HomeCentr - cron-base

This docker image is used as base image for all homecentr images which require a cron scheduler but can also be used on its own. The image executes a mounted script at the specified schedule and reports the results into a Prometheus push-gateway for easy monitoring and alerting.

Usage

version: "3.7"
services:
  cron-base:
    build: .
    image: homecentr/cron-base
    restart: unless-stopped
    environment:
      CRON_SCHEDULE: "* * * * *" # Run script every minute
      PUSH_GATEWAY_URL: "http://push_gateway:9091/metrics/job/cron/label-name/label-value"
    volumes:
      - ./example/success:/cron # must contain cron-tick script

Environment variables

Name	Default value	Description
PUID	7077	UID of the user the cron-tick script should be running as.
PGID	7077	GID of the group the cron-tick script should be running as.
CRON_SCHEDULE		Cron expression which defines when/how often the script will be executed. This variable is mandatory.
PUSH_GATEWAY_URL		URL of the push gateway job where the metrics should be reported. The reporting is skipped if the variable is not set.

Exposed ports

The image does not expose any ports.

Volumes

Container path	Description
/cron	Directory containing the script which should be executed, the script must be named cron-tick.

Security

The container is regularly scanned for vulnerabilities and updated. Further info can be found in the Security tab.

Container user

The container supports privilege drop. Even though the container starts as root, it will use the permissions only to perform the initial set up. The cron-tick script is executed as UID/GID provided in the PUID and PGID environment variables.

⚠️ Do not change the container user directly using the user Docker compose property or using the --user argument. This would break the privilege drop logic.