使用版本与别名安全发布

Every function has a mutable $LATEST version. Deploying overwrites it instantly, leaving no easy rollback. Versions solve this.

Publishing creates a numbered, immutable snapshot of code and configuration. Version 3 will always be exactly what you published.

An alias is a named pointer to a version, such as prod or staging. Clients invoke the alias, and you re-point it without changing callers.

Create an alias that points to a specific version. Move it later to promote a new release.

Callers reference the alias by qualifier. The actual version is decided by the alias, decoupling clients from deploys.

An alias can split traffic between two versions by weight, enabling canary deployments where a small percentage tries the new version.

In the example, version 4 receives 10 percent of traffic while version 3 keeps 90 percent. Increase the weight as confidence grows.

If the new version misbehaves, repoint the alias to the previous version. Rollback is immediate because old versions still exist.

You can grant invoke permission on a specific alias, so staging callers cannot accidentally hit production code.

Aliases can carry their own environment variable overrides, letting staging point at test resources while prod uses live ones.

AWS CodeDeploy can shift alias traffic automatically using canary or linear strategies, with CloudWatch alarms triggering automatic rollback.

Test your release knowledge.

You learned to publish immutable versions, point aliases at them, run weighted canary rollouts, and roll back instantly by re-pointing the alias.