*: evaluate env variables in prometheus.yml (#288)

Evaluate env vars in `prometheus.yml`.

ticket: #289

Author: KaloyanTanev

.env.sample

@@ -93,6 +93,12 @@
 # See available tags https://github.com/prometheus/prometheus/releases.
 #PROMETHEUS_VERSION=
 
+# Prometheus remote write token used for accessing external prometheus.
+#PROM_REMOTE_WRITE_TOKEN=
+
+# Prometheus service owner used to uniquely identify user from which metrics are pushed.
+#SERVICE_OWNER=charon_user
+
 ######### Voluntary Exit Config #########
 
 # This applies to compose-voluntary-exit.yml only

.gitignore

@@ -10,4 +10,5 @@ cluster-lock.json
 .DS_Store
 data/
 .idea
-.charon
+.charon
+prometheus/prometheus.yml

docker-compose.yml

@@ -142,12 +142,13 @@ services:
     image: prom/prometheus:${PROMETHEUS_VERSION:-v2.50.1}
     user: ":"
     networks: [dvnode]
+    environment:
+      - PROM_REMOTE_WRITE_TOKEN=${PROM_REMOTE_WRITE_TOKEN}
+      - SERVICE_OWNER=${SERVICE_OWNER}
     volumes:
-      - ./prometheus/prometheus.yml:/etc/prometheus/prometheus.yml
+      - ./prometheus:/etc/prometheus
       - ./data/prometheus:/prometheus
-    command: 
-      - "--enable-feature=expand-external-labels"
-      - "--config.file=/etc/prometheus/prometheus.yml"
+    entrypoint: /etc/prometheus/run.sh
     restart: unless-stopped
 
   grafana:

prometheus/prometheus.yml renamed to prometheus/prometheus.yml.example

@@ -7,7 +7,7 @@ global:
 remote_write:
   - url: https://vm.monitoring.gcp.obol.tech/write
     authorization:
-      credentials: $PROM_REMOTE_WRITE_TOKEN
+      credentials: ${PROM_REMOTE_WRITE_TOKEN}
     write_relabel_configs:
       - source_labels: [job]
         regex: "charon"

prometheus/run.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+
+if [ -z "$SERVICE_OWNER" ]
+then
+  echo "\$SERVICE_OWNER variable is empty"
+fi
+
+if [ -z "$PROM_REMOTE_WRITE_TOKEN" ]
+then
+  echo "\$PROM_REMOTE_WRITE_TOKEN variable is empty"
+fi
+
+# eval is used instead of envsubst, as prometheus user doesn't have permissions to install envsubst
+eval "echo \"$(cat /etc/prometheus/prometheus.yml.example)\"" > /etc/prometheus/prometheus.yml
+
+/bin/prometheus \
+  --config.file=/etc/prometheus/prometheus.yml