docker-exec-websocket-server

docker-exec-websocket-server

Purpose

A server that serves the results of docker exec over websockets.

See docker-exec-websocket-client for a client that communicates with this server.

Usage

Server:

var DockerServer = require('../lib/server.js');
var dockerServer = new DockerServer({
  port:8080, //automatically creates http server
  //OR
  server: //http.Serv object, can also be https, should already be listening

  path: '/'+slugid.v4(),    //Path to WebSocket
  containerId: 'servertest',  //Container to inject exec proccess into
  dockerSocket: '/var/run/docker.sock' //location of docker remote API socket
  maxSessions: 10 //maximum number of connected sessions
});
await dockerServer.execute();

By default, uses /var/run/docker.sock to communicate with Docker.

Message Types

Messages are prepended with a single byte which contains information about the encoded message. The payload is a Buffer in node, or a UInt8Array in browserify.

// stream related message types (carries a payload)
stdin: 0,
stdout: 1,
stderr: 2,
// data-flow related message types (carries no payload)
resume: 100, // Process is now ready to receive data
pause: 101, // Process is processing current data, don't send more right now
// resolution related message types
stopped: 200, // Process exited, payload is single byte exit code
shutdown: 201, // Server shut down
error: 202 // Some internal error occurred, expect undefined behaviour

Testing

Ensure Docker is installed (docker -v).

To test locally:

• Run yarn install to install the dependencies, including developer dependencies
• Run yarn test
• You can pass environment variables and commands to mocha as well, such as DEBUG=* yarn test -f 'docker exec wc'

To test with docker-compose, similar to CI:

• Run docker-compose build --build-arg NODE_VERSION=16-bullseye, or change to the desired Node.js image tag
• Run docker-compose run --rm test
• Repeat docker-compose build ... when the code changes or you want to try a different Node.js image.