACKAGE_CLASSES` – string – Set to the value of the Yocto
+      `PACKAGE_CLASSES` variable
+   7. `SDKEXTRAS` – list – Unknown.  To some end, the example appends
+      `SSTATE_MIRRORS` with the Yocto Project's shared state release mirror.
    8. `SDKMACHINE` – string – Examples are `x86_64`, `i686`, etc.
-   9. `SENDERRORS` – boolean – Executes the `upload-error-reports` script which ultimately runs the `send-error-report` script (from `poky/scripts`) to upload the results to a log server.
-   10. `SSTATEDIR` – list – Presumably a list of additions to the `SSTATE_DIR` variable where each item in the list appends or removes that variable.
-   11. `SSTATEDIR_RELEASE` – list – Presumably a list of additions to the `SSTATE_DIR` variable during release builds
-   12. `WRITECONFIG` – boolean – If enabled, the `setup-config` script is run.  **Required** if specifying `extravars`.
-   13. `extravars` – list – Contains additional BitBake varaibles that will be added to the tail of `build/conf/auto.conf`.
+   9. `SENDERRORS` – boolean – Executes the `upload-error-reports` script which
+      ultimately runs the `send-error-report` script (from `poky/scripts`) to
+      upload the results to a log server.
+   10. `SSTATEDIR` – list – Presumably a list of additions to the `SSTATE_DIR`
+       variable where each item in the list appends or removes that variable.
+   11. `SSTATEDIR_RELEASE` – list – Presumably a list of additions to the
+       `SSTATE_DIR` variable during release builds
+   12. `WRITECONFIG` – boolean – If enabled, the `setup-config` script is
+       run.  **Required** if specifying `extravars`.
+   13. `extravars` – list – Contains additional BitBake varaibles that will be
+       added to the tail of `build/conf/auto.conf`.
  2. _stepN_ -level variables:
-   1. `ADDLAYER` – list – These named layers will be added to the `bblayers.conf` file.  At the end of the step, the layers will be removed in reverse order.  This is useful if your `repo-defaults` -defined repository has `no-layer-add` set to `true`.  This will log as _stepN**a**_.
-   2. `BBTARGETS` – string – BitBake arguments passed to the bitbake, e.g., core-image-minimal.  These will be appended with -k (continue) so that all targets will be attempted rather than stopping at the first error.  This will log as _stepN**b**_.
-   3. `SANITYTARGETS` – string – BitBake targets that will be run in an emulated environment for testing.  This will log as _stepN**c**_.
-   4. `EXTRACMDS` – list – List of commands to run within the BitBake environment (e.g., wic).  This will log as _stepN**d**_.
-   5. `EXTRAPLAINCMDS` – list – List of commands to run without sourcing the oe-init-build-env script.  This will log as _stepN**d**_.
+   1. `ADDLAYER` – list – These named layers will be added to the
+      `bblayers.conf` file.  At the end of the step, the layers will be removed
+      in reverse order.  This is useful if your `repo-defaults` -defined
+      repository has `no-layer-add` set to `true`.  This will log
+      as _stepN**a**_.
+   2. `BBTARGETS` – string – BitBake arguments passed to the bitbake, e.g.,
+      core-image-minimal.  These will be appended with -k (continue) so that all
+      targets will be attempted rather than stopping at the first error.  This
+      will log as _stepN**b**_.
+   3. `SANITYTARGETS` – string – BitBake targets that will be run in an emulated
+      environment for testing.  This will log as _stepN**c**_.
+   4. `EXTRACMDS` – list – List of commands to run within the BitBake
+      environment (e.g., wic).  This will log as _stepN**d**_.
+   5. `EXTRAPLAINCMDS` – list – List of commands to run without sourcing
+      the oe-init-build-env script.  This will log as _stepN**d**_.
 
 ## Appendix A - Systemd Services