Config-watcher

Small go application for use as a sidecar container in a K8s environments. Watches configmap-provisioned files, and reloads processes if their config file changed.

Example usage

export RELOAD_SIGNAL=SIGHUP
export TARGET_FILES=/etc/prometheus/prometheus.yml,/etc/prometheus/rules.yml
export TARGET_PROCESS=prometheus

./config-watcher

Configuration

Configuration is done via the following environment variables.

• RELOAD_SIGNAL (required): Signal to send the process to triger a reload. Must be the full signal name, eg SIGHUP or SIGUSR1.
• TARGET_FILES (required): Comma-separated list of paths or glob patterns to files which to watch for changes. Note that these globs might be more restrictive than what you are used to, with not support for eg **/* to match files in arbitarily deep directory hierarchies. See https://golang.org/pkg/path/filepath/#Match for the pattern syntax.
• TARGET_PROCESS (required): Name of process which to send reload signal to.
• SLEEP_DURATION (default 1): Duration in seconds which to sleep between config file checks.
• SLEEP_BEFORE_RELOAD_DURATION (default 1): Duration in seconds which to sleep before sending a reload signal when a change in the watched file was detectd. Ensures config map changes were populated to all containers.