post-1.20-release: remove testing for release-1.18

[maelvls]

cert-manager 1.18 is no longer supported since the release of 1.20, so removing all the testing configuration, as per the release process:

(final release only) Create a PR on cert-manager/testing, removing any unsupported release versions from prow config.

Changes:

• Remove release-1.18 from prowgen knownBranches
• Delete release-1.18 prow job spec and associated periodics
• Remove release-1.18 branch-protection entry
• Remove release-1.18 testgrid dashboard
• Bump cert-manager helm install version to v1.20.1
• Adjust cron schedules for release-1.19 and release-1.20 periodics; a side-effect of running make prowgen

Part of:

• v1.20.0 release progress tracking cert-manager#8656

Based on:

• Remove cert-manager release-1.17 jobs and refs #1116

[Copilot]

Pull request overview

This PR updates cert-manager’s Prow job generation/config to drop testing for older cert-manager/Kubernetes versions as part of the post-v1.20 release process, including removing the release-1.18 branch from prowgen and updating generated jobs to stop targeting Kubernetes 1.31/1.32.

Changes:

• Remove the release-1.18 BranchSpec from prowgen branch definitions.
• Update generated presubmit/periodic job matrices for master, release-1.19, and release-1.20 to use Kubernetes 1.33–1.35 (and adjust crons accordingly).
• Regenerate job YAMLs reflecting the updated Kubernetes version targets.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 10 comments.

File	Description
config/prowgen/prowspecs/specs.go	Removes release-1.18 branch spec and updates Kubernetes version matrices for remaining branches.
config/jobs/cert-manager/cert-manager/master/cert-manager-master.yaml	Updates master presubmit/periodic jobs to Kubernetes 1.33–1.35 and adjusts schedules.
config/jobs/cert-manager/cert-manager/release-1.19/cert-manager-release-1.19.yaml	Updates release-1.19 presubmit/periodic jobs to Kubernetes 1.33–1.35 and adjusts schedules.
config/jobs/cert-manager/cert-manager/release-1.20/cert-manager-release-1.20.yaml	Updates release-1.20 presubmit/periodic jobs to Kubernetes 1.33–1.35 and adjusts schedules.

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[erikgb]

/lgtm

@maelvls, you can self-approve. Just in case you want to bump the cert-manager version.

[wallrj-cyberark]

I've compared this to the last two times I did this task (#1116 for 1.17, #1064 for 1.14). A few things stand out:

Outstanding fixes: The duplicate K8s version bug in otherKubernetesVersions (acknowledged in your reply to Copilot) and the v1.20.1 bump (suggested by Erik) haven't been pushed. The single commit is from March 27.

YAML reformatting noise in config.yaml: This PR reformats large sections of config.yaml — single quotes to double quotes, indentation changes throughout (branch-protection contexts, deck lenses, presets, tide queries). This is semantically equivalent YAML but makes the diff much noisier. In my #1116 and #1064, the config.yaml changes were limited to just removing the old branch's entries. Was the reformatting intentional (e.g. running a YAML formatter)? If so, splitting it into a separate commit would make the actual release-1.18 removal easier to verify.

K8s version matrix changes: My previous PRs (#1116, #1064) didn't change the K8s version matrix for remaining branches — they only removed the old branch. This PR also drops K8s 1.31/1.32 and changes the primary version for release-1.19. That's a bigger scope change; is it driven by K8s 1.31/1.32 going EOL, or something else? You mention it in the PR description, but it might be clearer as a separate PR or at least a separate commit.

Duplicate of #1168: Erik opened #1168 today doing the same 1.18 removal (without the K8s version changes or YAML reformatting). Should be closed in favour of this one.

What looks good: The core removal (specs.go, branch-protection, testgrid, job yaml deletion, cert-manager_install.sh bump) follows the same pattern as #1116.

Review conducted with assistance from Claude (Opus 4.6)

[erikgb]

Thanks @maelvls (and @wallrj)!

/lgtm
/approve

[cert-manager-prow]

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This pull-request has been approved by: erikgb

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[cert-manager-prow]

@maelvls: Updated the following 2 configmaps:

• job-config configmap in namespace default at cluster default using the following files:
  • key cert-manager-release-1.18.yaml using file ``
  • key cert-manager-release-1.19.yaml using file config/jobs/cert-manager/cert-manager/release-1.19/cert-manager-release-1.19.yaml
  • key cert-manager-release-1.20.yaml using file config/jobs/cert-manager/cert-manager/release-1.20/cert-manager-release-1.20.yaml
• config configmap in namespace default at cluster default using the following files:
  • key config.yaml using file config/config.yaml

Details

In response to this:

cert-manager 1.18 is no longer supported since the release of 1.20, so removing all the testing configuration, as per the release process:

(final release only) Create a PR on cert-manager/testing, removing any unsupported release versions from prow config.

Changes:

• Remove release-1.18 from prowgen knownBranches
• Delete release-1.18 prow job spec and associated periodics
• Remove release-1.18 branch-protection entry
• Remove release-1.18 testgrid dashboard
• Bump cert-manager helm install version to v1.20.1
• Adjust cron schedules for release-1.19 and release-1.20 periodics; a side-effect of running make prowgen

Part of:

• v1.20.0 release progress tracking cert-manager#8656

Based on:

• Remove cert-manager release-1.17 jobs and refs #1116

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