gRPC Bridge

Envoy gRPC

The gRPC bridge sandbox is an example usage of Envoy’s gRPC bridge filter.

This is an example of a key-value store where an http-based client CLI, written in Python, updates a remote store, written in Go, using the stubs generated for both languages.

The client send messages through a proxy that upgrades the HTTP requests from http/1.1 to http/2.

[client](http/1.1) -> [client-egress-proxy](http/2) -> [server-ingress-proxy](http/2) -> [server]

Another Envoy feature demonstrated in this example is Envoy’s ability to do authority base routing via its route configuration.

Running the Sandbox

The following documentation runs through the setup of the services.

Step 1: Install Docker

Ensure that you have a recent versions of docker and docker-compose.

A simple way to achieve this is via the Docker Desktop.

Step 2: Clone the Envoy repo

If you have not cloned the Envoy repo, clone it with:

git clone git@github.com:envoyproxy/envoy

or

git clone https://github.com/envoyproxy/envoy.git

Step 3: Generate the protocol stubs

A docker-compose file is provided that generates the stubs for both client and server from the specification in the protos directory.

Inspecting the docker-compose-protos.yaml file, you will see that it contains both the python and go gRPC protoc commands necessary for generating the protocol stubs.

Generate the stubs as follows:

$ pwd
envoy/examples/grpc-bridge
$ docker-compose -f docker-compose-protos.yaml up
Starting grpc-bridge_stubs_python_1 ... done
Starting grpc-bridge_stubs_go_1     ... done
Attaching to grpc-bridge_stubs_go_1, grpc-bridge_stubs_python_1
grpc-bridge_stubs_go_1 exited with code 0
grpc-bridge_stubs_python_1 exited with code 0

You may wish to clean up left over containers with the following command:

$ docker container prune

You can view the generated kv modules for both the client and server in their respective directories:

$ ls -la client/kv/kv_pb2.py
-rw-r--r--  1 mdesales  CORP\Domain Users  9527 Nov  6 21:59 client/kv/kv_pb2.py

$ ls -la server/kv/kv.pb.go
-rw-r--r--  1 mdesales  CORP\Domain Users  9994 Nov  6 21:59 server/kv/kv.pb.go

These generated python and go stubs can be included as external modules.

Step 4: Start all of our containers

To build this sandbox example and start the example services, run the following commands:

$ pwd
envoy/examples/grpc-bridge
$ docker-compose pull
$ docker-compose up --build -d
$ docker-compose ps

               Name                             Command               State                         Ports
---------------------------------------------------------------------------------------------------------------------------------------
grpc-bridge_grpc-client-proxy_1        /docker-entrypoint.sh /bin ... Up      10000/tcp, 0.0.0.0:9911->9911/tcp, 0.0.0.0:9991->9991/tcp
grpc-bridge_grpc-client_1              /bin/sh -c tail -f /dev/null   Up
grpc-bridge_grpc-server-proxy_1        /docker-entrypoint.sh /bin ... Up      10000/tcp, 0.0.0.0:8811->8811/tcp, 0.0.0.0:8881->8881/tcp
grpc-bridge_grpc-server_1              /bin/sh -c /bin/server         Up      0.0.0.0:8081->8081/tcp

Sending requests to the Key/Value store

To use the Python service and send gRPC requests:

$ pwd
envoy/examples/grpc-bridge

Set a key:

$ docker-compose exec python /client/client.py set foo bar
setf foo to bar

Get a key:

$ docker-compose exec python /client/client.py get foo
bar

Modify an existing key:

$ docker-compose exec python /client/client.py set foo baz
setf foo to baz

Get the modified key:

$ docker-compose exec python /client/client.py get foo
baz

In the running docker-compose container, you should see the gRPC service printing a record of its activity:

$ docker-compose logs grpc-server
grpc_1    | 2017/05/30 12:05:09 set: foo = bar
grpc_1    | 2017/05/30 12:05:12 get: foo
grpc_1    | 2017/05/30 12:05:18 set: foo = baz