runner: a lightweight wrapper for cron jobs

runner runs a program, capturing its output and printing it only if the program fails.

Output can also be printed if the program produces, or does not produce, a specific string; and output is optionally written to a log directory regardless of program exit status.

Use Cases

This is particularly useful when running a program via cron, when you only want to see its output (typically via email) in case of failure or when specific outputs occur.

Installation

Requirements: Go >= 1.13.

make install will build runner for your current OS/architecture and install it to /usr/local/bin.

Usage

[RUNNER_LOG_DIR="$HOME/log/runner"] runner [OPTIONS] -- /path/to/program --program-args

Options

• -healthy-exit int: "Healthy" or "success" exit codes. May be specified multiple times to provide more than one success exit code. (default: 0)
• -hide-env: Hide the process’s environment, which is normally printed & logged as part of the output.
• -job-name string: Job name used in failure notifications and log file name. (default: program name, without path)
• -log-dir string: The directory to write run logs to. Can also be set by the RUNNER_LOG_DIR environment variable; this flag overrides the environment variable.
• -print-if-match string: Print output if the given (case-sensitive) string appears in the program’s output, even if it was a healthy exit. May be specified multiple times.
• -print-if-not-match string: Print output if the given (case-sensitive) string does not appear in the program’s output, even if it was a healthy exit. May be specified multiple times.
• -retries int: If the program fails, retry it this many times.
• -work-dir string: Set the working directory for the program. Optional.

Sample Output

Success running exampledatejob
Command: /bin/date
Exit code: 0
Working directory: /home/ubuntu

Duration: 3.794033ms
Start time: 2020-05-27 09:17:59 -0400
End time: 2020-05-27 09:17:59 -0400

--- Program output follows: ---

Wed May 27 09:17:59 EDT 2020

Log Storage

I store my personal logs in $HOME/log/runner. Accomplish this by setting the RUNNER_LOG_DIR environment variable at the top of your crontab:

RUNNER_LOG_DIR=/home/myusername/log/runner

runner will create this folder for you if it doesn’t already exist.

Removing Old Logs

Schedule a cleanup job to run daily via cron:

RUNNER_LOG_DIR="/home/myusername/log/runner"
# ...
0	0	*	*	*	/usr/bin/find "$RUNNER_LOG_DIR" -mtime +30 -name "*.log" -delete

This will remove logs older than 30 days.

About

• Issues: https://github.com/cdzombak/runner/issues/new
• Author: Chris Dzombak