What is the first check performed when deploying a pod?

Kubelet performs an admission controller validation, which consists of several steps:

1. Validation: Checks whether the pod manifests conform to the Kubernetes schema and do not contain syntax errors.
2. Mutation: Changes can be made to the pod configuration based on configured admission controllers (e.g., adding sidecars, configuring network policies).
3. Resource Validation: Checks for the presence of necessary resources (quotas, limits) and whether the pod complies with restrictions set by policies (Policy Admission Controllers).
4. Security Context Validation: Checks whether the security settings of the pod comply with established policies (Pod Security Standards).

This is the first stage where a decision is made whether the pod will be allowed to proceed to further scheduling and execution.