HTTP CONNECT Tunnels

  3 minute read  

HTTP CONNECT tunnels are a mechanism that allows a client to establish a tunnel through an HTTP proxy server to communicate directly with a destination server. This is commonly used for HTTPS traffic through proxies, but can also be used for other protocols.

This task will help you get started using HTTP Connect based tunnels using Envoy Gateway.

Prerequisites

Follow the steps below to install Envoy Gateway and the example manifest. Before proceeding, you should be able to query the example backend using HTTP.

Expand for instructions

  1. Install the Gateway API CRDs and Envoy Gateway using Helm:

    helm install eg oci://docker.io/envoyproxy/gateway-helm --version v1.5.1 -n envoy-gateway-system --create-namespace

  2. Install the GatewayClass, Gateway, HTTPRoute and example app:

    kubectl apply -f https://github.com/envoyproxy/gateway/releases/download/v1.5.1/quickstart.yaml -n default

  3. Verify Connectivity:

    Get the External IP of the Gateway:

    export GATEWAY_HOST=$(kubectl get gateway/eg -o jsonpath='{.status.addresses[0].value}')

    Curl the example app through Envoy proxy:

    curl --verbose --header "Host: www.example.com" http://$GATEWAY_HOST/get

    The above command should succeed with status code 200.

    Get the name of the Envoy service created the by the example Gateway:

    export ENVOY_SERVICE=$(kubectl get svc -n envoy-gateway-system --selector=gateway.envoyproxy.io/owning-gateway-namespace=default,gateway.envoyproxy.io/owning-gateway-name=eg -o jsonpath='{.items[0].metadata.name}')

    Get the deployment of the Envoy service created the by the example Gateway:

    export ENVOY_DEPLOYMENT=$(kubectl get deploy -n envoy-gateway-system --selector=gateway.envoyproxy.io/owning-gateway-namespace=default,gateway.envoyproxy.io/owning-gateway-name=eg -o jsonpath='{.items[0].metadata.name}')

    Port forward to the Envoy service:

    kubectl -n envoy-gateway-system port-forward service/${ENVOY_SERVICE} 8888:80 &

    Curl the example app through Envoy proxy:

    curl --verbose --header "Host: www.example.com" http://localhost:8888/get

    The above command should succeed with status code 200.

Proxy CONNECT request

Envoy Gateway supports proxy CONNECT requests, allowing you to route traffic through a Gateway and HTTPRoute to a Backend service.

graph LR
    Client--CONNECT-->ProxyEnvoy[proxy the CONNECT request]
    ProxyEnvoy[proxy the CONNECT request]--CONNECT-->Socat

Create a Gateway and HTTPRoute to route proxy CONNECT requests to a Backend service:

cat <<EOF | kubectl apply -f -
# curl -ik -v -x 172.18.0.201:80 https://www.httpbin.org | grep -o "<title>.*</title>"
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: connect-proxy
spec:
  gatewayClassName: eg
  listeners:
    - name: http
      protocol: HTTP
      port: 80
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: connect-proxy
spec:
  parentRefs:
    - group: gateway.networking.k8s.io
      kind: Gateway
      name: connect-proxy
  rules:
    - backendRefs:
        - group: ""
          kind: Service
          name: socat
          port: 8080
      matches:
        - path:
            type: PathPrefix
            value: /
---
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: BackendTrafficPolicy
metadata:
  name: connect-proxy
spec:
  targetRef:
    group: gateway.networking.k8s.io
    kind: Gateway
    name: connect-proxy
  httpUpgrade:
    - type: CONNECT
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: socat
spec:
  selector:
    matchLabels:
      app: socat
  template:
    metadata:
      labels:
        app: socat
    spec:
      serviceAccountName: socat
      containers:
        - name: socat
          image: alpine/socat:1.8.0.3
          command:
            - socat
            - TCP-LISTEN:8080,fork,reuseaddr
            - TCP:httpbin.org:80
          imagePullPolicy: IfNotPresent
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: socat
---
apiVersion: v1
kind: Service
metadata:
  name: socat
  labels:
    app: socat
spec:
  ports:
    - port: 8080
      name: http
  selector:
    app: socat
---
EOF

Verify the Gateway status:

kubectl get gateway/connect-proxy -o yaml

Testing

Get the External IP of the Gateway:

export PROXY_GATEWAY_HOST=$(kubectl get gateway/connect-proxy -o jsonpath='{.status.addresses[0].value}')

curl -ik -v -x ${PROXY_GATEWAY_HOST}:80 https://httpbin.org | grep -o "<title>.*</title>"

Verify the method from the access log:

kubectl logs -n envoy-gateway-system deployments/envoy-default-connect-proxy-f7d7286e | tail -n 1 | jq | grep method

Get the name of the Envoy service created the by the example Gateway:

export ENVOY_SERVICE=$(kubectl get svc -n envoy-gateway-system --selector=gateway.envoyproxy.io/owning-gateway-namespace=default,gateway.envoyproxy.io/owning-gateway-name=connect-proxy -o jsonpath='{.items[0].metadata.name}')

Port forward to the Envoy service:

kubectl -n envoy-gateway-system port-forward service/${ENVOY_SERVICE} 8080:80 &

curl -ik -v -x localhost:8080 https://httpbin.org

Clean up

kubectl delete HTTPRoute connect-proxy
kubectl delete Gateway connect-proxy
kubectl delete BackendTrafficPolicy connect-proxy
kubectl delete deployment socat
kubectl delete service socat
kubectl delete serviceaccount socat