Add CONSUL_RETRY_JOIN_WAN env

README.md

@@ -82,6 +82,15 @@ services:
 
 In our experience, including a Consul cluster within a project's `docker-compose.yml` can help developers understand and test how a service should be discovered and registered within a wider infrastructure context.
 
+#### Environment Variables
+
+- `CONSUL_DATACENTER_NAME`: sets the name of the data center in which the Consul cluster is running.
+- `CONSUL_RETRY_JOIN_WAN`: sets the remote datacenter addresses to join. Must be a valid HCL list (i.e. comma-separated quoted addresses). See Consul's [configuration documentation](https://www.consul.io/docs/agent/options.html#retry_join_wan) for more information.
+    - The following error will occur if `CONSUL_RETRY_JOIN_WAN` is provided but improperly formatted:
+    ```
+    ==> Error parsing /etc/consul/consul.hcl: ... unexpected token while parsing list: IDENT
+    ```
+
 ### Clients
 
 ContainerPilot utilizes Consul's [HTTP Agent API](https://www.consul.io/api/agent.html) for a handful of endpoints, such as `UpdateTTL`, `CheckRegister`, `ServiceRegister` and `ServiceDeregister`. Connecting ContainerPilot to Consul can be achieved by running Consul as a client to a cluster (mentioned above). It's easy to run this Consul client agent from ContainerPilot itself.

bin/consul-manage

@@ -8,6 +8,14 @@ set -eo pipefail
 preStart() {
     _log "Updating consul advertise address"
     sed -i "s/CONTAINERPILOT_CONSUL_IP/${CONTAINERPILOT_CONSUL_IP}/" /etc/consul/consul.hcl
+
+    _log "Updating consul datacenter name"
+    sed -i "s/CONSUL_DATACENTER_NAME/${CONSUL_DATACENTER_NAME:-dc1}/" /etc/consul/consul.hcl
+
+    if [ ! -z "$CONSUL_RETRY_JOIN_WAN" ]; then
+        _log "Updating consul retry_join_wan field"
+        echo "retry_join_wan = [${CONSUL_RETRY_JOIN_WAN}]" >> /etc/consul/consul.hcl
+    fi
 }
 
 #

etc/consul.hcl

@@ -1,4 +1,5 @@
 bind_addr = "CONTAINERPILOT_CONSUL_IP"
+datacenter = "CONSUL_DATACENTER_NAME"
 data_dir = "/data"
 client_addr = "0.0.0.0"
 ports {

local-compose.yml

@@ -7,13 +7,39 @@ services:
   # created user-defined network and internal DNS for the name "consul".
   # Nodes will use Docker DNS for the service (passed in via the CONSUL
   # env var) to find each other and bootstrap the cluster.
-  consul:
+  consul1:
     build: .
+    image: autopilotpattern/consul:${TAG:-latest}
     restart: always
     mem_limit: 128m
     ports:
         - 8500
     environment:
-      - CONSUL=consul
+      - CONSUL=consul1
+      - CONSUL_DATACENTER_NAME=dc1
     command: >
       /usr/local/bin/containerpilot
+
+  # The following service block defines a nearly-identical deployment in a
+  # fictional second datacenter. This can be used to test multi-datacenter
+  # behavior in Consul.
+  # NOTE: CONSUL_RETRY_JOIN_WAN *must* be a valid HCL list,
+  # e.g.:
+  #    "1.1.1.1"
+  # or
+  #    "1.1.1.1","2.2.2.2"
+
+  consul2:
+    image: autopilotpattern/consul:${TAG:-latest}
+    restart: always
+    mem_limit: 128m
+    ports:
+        - 8500
+    environment:
+      - CONSUL=consul2
+      - CONSUL_DATACENTER_NAME=dc2
+      - CONSUL_RETRY_JOIN_WAN="consul1"
+    command: >
+      /usr/local/bin/containerpilot
+    links:
+      - consul1