TripleO CI Promotions¶
This section introduces the concept of promotions in TripleO. In short, a promotion happens when we can certify the latest version of all packages required for a TripleO deployment of OpenStack as being in a good state and without regressions.
The certification consists of running Zuul CI jobs with the latest packages built from source for TripleO code (list of TripleO repos at 1) and the latest packages built from source for non-tripleo code. If the tests are successful, then the result is certified as current-tripleo, ready to be consumed by the TripleO CI check and gate jobs (see 2 for more information about check and gate).
This process is continuous as new code is merged into the various repos. Every time we get a successful completion of the promotion CI jobs, the tested content is ‘promoted’ to be the new current-tripleo, hence the name this workflow is known by. At a given time, the latest current-tripleo is the baseline by which we test all new code submissions to the TripleO project.
TripleO vs non-tripleo repos¶
All proposed code submissions across the various tripleo repos are gated by the TripleO community which owns and manages the zuul check and gate jobs for those repos.
However, we cannot gate changes to anything outside TripleO, including all the OpenStack projects used by TripleO as well as any dependencies such as Open vSwitch or Pacemaker.
Even though we cannot gate on those external repos, the promotion process allows us to test our TripleO code with their latest versions. If there are regressions or any other bugs (and assuming ideal test coverage) the promotion jobs will fail accordingly allowing the TripleO CI team to investigate and file launchpad bugs so the issue(s) can be addressed.
RDO DLRN & Promotion Criteria¶
TripleO CI jobs consume packages built by the RDO DLRN service (‘delorean’) so we first introduce it here. An overview is given on the RDO project site at 3.
In short, RDO DLRN builds RPMs from source and publishes the resulting packages and repos. Each build or repo is identifiable using a unique build ID.
RDO DLRN assigns named tags to particular build IDs. You can see all of these named tags by browsing at the RDO DLRN package root, for example for Centos8 master branch at 4. Of particular importance to the TripleO promotion workflow are:
The list of tags in the order given above gives the logical progression through the TripleO promotion workflow.
The build ID referenced by each of those named tags is constantly updated as new content is ‘promoted’ to become the new named tag.
A general pattern in DLRN is that current is applied to the very latest build, that is, the latest commits to a particular repo. A new current build is generated periodically (e.g. every half hour). The consistent tag represents the latest version of packages where there were no errors encountered during the build for any of those (i.e. all packages were built successfully). The consistent build is what TripleO consumes as the entry point to the TripleO promotion workflow.
One last point to be made about RDO DLRN is that after the TripleO promotion CI jobs are executed against a particular DLRN build ID, the results are reported back to DLRN. For example, you can query using the build ID at 5 to get the list of jobs that were executed against that specific content, together with the results for each.
The list of jobs that are required to pass before we can promote a particular build is known as the ‘promotion criteria’. In order to promote, TripleO queries the DLRN API to get the results for a particular build and compares the passing jobs to the promotion criteria, before promoting or rejecting that content accordingly. You can find the master centos8 promotion criteria at 6 for example.
The TripleO Promotion Pipelines¶
A pipeline refers to a series of Zuul CI jobs and what we refer to as the TripleO promotion workflow is actually a number of interconnected pipelines. At the highest level conceptually these are grouped into either Component or Integration pipelines. The output of the Component pipeline serves as input to the Integration pipeline.
A Component is a conceptual grouping of packages related by functional area (with respect to an OpenStack deployment). This grouping is enforced in practice by the RDO DLRN server and the current list of all components can be found at 7. For example, you can expect to find the ‘openstack-nova-‘ packages within the Compute component.
The Component pipeline actually consists of a number of individual pipelines, one for each of the components. The starting point for each of these is the latest consistent build of the component packages and we will go into more detail about the flow inside the component pipelines in the following section.
A successful run of the jobs for the given component allows us to certify that content as being the new promoted-components, ready to be used as input to the Integration pipeline. The Integration pipeline qualifies the result of the components tested together and when that is successful we can promote to a new current-tripleo. This is shown conceptually for a subset of components here:
In the diagram above, you can see the component pipeline at the top with the compute, cinder and security components. This feeds into the integration pipeline in the bottom half of the diagram where promoted-components will be tested together and if successful produce the new current-tripleo.
The Component Promotion Pipeline¶
As noted above, the “Component pipeline” is actually a series of individual pipelines, one for each component. While these all operate and promote in the same way, they do so independently of each other. So the latest compute/promoted-components may be much newer than the latest security/promoted-components, if the latter is failing to promote for example. The following flowchart shows the progression of the RDO DLRN tags through a single component pipeline while in practice this flow is repeated in parallel per component.
As illustrated above, the entry point to the component pipelines is the latest consistent build from RDO DLRN. Once a day a periodic job tags the latest consistent build as component-ci-testing. For example you can see the history for the baremetal component job at 8 descriptively named periodic-tripleo-centos-8-master-component-baremetal-promote-consistent-to-component-ci-testing.
After this job has completed the content marked as component-ci-testing becomes the new candidate for promotion to be passed through the component CI jobs. The component-ci-testing repo content is tested with the latest current-tripleo repos of everything else. Remember that at a given time current-tripleo is the known good baseline by which we test all new content and the same applies to new content tested in the component pipelines.
As an example of the component CI jobs, you can see the history for the baremetal component standalone job at 9. If you navigate to the logs/undercloud/etc/yum.repos.d/ directory for one of those job runs you will see (at least) the following repos:
delorean.repo - which provides the latest current-tripleo content
baremetal-component.repo - which provides the ‘component-ci-testing’ content that we are trying to promote.
You may notice that the trick allowing the baremetal-component.repo to have precedence for the packages it provides is to set the repo priority accordingly (1 for the component and 20 for delorean.repo).
Another periodic job checks the result of the component-ci-testing job runs and if the component promotion criteria is satisfied the candidate content is promoted and tagged as the new promoted-components. You can find the promotion criteria for Centos8 master components at 10.
As an example the history for the zuul job that handles promotion to promoted-components for the cinder component can be found at 11
You can explore the latest content tagged as promoted-components for the compute component at 12. All the component promoted-components are aggregated into one repo that can be found at 13 and looks like the following:
Every time a component promotes a new component/promoted-components the aggregated promoted-components delorean.repo on the RDO DLRN server is updated with the new content.
This promoted-components repo is used as the starting point for the TripleO Integration promotion pipeline.
The Integration Promotion Pipeline¶
The Integration pipeline as the name suggests is the integration point where we test new content from all components together. The consolidated promoted-components delorean.repo produced by the component pipeline is tested with a series of CI jobs. If the jobs listed in the promotion criteria pass, we promote that content and tag it as current-tripleo.
As can be seen in the flowchart above, the promoted-components content is periodically promoted (pinned) to tripleo-ci-testing, which becomes the new promotion candidate to be tested. You can find the build history for the job that promotes to tripleo-ci-testing for Centos 8 master, descriptively named periodic-tripleo-centos-8-master-promote-promoted-components-to-tripleo-ci-testing, at 14.
First the tripleo-ci-testing content is used to build containers and overcloud deployment images and these are pushed to RDO cloud to be used by the rest of the jobs in the integration pipeline.
The periodic promotion jobs are then executed with the results being reported back to DLRN. If the right jobs pass according to the promotion criteria then the tripleo-ci-testing content is promoted and tagged to become the new current-tripleo.
An important distinction in the integration pipeline compared to the promotion pipeline is in the final promotion of content. In the component pipeline the promoted-components content is tagged by a periodic Zuul job as described above. For the Integration pipeline however, the promotion to current-tripleo happens with the use of a dedicated service. This service is known to the tripleo-ci squad by a few names including ‘the promotion server’, ‘the promoter server’ and ‘the promoter’.
In short the promoter periodically queries delorean for the results of the last few tripleo-ci-testing runs. It compares the results to the promotion criteria and if successful it re-tags the container and overcloud deployment images as current-tripleo and pushes back to RDO cloud (as well as to the quay.io and docker registries). It also talks to the DLRN server and retags the successful tripleo-ci-testing repo as the new current-tripleo. You can read more about the promoter with links to the code at 15.