Envoy Proxy

In the last post, I talked about proxy servers and how they are an integral part of the cloud and microservices-based design. It makes sense to get our hands dirty and try out setting a reverse proxy. I have chosen the Envoy proxy for this example.

Envoy proxy can be installed on most of the popular OS and also has a docker installation. The site gives very good documentation for getting started –https://www.envoyproxy.io/docs/envoy/latest/start/start. For this example, I am setting up an envoy proxy on Mac OS.

First of all, make sure you have brew installed. Then execute the following commands to install envoy proxy

Once we are satisfied with the overall installation, we can run a simple test case, where we will redirect traffic coming to the envoy proxy to an application server. To start with, I have deployed a simple hello world application on port 1111.

$curl localhost:1111

Hello World

Now in order to get started with envoy proxy, we will take simple YAML settings file and modify it to our needs. https://www.envoyproxy.io/docs/envoy/latest/configuration/overview/examples#static

static_resources:
  listeners:
    - name: listener_0
      address:
        socket_address: { address: 127.0.0.1, port_value: 8080 }
      filter_chains:
        - filters:
          - name: envoy.filters.network.http_connection_manager
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
              stat_prefix: ingress_http
              codec_type: AUTO
              route_config:
                name: local_route
                virtual_hosts:
                - name: local_service
                  domains: ["*"]
                  routes:
                  - match: { prefix: "/" }
                    route: { cluster: some_service }
              http_filters:
              - name: envoy.filters.http.router
  clusters:
    - name: some_service
      connect_timeout: 1s
      type: STATIC
      lb_policy: round_robin
      load_assignment:
        cluster_name: some_service
        endpoints:
          - lb_endpoints:
            - endpoint:
                address:
                  socket_address:
                    address: 127.0.0.1
                    port_value: 1111

A couple of things to observe in the above YAML file, first observe the filter we are using here. We are using envoy.filters.network.http_connection_manager which is the simplest filter we use to redirect traffic. The second important thing to observe is the source and destination ports. We are listening to the traffic at port 8080 and redirecting to port 1111. This is a simple example where both envoy proxy and application server are running on the same local machine, whereas this would not be the case in the real world and we will see more meaningful usage of cluster address. For now, let’s run and test the envoy proxy.

Start envoy proxy with the config YAML created.

envoy --config-path ~/Desktop/workspace/envoyexample.yaml

Once the envoy is started successfully, you will see we are able to hit port 8080 and getting the output from port 1111 that we started earlier.

$curl localhost:8080

Hello World