GitLab Kubernetes Agent

Version history
  • Introduced in GitLab Premium 13.4.
  • In GitLab 13.10, KAS became available on GitLab.com under wss://kas.gitlab.com through an Early Adopter Program.
  • Introduced in GitLab 13.11, the GitLab Kubernetes Agent became available to every project on GitLab.com.

The GitLab Kubernetes Agent is an active in-cluster component for solving GitLab and Kubernetes integration tasks in a secure and cloud-native way. It enables:

  • Integrating GitLab with a Kubernetes cluster behind a firewall or NAT (network address translation).
  • Pull-based GitOps deployments by leveraging the GitOps Engine.
  • Real-time access to API endpoints in a cluster.
  • Alert generation based on Container network policy.
  • CI/CD Tunnel that enables users to access Kubernetes clusters from GitLab CI/CD jobs even if there is no network connectivity between GitLab Runner and a cluster.

Many more features are planned. Please review our roadmap and our development documentation.

GitLab Agent GitOps workflow

The GitLab Agent uses multiple GitLab projects to provide a flexible workflow that can suit various needs. This diagram shows these repositories and the main actors involved in a deployment:

sequenceDiagram participant D as Developer participant A as Application code repository participant M as Manifest repository participant K as Kubernetes Agent participant C as Agent configuration repository K->C: Grab the configuration D->>+A: Pushing code changes A->>M: Updating manifest loop Regularly K-->>M: Watching changes M-->>K: Pulling and applying changes end

There are several components that work in concert for the Agent to accomplish GitOps deployments:

  • A properly-configured Kubernetes cluster where the Agent is running.
  • A configuration repository that contains a config.yaml file, which tells the Agent which repositories to synchronize with the cluster.
  • A manifest repository that contains manifest files. Any changes to manifest files are applied to the cluster.

You can use the same GitLab project or separate projects for configuration and manifest files, as follows:

  • Single GitLab project (recommended): when you use a single repository to hold both the manifest and the configuration files, these projects can be either private or public, as you prefer.
  • Two GitLab projects: when you opt to use two different GitLab projects, one for manifest files, and another for configuration files, the manifests project must be public, while the configuration project can be either private or public. Our backlog contains issues for adding support for private manifest repositories outside of the configuration project and group level agents in the future.

For more details, please refer to our full architecture documentation in the Agent project.

Get started with GitOps and the GitLab Agent

The setup process involves a few steps to enable GitOps deployments:

  1. Set up the Kubernetes Agent Server for your GitLab instance.
  2. Define a configuration repository.
  3. Create an Agent record in GitLab.
  4. Generate and copy a Secret token used to connect to the Agent.
  5. Install the Agent into the cluster.
  6. Create manifest files.

Upgrades and version compatibility

As the GitLab Kubernetes Agent is a new product, we are constantly adding new features to it. As a result, while shipped features are production ready, its internal API is neither stable nor versioned yet. For this reason, GitLab only guarantees compatibility between corresponding major.minor (X.Y) versions of GitLab and its cluster side component, agentk.

Upgrade your agent installations together with GitLab upgrades. To decide which version of agentk to install follow:

  1. Open the GITLAB_KAS_VERSION file from the GitLab Repository, which contains the latest agentk version associated with the master branch.
  2. Change the master branch and select the Git tag associated with your version. For instance, you could change it to GitLab v13.5.3-ee release

The available agentk and kas versions can be found in the container registry.

Set up the Kubernetes Agent Server

Introduced in GitLab Premium 13.10, the GitLab Kubernetes Agent Server (KAS) became available on GitLab.com under wss://kas.gitlab.com.

To use the KAS:

Define a configuration repository

Introduced in GitLab 13.7, the Agent manifest configuration can be added to multiple directories (or subdirectories) of its repository.

To configure an Agent, you need:

  1. A GitLab repository to hold the configuration file.
  2. Install the Agent in a cluster.

After installed, when you update the configuration file, GitLab transmits the information to the cluster automatically without downtime.

In your repository, add the Agent configuration file under: 

.gitlab/agents/<agent-name>/config.yaml

Your config.yaml file specifies all configurations of the Agent, such as:

  • The manifest projects to synchronize.
  • The address of the hubble-relay for the Network Security policy integrations.

As an example, a minimal Agent configuration that sets up only the manifest synchronizations is: 

gitops:
  manifest_projects:
  - id: "path-to/your-manifest-project-1"
    paths:
    - glob: '/**/*.{yaml,yml,json}'

All the options for the Kubernetes Agent configuration repository are documented separately.

Create an Agent record in GitLab

Next, create a GitLab Rails Agent record to associate it with the configuration repository project. Creating this record also creates a Secret needed to configure the Agent in subsequent steps. You can create an Agent record with GraphQL: 

  mutation createAgent {
    # agent-name should be the same as specified above in the config.yaml
    createClusterAgent(input: { projectPath: "path-to/your-configuration-project", name: "<agent-name>" }) {
      clusterAgent {
        id
        name
      }
      errors
    }
  }

  mutation createToken {
    clusterAgentTokenCreate(
      input: {
        clusterAgentId: "<cluster-agent-id-taken-from-the-previous-mutation>"
        description: "<optional-description-of-token>"
        name: "<required-name-given-to-token>"
      }
    ) {
      secret # This is the value you need to use on the next step
      token {
        createdAt
        id
      }
      errors
    }
  }
cautionGraphQL only displays the token and ids one time after creating it. Make sure to write down the secret, clusterAgentId, and clusterAgentTokenId; you’ll need them later.

If you are new to using the GitLab GraphQL API, refer to the Getting started with the GraphQL API page, or the GraphQL Explorer.

Install the Agent into the cluster

To install the in-cluster component of the Agent, first you need to define a namespace. To create a new namespace, for example, gitlab-kubernetes-agent, run: 

kubectl create namespace gitlab-kubernetes-agent

To perform a one-liner installation, run the command below. Make sure to replace:

  • your-agent-token with the token received from the previous step.
  • gitlab-kubernetes-agent with the namespace you defined in the previous step.
  • wss://kas.gitlab.example.com with the configured access of the Kubernetes Agent Server (KAS). For GitLab.com users, the KAS is available under wss://kas.gitlab.com. 
docker run --pull=always --rm registry.gitlab.com/gitlab-org/cluster-integration/gitlab-agent/cli:stable generate --agent-token=your-agent-token --kas-address=wss://kas.gitlab.example.com --agent-version stable --namespace gitlab-kubernetes-agent | kubectl apply -f -

Set --agent-version to the latest released patch version matching your GitLab installation’s major and minor versions. For example, if you have GitLab v13.9.0, set --agent-version=v13.9.1.

cautionVersion stable can be used to refer to the latest stable release at the time when the command runs. It’s fine for testing purposes but for production please make sure to specify a matching version explicitly.

To find out the various options the above Docker container supports, run: 

docker run --pull=always --rm registry.gitlab.com/gitlab-org/cluster-integration/gitlab-agent/cli:stable generate --help

Advanced installation

For more advanced configurations, we recommend to use the kpt based installation method.

Otherwise, follow the manual installation steps described below.

Create the Kubernetes secret

After generating the token, you must apply it to the Kubernetes cluster.

To create your Secret, run: 

kubectl create secret generic -n gitlab-kubernetes-agent gitlab-kubernetes-agent-token --from-literal=token='YOUR_AGENT_TOKEN'

The following example file contains the Kubernetes resources required for the Agent to be installed. You can modify this example resources.yml file in the following ways:

  • Replace namespace: gitlab-kubernetes-agent with namespace: <YOUR-DESIRED-NAMESPACE>.
  • You can configure kas-address (Kubernetes Agent Server) in several ways. The agent can use the WebSockets or gRPC protocols to connect to the Agent Server. Select the option appropriate for your cluster configuration and GitLab architecture:
    • The wss scheme (an encrypted WebSockets connection) is specified by default after you install the gitlab-kas sub-chart, or enable gitlab-kas for Omnibus GitLab. When using the sub-chart, you must set wss://kas.host.tld:443 as kas-address, where host.tld is the domain you’ve setup for your GitLab installation. When using Omnibus GitLab, you must set wss://GitLab.host.tld:443/-/kubernetes-agent/ as kas-address, where GitLab.host.tld is your GitLab hostname.
    • When using the sub-chart, specify the ws scheme (such as ws://kas.host.tld:80) to use an unencrypted WebSockets connection. When using the Omnibus GitLab, specify the ws scheme (such as ws://GitLab.host.tld:80/-/kubernetes-agent/).
    • Specify the grpc scheme if both Agent and Server are installed in one cluster. In this case, you may specify kas-address value as grpc://gitlab-kas.<your-namespace>:8150) to use gRPC directly, where gitlab-kas is the name of the service created by gitlab-kas chart, and your-namespace is the namespace where the chart was installed. Encrypted gRPC is not supported yet. Follow the Support TLS for gRPC communication issue for progress updates.
    • When deploying KAS through the GitLab chart, it’s possible to customize the kas-address for wss and ws schemes to whatever you need. Check the chart’s KAS Ingress documentation to learn more about it.
    • In the near future, Omnibus GitLab intends to provision gitlab-kas under a sub-domain by default, instead of the /-/kubernetes-agent/ path. Please follow this issue for details.
  • If you defined your own secret name, replace gitlab-kubernetes-agent-token with your secret name in the secretName: section.

To apply this file, run the following command: 

kubectl apply -n gitlab-kubernetes-agent -f ./resources.yml

To review your configuration, run the following command: 

$ kubectl get pods -n gitlab-kubernetes-agent

NAMESPACE                NAME                                          READY   STATUS    RESTARTS   AGE
gitlab-kubernetes-agent  gitlab-kubernetes-agent-77689f7dcb-5skqk      1/1     Running   0          51s
Example resources.yml file 
---
apiVersion: v1
kind: Namespace
metadata:
  name: gitlab-kubernetes-agent
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: gitlab-kubernetes-agent
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gitlab-kubernetes-agent
spec:
  replicas: 1
  selector:
    matchLabels:
      app: gitlab-kubernetes-agent
  template:
    metadata:
      labels:
        app: gitlab-kubernetes-agent
    spec:
      serviceAccountName: gitlab-kubernetes-agent
      containers:
      - name: agent
        # Make sure to specify a matching version for production
        image: "registry.gitlab.com/gitlab-org/cluster-integration/gitlab-agent/agentk:stable"
        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
      volumes:
      - name: token-volume
        secret:
          secretName: gitlab-kubernetes-agent-token
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 0
      maxUnavailable: 1
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: gitlab-kubernetes-agent-write
rules:
- resources:
  - '*'
  apiGroups:
  - '*'
  verbs:
  - create
  - update
  - delete
  - patch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: gitlab-kubernetes-agent-write-binding
roleRef:
  name: gitlab-kubernetes-agent-write
  kind: ClusterRole
  apiGroup: rbac.authorization.k8s.io
subjects:
- name: gitlab-kubernetes-agent
  kind: ServiceAccount
  namespace: gitlab-kubernetes-agent
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: gitlab-kubernetes-agent-read
rules:
- resources:
  - '*'
  apiGroups:
  - '*'
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: gitlab-kubernetes-agent-read-binding
roleRef:
  name: gitlab-kubernetes-agent-read
  kind: ClusterRole
  apiGroup: rbac.authorization.k8s.io
subjects:
- name: gitlab-kubernetes-agent
  kind: ServiceAccount
  namespace: gitlab-kubernetes-agent

Create manifest files

In a previous step, you configured a config.yaml to point to the GitLab projects the Agent should synchronize. Agent monitors each of those projects for changes to the manifest files it contains. You can auto-generate manifest files with a templating engine or other means.

The agent is authorized to download manifests for the configuration project, and public projects. Support for other private projects is planned in the issue Agent authorization for private manifest projects.

Each time you push a change to a monitored manifest repository, the Agent logs the change: 

2020-09-15_14:09:04.87946 gitlab-k8s-agent      : time="2020-09-15T10:09:04-04:00" level=info msg="Config: new commit" agent_id=1 commit_id=e6a3651f1faa2e928fe6120e254c122451be4eea

Example manifest file

This file creates an NGINX deployment. 

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: gitlab-kubernetes-agent  # Can be any namespace managed by you that the agent has access to.
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

Example projects

The following example projects can help you get started with the Kubernetes Agent.

Deploying GitLab Runner with the Agent

You can use the Kubernetes Agent to deploy GitLab Runner in a Kubernetes cluster.

Kubernetes Network Security Alerts

The GitLab Agent also provides an integration with Cilium. This integration provides a simple way to generate network policy-related alerts and to surface those alerts in GitLab.

There are several components that work in concert for the Agent to generate the alerts:

  • A working Kubernetes cluster.
  • Cilium integration through either of these options:
  • One or more network policies through any of these options:
  • Use a configuration repository to inform the Agent through a config.yaml file, which repositories can synchronize with. This repository might be the same, or a separate GitLab project.

The setup process follows the same steps as GitOps, with the following differences:

  • When you define a configuration repository, you must do so with Cilium settings.
  • You do not need to specify the gitops configuration section.

Define a configuration repository with Cilium settings

You need a GitLab repository to contain your Agent configuration. The minimal repository layout looks like this: 

.gitlab/agents/<agent-name>/config.yaml

Your config.yaml file must specify the host and port of your Hubble Relay service. If your Cilium integration was performed through GitLab Managed Apps, you can use hubble-relay.gitlab-managed-apps.svc.cluster.local:80: 

cilium:
  hubble_relay_address: "<hubble-relay-host>:<hubble-relay-port>"
  ...

Management interfaces

Users with at least the Developer can access the user interface for the GitLab Kubernetes agent at Infrastructure > Kubernetes clusters, under the GitLab Agent managed clusters tab. This page lists all registered agents for the current project, and the configuration directory for each agent:

GitLab Kubernetes Agent list UI

Additional management interfaces are planned for the GitLab Kubernetes Agent. Provide more feedback in the related epic.

Troubleshooting

If you face any issues while using GitLab Kubernetes Agent, you can read the service logs with the following command 

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

GitLab administrators can additionally view the Kubernetes Agent Server logs.

Agent 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 is shown if there are some connectivity issues between the address specified as kas-address, and your Agent pod. To fix it, make sure that you specified the kas-address correctly.

Agent logs - 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 is shown if a manifest file is malformed, and Kubernetes can’t create specified objects. Make sure that your manifest files are valid. You may try using them to create objects in Kubernetes directly for more troubleshooting.

Agent logs - 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 is shown if you configured wss as kas-address on the agent side, but KAS on the server side is not available via wss. To fix it, make sure the same schemes are configured on both sides.

It’s not possible to set the grpc scheme due to the issue It is not possible to configure KAS to work with grpc without directly editing GitLab KAS deployment. To use grpc while the issue is in progress, directly edit the deployment with the kubectl edit deployment gitlab-kas command, and change --listen-websocket=true to --listen-websocket=false. After running that command, you should be able to use grpc://gitlab-kas.<YOUR-NAMESPACE>:8150.

Agent logs - 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 is shown if the version of the agent is newer that the version of KAS. To fix it, make sure that both agentk and KAS use the same versions.

Agent logs - 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 is shown if your GitLab instance is using a certificate signed by an internal CA that is unknown to the agent. One approach to fixing it is to present the CA certificate file to the agent via 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-kubernetes-agent create configmap ca-pemstore --from-file=myCA.pem

Then in resources.yml: 

    spec:
      serviceAccountName: gitlab-kubernetes-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-kubernetes-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 include it using 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

Remove the GitLab Kubernetes Agent

  1. Remove an Agent record with GraphQL by deleting the clusterAgent and the clusterAgentToken. 

    mutation deleteAgent {
  clusterAgentDelete(input: { id: "<cluster-agent-id>" } ) {
    errors
  }
}

mutation deleteToken {
  clusterAgentTokenDelete(input: { id: "<cluster-agent-token-id>" }) {
    errors
  }
}

  2. Verify whether the removal occurred successfully. If the output in the Pod logs includes unauthenticated, it means that the agent was successfully removed: 

       {"level":"warn","time":"2021-04-29T23:44:07.598Z","msg":"GetConfiguration.Recv failed","error":"rpc error:
   code = Unauthenticated desc = unauthenticated"}

  3. Delete the GitLab Kubernetes Agent in your cluster: 

    kubectl delete -n gitlab-kubernetes-agent -f ./resources.yml