Remove cflinuxfs3 stack from CI infrastructure

[ivanovac]

Remove cflinuxfs3 stack from CI infrastructure

Motivation

The cflinuxfs3 stack (Ubuntu 18.04 based) has been superseded by cflinuxfs4 (Ubuntu 22.04). The cf-deployment project now ships exclusively with cflinuxfs4, and all buildpack pipelines have migrated to cflinuxfs4. This PR completes the cleanup by removing all cflinuxfs3-specific code and configurations from the buildpacks-ci repository.

Changes

Configuration Updates

pipelines/cf-release/cf-release-config.yml

• Changed default_stacks from ['cflinuxfs3'] to ['cflinuxfs4']
• Impact: All cf-release pipeline builds now use cflinuxfs4 as the default stack

pipelines/dependency-builds/config.yml

• Removed skip_lines_cflinuxfs3: [ '22.X.X' ] for Node.js dependency
• Rationale: This configuration was only needed when cflinuxfs3 was still supported; Node 22 requires newer dependencies only available in cflinuxfs4

Task Updates

tasks/update-libbuildpack/run.sh

• Changed default CF_STACK from cflinuxfs3 to cflinuxfs4
• Impact: Unit tests now run against cflinuxfs4 by default

tasks/update-buildpack-dependency/run.rb

• Removed PHP cflinuxfs3.json special case handling (lines 55-56)
• Removed cflinuxfs3 stack name normalization logic (line 78)
• Removed skip_lines_cflinuxfs3 version filtering (lines 92-94)
• Rationale: These were edge cases for cflinuxfs3-specific dependency builds

tasks/repackage-dependency/task.yml

• Updated Docker image from cloudfoundry/cflinuxfs3 to cloudfoundry/cflinuxfs4
• Impact: Metadata repackaging tasks now run in cflinuxfs4 container

tasks/cf/redeploy/task.sh

• Removed ADD_CFLINUXFS3_STACK conditional block (lines 84-93)
• Rationale: This code uploaded cflinuxfs3 BOSH release and applied cflinuxfs3 operations files; no longer needed as cf-deployment includes only cflinuxfs4

tasks/cf/redeploy/task.yml

• Removed ADD_CFLINUXFS3_STACK parameter declaration
• Clean up unused parameter definition

tasks/generate-rootfs-release-notes/run.rb

• Removed cflinuxfs3 CVE feed URL
• Impact: Release notes generation now only processes cflinuxfs4 CVEs

lib/rootfs-cve-feed.rb

• Removed cflinuxfs3 stack handling from CVE feed processing
• Impact: CVE tracking now only applies to cflinuxfs4

Deleted Folders

tasks/build-binary-new/

• Entire folder deleted (15 files, ~1600 lines)
• Rationale: This task used the cloudfoundry/cflinuxfs3 Docker image to build binaries. Not referenced in any active pipeline. Superseded by tasks/build-binary-new-cflinuxfs4/

tasks/check-for-new-rootfs-cves/

• Entire folder deleted (2 files)
• Rationale: Hardcoded to check cflinuxfs3 CVEs from Ubuntu 18.04. Not referenced in any pipeline. Superseded by tasks/check-for-new-rootfs-cves-cflinuxfs4/

Deleted Operations Files

tasks/cf/redeploy/operations/add-cflinuxfs3-to-current.yml

• BOSH operations file that added cflinuxfs3 stack alongside cflinuxfs4
• No longer needed as environments only use cflinuxfs4

tasks/cf/redeploy/operations/cflinuxfs3-rootfs-certs.yml

• Configured trusted certificates for cflinuxfs3 rootfs
• No longer needed

deployments/operations/cflinuxfs3.yml

• Previously deleted deployment configuration

deployments/operations/cflinuxfs3-rootfs-certs-as-list.yml

• Previously deleted certificate configuration

deployments/operations/substitute-with-cflinuxfs4-trusted-certs.yml

• Migration operations file that removed cflinuxfs3 and added cflinuxfs4
• Rationale: Obsolete since cf-deployment now ships with only cflinuxfs4 by default (verified in cf-deployment v54.2.0)

Deleted Docker Assets

.github/workflows/build-cflinuxfs3-dev-image.yml

• GitHub Actions workflow that built cflinuxfs3-dev Docker image
• Rationale: References deleted dockerfiles/cflinuxfs3-dev.Dockerfile; no equivalent cflinuxfs4-dev workflow exists

dockerfiles/cflinuxfs3-dev.Dockerfile

• Previously deleted in earlier commit

Testing

• All deleted tasks verified as unused via pipeline grep searches
• All buildpack values files already configured for cflinuxfs4 only
• cf-deployment repository confirmed to ship with cflinuxfs4 as default stack

Related Work

This PR builds on previous cflinuxfs3 removal work and completes the cleanup across:

• CI pipeline configurations
• Task definitions and scripts
• BOSH operations files
• Docker image builds
• CVE tracking infrastructure