Roll back configuration without rolling back application code
A new timeout revision overloads the fake provider, but the only recovery script redeploys the entire previous application artifact.
- Focused work estimate
- 6h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Configuration rollback · Compatibility · Incident recovery
Estimated field mix
- DevOps60%
- Site reliability40%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional notification service uses environment files assembled by shell scripts. Defaults differ by machine, secret values appear in diagnostics, and emergency flags have no expiry. Build a typed local configuration compiler with fake secret references and synthetic environments; no real credentials or notification providers are supplied.
Setup prerequisites
- Configuration precedence
- Schema validation
- Least privilege
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- DENV-101 · Define precedence without depending on process order
- DENV-102 · Reject missing required values before service startup
- DENV-103 · Keep secret values out of configuration diffs
- DENV-104 · Validate cross-field configuration invariants
- DENV-106 · Promote configuration by immutable revision
- DENV-107 · Resolve secret rotation without restarting into a mixed revision
- DENV-108 · Detect environment drift without copying secret data
Acceptance criteria
- Rollback selects a prior compatible configuration revision
- Compatibility is checked against the current application contract
- History retains failed and restored revisions plus observed outcome
Implementation constraints
- Rollback never mutates a historical revision or reuses its approval for another environment.
Verification to include
- Deploy a bad timeout revision and restore the prior compatible configuration.
- Choose a revision requiring an older schema and block rollback with an actionable result.
Deliverables
- Configuration rollback command and recovery rehearsal
Rollout and recovery
Maintain one known-compatible revision for each simulated environment.
Value of the work
For the engineer: Practice configuration as a reviewed contract with safe diagnostics, provenance, and rollback.
For the team: Review environment changes before deployment and reduce outages caused by missing, stale, or silently defaulted settings.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.