feat: add container-structure-test action kickstart

[Copilot]

Implements a production-ready GitHub Action wrapping GoogleContainerTools/container-structure-test following the devops-infra action pattern. Supports all CST CLI inputs, exports key test stats as outputs, and ships a multi-arch (amd64/arm64) Alpine-based Docker image.

Dockerfile

• Replaces Ubuntu base with alpine:3.21
• Installs bash, curl, jq via apk --no-cache
• Downloads the container-structure-test binary from GitHub Releases using TARGETARCH for multi-arch builds; binary version pinned via ARG CST_VERSION with a Renovate annotation for automatic updates

action.yml

Full input surface covering all CST test subcommand flags:

Category	Inputs
Image source	image, image_from_oci_layout, default_image_tag, ignore_ref_annotation
Config	config (space- or newline-separated paths)
Driver	driver, platform, runtime, force
Behaviour	pull, save, quiet, no_color
Reporting	output (text/json/junit), test_report, junit_suite_name, metadata
Debug	debug

Outputs: total, passed, failed, exit_code

entrypoint.sh

• Builds the CST command array from inputs; config paths split on both spaces and newlines via tr -s '[:space:]' ' '
• Two execution paths: test_report set → CST writes to file, action cats it and parses JSON; test_report unset → output captured via tee, stats parsed per format (text: grep, json: jq, junit: grep XML attributes)
• Exit code captured independently of the ERR trap so a failing test suite propagates correctly

README.md

Full API reference tables, four usage examples (basic, multi-config JSON, JUnit, TAR driver), and a test config YAML reference.

Example usage

- name: Run structure tests
  id: cst
  uses: devops-infra/container-structure-test@v1
  with:
    image: my-image:latest
    config: |
      tests/command-tests.yaml
      tests/file-tests.yaml
    output: json

- run: |
    echo "Passed ${{ steps.cst.outputs.passed }}/${{ steps.cst.outputs.total }}"

Original prompt

Using my style of https://github.com/devops-infra github actions create comprehensive github action serving https://github.com/googlecontainertools/container-structure-test. refer to docs to cover all inputs, export important outputs.
image must suport amd64 and arm64, like all my actions. use alpine as base image.

[Copilot]

Pull request overview

Adds a production-ready Docker-based GitHub Action for running Google container-structure-test against images/OCI layouts, following the devops-infra action pattern.

Changes:

• Implement CST wrapper in entrypoint.sh with full input validation, command construction, and metrics extraction as outputs.
• Switch image to Alpine and install CST binary with checksum verification for multi-arch builds.
• Add local build/smoke-test Task targets and bash unit tests for the entrypoint, plus smoke-test jobs in workflows.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
entrypoint.sh	Builds/validates CST CLI args, runs CST, parses totals/passed/failed, exports outputs
Dockerfile	Alpine-based image, installs bash/curl/jq, downloads CST per-arch + checksum verify
action.yml	Defines action inputs/outputs and points to the published Docker image
Taskfile.docker.yml	Adds local build + local run + smoke test helpers
Taskfile.cicd.yml	Adds task test + test:entrypoint runner task
tests/test_entrypoint.sh	Adds bash unit tests with a fake container-structure-test binary
tests/fixtures/local-image.yml	Container-structure-test config to validate the built action image
.github/workflows/*	Adds a post-job smoke-test stage to multiple workflows
.env.example	Adds example env vars for Docker/GitHub publishing workflows
README.md	Updates documentation for the new action (usage, inputs/outputs, local tasks)

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