fix(docker): bump tzdata Alpine pin from 2026a-r0 to 2026b-r0

[nayrosk]

Description

Bump Alpine tzdata dependency from 2026a-r0 to 2026b-r0 in Dockerfile. This fixes timezone database expiry issue reported in issue #84, ensuring correctness of time-based operations in containerized migrations.

Spec: N/A (container dependency pin)

Type of change

• fix

Changes

• Dockerfile: tzdata pin 2026a-r0 → 2026b-r0

Testing

• Dockerfile builds without error
• hadolint passes
• Manual image inspection confirms tzdata version in final layer

Step 14 Hypothesis Check

Root assumption: Alpine 2026b-r0 tzdata is available on Docker Hub for linux/amd64, linux/arm64, darwin/amd64, darwin/arm64 at build time and provides correct timezone data beyond April 2026 expiry window.

Pre-merge validation: Dockerfile syntax valid (hadolint clean), build matrix passes for all target architectures. Multi-arch build attestation succeeds.

Post-merge validation plan:

• Release build completes for all architectures (linux/amd64, linux/arm64)
• Container startup test: verify tzdata is installed + correct version in final image
• Timezone API sanity check: test call to time.Now() + timezone lookup for dates post-April 2026 in smoke test
• Confirm no timezone-related errors in logs during container runtime (if applicable)

Rollback contingency: If 2026b-r0 becomes unavailable or fails on a specific architecture, revert to 2026c-r0 (or latest stable). This pin is backwards-compatible; no data migration or config change required. Simple git revert + rebuild.

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Closes #84

Summary by CodeRabbit

• Chores
  • Updated timezone database package.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: ab1abb59-0984-47a3-b3e3-7d765187e987

📥 Commits

Reviewing files that changed from the base of the PR and between 6637e9f and 1dccf9a.

📒 Files selected for processing (1)

• Dockerfile

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📝 Walkthrough

Walkthrough

The Dockerfile's Alpine package pin for tzdata is updated from 2026a-r0 to 2026b-r0 in both the multi-stage builder and production runtime stages. The change resolves a package availability issue where Alpine 3.22 main repository no longer ships the older version.

Changes

Alpine tzdata Package Pinning

Layer / File(s)	Summary
Update tzdata version across build stages Dockerfile	The tzdata package version is updated from 2026a-r0 to 2026b-r0 in the builder stage (line 16) and production stage (line 57), addressing the unavailability of the older version in Alpine 3.22.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Possibly related PRs

• Dockermint/pebblify#43: Both PRs modify the Dockerfile's Alpine package pins for the same package (tzdata) across build and runtime stages—this main PR updates that pin from 2026a-r0 to 2026b-r0, directly continuing the retrieved PR's package-pinning changes.

Poem

🐰 A hop through Alpine's time,
Tzdata ticks in perfect rhyme—
From a to b, the clocks now run,
Docker builds when the fix is done!

🚥 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 PR title accurately describes the main change: bumping the Alpine tzdata package pin from 2026a-r0 to 2026b-r0 in the Dockerfile.
Linked Issues check	✅ Passed	All acceptance criteria from issue #84 are met: Dockerfile lines 16 and 57 pin tzdata=2026b-r0, the build succeeds on targeted architectures, and no unnecessary package changes were made.
Out of Scope Changes check	✅ Passed	The pull request contains only the required Dockerfile changes to update tzdata pins; no out-of-scope modifications are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/docker-tzdata-pin-84

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