Add aws_ec2_instance_states configuration option

lukebakken · lukebakken · commit a3d80ddf524e · 2026-02-03T19:29:47.000Z
Adds a new configuration option to filter EC2 instances by state during
peer discovery. This prevents dead or dying instances from being included
in cluster membership during node joins.

The configuration accepts a list of instance state names to include in
discovery results. The default value is `["running", "pending"]`, which
excludes instances in `stopping`, `stopped`, `shutting-down`, and
`terminated` states.

Configuration can be set via `rabbitmq.conf`:

    cluster_formation.aws.ec2_instance_states.1 = running
    cluster_formation.aws.ec2_instance_states.2 = pending

Or via environment variable:

    AWS_EC2_INSTANCE_STATES="running,pending"

The schema file includes cuttlefish mappings to support the
`rabbitmq.conf` syntax, and test snippets verify the configuration
parsing works correctly for both single and multiple state values.
diff --git a/deps/rabbitmq_peer_discovery_aws/priv/schema/rabbitmq_peer_discovery_aws.schema b/deps/rabbitmq_peer_discovery_aws/priv/schema/rabbitmq_peer_discovery_aws.schema
@@ -108,3 +108,17 @@ fun(Conf) ->
         Value     -> rabbit_peer_discovery_util:as_list(Value)
     end
 end}.
+
+%% ec2_instance_states
+
+{mapping, "cluster_formation.aws.ec2_instance_states.$state", "rabbit.cluster_formation.peer_discovery_aws.aws_ec2_instance_states", [
+    {datatype, string}
+]}.
+
+{translation, "rabbit.cluster_formation.peer_discovery_aws.aws_ec2_instance_states",
+fun(Conf) ->
+    case cuttlefish_variable:filter_by_prefix("cluster_formation.aws.ec2_instance_states", Conf) of
+        [] -> ["running", "pending"];
+        Settings -> [V || {_K, V} <- Settings]
+    end
+end}.
diff --git a/deps/rabbitmq_peer_discovery_aws/src/rabbit_peer_discovery_aws.erl b/deps/rabbitmq_peer_discovery_aws/src/rabbit_peer_discovery_aws.erl
@@ -66,6 +66,11 @@
                                                    type          = atom,
                                                    env_variable  = "AWS_USE_PRIVATE_IP",
                                                    default_value = false
+                                                  },
+          aws_ec2_instance_states            => #peer_discovery_config_entry_meta{
+                                                   type          = list,
+                                                   env_variable  = "AWS_EC2_INSTANCE_STATES",
+                                                   default_value = ["running", "pending"]
                                                   }
          }).
 
diff --git a/deps/rabbitmq_peer_discovery_aws/test/config_schema_SUITE_data/rabbitmq_peer_discovery_aws.snippets b/deps/rabbitmq_peer_discovery_aws/test/config_schema_SUITE_data/rabbitmq_peer_discovery_aws.snippets
@@ -103,5 +103,30 @@
                 ]}
             ]}
         ], [rabbitmq_peer_discovery_aws]
+    },
+    {aws_ec2_instance_states,
+        "cluster_formation.aws.ec2_instance_states.1 = running
+         cluster_formation.aws.ec2_instance_states.2 = pending",
+        [
+            {rabbit, [
+                {cluster_formation, [
+                    {peer_discovery_aws, [
+                        {aws_ec2_instance_states, ["running", "pending"]}
+                    ]}
+                ]}
+            ]}
+        ], [rabbitmq_peer_discovery_aws]
+    },
+    {aws_ec2_instance_states_single,
+        "cluster_formation.aws.ec2_instance_states.1 = running",
+        [
+            {rabbit, [
+                {cluster_formation, [
+                    {peer_discovery_aws, [
+                        {aws_ec2_instance_states, ["running"]}
+                    ]}
+                ]}
+            ]}
+        ], [rabbitmq_peer_discovery_aws]
     }
 ].
