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Deploying OPA on Docker

Docker makes OPA easy to deploy in different types of environments.

This section explains how to use the official OPA Docker images. If this is your first time deploying OPA and you plan to use one of the Docker images, we recommend you review this section to familiarize yourself with the basics.

OPA releases are available as images on Docker Hub (openpolicyagent/opa).

Running with Docker​

If you start OPA outside of Docker without any arguments, it prints a list of available commands. By default, the official OPA Docker image executes the run command which starts an instance of OPA as an interactive shell. This is nice for development, however, for deployments, we want to run OPA as a server.

The run command accepts a --server (or -s) flag that starts OPA as a server. See --help for more information on other arguments. The most important command line arguments for OPA's server mode are:

  • --addr to set the listening address (default: localhost:8181).
  • --log-level (or -l) to set the log level (default: "info").
  • --log-format to set the log format (default: "json").

By default, OPA listens for normal HTTP connections on localhost:8181. To make OPA listen for HTTPS connections, see Security.

We can run OPA as a server using Docker:

docker run -p 8181:8181 openpolicyagent/opa \
    run --server --log-level debug --addr=0.0.0.0:8181
info

We have to use --addr here to bind to all interfaces to ensure OPA is accessible from outside the container. This is not necessary when running OPA in other environments.

More information can be found in the security documentation.

Test that OPA is available:

curl -i localhost:8181/

Logging​

OPA logs to stderr and the level can be set with --log-level/-l. The default log level is info which causes OPA to log request/response information.

{"client_addr":"[::1]:64427","level":"debug","msg":"Received request.","req_body":"","req_id":1,"req_method":"GET","req_params":{},"req_path":"/v1/data","time":"20.7.13-11T18:22:18-08:00"}
{"client_addr":"[::1]:64427","level":"debug","msg":"Sent response.","req_id":1,"req_method":"GET","req_path":"/v1/data","resp_bytes":13,"resp_duration":0.392554,"resp_status":200,"time":"20.7.13-11T18:22:18-08:00"}

If the log level is set to debug the request and response message bodies will be logged. This is useful for development however it can be expensive in production.

{"addrs":[":8181"],"insecure_addr":"","level":"info","msg":"First line of log stream.","time":"2019-05-08T17:25:26-07:00"}
{"level":"info","msg":"Starting decision log uploader.","plugin":"decision_logs","time":"2019-05-08T17:25:26-07:00"}
{"client_addr":"[::1]:63902","level":"info","msg":"Received request.","req_body":"","req_id":1,"req_method":"GET","req_params":{},"req_path":"/v1/data","time":"2019-05-08T17:25:41-07:00"}
{"client_addr":"[::1]:63902","level":"info","msg":"Sent response.","req_id":1,"req_method":"GET","req_path":"/v1/data","resp_body":"{\"decision_id\":\"f4b41501-2408-4a14-8269-1c1085abeda4\",\"result\":{}}","resp_bytes":66,"resp_duration":2.545972,"resp_status":200,"time":"2019-05-08T17:25:41-07:00"}

The default log format is json and intended for production use. For more human readable formats use "json-pretty" or "text".

Note: The text log format is not performance optimized or intended for production use.

Volume Mounts​

By default, OPA does not include any data or policies.

The simplest way to load data and policies into OPA is to provide them via the file system as command line arguments. When running inside Docker, you can provide files via volume mounts.

docker run -v $PWD:/example openpolicyagent/opa eval -d /example 'data.example.greeting'
policy.rego
package example

greeting := msg if {
    info := opa.runtime()

    # Docker sets the HOSTNAME environment variable.
    hostname := info.env["HOSTNAME"]

    msg := sprintf("hello from container %q!", [hostname])
}

More Information​

For more information on OPA's command line, see --help:

docker run openpolicyagent/opa run --help

Tagging​

The Docker Hub repository contains tags for every release of OPA. For more information on each release see the GitHub Releases page.

The "latest" tag refers to the most recent release. The latest tag is convenient if you want to quickly try out OPA however for production deployments, we recommend using an explicit version tag.

Development builds are also available on Docker Hub. For each version the {version}-dev tag refers the most recent development build for that version.

The edge tag refers to the current main branch of OPA. Useful for testing unreleased features. It is not recommended to use edge for production deployments.

The version information is contained in the OPA executable itself. You can check the version with the following command:

docker run openpolicyagent/opa version

Running in Kubernetes​

This section shows how to quickly deploy OPA on top of Kubernetes to try it out.

If you are interested in using OPA to enforce admission control policies in Kubernetes, see the Kubernetes Admission Control Tutorial.

These steps assume Kubernetes is deployed with minikube. If you are using a different Kubernetes provider, the steps should be similar. You may need to use a different Service configuration at the end.

First, create a ConfigMap containing a test policy.

In this case, the policy file does not contain sensitive information so it's fine to store as a ConfigMap. If the file contained sensitive information, then we recommend you store it as a Secret.

example.rego
package example

greeting := msg if {
    info := opa.runtime()

    # Kubernetes sets the HOSTNAME environment variable.
    hostname := info.env["HOSTNAME"]

    msg := sprintf("hello from pod %q!", [hostname])
}
kubectl create configmap example-policy --from-file example.rego

Next, create a Deployment to run OPA. The ConfigMap containing the policy is volume mounted into the container. This allows OPA to load the policy from the file system.

deployment-opa.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: opa
  labels:
    app: opa
spec:
  replicas: 1
  selector:
    matchLabels:
      app: opa
  template:
    metadata:
      labels:
        app: opa
      name: opa
    spec:
      containers:
      - name: opa
        image: openpolicyagent/opa:1.8.0
        ports:
        - name: http
          containerPort: 8181
        args:
        - "run"
        - "--ignore=.*" # exclude hidden dirs created by Kubernetes
        - "--server"
        - "/policies"
        volumeMounts:
        - readOnly: true
          mountPath: /policies
          name: example-policy
      volumes:
      - name: example-policy
        configMap:
          name: example-policy
kubectl create -f deployment-opa.yaml

At this point OPA is up and running. Create a Service to expose the OPA API so that you can query it:

service-opa.yaml
kind: Service
apiVersion: v1
metadata:
  name: opa
  labels:
    app: opa
spec:
  type: NodePort
  selector:
    app: opa
  ports:
  - name: http
    protocol: TCP
    port: 8181
    targetPort: 8181
kubectl create -f service-opa.yaml

Get the URL of OPA using minikube:

OPA_URL=$(minikube service opa --url)

Now you can query OPA's API:

curl $OPA_URL/v1/data

OPA will respond with the greeting from the policy (the pod hostname will differ):

{
  "result": {
    "example": {
      "greeting": "hello from pod \"opa-78ccdfddd-xplxr\"!"
    }
  }
}

Readiness and Liveness Probes​

OPA exposes a /health API endpoint that you can configure Kubernetes Readiness and Liveness Probes to call. For example:

containers:
- name: opa
  image: openpolicyagent/opa:1.8.0
  ports:
  - name: http
    containerPort: 8181
  args:
  - "run"
  - "--ignore=.*" # exclude hidden dirs created by Kubernetes
  - "--server"
  - "/policies"
  volumeMounts:
  - readOnly: true
    mountPath: /policies
    name: example-policy
  livenessProbe:
    httpGet:
      path: /health
      scheme: HTTP # assumes OPA listens on localhost:8181
      port: 8181
    initialDelaySeconds: 5 # tune these periods for your environment
    periodSeconds: 5
  readinessProbe:
    httpGet:
      path: /health?bundle=true # Include bundle activation in readiness
      scheme: HTTP
      port: 8181
    initialDelaySeconds: 5
    periodSeconds: 5

See the Health API documentation for more detail on the /health API endpoint.