mkalertmanagercfg

#!/bin/sh
set -o errexit -o nounset -o pipefail

if [ -z "${SMTP_TO-}" ]; then
	echo "SMTP_TO recipient required"
	exit 1
fi

alertmanager_cfg="$1"

cat > "$alertmanager_cfg" << EOF
global:
  smtp_smarthost: '${SMTP_SMARTHOST:-localhost:25}'
  smtp_from: '${SMTP_FROM:-noreply@example.com}'
EOF
if [ -n "${SMTP_LOGIN-}" -a -n "${SMTP_PASSWORD-}" ]; then
cat >> "$alertmanager_cfg" << EOF
  smtp_auth_username: '$SMTP_LOGIN'
  smtp_auth_password: '$SMTP_PASSWORD'
EOF
fi

cat >> "$alertmanager_cfg" << EOF

route:
 group_by: [cluster]
 group_wait: 30s
 group_interval: 5m
 repeat_interval: 3h
 receiver: email
EOF

routes=''
receivers=''
for pd_key in $(env | grep -e '^PAGERDUTY_[A-Za-z0-9_]\+_KEY')
do
	key=$(echo $pd_key | cut -d = -f 1 | tr A-Z a-z)
	value=$(echo $pd_key | cut -d = -f 2-)  # BusyBox's ash doesn't know about ${!key} or arrays
	key=${key:10}; key=${key%_key}; key=${key//_/-}
  if [ -z "$routes" ]; then
    routes=" routes:\n"
  fi
  echo "Adding PagerDuty Service $key"
	routes="$routes  - match:\n      severity: $key\n    receiver: pagerduty-$key\n"
  receivers="$receivers- name: pagerduty-$key\n  pagerduty_configs:\n  - service_key: '$value'\n"
done

if [ -n "$routes" ]; then
  echo -ne "$routes" >> "$alertmanager_cfg"
fi

cat >> "$alertmanager_cfg" << EOF

receivers:
- name: email
  email_configs:
  - to: '$SMTP_TO'
EOF
if [ -n "$receivers" ]; then
  echo -ne "$receivers" >> "$alertmanager_cfg"
fi