Improve upgrade_tasks CI coverage with the standalone installer

https://blueprints.launchpad.net/tripleo/+spec/upgrades-ci-standalone

The main goal of this work is to improve coverage of service upgrade_tasks in tripleo ci upgrades jobs, by making use of the Standalone_installer_work. Using a standalone node as a single node ‘overcloud’ allows us to exercise both controlplane and dataplane services in the same job and within current resources of 2 nodes and 3 hours. Furthermore and once proven successful this approach can be extended to include even single service upgrades testing to vastly improve on the current coverage with respect to all the service upgrade_tasks defined in the tripleo-heat-templates (which is currently minimal).

Traditionally upgrades jobs have been restricted by resource constraints (nodes and walltime). For example the undercloud and overcloud upgrade are never exercised in the same job, that is an overcloud upgrade job uses an undercloud that is already on the target version (so called mixed version deployment).

A further example is that upgrades jobs have typically exercised either controlplane or dataplane upgrades (i.e. controllers only, or compute only) and never both in the same job, again because constraints. The currently running tripleo-ci-centos-7-scenario000-multinode-oooq-container-upgrades job for example has 2 nodes, where one is undercloud and one is overcloud controller. The workflow is being exercised, but controller only. Furthermore, whilst the current_upgrade_ci_scenario is only exercising a small subset of the controlplane services, it is still running at well over 140 minutes. So there is also very little coverage with respect to the upgrades_tasks across the many different service templates defined in the tripleo-heat-templates.

Thus the main goal of this work is to use the standalone installer to define ci jobs that test the service upgrade_tasks for a one node ‘overcloud’ with both controlplane and dataplane services. This approach is composable as the services in the stand-alone are fully configurable. Thus after the first iteration of compute/control, we can also define per-service ci jobs and over time hopefully reach coverage for all the services deployable by TripleO.

Finally it is worth emphasising that the jobs defined as part of this work will not be testing the TripleO upgrades workflow at all. Rather this is about testing the service upgrades_tasks specifically. The workflow instead will be tested using the existing ci upgrades job (tripleo-ci-centos-7-scenario000-multinode-oooq-container-upgrades) subject to modifications to strip it down to a bare minimum required (e.g. hardly any services). There are more pointers to this from the discussion at the TripleO-Stein-PTG but ultimately we will have two approximations of the upgrade tested in ci - the service upgrade_tasks as described by this spec, and the workflow itself using a different ci job or modifying the existing one.

Problem Description

As described above we have not been able to have control and dataplane services upgraded as part of the same tripleo ci job. Such a job would have to be 3 nodes for starters (undercloud,controller,compute).

A full upgrade workflow would need the following steps:

  • deploy undercloud, deploy overcloud
  • upgrade undercloud
  • upgrade prepare the overcloud (heat stack update generates playbooks)
  • upgrade run controllers (ansible-playbook via mistral workflow)
  • upgrade run computes/storage etc (repeat until all done)
  • upgrade converge (heat stack update).

The problem being solved here is that we can run only some approximation of the upgrade workflow, specifically the upgrade_tasks, for a composed set of services and do so within the ci timeout. The first iteration will focus on modelling a one node ‘overcloud’ with both controller and compute services. If we prove this to be successful we can also consider single-service upgrades jobs (a job for testing just nova,or glance upgrade tasks for example) for each of services that we want to test the upgrades tasks. Thus even though this is just an approximation of the upgrade (upgrade_tasks only, not the full workflow), it can hopefully allow for a wider coverage of services in ci than is presently possible.

One of the early considerations when writing this spec was how we could enforce a separation of services with respect to the upgrade workflow. That is, enforce that controlplane upgrade_tasks and deploy_steps are executed first and then dataplane compute/storage/ceph as is usually the case with the upgrade workflow. However review comments on this spec as well as PTG discussions around it, in particular that this is just some approximation of the upgrade (service upgrade tasks, not workflow) in which case it may not be necessary to artificially induce this control/dataplane separation here. This may need to be revisited once implementation begins.

Another core challenge that needs solving is how to collect ansible playbooks from the tripleo-heat-templates since we don’t have a traditional undercloud heat stack to query. This will hopefully be a lesser challenge assuming we can re-use the transient heat process used to deploy the standalone node. Futhermore discussion around this point at the TripleO-Stein-PTG has informed us of a way to keep the heat stack after deployment with keep-running so we could just re-use it as we would with a ‘normal’ deployment.

Proposed Change

Overview

We will need to define a new ci job in the tripleo-ci_zuul.d_standalone-jobs (preferably following the currently ongoing ci_v3_migrations define this as v3 job).

For the generation of the playbooks themselves we hope to use the ephemeral heat service that is used to deploy the stand-alone node, or use the keep-running option to the stand-alone deployment to keep the stack around after deployment.

As described in the problem statement we hope to avoid the task of having to distinguish between control and dataplane services in order to enforce that controlplane services are upgraded first.

Alternatives

Add another node and have 3 node upgrades jobs together with increasing the walltime but this is not scalable in the long term assuming limited resources!

Security Impact

None

Other End User Impact

None

Performance Impact

None

Other Deployer Impact

More coverage of services should mean less breakage because of upgrades incompatible things being merged.

Developer Impact

Might be easier for developers too who may have limited access to resources to take the reproducer script with the standalone jobs and get a dev env for testing upgrades.

Implementation

Assignee(s)

tripleo-ci and upgrades squads

Work Items

First we must solve the problem of generating the ansible playbooks, that will include all the latest configuration from the tripleo-heat-templates at the time of upgrade (including all upgrade_tasks etc) when there is no undercloud Heat stack to query.

We might consider some non-heat solution by parsing the tripleo-heat-templates but I don’t think that is a feasible solution (re-inventing wheels). There is ongoing work to transfer tasks to roles which is promising and that is another area to explore.

One obvious mechanism to explore given the current tools is to re-use the same ephemeral heat process that the stand-alone uses in deploying the overcloud, but setting the usual ‘upgrade-init’ environment files for a short stack ‘update’. This is not tested at all yet so needs to be investigated further. As identified earlier there is now in fact a keep-running option to the tripleoclient that will keep this heat process around

For the first iteration of this work we will aim to use the minimum possible combination of services to implement a ‘compute’/’control’ overcloud. That is, using the existing services from the current current_upgrade_ci_scenario with the addition of nova-compute and any dependencies.

Finally a third major consideration is how to execute this service upgrade, that is how to invoke the playbook generation and then run the resulting playbooks (it probably doesn’t need to converge if we are just interested in the upgrades tasks). One consideration might be to re-use the existing python-tripleoclient “openstack overcloud upgrade” prepare and run sub-commands. However the first and currently favored approach will be to use the existing stand-alone client commands (tripleo_upgrade tripleo_deploy). So one work item is to try these and discover any modifications we might need to make them work for us.

Items:
  • Work out/confirm generation the playbooks for the standalone upgrade tasks.
  • Work out any needed changes in the client/tools to execute the ansible playbooks
  • Define new ci job in the tripleo-ci_zuul.d_standalone-jobs with control and compute services, that will exercise upgrade_tasks, deployment_tasks and post_upgrade_tasks playbooks.

Once this first iteration is complete we can then consider defining multiple jobs for small subsets of services, or even for single services.

Dependencies

This obviously depends on stand-alone installer

Testing

There will be at least one new job defined here

Documentation Impact

None

References