ci(docker): use zstd compression for release images

[SantiagoDePolonia]

Summary

• Enable zstd compression for release Docker image exports
• Use compression level 3 and force recompression for release layers

Validation

• pre-commit checks from git commit passed

Summary by CodeRabbit

• Chores
  • Optimized Docker image layer compression in the release workflow to improve build efficiency.

[coderabbitai]

📝 Walkthrough

Walkthrough

The Docker build-and-push step in the GitHub Actions release workflow now includes Zstd compression (level 3) and force-compression settings in the Buildx outputs configuration, replacing the previous digest-only pushing approach.

Changes

Cohort / File(s)	Summary
Docker Build Configuration .github/workflows/release.yml	Modified Buildx outputs configuration to add Zstd compression (level 3) and enable force-compression=true for Docker image layer compression during release builds.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

• fix(docker): stamp release image metadata #224: Modifies the same GitHub Actions release workflow's docker/build-push-action invocation with additional build arguments and metadata configuration.
• ci(release): harden release publishing #273: Also modifies release.yml's Docker Buildx publish configuration, restructuring multi-architecture build and promotion logic.

Poem

🐰 A rabbit hops with joy so bright,
Compression magic, done just right!
Zstd flows where digests once lived,
Smaller images, the gift it's give! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: enabling zstd compression for Docker release images, which aligns with the primary modification in the workflow configuration.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ci/docker-zstd-level-3

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[greptile-apps]

Greptile Summary

This PR adds zstd compression (compression=zstd,compression-level=3,force-compression=true) to the Docker image export step in the release workflow, enabling more efficient layer storage and transfer for release images pushed to Docker Hub.

Confidence Score: 5/5

This PR is safe to merge — the change is a single-line CI tweak with no logic risk.

The only change is appending three well-documented Docker Buildx output options (compression, compression-level, force-compression) to an existing outputs string. All options are valid for the type=image exporter, Docker Hub supports zstd-compressed OCI layers, and the downstream imagetools create promotion step is unaffected. No P0/P1 findings exist.

No files require special attention.

Important Files Changed

Filename	Overview
.github/workflows/release.yml	Adds zstd compression options to the docker/build-push-action outputs parameter; change is syntactically correct and well-scoped.

Sequence Diagram

sequenceDiagram
    participant GHA as GitHub Actions
    participant Buildx as Docker Buildx
    participant DH as Docker Hub

    GHA->>Buildx: Build multi-platform image (amd64, arm64, arm/v7)
    Note over Buildx: compression=zstd<br/>compression-level=3<br/>force-compression=true
    Buildx->>DH: Push layer blobs (zstd-compressed) by digest
    DH-->>Buildx: Digest per platform
    Buildx-->>GHA: outputs.digest

    GHA->>Buildx: imagetools create (docker-promote)
    Note over Buildx: Assemble multi-arch manifest<br/>pointing to existing digests
    Buildx->>DH: Push manifest (semver + latest tags)
    DH-->>GHA: Tagged release published

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_{Reviews (1): Last reviewed commit: "ci(docker): use zstd compression for rel..." | Re-trigger Greptile}

[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

.github/workflows/release.yml (1)

17-17: 🧹 Nitpick | 🔵 Trivial

Stale step name.

The job name still says "Build and push Docker image by digest" which is accurate, but worth noting this step now also dictates the on-wire compression for every published tag (since docker-promote uses imagetools create which copies blobs as-is). Consider updating the job description/comment to mention zstd so future readers understand why pulls behave differently across runtimes.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In @.github/workflows/release.yml at line 17, Update the job name/comment "Build
and push Docker image by digest" to reflect that it now also dictates on-wire
compression (zstd) for published tags; specifically, change the visible job name
or add a clarifying comment in the workflow so it mentions zstd/on-wire
compression and that docker-promote uses `imagetools create` which copies blobs
as-is, so pulls may differ across runtimes.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Outside diff comments:
In @.github/workflows/release.yml:
- Line 17: Update the job name/comment "Build and push Docker image by digest"
to reflect that it now also dictates on-wire compression (zstd) for published
tags; specifically, change the visible job name or add a clarifying comment in
the workflow so it mentions zstd/on-wire compression and that docker-promote
uses `imagetools create` which copies blobs as-is, so pulls may differ across
runtimes.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 98789765-86c3-4470-8c4c-da0c9146330a

📥 Commits

Reviewing files that changed from the base of the PR and between ca1be02 and a3d15a2.

📒 Files selected for processing (1)

• .github/workflows/release.yml

[codecov-commenter]

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Codecov Report

✅ All modified and coverable lines are covered by tests.

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