Header manipulation
Append or remove HTTP request and response headers at the route level.
Appending or removing headers can increase the security of your network. You can even manipulate headers on ingress traffic that goes through Gloo Mesh Enterprise to services outside your service mesh environment. For example, you might append a custom request header and then also enable a cross-origin request sharing (CORS) policy that requires this custom header. You might also remove any headers that provide details about your server, such as the operating system or upstream service time, to reduce the amount of information that could be used in targeted attacks.
For more information, see the following resources.
If you import or export resources across workspaces, your policies might not apply. For more information, see Import and export policies.
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
meshctl
CLI, along with other CLI tools such askubectl
andistioctl
. - 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.
Configure header manipulation policies
You can apply a header manipulation policy at the route level. For more information, see Applying policies.
Review the following sample configuration file.
cat > header-manipulation.yaml << EOF
apiVersion: trafficcontrol.policy.gloo.solo.io/v2
kind: HeaderManipulationPolicy
metadata:
name: modify-header-hsts
namespace: bookinfo
spec:
applyToRoutes:
- route:
labels:
route: ratings
config:
appendRequestHeaders:
x-custom-request: bookinfo
appendResponseHeaders:
strict-transport-security: max-age=16070400; includeSubDomains
x-content-type-options: nosniff
x-frame-options: deny
x-custom-response: bookinfo
removeRequestHeaders:
- user-agent
removeResponseHeaders:
- x-server
- x-envoy-upstream-service-time
EOF
Review the following table to understand this configuration. For more information, see the API docs.
Setting | Description |
---|---|
applyToRoutes | Use labels to configure which routes to apply the policy to. This example label matches the app and route from the example route table that you apply separately. If omitted and you do not have another selector such as applyToDestinations , the policy applies to all routes in the workspace. |
appendRequestHeaders | Specify the HTTP headers to add before forwarding a request to the destination. Headers are specified in a key: value pair. The example sets strict-transport-security and x-custom-request headers. |
appendResponseHeaders | Specify the HTTP headers to add before returning a response to the caller. Headers are specified in a key: value pair. The example sets x-content-type-options , x-frame-options , and x-custom-response headers. |
removeRequestHeaders | Specify the HTTP headers to remove before forwarding a request to the destination. Headers are specified by their key names. The example removes user-agent headers. |
removeResponseHeaders | Specify the HTTP headers to remove before returning a response to the caller. Headers are specified by their key names. The example removes x-server and x-envoy-upstream-service-time headers. |
Verify header manipulation policies
Apply the example header manipulation policy in the cluster with the Bookinfo workspace in your example setup.
kubectl apply --context $REMOTE_CONTEXT1 -f header-manipulation-policy.yaml
Create a route table for the ratings app. Because the policy applies at the route level, Gloo checks for the route in a route table resource.
kubectl apply --context ${REMOTE_CONTEXT1} -f - << EOF apiVersion: networking.gloo.solo.io/v2 kind: RouteTable metadata: name: ratings-rt namespace: bookinfo spec: hosts: - ratings http: - forwardTo: destinations: - ref: name: ratings namespace: bookinfo labels: route: ratings workloadSelectors: - {} EOF
Review the following table to understand this configuration. For more information, see the API docs.
Setting Description hosts
The host that the route table routes traffic for. In this example, the ratings
host matches the ratings service within the mesh.http.forwardTo.destinations
The destination to forward requests that come in along the host route. In this example, the ratings service is selected. http.labels
The label for the route. This label must match the label that the policy selects. workloadSelectors
The source workloads within the mesh that this route table routes traffic for. In the example, all workloads are selected. This way, the curl container that you create in subsequent steps can send a request along the ratings route. Send a request to the app. 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.- Create the curl pod.
kubectl run -it -n bookinfo --context $REMOTE_CONTEXT1 curl \ --image=curlimages/curl:7.73.0 --rm -- sh
- Send a request to the ratings app.
curl http://ratings:9080/ratings/1 -v
- Exit the temporary pod. The pod deletes itself.
exit
- Create the curl pod.
Verify that you notice the added or removed request and response headers.
Example response:
< HTTP/1.1 200 OK < content-type: application/json < date: Mon, 05 Sep 2022 19:02:58 GMT < server: envoy < x-content-type-options: nosniff < x-custom-response: bookinfo < x-frame-options: deny < transfer-encoding: chunked
Cleanup
You can optionally remove the resources that you set up as part of this guide.
kubectl --context $REMOTE_CONTEXT1 -n bookinfo delete RouteTable ratings-rt
kubectl --context $REMOTE_CONTEXT1 -n bookinfo delete HeaderManipulationPolicy modify-header-hsts