monit-docker

Monit packaged as a small Alpine-based Docker image, with built-in Slack and Pushover notification scripts.

Monit is a free open-source utility for managing and monitoring processes, programs, files, directories and filesystems on UNIX systems. It conducts automatic maintenance and repair and can execute meaningful causal actions in error situations.

Image

ghcr.io/diogopms/monit-docker

Tag	Meaning
latest	Latest release
X	Latest release in that major version
X.Y	Latest release in that minor version
X.Y.Z	Exact release

Supported platforms: linux/amd64, linux/arm64 (Raspberry Pi 3/4/5 with a 64-bit OS).

Quick start

Write a monitrc (see samples/ and the examples below), then:

docker run -d \
  -p 2812:2812 \
  -v "$(pwd)/monitrc:/etc/monitrc" \
  ghcr.io/diogopms/monit-docker

Or with Docker Compose (docker-compose.yaml):

services:
  monit:
    image: ghcr.io/diogopms/monit-docker:latest
    container_name: monit
    environment:
      - TZ=Europe/Lisbon
    volumes:
      - ./monitrc:/etc/monitrc
    ports:
      - 2812:2812
    restart: unless-stopped

To use Monit's web interface, uncomment set httpd port 2812 in your monitrc and open http://localhost:2812.

Configuration

Mount your Monit control file at /etc/monitrc. The entrypoint copies it to a root-owned file with 0700 permissions before starting Monit (Monit refuses configs with looser permissions), so you don't need to fix permissions on the host.

Environment variables

Variable	Description
SLACK_URL	Slack incoming-webhook URL (required for /bin/slack)
PUSH_OVER_TOKEN	Pushover API token (required for /bin/pushover)
PUSH_OVER_USER	Pushover API user key (required for /bin/pushover)
DEBUG	Set to 1 to run Monit in verbose mode

docker run -d \
  -p 2812:2812 \
  -v "$(pwd)/monitrc:/etc/monitrc" \
  -e "SLACK_URL=<SLACK_URL>" \
  -e "PUSH_OVER_TOKEN=<PUSH_OVER_TOKEN>" \
  -e "PUSH_OVER_USER=<PUSH_OVER_USER>" \
  ghcr.io/diogopms/monit-docker

Notifications

The image ships two notification scripts you can call from exec actions in your monitrc:

• /bin/slack — posts the Monit event to a Slack incoming webhook (SLACK_URL)
• /bin/pushover — sends the Monit event via Pushover (PUSH_OVER_TOKEN + PUSH_OVER_USER)

Example monitrc (Slack)

set daemon 20
set log syslog
# Web interface
# set httpd port 2812 and allow admin:monit

check host www.google.com with address www.google.com
  if failed
      port 443 protocol https
      request /
      status = 200
      for 2 cycles
  then exec "/bin/slack"
    else if succeeded then exec "/bin/slack"

Example monitrc (Pushover)

set daemon 20
set log syslog
# Web interface
# set httpd port 2812 and allow admin:monit

check host www.google.com with address www.google.com
  if failed
      port 443 protocol https
      request /
      status = 200
      for 2 cycles
  then exec "/bin/pushover"
    else if succeeded then exec "/bin/pushover"

More examples in samples/.

Building locally

docker build -t monit .
docker run -d -p 2812:2812 -v "$(pwd)/monitrc:/etc/monitrc" monit

The build compiles Monit from source (checksum-verified) in a builder stage and ships only the compiled binary plus runtime dependencies.

Releases & versioning

Versions follow SemVer driven by Conventional Commits:

• A scheduled workflow runs monthly; if any feat/fix/breaking commit landed since the last tag, it builds and pushes the multi-arch image to GHCR, then creates the git tag and GitHub Release.
• fix: → patch, feat: → minor, feat!:/BREAKING CHANGE → major. Anything else does not release.
• A release can be forced manually: Actions → Release → "Run workflow" → pick a bump level.

Troubleshooting

• The control file '/etc/monitrc' permission 0755 is wrong, maximum 0700 allowed — the entrypoint normally handles this; if you run Monit against the mounted file directly, run chmod 700 monitrc on the host.
• Verbose logging — set DEBUG=1 to start Monit with -v.

License

MIT