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Andrew Geisslerf0343792020-11-18 10:42:21 -06001.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
Andrew Geisslerc9f78652020-09-18 14:11:35 -05002
3*******************************************
4Understanding the Yocto Project Autobuilder
5*******************************************
6
7Execution Flow within the Autobuilder
8=====================================
9
10The "a-full" and "a-quick" targets are the usual entry points into the
11Autobuilder and it makes sense to follow the process through the system
12starting there. This is best visualised from the Autobuilder Console
13view (:yocto_ab:`/typhoon/#/console`).
14
15Each item along the top of that view represents some "target build" and
16these targets are all run in parallel. The 'full' build will trigger the
17majority of them, the "quick" build will trigger some subset of them.
18The Autobuilder effectively runs whichever configuration is defined for
19each of those targets on a seperate buildbot worker. To understand the
20configuration, you need to look at the entry on ``config.json`` file
21within the ``yocto-autobuilder-helper`` repository. The targets are
22defined in the ‘overrides' section, a quick example could be qemux86-64
23which looks like::
24
25 "qemux86-64" : {
26 "MACHINE" : "qemux86-64",
27 "TEMPLATE" : "arch-qemu",
28 "step1" : {
29 "extravars" : [
30 "IMAGE_FSTYPES_append = ' wic wic.bmap'"
31 ]
32 }
33 },
34
35And to expand that, you need the "arch-qemu" entry from
36the "templates" section, which looks like::
37
38 "arch-qemu" : {
39 "BUILDINFO" : true,
40 "BUILDHISTORY" : true,
41 "step1" : {
42 "BBTARGETS" : "core-image-sato core-image-sato-dev core-image-sato-sdk core-image-minimal core-image-minimal-dev core-image-sato:do_populate_sdk",
43 "SANITYTARGETS" : "core-image-minimal:do_testimage core-image-sato:do_testimage core-image-sato-sdk:do_testimage core-image-sato:do_testsdk"
44 },
45 "step2" : {
46 "SDKMACHINE" : "x86_64",
47 "BBTARGETS" : "core-image-sato:do_populate_sdk core-image-minimal:do_populate_sdk_ext core-image-sato:do_populate_sdk_ext",
48 "SANITYTARGETS" : "core-image-sato:do_testsdk core-image-minimal:do_testsdkext core-image-sato:do_testsdkext"
49 },
50 "step3" : {
51 "BUILDHISTORY" : false,
52 "EXTRACMDS" : ["${SCRIPTSDIR}/checkvnc; DISPLAY=:1 oe-selftest ${HELPERSTMACHTARGS} -j 15"],
53 "ADDLAYER" : ["${BUILDDIR}/../meta-selftest"]
54 }
55 },
56
57Combining these two entries you can see that "qemux86-64" is a three step build where the
58``bitbake BBTARGETS`` would be run, then ``bitbake SANITYTARGETS`` for each step; all for
59``MACHINE="qemx86-64"`` but with differing SDKMACHINE settings. In step
601 an extra variable is added to the ``auto.conf`` file to enable wic
61image generation.
62
63While not every detail of this is covered here, you can see how the
64template mechanism allows quite complex configurations to be built up
65yet allows duplication and repetition to be kept to a minimum.
66
67The different build targets are designed to allow for parallelisation,
68so different machines are usually built in parallel, operations using
69the same machine and metadata are built sequentially, with the aim of
70trying to optimise build efficiency as much as possible.
71
72The ``config.json`` file is processed by the scripts in the Helper
73repository in the ``scripts`` directory. The following section details
74how this works.
75
Andrew Geisslerc9f78652020-09-18 14:11:35 -050076Autobuilder Target Execution Overview
77=====================================
78
79For each given target in a build, the Autobuilder executes several
80steps. These are configured in ``yocto-autobuilder2/builders.py`` and
81roughly consist of:
82
83#. *Run clobberdir*.
84
85 This cleans out any previous build. Old builds are left around to
86 allow easier debugging of failed builds. For additional information,
Andrew Geissler09209ee2020-12-13 08:44:15 -060087 see :ref:`test-manual/understand-autobuilder:clobberdir`.
Andrew Geisslerc9f78652020-09-18 14:11:35 -050088
89#. *Obtain yocto-autobuilder-helper*
90
91 This step clones the ``yocto-autobuilder-helper`` git repository.
92 This is necessary to prevent the requirement to maintain all the
93 release or project-specific code within Buildbot. The branch chosen
94 matches the release being built so we can support older releases and
95 still make changes in newer ones.
96
97#. *Write layerinfo.json*
98
99 This transfers data in the Buildbot UI when the build was configured
100 to the Helper.
101
102#. *Call scripts/shared-repo-unpack*
103
104 This is a call into the Helper scripts to set up a checkout of all
105 the pieces this build might need. It might clone the BitBake
106 repository and the OpenEmbedded-Core repository. It may clone the
107 Poky repository, as well as additional layers. It will use the data
108 from the ``layerinfo.json`` file to help understand the
109 configuration. It will also use a local cache of repositories to
110 speed up the clone checkouts. For additional information, see
Andrew Geissler09209ee2020-12-13 08:44:15 -0600111 :ref:`test-manual/understand-autobuilder:Autobuilder Clone Cache`.
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500112
113 This step has two possible modes of operation. If the build is part
114 of a parent build, its possible that all the repositories needed may
115 already be available, ready in a pre-prepared directory. An "a-quick"
116 or "a-full" build would prepare this before starting the other
117 sub-target builds. This is done for two reasons:
118
119 - the upstream may change during a build, for example, from a forced
120 push and this ensures we have matching content for the whole build
121
122 - if 15 Workers all tried to pull the same data from the same repos,
123 we can hit resource limits on upstream servers as they can think
124 they are under some kind of network attack
125
126 This pre-prepared directory is shared among the Workers over NFS. If
127 the build is an individual build and there is no "shared" directory
128 available, it would clone from the cache and the upstreams as
129 necessary. This is considered the fallback mode.
130
131#. *Call scripts/run-config*
132
133 This is another call into the Helper scripts where its expected that
134 the main functionality of this target will be executed.
135
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500136Autobuilder Technology
137======================
138
139The Autobuilder has Yocto Project-specific functionality to allow builds
140to operate with increased efficiency and speed.
141
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500142clobberdir
143----------
144
145When deleting files, the Autobuilder uses ``clobberdir``, which is a
146special script that moves files to a special location, rather than
147deleting them. Files in this location are deleted by an ``rm`` command,
148which is run under ``ionice -c 3``. For example, the deletion only
149happens when there is idle IO capacity on the Worker. The Autobuilder
Andrew Geissler09209ee2020-12-13 08:44:15 -0600150Worker Janitor runs this deletion. See :ref:`test-manual/understand-autobuilder:Autobuilder Worker Janitor`.
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500151
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500152Autobuilder Clone Cache
153-----------------------
154
155Cloning repositories from scratch each time they are required was slow
156on the Autobuilder. We therefore have a stash of commonly used
157repositories pre-cloned on the Workers. Data is fetched from these
158during clones first, then "topped up" with later revisions from any
Andrew Geissler4c19ea12020-10-27 13:52:24 -0500159upstream when necessary. The cache is maintained by the Autobuilder
Andrew Geissler09209ee2020-12-13 08:44:15 -0600160Worker Janitor. See :ref:`test-manual/understand-autobuilder:Autobuilder Worker Janitor`.
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500161
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500162Autobuilder Worker Janitor
163--------------------------
164
165This is a process running on each Worker that performs two basic
Andrew Geissler09209ee2020-12-13 08:44:15 -0600166operations, including background file deletion at IO idle (see :ref:`test-manual/understand-autobuilder:Autobuilder Target Execution Overview`: Run clobberdir) and
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500167maintainenance of a cache of cloned repositories to improve the speed
168the system can checkout repositories.
169
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500170Shared DL_DIR
171-------------
172
173The Workers are all connected over NFS which allows DL_DIR to be shared
174between them. This reduces network accesses from the system and allows
175the build to be sped up. Usage of the directory within the build system
176is designed to be able to be shared over NFS.
177
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500178Shared SSTATE_DIR
179-----------------
180
181The Workers are all connected over NFS which allows the ``sstate``
182directory to be shared between them. This means once a Worker has built
183an artifact, all the others can benefit from it. Usage of the directory
184within the directory is designed for sharing over NFS.
185
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500186Resulttool
187----------
188
189All of the different tests run as part of the build generate output into
190``testresults.json`` files. This allows us to determine which tests ran
191in a given build and their status. Additional information, such as
192failure logs or the time taken to run the tests, may also be included.
193
194Resulttool is part of OpenEmbedded-Core and is used to manipulate these
195json results files. It has the ability to merge files together, display
196reports of the test results and compare different result files.
197
Andrew Geissler09209ee2020-12-13 08:44:15 -0600198For details, see :yocto_wiki:`/Resulttool`.
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500199
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500200run-config Target Execution
201===========================
202
203The ``scripts/run-config`` execution is where most of the work within
204the Autobuilder happens. It runs through a number of steps; the first
205are general setup steps that are run once and include:
206
207#. Set up any ``buildtools-tarball`` if configured.
208
209#. Call "buildhistory-init" if buildhistory is configured.
210
211For each step that is configured in ``config.json``, it will perform the
212following:
213
214#. Add any layers that are specified using the
215 ``bitbake-layers add-layer`` command (logging as stepXa)
216
217#. Call the ``scripts/setup-config`` script to generate the necessary
218 ``auto.conf`` configuration file for the build
219
220#. Run the ``bitbake BBTARGETS`` command (logging as stepXb)
221
222#. Run the ``bitbake SANITYTARGETS`` command (logging as stepXc)
223
224#. Run the ``EXTRACMDS`` command, which are run within the BitBake build
225 environment (logging as stepXd)
226
227#. Run the ``EXTRAPLAINCMDS`` command(s), which are run outside the
228 BitBake build environment (logging as stepXd)
229
230#. Remove any layers added in step
231 1 using the ``bitbake-layers remove-layer`` command (logging as stepXa)
232
233Once the execution steps above complete, ``run-config`` executes a set
234of post-build steps, including:
235
236#. Call ``scripts/publish-artifacts`` to collect any output which is to
237 be saved from the build.
238
239#. Call ``scripts/collect-results`` to collect any test results to be
240 saved from the build.
241
242#. Call ``scripts/upload-error-reports`` to send any error reports
243 generated to the remote server.
244
245#. Cleanup the build directory using
Andrew Geissler09209ee2020-12-13 08:44:15 -0600246 :ref:`test-manual/understand-autobuilder:clobberdir` if the build was successful,
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500247 else rename it to "build-renamed" for potential future debugging.
248
Andrew Geisslerc9f78652020-09-18 14:11:35 -0500249Deploying Yocto Autobuilder
250===========================
251
252The most up to date information about how to setup and deploy your own
253Autbuilder can be found in README.md in the ``yocto-autobuilder2``
254repository.
255
256We hope that people can use the ``yocto-autobuilder2`` code directly but
257it is inevitable that users will end up needing to heavily customise the
258``yocto-autobuilder-helper`` repository, particularly the
259``config.json`` file as they will want to define their own test matrix.
260
261The Autobuilder supports wo customization options:
262
263- variable substitution
264
265- overlaying configuration files
266
267The standard ``config.json`` minimally attempts to allow substitution of
268the paths. The Helper script repository includes a
269``local-example.json`` file to show how you could override these from a
270separate configuration file. Pass the following into the environment of
271the Autobuilder::
272
273 $ ABHELPER_JSON="config.json local-example.json"
274
275As another example, you could also pass the following into the
276environment::
277
278 $ ABHELPER_JSON="config.json /some/location/local.json"
279
280One issue users often run into is validation of the ``config.json`` files. A
281tip for minimizing issues from invalid json files is to use a Git
282``pre-commit-hook.sh`` script to verify the JSON file before committing
283it. Create a symbolic link as follows::
284
285 $ ln -s ../../scripts/pre-commit-hook.sh .git/hooks/pre-commit