elastic_cron/README.md

Luzifer / rsyslog_cron

This project is a quick and dirty replacement for running a cron daemon inside docker containers.

Advantages

• It logs the output of the jobs into a remote syslog target (like Papertrail) using TCP syslog
• Crons can be started on seconds, not only on minutes like a conventional cron
• Due to the logs cron jobs can get debugged
• On success and failure a HTTP ping to Healthchecks or Cronitor can be executed

Usage

1. Put the binary into your container
2. Generate a YAML file containing the cron definition
3. Watch your crons get executed in your log stream

Config format

---
rsyslog_target: logs.myserver.com:12345
log_format: '<{{ syslogpri .Severity }}>{{ .Date.Format "Jan 02 15:04:05" }} {{ .Hostname }} {{ .JobName }}: {{ .Message }}'
jobs:
  - name: date
    schedule: "0 * * * * *"
    cmd: "/bin/date"
    args:
      - "+%+"
    ping_success: "https://..."
    ping_failure: "https://..."

• rsyslog_target - needs to be a rsyslog endpoint supporting TCP plain connections like Loggly or Papertrail does.
• log_format - format to use for generating the log line (above shown is default and does not need to be provided)
• schedule - consists of 6 instead of the normal 5 fields:

field         allowed values
-----         --------------
second        0-59
minute        0-59
hour          0-23
day of month  1-31
month         1-12 (or names, see below)
day of week   0-7 (0 or 7 is Sun, or use names)

Standard format for crontab entries is supported. (See man 5 crontab)