debian-mirror-gitlab/doc/user/clusters/agent/index.md

stage	group	info
Configure	Configure	To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers

GitLab Kubernetes Agent (PREMIUM ONLY)

Introduced in GitLab Premium 13.4.

Goals

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

Features:

1. Makes it possible to integrate GitLab with a Kubernetes cluster behind a firewall or NAT
2. Enables pull-based GitOps deployments by leveraging the GitOps Engine
3. Allows for real-time access to API endpoints within a cluster.
4. Many more features are planned. Please review our roadmap.

Architecture

GitLab Agent GitOps workflow

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

Please refer to our full architecture documentation in the Agent project.

Getting started with GitOps using the GitLab Agent and the GitLab Cloud Native Helm chart

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

1. A Kubernetes cluster that is properly configured
2. A configuration repository that contains a config.yaml file. This config.yaml tells the Agent which repositories to synchronize with.
3. A manifest repository that contains a manifest.yaml. This manifest.yaml (which can be autogenerated) is tracked by the Agent and any changes to the file are automatically applied to the cluster.

The setup process involves a few steps that, once completed, will enable GitOps deployments to work

1. Installing the Agent server via GitLab Helm chart
2. Defining a configuration directory
3. Creating an Agent record in GitLab
4. Generating and copying a Secret token used to connect to the Agent
5. Installing the Agent into the cluster
6. Creating a manifest.yaml

Installing the Agent server via Helm

Currently the GitLab Kubernetes Agent can only be deployed via our Helm chart.

NOTE: We are working quickly to include the Agent in Official Linux Package.

If you don't already have GitLab installed via Helm please refer to our installation documentation

When installing/upgrading the GitLab Helm chart please consider the following Helm 2 example (if using Helm 3 please modify):

helm repo update
helm upgrade --force --install gitlab gitlab/gitlab \
  --timeout 600 \
  --set global.hosts.domain=<YOUR_DOMAIN> \
  --set global.hosts.externalIP=<YOUR_IP> \
  --set certmanager-issuer.email=<YOUR_EMAIL> \
  --set name=gitlab-instance \
  --set global.kas.enabled=true

global.kas.enabled=true must be set in order for the Agent to be properly installed and configured.

Defining a configuration repository

Next you will need a GitLab repository that will contain your Agent configuration.

The minimal repository layout looks like this:

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

The config.yaml file contents should look like this:

gitops:
  manifest_projects:
  - id: "path-to/your-awesome-project"

Creating an Agent record in GitLab

Next you will need to create an GitLab Rails Agent record so that your GitLab project so that the Agent itself can associate with a GitLab project. This process will also yield a Secret that you will use to configure the Agent in subsequent steps.

There are two ways to accomplish this:

1. Via the Rails console
2. Via GraphQL

To do this you could either run rails c or via GraphQL. From rails c:

  project = ::Project.find_by_full_path("path-to/your-awesome-project")
  agent = ::Clusters::Agent.create(name: "<agent-name>", project: project)
  token = ::Clusters::AgentToken.create(agent: agent)
  token.token # this will print out the token you need to use on the next step

or using GraphQL:

with this approach, you'll need a premium license to use this feature.

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

  mutation createAgent {
    createClusterAgent(input: { projectPath: "path-to/your-awesome-project", name: "<agent-name>" }) {
      clusterAgent {
        id
        name
      }
      errors
    }
  }

  mutation createToken {
    clusterAgentTokenCreate(input: { clusterAgentId: <cluster-agent-id-taken-from-the-previous-mutation> }) {
      secret # This is the value you need to use on the next step
      token {
        createdAt
        id
      }
      errors
    }
  }

Note that GraphQL will only show you the token once, after you've created it.

Creating the Kubernetes secret

Once the token has been generated it needs to be applied to the Kubernetes cluster.

If you didn't previously define or create a namespace you need to do that first:

kubectl create namespace <YOUR-DESIRED-NAMESPACE>

Run the following command to create your Secret:

kubectl create secret generic -n <YOUR-DESIRED-NAMESPACE> gitlab-agent-token --from-literal=token='YOUR_AGENT_TOKEN'

Installing the Agent into the cluster

Next you are now ready to install the in-cluster component of the Agent. The below is an example YAML file of the Kubernetes resources required for the Agent to be installed.

Let's highlight a few of the details in the example below:

1. You can replace gitlab-agent with
2. For the kas-address (Kubernetes Agent Server), you can replace grpc://host.docker.internal:5005 with the address of the kas agent that was initialized via your Helm install.
3. If you defined your own secret name, then replace gitlab-agent-token with your secret name.

./resources.yml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: gitlab-agent
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gitlab-agent
spec:
  replicas: 1
  selector:
    matchLabels:
      app: gitlab-agent
  template:
    metadata:
      labels:
        app: gitlab-agent
    spec:
      serviceAccountName: gitlab-agent
      containers:
      - name: agent
        image: "registry.gitlab.com/gitlab-org/cluster-integration/gitlab-agent/agentk:latest"
        args:
        - --token-file=/config/token
        - --kas-address
        - grpc://host.docker.internal:5005 # {"$openapi":"kas-address"}
        volumeMounts:
        - name: token-volume
          mountPath: /config
      volumes:
      - name: token-volume
        secret:
          secretName: gitlab-agent-token
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 0
      maxUnavailable: 1
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: gitlab-agent-write
rules:
- resources:
  - '*'
  apiGroups:
  - '*'
  verbs:
  - create
  - update
  - delete
  - patch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: gitlab-agent-write-binding
roleRef:
  name: gitlab-agent-write
  kind: ClusterRole
  apiGroup: rbac.authorization.k8s.io
subjects:
- name: gitlab-agent
  kind: ServiceAccount
  namespace: gitlab-agent
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: gitlab-agent-read
rules:
- resources:
  - '*'
  apiGroups:
  - '*'
  verbs:
  - get
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: gitlab-agent-read-binding
roleRef:
  name: gitlab-agent-read
  kind: ClusterRole
  apiGroup: rbac.authorization.k8s.io
subjects:
- name: gitlab-agent
  kind: ServiceAccount
  namespace: gitlab-agent

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

$ kubectl get pods --all-namespaces
NAMESPACE     NAME                               READY   STATUS    RESTARTS   AGE
gitlab-agent  gitlab-agent-77689f7dcb-5skqk      1/1     Running   0          51s
kube-system   coredns-f9fd979d6-n6wcw            1/1     Running   0          14m
kube-system   etcd-minikube                      1/1     Running   0          14m
kube-system   kube-apiserver-minikube            1/1     Running   0          14m
kube-system   kube-controller-manager-minikube   1/1     Running   0          14m
kube-system   kube-proxy-j6zdh                   1/1     Running   0          14m
kube-system   kube-scheduler-minikube            1/1     Running   0          14m
kube-system   storage-provisioner                1/1     Running   0          14m

Creating a manifest.yaml

In the above step, you configured a config.yaml to point to which GitLab projects the Agent should synchronize. Within each one of those projects, you need to create a manifest.yaml file which the Agent will monitor. This manifest.yaml can be autogenerated by a templating engine or other means.

Example manifest.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: gitlab-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

The above file creates a simple NGINX deployment.

Each time you commit and push a change to the manifest.yaml the Agent will observe the change. Example log:

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 projects

Basic GitOps example deploying NGINX: Configuration repository, Manifest repository