mux's Introduction

mux

Process muxer written in TypeScript.

Allows configuration of installation, runtime, and clean up of individual processes. Built in menu allows tailing, restarting, and rebuilding of processes within a single terminal session.

Particularly useful for monorepo setups where you have to run frontend, backend, and infrastructure locally.

Getting started

Install package

npm install @mrdiggles2/mux

Create a mux.config.ts at the root level of your project. Sample:

import { MuxConfig } from '@mrdiggles2/mux/config';

const config: MuxConfig = {
  rootDir: __dirname,
  logPath: '.mux/logs',
  processes: [
    {
      name: 'long sleeper',
      run: {
        exec: 'sleep 1000',
      }
    }
  ]
};

export default config;

Execute mux

npx mux

Configuration

Each process in mux.config.ts can be configured:

...
{
  name: 'YOUR PROCESS NAME HERE',
  run: MuxCommand,
  install?: MuxCommand,
  cleanup?: MuxCommand,

}

Where MuxCommand takes the form:

{
    exec: <Command to run in a separate process>;
    dir?: <Path to run `exec` from. Appended to provided `rootDir` in mux.config.ts>
    env?: {
      <Additional environment variables to run command with>
    }
}

Since mux.config.ts is a TypeScript file, you can also add dynamic configuration. Here is a more complete sample:

import path from "path";
import { MuxConfig } from '@mrdiggles2/mux/config';

const dockerComposeFiles = [
  'docker-compose.yml',
  'docker-compose.local.yaml'
].map(file => path.join(__dirname, file));

const dcBin = `docker compose --ansi=always ` + dockerComposeFiles.map(file => `-f ${file}`).join(' ');

const config: MuxConfig = {
  rootDir: __dirname,
  logPath: '.mux',
  processes: [
    {
      name: 'docker-services',
      install: {
        exec: `${dcBin} up --build -d --remove-orphans --wait`
      },
      run: {
        // Run `up` here again to smoothly support restarts. Effectively a no-op
        // if the containers are already running
        exec: `${dcBin} up -d --remove-orphans --wait && ${dcBin} logs -f`
      },
      stop: {
        exec: `${dcBin} down`
      }
    },
    {
      name: 'nest-backend',
      install: {
        exec: 'npm ci',
        dir: 'backend',
      },
      run: {
        exec: 'npx nest --watch',
        dir: 'backend',
        env: {
          NODE_ENV: development
          ...<ENV VARS>
        },
      }
    },
    {
      name: 'react-frontend',
      install: {
        exec: `npm ci`,
        dir: 'frontend',
      },
      run: {
        exec: `npx react-scripts start`,
        dir: 'frontend',
        env: {
          FORCE_COLOR: '1'
          ...<ENV VARS>
        }
      }
    },
  ]
};

export default config;

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mux's Issues

Error: ENFILE: file table overflow

Occasionally getting the following error:

Error: ENFILE: file table overflow, open '<PATH TO LOG FILE>'

Likely caused by stale file descriptors: https://stackoverflow.com/questions/45004352/error-enfile-file-table-overflow-scandir-while-run-reaction-on-mac

When switching between services, FD's don't get cleaned up.

Current behavior

Start mux
Open tail:... multiple times
Run lsof -p <PID of mux start>
- ps | grep "mux start" | grep -v grep | awk '{print $1}' | xargs lsof -p
Observe that there are duplicate FDs for the log file

Expected behavior

There should only be one open FD for each log file