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Expose and secure a workload with OAuth2

This tutorial shows how to expose and secure services or Functions using API Gateway Controller. The controller reacts to an instance of the APIRule custom resource (CR) and creates an Istio VirtualService and Oathkeeper Access Rules according to the details specified in the CR. To interact with the secured services, the tutorial uses an OAuth2 client registered through the Hydra Maester controller.

You can use it as a follow-up to the Set up a custom domain for a workload tutorial.

Prerequisites

This tutorial is based on a sample HttpBin service deployment and a sample Function. To deploy or create one of those, follow the Create a workload tutorial.

Register an OAuth2 client and get tokens

Export your client as an environment variable:
Click to copy
```
export CLIENT_NAME={YOUR_CLIENT_NAME}
```

Create an OAuth2 client with "read" and "write" scopes. Run:

Click to copy

cat <<EOF | kubectl apply -f -
apiVersion: hydra.ory.sh/v1alpha1
kind: OAuth2Client
metadata:
  name: $CLIENT_NAME
  namespace: $NAMESPACE
spec:
  grantTypes:
    - "client_credentials"
  scope: "read write"
  secretName: $CLIENT_NAME
EOF

Export the credentials of the created client as environment variables. Run:

Click to copy

export CLIENT_ID="$(kubectl get secret -n $NAMESPACE $CLIENT_NAME -o jsonpath='{.data.client_id}' | base64 --decode)"
export CLIENT_SECRET="$(kubectl get secret -n $NAMESPACE $CLIENT_NAME -o jsonpath='{.data.client_secret}' | base64 --decode)"

Encode your client credentials and export them as an environment variable:
Click to copy
```
export ENCODED_CREDENTIALS=$(echo -n "$CLIENT_ID:$CLIENT_SECRET" | base64)
```
Get tokens to interact with secured resources using client credentials flow:
- Token with "read" scope
- Token with "write" scope
Export the following value as an environment variable:
Click to copy
export KYMA_DOMAIN={KYMA_DOMAIN_NAME}
Get the token:
Click to copy
curl -ik -X POST "https://oauth2.$KYMA_DOMAIN/oauth2/token" -H "Authorization: Basic $ENCODED_CREDENTIALS" -F "grant_type=client_credentials" -F "scope=read"
Export the issued token as an environment variable:
Click to copy
export ACCESS_TOKEN_READ={ISSUED_READ_TOKEN}

Expose and secure your workload

Follow the instructions in the tabs to expose an instance of the HttpBin service or a sample Function, and secure them with Oauth2 scopes.

HttpBin
Function

Export the following value as an environment variable:
Click to copy
```
export DOMAIN_TO_EXPOSE_WORKLOADS={DOMAIN_NAME}
export GATEWAY=$NAMESPACE/httpbin-gateway
```
NOTE: DOMAIN_NAME is the domain that you own, for example, api.mydomain.com. If you don't want to use your custom domain, replace DOMAIN_NAME with a Kyma domain and $NAMESPACE/httpbin-gateway with Kyma's default Gateway kyma-system/kyma-gateway

Expose the service and secure it by creating an APIRule CR in your Namespace. Run:

Click to copy

cat <<EOF | kubectl apply -f -
apiVersion: gateway.kyma-project.io/v1beta1
kind: APIRule
metadata:
  name: httpbin
  namespace: $NAMESPACE
spec:
  gateway: $GATEWAY
  host: httpbin.$DOMAIN_TO_EXPOSE_WORKLOADS
  service:
    name: httpbin
    port: 8000
  rules:
    - path: /.*
      methods: ["GET"]
      accessStrategies:
        - handler: oauth2_introspection
          config:
            required_scope: ["read"]
    - path: /post
      methods: ["POST"]
      accessStrategies:
        - handler: oauth2_introspection
          config:
            required_scope: ["write"]
EOF

NOTE: If you are running Kyma on k3d, add httpbin.kyma.local to the entry with k3d IP in your system's /etc/hosts file.

The exposed service requires tokens with "read" scope for GET requests in the entire service, and tokens with "write" scope for POST requests to the /post endpoint of the service.

CAUTION: When you secure a workload, don't create overlapping Access Rules for paths. Doing so can cause unexpected behavior and reduce the security of your implementation.

Access the secured resources

Follow the instructions in the tabs to call the secured service or Functions using the tokens issued for the client you registered.

Call secured endpoints of a service
Call the secured Function

Send a GET request with a token that has the "read" scope to the HttpBin service:

Click to copy

curl -ik -X GET https://httpbin.$DOMAIN_TO_EXPOSE_WORKLOADS/headers -H "Authorization: Bearer $ACCESS_TOKEN_READ"

Send a POST request with a token that has the "write" scope to the HttpBin's /post endpoint:
Click to copy
```
curl -ik -X POST https://httpbin.$DOMAIN_TO_EXPOSE_WORKLOADS/post -d "test data" -H "Authorization: bearer $ACCESS_TOKEN_WRITE"
```
These calls return the code 200 response. If you call the service without a token, you get the code 401 response. If you call the service or its secured endpoint with a token with the wrong scope, you get the code 403 response.

TIP: To learn more about the security options, read the document describing authorization configuration.