KAS / Kubernetes integration

The GitLab Kubernetes Agent Server (KAS) and the in-cluster agentk agent.

Components

Component	Where	Role
KAS	external Go service (gitlab-org/cluster-integration/gitlab-agent)	Brokers connections between GitLab and agentk
agentk	Helm chart, in customer cluster	Long-lived gRPC client connected to KAS
Rails KAS bridge	lib/gitlab/kas.rb (~4K LoC), app/models/clusters/agent.rb, app/models/cluster_agent_token.rb	Issues tokens, exposes APIs

KAS version pinned in GITLAB_KAS_VERSION.

Why

Cluster admins don't want GitLab punching outbound holes into their cluster. KAS inverts the direction: the cluster opens an outbound gRPC stream to KAS, and Rails sends commands over that stream. The connection is multiplexed for many features.

Source

app/models/clusters/
├── agent.rb
├── agent_token.rb
├── agent_url_configuration.rb
└── ...
app/services/clusters/
├── agents/
└── agent_tokens/
ee/app/services/clusters/agents/
ee/app/models/clusters/agents/
ee/app/policies/clusters/agents/
lib/api/internal/kubernetes.rb        # KAS callbacks
lib/api/clusters/agent_tokens.rb
config/initializers/kas.rb

What flows over the gRPC stream

Channel	Purpose
GitOps (Flux integration)	Push manifests / monitor sync
Kubectl proxy	Run kubectl from the GitLab UI
Vulnerability scanning	Continuous scan of cluster workloads
Observability	Metrics from cluster
Remote development	Remote IDE workspaces

Tokens and auth

Clusters::AgentToken is the long-lived secret the in-cluster agent uses. It's verified by KAS, which then calls back into Rails internal API (/api/v4/internal/kubernetes/agent_info) to authenticate.

CI access from cluster

The ci_access mechanism lets CI jobs use kubectl against allowed agents without giving runners cluster credentials. Rails issues short-lived tokens scoped to a specific agent + project.

Remote Development workspaces

ee/lib/remote_development/, app/models/remote_development/, app/services/remote_development/. KAS-backed Web IDE workspaces that run pods in a customer cluster.

Related

• Authentication — agent tokens.
• Internal API — /api/v4/internal/kubernetes/*.