A policy gate is a control point in a delivery pipeline that blocks a release unless predefined security rules are satisfied. Those rules can include passing image scans, approving exceptions, using trusted base images, or meeting compliance thresholds. In practice, the gate turns security findings into an action: ship, stop, or require review.
Policy gates matter because they move security left from observation to enforcement. A scan that only reports vulnerabilities may be ignored, but a gate can prevent a vulnerable container image from reaching production. Defenders use gates to reduce the chance that exposed packages, unsafe configurations, or untrusted artifacts enter runtime. Attackers benefit when pipelines lack these checks, because a compromised or outdated image can be promoted unchanged. Good policy gates are paired with audit logs and exception handling so teams can enforce standards without blocking every legitimate release.