mutations-and-gating

command

v0.7.1 Latest Latest Go to latest Published: Apr 1, 2026 License: Apache-2.0 Imports: 13 Imported by: 0

README ¶

Mutations and Gating

This example demonstrates how to use version-gated and boolean-gated mutations within a single component that manages two resources: a Deployment and a ConfigMap.

What it shows

Baseline as latest version: The base Deployment represents the v2 layout (container named "app" with HTTP and health ports). This follows the guideline that the baseline always reflects the latest desired state.
Version-gated backward compat mutation: BackwardCompatV1Container activates for versions < 2.0.0 and rolls the baseline back to the v1 layout (container named "server", HTTP port only). Uses a semver.Constraint as a feature.VersionConstraint. The BackwardCompat prefix makes the pattern immediately recognizable.
Boolean-gated mutation: TracingSidecarMutation injects a Jaeger sidecar. It is gated via .When(enabled), so the sidecar is added only when tracing is on and removed when it is off.
Mutation ordering for container name stability: DebugLoggingMutation targets ContainerNamed("app") and is registered before BackwardCompatV1Container. This ensures it always sees the baseline name, even though the backward compat mutation renames the container for older versions. The env var edit carries through the rename because the backward compat mutation only overwrites Name and Ports, not Env.
Resource-level gating: The ConfigMap is registered with NewResourceOptionsBuilder().When(owner.Spec.EnableMetrics).Build(). When metrics are disabled, the framework deletes the ConfigMap entirely rather than leaving an empty one behind.
Mutation-level gating within a resource: MetricsConfigMutation on the ConfigMap is separately boolean-gated, showing that gating can happen at both the resource and mutation levels.
Suspension: The component supports suspension via Suspend(owner.Spec.Suspended).

Reconciliation steps

v1.9.0 with tracing and metrics: backward compat container layout ("server", single port).
Enable debug logging on v1: LOG_LEVEL=debug targets "app" (baseline name) and carries through the backward compat rename.
Upgrade to v2.0.0: container switches to "app" with a health port added, debug logging still active.
Disable debug logging and tracing: sidecar removed, LOG_LEVEL removed from the Deployment.
Disable metrics: the entire ConfigMap is deleted via resource-level gating.
Suspend the application.

Running

go run ./examples/mutations-and-gating/.

Documentation ¶

Overview ¶

Package main demonstrates mutations and resource-level gating.

A single component manages a Deployment and a ConfigMap. The Deployment uses version-gated and boolean-gated mutations. The ConfigMap is gated at the resource level so it is created only when metrics are enabled.

Source Files ¶

View all Source files

main.go

Directories ¶

Path	Synopsis
app Package app provides a sample controller demonstrating mutations and gating.	Package app provides a sample controller demonstrating mutations and gating.
features Package features provides example mutations for the mutations-and-gating example.	Package features provides example mutations for the mutations-and-gating example.
resources Package resources provides resource factories for the mutations-and-gating example.	Package resources provides resource factories for the mutations-and-gating example.

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