ci/docs: add act local CI workflow support to all build pipelines

[ibtisam-iq]

Summary

Introduces act-aware guards to all build-*.yml workflows so the full CI pipeline can be run locally without GHCR credentials, and updates all corresponding READMEs with a Local CI Workflow Testing with act section.

Workflow Changes (6 files)

Applied the same 4-change pattern to all remaining build-*.yml files (already present in build-dev-machine-rootfs.yml):

Step	Change
Log in to GHCR	Added if: ${{ !env.ACT }}
Extract metadata	Added if: ${{ !env.ACT }}
Build and push	load, push, and tags made act-aware
Image digest	Added if: ${{ !env.ACT }}

Files updated:

• .github/workflows/build-dev-cicd-rootfs.yml
• .github/workflows/build-guacamole-rootfs.yml
• .github/workflows/build-jenkins-rootfs.yml
• .github/workflows/build-nexus-rootfs.yml
• .github/workflows/build-sonarqube-rootfs.yml
• .github/workflows/build-ubuntu-rootfs.yml

README Changes (5 files)

Added Local CI Workflow Testing with act section between Local Build and Published Image in each README. Also added the GitHub Actions publish context line to Published Image sections where missing.

Files updated:

• iximiuz/rootfs/jenkins/README.md
• iximiuz/rootfs/nexus/README.md
• iximiuz/rootfs/sonarqube/README.md
• iximiuz/rootfs/ubuntu/README.md
• iximiuz/rootfs/guacamole/README.md (also added missing Published Image section)

Testing

Verified locally on build-dev-machine-rootfs.yml:

act push \
  -W .github/workflows/build-dev-machine-rootfs.yml \
  --no-cache-server

Image builds and loads into local Docker daemon. No secrets required.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Keep act's cache server enabled

Remove --no-cache-server from this command and the equivalent commands in the other new README sections. The workflows always configure cache-from/cache-to: type=gha; Docker documents that this backend requires a cache URL and runtime token, while act defines this flag as disabling its local cache server (Docker cache authentication, act flag definition). With no GitHub runtime credentials supplied, the documented invocation leaves BuildKit without a usable cache endpoint and the build fails rather than producing the promised local image.

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[chatgpt-codex-connector]

Restrict local loads to one platform

When act sets ACT, this enables load while the build still targets both linux/amd64 and linux/arm64; the Ubuntu workflow has the same combination. Docker documents --load as loading a single-platform result and notes that the default Engine image store cannot load multi-platform images (Buildx --load documentation). Consequently, the documented local run fails on standalone/classic Docker installations; select the host platform for act runs or use a multi-platform-capable output/store.

Useful? React with 👍 / 👎.