Troubleshooting the GitLab agent for Kubernetes

When you are using the GitLab agent for Kubernetes, you might experience issues you need to troubleshoot.

You can start by viewing the service logs:

kubectl logs -f -l=app=gitlab-agent -n gitlab-agent

If you are a GitLab administrator, you can also view the GitLab agent server logs.

Transport: Error while dialing failed to WebSocket dial

{
  "level": "warn",
  "time": "2020-11-04T10:14:39.368Z",
  "msg": "GetConfiguration failed",
  "error": "rpc error: code = Unavailable desc = connection error: desc = \"transport: Error while dialing failed to WebSocket dial: failed to send handshake request: Get \\\"https://gitlab-kas:443/-/kubernetes-agent\\\": dial tcp: lookup gitlab-kas on 10.60.0.10:53: no such host\""
}

This error occurs when there are connectivity issues between the kas-address and your agent pod. To fix this issue, make sure the kas-address is accurate.

{
  "level": "error",
  "time": "2021-06-25T21:15:45.335Z",
  "msg": "Reverse tunnel",
  "mod_name": "reverse_tunnel",
  "error": "Connect(): rpc error: code = Unavailable desc = connection error: desc= \"transport: Error while dialing failed to WebSocket dial: expected handshake response status code 101 but got 301\""
}

This error occurs when the kas-address doesn’t include a trailing slash. To fix this issue, make sure that the wss or ws URL ends with a trailing slash, like wss://GitLab.host.tld:443/-/kubernetes-agent/ or ws://GitLab.host.tld:80/-/kubernetes-agent/.

ValidationError(Deployment.metadata)

{
  "level": "info",
  "time": "2020-10-30T08:56:54.329Z",
  "msg": "Synced",
  "project_id": "root/kas-manifest001",
  "resource_key": "apps/Deployment/kas-test001/nginx-deployment",
  "sync_result": "error validating data: [ValidationError(Deployment.metadata): unknown field \"replicas\" in io.k8s.apimachinery.pkg.apis.meta.v1.ObjectMeta, ValidationError(Deployment.metadata): unknown field \"selector\" in io.k8s.apimachinery.pkg.apis.meta.v1.ObjectMeta, ValidationError(Deployment.metadata): unknown field \"template\" in io.k8s.apimachinery.pkg.apis.meta.v1.ObjectMeta]"
}

This error occurs when a manifest file is malformed and Kubernetes can’t create the specified objects. Make sure that your manifest files are valid.

For additional troubleshooting, try to use the manifest files to create objects in Kubernetes directly.

Error while dialing failed to WebSocket dial: failed to send handshake request

{
  "level": "warn",
  "time": "2020-10-30T09:50:51.173Z",
  "msg": "GetConfiguration failed",
  "error": "rpc error: code = Unavailable desc = connection error: desc = \"transport: Error while dialing failed to WebSocket dial: failed to send handshake request: Get \\\"https://GitLabhost.tld:443/-/kubernetes-agent\\\": net/http: HTTP/1.x transport connection broken: malformed HTTP response \\\"\\\\x00\\\\x00\\\\x06\\\\x04\\\\x00\\\\x00\\\\x00\\\\x00\\\\x00\\\\x00\\\\x05\\\\x00\\\\x00@\\\\x00\\\"\""
}

This error occurs when you configured wss as kas-address on the agent side, but the agent server is not available at wss. To fix this issue, make sure the same schemes are configured on both sides.

Decompressor is not installed for grpc-encoding

{
  "level": "warn",
  "time": "2020-11-05T05:25:46.916Z",
  "msg": "GetConfiguration.Recv failed",
  "error": "rpc error: code = Unimplemented desc = grpc: Decompressor is not installed for grpc-encoding \"gzip\""
}

This error occurs when the version of the agent is newer that the version of the agent server (KAS). To fix it, make sure that both agentk and the agent server are the same version.

Certificate signed by unknown authority

{
  "level": "error",
  "time": "2021-02-25T07:22:37.158Z",
  "msg": "Reverse tunnel",
  "mod_name": "reverse_tunnel",
  "error": "Connect(): rpc error: code = Unavailable desc = connection error: desc = \"transport: Error while dialing failed to WebSocket dial: failed to send handshake request: Get \\\"https://GitLabhost.tld:443/-/kubernetes-agent/\\\": x509: certificate signed by unknown authority\""
}

This error occurs when your GitLab instance is using a certificate signed by an internal certificate authority that is unknown to the agent.

To fix this issue, you can present the CA certificate file to the agent by using a Kubernetes configmap and mount the file in the agent /etc/ssl/certs directory from where it will be picked up automatically.

For example, if your internal CA certificate is myCA.pem:

kubectl -n gitlab-agent create configmap ca-pemstore --from-file=myCA.pem

Then in resources.yml:

    spec:
      serviceAccountName: gitlab-agent
      containers:
      - name: agent
        image: "registry.gitlab.com/gitlab-org/cluster-integration/gitlab-agent/agentk:<version>"
        args:
        - --token-file=/config/token
        - --kas-address
        - wss://kas.host.tld:443 # replace this line with the line below if using Omnibus GitLab or GitLab.com.
        # - wss://gitlab.host.tld:443/-/kubernetes-agent/
        # - wss://kas.gitlab.com # for GitLab.com users, use this KAS.
        # - grpc://host.docker.internal:8150 # use this attribute when connecting from Docker.
        volumeMounts:
        - name: token-volume
          mountPath: /config
        - name: ca-pemstore-volume
          mountPath: /etc/ssl/certs/myCA.pem
          subPath: myCA.pem
      volumes:
      - name: token-volume
        secret:
          secretName: gitlab-agent-token
      - name: ca-pemstore-volume
        configMap:
          name: ca-pemstore
          items:
          - key: myCA.pem
            path: myCA.pem

Alternatively, you can mount the certificate file at a different location and specify it for the --ca-cert-file agent parameter:

      containers:
      - name: agent
        image: "registry.gitlab.com/gitlab-org/cluster-integration/gitlab-agent/agentk:<version>"
        args:
        - --ca-cert-file=/tmp/myCA.pem
        - --token-file=/config/token
        - --kas-address
        - wss://kas.host.tld:443 # replace this line with the line below if using Omnibus GitLab or GitLab.com.
        # - wss://gitlab.host.tld:443/-/kubernetes-agent/
        # - wss://kas.gitlab.com # for GitLab.com users, use this KAS.
        # - grpc://host.docker.internal:8150 # use this attribute when connecting from Docker.
        volumeMounts:
        - name: token-volume
          mountPath: /config
        - name: ca-pemstore-volume
          mountPath: /tmp/myCA.pem
          subPath: myCA.pem

Project not found

{
  "level ":"error ",
  "time ":"2022-01-05T15:18:11.331Z",
  "msg ":"GetObjectsToSynchronize.Recv failed ",
  "mod_name ":"gitops ",
  "error ":"rpc error: code = NotFound desc = project not found ",
}

This error occurs when the project where you keep your manifests is not public. To fix it, make sure your project is public or your manifest files are stored in the repository where the agent is configured.

Failed to perform vulnerability scan on workload: jobs.batch already exists

{
  "level": "error",
  "time": "2022-06-22T21:03:04.769Z",
  "msg": "Failed to perform vulnerability scan on workload",
  "mod_name": "starboard_vulnerability",
  "error": "running scan job: creating job: jobs.batch \"scan-vulnerabilityreport-b8d497769\" already exists"
}

The GitLab agent performs vulnerability scans by creating a job to scan each workload. If a scan is interrupted, these jobs may be left behind and will need to be cleaned up before more jobs can be run. You can clean up these jobs by running:

kubectl delete jobs -l app.kubernetes.io/managed-by=starboard -n gitlab-agent

We’re working on making the cleanup of these jobs more robust.