Admission controllers are Kubernetes components that intercept requests to the API server before the persistence of objects. These policies ensure that workloads meet specific requirements by either validating or modifying them. In Chainguard environments, admission controller policies focus on signature verification for container images and conducting image provenance checks to uphold security and compliance.
How It Works
Admission controllers function as a series of webhooks that receive a request when a user tries to create or modify a Kubernetes resource. After the API server processes the request, it invokes the appropriate admission controller based on predefined policies. For example, in a Chainguard context, policy checks might confirm that container images are signed with a trusted key and derive from a secure source. If an image fails validation, the controller can reject the deployment or mutate it to align with compliance standards.
These policies can operate in two primary modes: validating and mutating. Validating admission controllers examine requests and can deny those that do not meet criteria, while mutating controllers can alter the configurations of workloads before they are accepted. This ensures that all deployments conform to established security practices by enforcing integrity and provenance checks on the images being run.
Why It Matters
Implementing these policies fosters a higher security posture by proactively blocking potentially harmful workloads before they can compromise the system. This pre-deployment scrutiny mitigates risks associated with unverified code and enhances overall infrastructure reliability. Organizations benefit from improved compliance with industry regulations, thereby reducing the likelihood of costly security breaches and operational downtime.
Key Takeaway
Admission controller policies enforce security and compliance by validating container images before deployment, ensuring only trusted workloads run in the environment.