diff --git a/.env.sample b/.env.sample
index 1fb4d18..79335e9 100644
--- a/.env.sample
+++ b/.env.sample
@@ -4,24 +4,27 @@ LETS_ENCRYPT_ENV=production
 COMPOSE_FILE=compose.yml
 DOMAIN=monitoring.example.com
 
-# Gathering Metrics (Node Exporter, Cadvisor)
-COMPOSE_FILE="$COMPOSE_FILE:compose.metrics.yml"
-SECRET_BASIC_AUTH_ADMIN_PASSWORD_VERSION=v1
-
-
-# Gathering Logs (Promtail)
+# Monitoring Client
+#
+## Node Exporter, Cadvisor (Gathering Metrics)
+# COMPOSE_FILE="$COMPOSE_FILE:compose.metrics.yml"
+#
+## Enable this secret for Promtail / Prometheus
+# SECRET_BASIC_AUTH_ADMIN_PASSWORD_VERSION=v1
+#
+# Promtail (Gathering Logs)
 # COMPOSE_FILE="$COMPOSE_FILE:compose.promtail.yml"
 # LOKI_PUSH_URL=https://loki.monitoring.example.org/loki/api/v1/push
 
-
+# Monitoring Server
+#
 ## Prometheus, Alertmanager
 # COMPOSE_FILE="$COMPOSE_FILE:compose.prometheus.yml"
 # ALERTMANAGER_SMTP_FROM=noreply@autonomic.zone
 # ALERTMANAGER_SMTP_HOST=mail.gandi.net:587
 # ALERTMANAGER_SMTP_TO=kaboom@autonomic.zone
 # SECRET_ALERTMANAGER_SMTP_PASSWORD_VERSION=v1
-
-
+# PROMETHEUS_RETENTION_TIME=1y
 ## Loki
 # Loki Server
 #
@@ -35,8 +38,7 @@ SECRET_BASIC_AUTH_ADMIN_PASSWORD_VERSION=v1
 # LOKI_ACCESS_KEY_ID=bush-debrief-approval-robust-scraggly-molecule
 # LOKI_BUCKET_NAMES=loki
 # SECRET_LOKI_AWS_SECRET_ACCESS_KEY_VERSION=v1
-
-
+#
 ## Grafana
 #
 # COMPOSE_FILE="$COMPOSE_FILE:compose.grafana.yml"
diff --git a/compose.prometheus.yml b/compose.prometheus.yml
index eccea5e..13d390e 100644
--- a/compose.prometheus.yml
+++ b/compose.prometheus.yml
@@ -15,6 +15,7 @@ services:
       - "--storage.tsdb.path=/prometheus"
       - "--web.console.libraries=/usr/share/prometheus/console_libraries"
       - "--web.console.templates=/usr/share/prometheus/consoles"
+      - "--storage.tsdb.retention.time=${PROMETHEUS_RETENTION_TIME}"
     networks:
       - proxy
       - internal
@@ -23,7 +24,7 @@ services:
         condition: on-failure
       labels:
         - "traefik.enable=true"
-        - "traefik.http.services.${STACK_NAME}_prometheus.loadbalancer.server.port=9090"
+        - "traefik.http.services.${STACK_NAME}-prometheus.loadbalancer.server.port=9090"
         - "traefik.http.routers.${STACK_NAME}-prometheus.rule=Host(`prometheus.${DOMAIN}`)"
         - "traefik.http.routers.${STACK_NAME}-prometheus.entrypoints=web-secure"
         - "traefik.http.routers.${STACK_NAME}-prometheus.tls=true"