MJML TCP-Server

A MJML Server over TCP protocol.

Mainly created for django-mjml.

Requirements

• Node v24
• MJML v4 / v5

Using directly

You can run the server just running the file with arguments like:

$ node tcpserver.js --host=0.0.0.0 --port=28101 --mjml.minify=true --mjml.validationLevel=strict

Use --maxconnections=1000 to limit the number of simultaneously served connections (1000 by default). Connections above the limit are dropped immediately, which keeps the server from being exhausted by clients that open sockets and never send anything.

Using Docker

Build the image:

$ docker build -t mjml-tcpserver .

You can specify build arguments:

$ docker build -t mjml-tcpserver \
  --build-arg MJML_VERSION=4.18.0 \
  --build-arg EXPOSE=28101 \
  --no-cache .

Look at the Dockerfile to see the default values of arguments.

Then run a docker container:

$ docker run -d --rm -p 28101:28101 mjml-tcpserver

You can set host and port of the server using env vars:

$ docker run -d --rm -p 28105:28105 -e HOST=127.0.0.1 -e PORT=28105 mjml-tcpserver

To set mjml options pass arguments as cmd using mjml. prefix:

$ docker run -d --rm -p 28101:28101 mjml-tcpserver --mjml.minify=true --mjml.validationLevel=strict

All MJML arguments are listed here.

Stop the server on touch a file

If you wish the server to be stopped when a file is touched, use --touchstop=/tmp/mjmltcpserver.stop.

Be sure the file exists. In case with Docker you can mount that file using a volume.

Daemonize the server using supervisor

Example of configuration file:

/etc/supervisor/conf.d/mjmltcpserver.conf

[program:mjmltcpserver]
user=user
environment=NODE_PATH=/home/user/node_modules
command=node
    /home/user/mjml-tcpserver/tcpserver.js
    --port=28101 --host=127.0.0.1 --touchstop=/tmp/mjmltcpserver.stop --mjml.minify=true --mjml.validationLevel=strict
stdout_logfile=/var/log/supervisor/mjmltcpserver.log
autostart=true
autorestart=true
redirect_stderr=true
stopwaitsecs=10
stopsignal=INT

Docker compose

Example:

services:
  mjml-1:
    image: liminspace/mjml-tcpserver:1
    restart: always
    ports:
      - "28101:28101"

  mjml-2:
    image: liminspace/mjml-tcpserver:1
    restart: always
    environment:
      HOST: "0.0.0.0"
      PORT: "28102"
    expose:
      - "28102"
    ports:
      - "28102:28102"
    command: ["--mjml.minify=true", "--mjml.validationLevel=strict"]

  mjml-3:
    build:
      context: .
      args:
        - MJML_VERSION=4.17.2
        - EXPOSE=28103
    restart: always
    ports:
      - "28103:28103"

Verbosity

To get more std output, use --verbose=true:

node tcpserver.js --host=0.0.0.0 --port=28101 --verbose=true

docker run -d --rm -p 28101:28101 mjml-tcpserver --verbose=true