Feat: add support for deployment strategy

[alekc]

Sourcebot mounts a PersistentVolumeClaim for its /data directory. The most common PVC storage class access mode is ReadWriteOnce (RWO), which allows the volume to be mounted by only one node at a time.

With the default RollingUpdate strategy, Kubernetes starts the new pod before terminating the old one. When both pods attempt to bind the same RWO volume simultaneously, the new pod gets stuck in Pending or ContainerCreating.

This makes rolling updates effectively broken for single-node PVC setups — which is the majority of self-hosted deployments.

What this PR does

• Adds a sourcebot.strategy value to configure the Kubernetes deployment strategy
• Defaults to RollingUpdate (Kubernetes default, correct for RWX volumes or no persistence)
• Users with RWO volumes can now switch to Recreate to ensure the old pod is fully terminated before the new one starts, allowing the volume to detach cleanly

sourcebot:
  strategy:
    type: Recreate

Impact: no breaking change, default behaviour is maintained with type: RollingUpdate

Fixes #83

Summary by CodeRabbit

• New Features
  • Added configurable deployment strategy support, letting users choose RollingUpdate or Recreate with sensible defaults.
• Documentation
  • Added docs and examples explaining deployment strategy options, upgrade behavior, and guidance for zero-downtime upgrades on multi-node clusters.
• Chores
  • Updated chart values schema and changelog to reflect the new strategy configuration.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: f2e90db4-e760-4767-bf6a-8fd36ec2e73f

📥 Commits

Reviewing files that changed from the base of the PR and between 741712a and 75dac5f.

📒 Files selected for processing (3)

• CHANGELOG.md
• README.md
• charts/sourcebot/README.md

✅ Files skipped from review due to trivial changes (3)

• CHANGELOG.md
• charts/sourcebot/README.md
• README.md

---

Walkthrough

The Helm chart adds a configurable sourcebot.strategy value, validates it in the chart JSON schema, and conditionally renders a spec.strategy block in the Deployment template. Documentation and changelog entries were added to describe the new configuration.

Changes

Cohort / File(s)	Summary
Deployment Template charts/sourcebot/templates/deployment.yaml	Conditionally emit spec.strategy when sourcebot.strategy is set; rendered via toYaml with proper indentation.
Values Schema charts/sourcebot/values.schema.json	Add sourcebot.strategy schema with oneOf branches for RollingUpdate (optional rollingUpdate) and Recreate, constraining type values.
Values Defaults charts/sourcebot/values.yaml	Introduce sourcebot.strategy default block set to type: RollingUpdate (plus minor whitespace cleanup).
Documentation & Changelog CHANGELOG.md, README.md, charts/sourcebot/README.md	Document the new sourcebot.strategy value, describe deployment strategy behavior and zero-downtime guidance for multi-node clusters; add changelog entry for the feature.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 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 clearly and concisely describes the main feature addition: support for configurable deployment strategy in the Helm chart.
Linked Issues check	✅ Passed	The PR fully addresses issue #83 objectives: exposes sourcebot.strategy in Deployment template, adds schema/values configuration with RollingUpdate default, and supports both RollingUpdate and Recreate types for single-replica RWO workloads.
Out of Scope Changes check	✅ Passed	All changes directly support deployment strategy configuration: template logic, values schema, defaults, changelog, and documentation. No extraneous modifications detected beyond the stated objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

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

Inline comments:
In `@charts/sourcebot/values.schema.json`:
- Around line 39-50: The schema currently allows a "strategy" object with "type"
and "rollingUpdate" together even when "type" is "Recreate"; update the
"strategy" definition to validate that "rollingUpdate" is only permitted when
"type" is "RollingUpdate" (e.g., replace the loose properties with a
conditional/oneOf rule using "if": {"properties": {"type": {"const":
"Recreate"}}}, "then": {"not": {"required": ["rollingUpdate"]}} or equivalent,
or use oneOf branches for the two strategy shapes) so that the "strategy" object
rejects any object that has type "Recreate" and a "rollingUpdate" property while
still allowing "rollingUpdate" when type is "RollingUpdate".

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 80eb5c3e-3cae-4a2c-957b-c2cd0649cd2d

📥 Commits

Reviewing files that changed from the base of the PR and between cc8e9b1 and 3cdbb59.

📒 Files selected for processing (4)

• charts/sourcebot/Chart.yaml
• charts/sourcebot/templates/deployment.yaml
• charts/sourcebot/values.schema.json
• charts/sourcebot/values.yaml

[brendan-kellam]

@alekc thanks for the PR! will take a look today

[brendan-kellam]

lgtm thanks for your contribution!