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API keys

Authenticate requests by using an API key.

If you import or export resources across workspaces, your policies might not apply. For more information, see Import and export policies.

About API keys

API keys are secure, long-lived UUIDs that clients provide when they send a request to your service. You might use API keys in the following scenarios:

You know the set of users that need access to your service. These users do not change often, or you have automation that easily generates or deletes the API key when the users do change.
You want direct control over how the credentials are generated and expire.

When you use API keys, your services are only as secure as the API keys. Storing and rotating the API key securely is up to the user.

How API keys work with Gloo Mesh

To secure your services with API keys, first provide Gloo Mesh with your API keys in the form of Kubernetes secrets. Then in the external auth policy, you refer to the secrets in one of two ways.

Specify a label selector that matches the label of one or more API key secrets. Labels are the more flexible, scalable approach.
Refer to the name and namespace of each secret.

Gloo Mesh Gateway matches a request to a route that is secured by the external auth policy. The request must have a valid API key in a header. You can configure the name of the expected header. If the header is missing, or the API key is invalid, Gloo Mesh denies the request and returns a 401 response.

Internally, Gloo Mesh maps API keys to user identities for all API keys in the system. The user identity for an API key is the name of the secret that has the API key. Gloo Mesh adds the user identity to the request as a header, x-user-id by default. Gloo Mesh can use this header in subsequent filters. For security purposes, Gloo Mesh sanitizes the header from the response before the response leaves the gateway proxy.

Before you begin

This guide assumes that you use the same names for components like clusters, workspaces, and namespaces as in the getting started. If you have different names, make sure to update the sample configuration files in this guide.

Complete the multicluster getting started guide to set up the following testing environment.
- Three clusters along with environment variables for the clusters and their Kubernetes contexts.
- The Gloo Platform CLI, meshctl, along with other CLI tools such as kubectl and istioctl.
- The Gloo management server in the management cluster, and the Gloo agents in the workload clusters.
- Istio installed in the workload clusters.
- A simple Gloo workspace setup.
Install Bookinfo and other sample apps.
Make sure that the external auth service is installed and running. If not, install the external auth service.
```
kubectl get pods --context ${REMOTE_CONTEXT1} -A -l app=ext-auth-service
```
Make sure that you have the following CLI tools, or something comparable:
- base64 to encode strings.

Configure an external auth policy with an API key

Create the external auth policy that uses API keys to verify identity.

You can do the following steps in a different order, depending on when you want the policy to take effect. For example, you might want the policy to always take effect as soon as the route is created. To do so, you can create the policy before you add the route to the route table.

From your API management tool such as Gloo Portal or Google Developer Portal, generate an API key to use for your app's domain. For example, your key might be N2YwMDIxZTEtNGUzNS1jNzgzLTRkYjAtYjE2YzRkZGVmNjcy.

Encode the API key value so that you can store the API key in a Kubernetes secret. You can optionally encode other details that you want to pass in with the API key, such as a user ID and email address.

echo -n N2YwMDIxZTEtNGUzNS1jNzgzLTRkYjAtYjE2YzRkZGVmNjcy | base64
echo -n user-id-12345 | base64
echo -n user12345@email.com | base64

Example output:

TjJZd01ESXhaVEV0TkdVek5TMWpOemd6TFRSa1lqQXRZakUyWXpSa1pHVm1OamN5
dXNlci1pZC0xMjM0NQ==
dXNlcjEyMzQ1QGVtYWlsLmNvbQ==

Store the encoded API key and any additional data as a Kubernetes secret in the workload cluster that you want to create the external auth policy in. Make sure to use a label so that you can select the secret later.

kubectl apply -f - <<EOF
apiVersion: v1
kind: Secret
metadata:
  name: user-id-12345
  namespace: bookinfo
  labels:
    extauth: apikey
type: extauth.solo.io/apikey
data:
  api-key: TjJZd01ESXhaVEV0TkdVek5TMWpOemd6TFRSa1lqQXRZakUyWXpSa1pHVm1OamN5
  user-id: dXNlci1pZC0xMjM0NQ==
  user-email: dXNlcjEyMzQ1QGVtYWlsLmNvbQ==
EOF

Create an external auth server to use for your policy. The following example refers directly to the default Gloo Mesh external auth service, but you can also use a virtual destination instead. For more information, see External auth server setup.

kubectl apply -f - <<EOF
apiVersion: admin.gloo.solo.io/v2
kind: ExtAuthServer
metadata:
  name: ext-auth-server
  namespace: bookinfo
spec:
  destinationServer:
    port:
      number: 8083
    ref:
      cluster: cluster1
      name: ext-auth-service
      namespace: gloo-mesh-addons
EOF

Create an external auth policy that uses the API key.

When you create the policy with a destination selector, only Kubernetes services can be specified in the applyToDestination section. Gloo virtual destinations or Gloo external services are not supported.

kubectl --context ${REMOTE_CONTEXT1} apply -f - <<EOF
apiVersion: security.policy.gloo.solo.io/v2
kind: ExtAuthPolicy
metadata:
  name: ratings-apikey
  namespace: bookinfo
spec:
  applyToDestinations:
  - selector:
      labels:
        app: ratings
  config:
    server:
      name: ext-auth-server
      namespace: bookinfo
      cluster: $REMOTE_CLUSTER1
    glooAuth:
      configs:
      - apiKeyAuth:
          headerName: api-key
          headersFromMetadataEntry:
            x-user-email: 
              name: user-email
          k8sSecretApikeyStorage:
            labelSelector:
              extauth: apikey
EOF

Review the following table to understand this configuration. For more information, see the API reference.

Setting	Description
`applyToDestinations`	Configure which destinations to apply the policy to, by using labels. Destinations can be a Kubernetes service, VirtualDestination, or ExternalService. If you do not specify any destinations or routes, the policy applies to all destinations in the workspace by default. If you do not specify any destinations but you do specify a route, the policy applies to the route but to no destinations.
`server`	The external auth server to use for the policy.
`apiKeyAuth`	Configure the API key authentication details.
`headerName`	The header that the Gloo Mesh external auth server looks at to get the API key. If not set, the default `api-key` header name is used.
`headersFromMetadataEntry`	Additional headers from the secret metadata to add to the authenticated requests so that other external auth modules can perform additional validation checks. For example, you might configure the API key secret to include extra data such as the user email. The key in this field is the name of the header to add to the request. The value in this field is the key in the secret data field. That key's value is injected as the header value. In this example, Gloo Mesh adds an x-user-email header into authenticated requests, with the value of the user-email from the user-id-12345 secret (dXNlcjEyMzQ1QGVtYWlsLmNvbQ==) that other external auth modules can process, such as OPA. To find an example of combining API key and OPA to authenticate requests, see API key and OPA.
`k8sSecretApikeyStorage`	The label to match the policy with valid API key secrets. Any secrets that match the label are selected and can be used to authenticate requests. The API key secrets must be in the same workspace as the external auth server.

Verify the external auth API key policy

Send a request to the ratings app without authorization. Now, the request is blocked with a 401 response.
- Kubernetes 1.22 or earlier
- Kubernetes 1.23 or later
Create a temporary curl pod in the bookinfo namespace, so that you can test the app setup. You can also use this method in Kubernetes 1.23 or later, but an ephemeral container might be simpler, as shown in the other tab.
1. Create the curl pod.
  kubectl run -it -n bookinfo --context $REMOTE_CONTEXT1 curl \ --image=curlimages/curl:7.73.0 --rm -- sh
2. Send a request to the ratings app.
  curl http://ratings:9080/ratings/1 -v
Use the kubectl debug command to create an ephemeral curl container in the deployment. This way, the curl container inherits any permissions from the app that you want to test. If you don't run Kubernetes 1.23 or later, you can deploy a separate curl pod or manually add the curl container as shown in the other tab.
```
kubectl --context ${REMOTE_CONTEXT1} -n bookinfo debug -i pods/$(kubectl get pod --context ${REMOTE_CONTEXT1} -l app=reviews -A -o jsonpath='{.items[0].metadata.name}') --image=curlimages/curl -- curl -v http://ratings:9080/ratings/1
```
If the output has an error about EphemeralContainers, see Ephemeral containers don’t work when testing Bookinfo.
Example output:
```
   > GET /posts/1 HTTP/1.1
   > Host: foo
   > User-Agent: curl/7.54.0
   > Accept: */*
   >
   < HTTP/1.1 401 Unauthorized
   < www-authenticate: API key is missing or invalid
   < date: Mon, 07 Oct 2019 19:28:14 GMT
   < server: envoy
   < content-length: 0
   
```
Send the request again, this time with a header that contains your API key data.
- Kubernetes 1.22 or earlier
- Kubernetes 1.23 or later
Create a temporary curl pod in the bookinfo namespace, so that you can test the app setup. You can also use this method in Kubernetes 1.23 or later, but an ephemeral container might be simpler, as shown in the other tab.
1. Send a request to the ratings app.
  curl -v -H "api-key: N2YwMDIxZTEtNGUzNS1jNzgzLTRkYjAtYjE2YzRkZGVmNjcy" http://ratings:9080/ratings/1
2. Exit the temporary pod. The pod deletes itself.
  exit
Use the kubectl debug command to create an ephemeral curl container in the deployment. This way, the curl container inherits any permissions from the app that you want to test. If you don't run Kubernetes 1.23 or later, you can deploy a separate curl pod or manually add the curl container as shown in the other tab.
```
kubectl --context ${REMOTE_CONTEXT1} -n bookinfo debug -i pods/$(kubectl get pod --context ${REMOTE_CONTEXT1} -l app=reviews -A -o jsonpath='{.items[0].metadata.name}') --image=curlimages/curl -- curl -v -H "api-key: N2YwMDIxZTEtNGUzNS1jNzgzLTRkYjAtYjE2YzRkZGVmNjcy" http://ratings:9080/ratings/1
```
You can reach the ratings app again!
```
{"id":1,"ratings":{"Reviewer1":5,"Reviewer2":4}}
```

Optional: Clean up the resources that you created.

kubectl --context $REMOTE_CONTEXT1 -n bookinfo delete Secret user-id-12345
kubectl --context $REMOTE_CONTEXT1 -n bookinfo delete ExtAuthPolicy ratings-apikey
kubectl --context $REMOTE_CONTEXT1 -n bookinfo delete ExtAuthServer ext-auth-server