ArgoCD Notifications#

ArgoCD Notifications is a built-in component (since ArgoCD 2.5) that monitors applications and sends alerts when specific events occur – sync succeeded, sync failed, health degraded, new version deployed. Before notifications existed, teams polled the ArgoCD UI or built custom watchers. Notifications eliminates that.

Architecture#

ArgoCD Notifications runs as a controller alongside the ArgoCD application controller. It watches Application resources for state changes and matches them against triggers. When a trigger fires, it renders a template and sends it through a configured service (Slack, Teams, webhook, email, etc.).

Admission Controllers and Webhooks#

Every request to the Kubernetes API server passes through a chain: authentication, authorization, and then admission control. Admission controllers are plugins that intercept requests after a user is authenticated and authorized but before the object is persisted to etcd. They can validate requests, reject them, or mutate objects on the fly. This is where you enforce organizational policy, inject sidecar containers, set defaults, and block dangerous configurations.