Push freshness metric to Prometheus Pushgateway

README.md

Generic Docker image to push a freshness metric to the Prometheus Pushgateway.

This metric can be used to determine whether a (cron) job was executed within a certain period or not.

This will push the metric freshness{job="Example",name="Foo",branch="Bar"} to the Pushgateway:

PUSHGATEWAY=https://prometheus.example.com:9091
docker run -t --rm -e PUSHGATEWAY=$PUSHGATEWAY freshness job=Example name=Foo branch=Bar

Note that you must always specify the PUSHGATEWAY endpoint and the job key-value pair.

Dockerfile

FROM alpine

RUN apk add --update bash curl ca-certificates

ADD freshness.sh /usr/bin/freshness

ENTRYPOINT ["/usr/bin/freshness"]

freshness.sh

#!/bin/bash

set -e
set -o pipefail

job=
suffix=

while test $# -gt 0; do
    key=$(echo $1 | cut -d= -f1)
    value=$(echo $1 | cut -d= -f2)
    case "$key" in
    job)  job="$value" ;;
    *)    suffix="$suffix/$key/$value" ;;
    esac
    shift
done

if test -z "$job"; then
    echo "error: job key-value pair missing"
    exit 1
fi

if test -z "$PUSHGATEWAY"; then
    echo "error: PUSHGATEWAY env var not set"
    exit 1
fi

freshness=$(date +%s)
echo "freshness = $freshness"

cat <<EOF | curl -fsSL -XPUT --data-binary @- "$PUSHGATEWAY/metrics/job/$job$suffix"
# TYPE freshness gauge
freshness $freshness
EOF