Auto init via environment variables support, qu init for systemd

docker/docker-compose-tailscale.yml

@@ -1,5 +1,14 @@
 # An example of a docker compose with Tailscale & QUptime.
-# This setup is specifically intended for hosts that may not be able to reach each other directly or have a public IP address.
+# This setup is specifically intended for hosts that may not be able to
+# reach each other directly or have a public IP address.
+#
+# Bring it up with `docker compose -f docker-compose-tailscale.yml up -d`.
+# QUptime auto-initialises on first start using the QUPTIME_* env vars
+# below — no separate `qu init` step is required.
+#
+# On the first node, omit QUPTIME_CLUSTER_SECRET to have one generated
+# for you. Read it out of the logs (`docker logs quptime`) and copy it
+# into the .env of every other node before bringing them up.
 
 services:
   tailscale:
@@ -18,20 +27,28 @@ services:
   quptime:
     image: git.cer.sh/axodouble/quptime:master
     container_name: quptime
+    environment:
+      # host:port other QUptime nodes use to reach this one. Use the
+      # Tailscale IP / MagicDNS name of this host. Required behind NAT.
+      - QUPTIME_ADVERTISE=${QUPTIME_ADVERTISE}
+      # Shared cluster join secret. Set on every node. Leave unset on
+      # the very first node — one will be generated and logged for you
+      # to copy to the others. Followers MUST set this before starting.
+      - QUPTIME_CLUSTER_SECRET=${QUPTIME_CLUSTER_SECRET:-}
+      # Optional: pin a port other than the default 9901.
+      # - QUPTIME_BIND_PORT=9901
     volumes:
       - quptime:/etc/quptime
     ports:
       - "9901:9901"
     depends_on:
       - tailscale
-    # No restart directive, user needs to init quptime first
-    # Run `docker compose -f docker-compose-tailscale.yml run --rm quptime init` to initialize 
-    # the data volume before starting the service
-    # If this is not the master node, use 
-    # `docker compose -f docker-compose-tailscale.yml run --rm quptime --advertise <TAILSCALE_IP>:9901 --secret <SECRET>`
-    # And add the individual nodes to the cluster with `docker compose -f docker-compose-tailscale.yml run --rm quptime node add <OTHER_NODE_IP>:9901`
     network_mode: "service:tailscale" # Use the Tailscale network stack
+    restart: unless-stopped
+    # After this node is up, add peers from the master with:
+    #   docker compose -f docker-compose-tailscale.yml exec quptime \
+    #     qu node add <OTHER_NODE_TAILSCALE_IP>:9901
 
 volumes:
   tailscale:
-  quptime:
+  quptime: