Overview

Extends the prom/alertmanager image and includes a8m/envsubst to provide environment substitation.

This is intended to be used with https://github.com/coreos/prometheus-operator (hence it's Kubernetes specific).

Why?

Alertmanager does not provide an easy way to substitute secrets into its configuration file.

Various receivers require credentials to authenticate. We want to commit alertmanager configs to Git, but we don't want to commit the credentials (at least not in the same file).

Usage

The Alertmanager CRD supports mounting of both secrets and configmaps.

configMaps: ConfigMaps is a list of ConfigMaps in the same namespace as the Alertmanager object, which shall be mounted into the Alertmanager Pods. The ConfigMaps are mounted into /etc/alertmanager/configmaps/.

secrets: Secrets is a list of Secrets in the same namespace as the Alertmanager object, which shall be mounted into the Alertmanager Pods. The Secrets are mounted into /etc/alertmanager/secrets/.

Create a configmap

You must create a ConfigMap named alertmanager containing the config to be templated.

This must be added to the configMaps option in the CRD.

Create 1 or more secrets

You must create 1 or more secrets and add them to the secrets option in the CRD.

Example:

kubectl create secret generic alertmanager \
 --from-literal=TEAM_DB_API_KEY=foo \
 --from-literal=TEAM_X_API_KEY=foo \
 --from-literal=TEAM_Y_API_KEY=foo --dry-run -o yaml

You can test this locally with the example ./configmaps and ./secrets directories in this repo.

Local testing

docker run \
    -v $(pwd)/configmaps:/etc/alertmanager/configmaps \
    -v $(pwd)/secrets:/etc/alertmanager/secrets
    mintel/docker-alertmanager