Adds better local-run instructions for misbehaving-jmx-server in docker

tools/misbehaving-jmx-server/README.md

@@ -52,9 +52,18 @@ There are a couple of ways you can get the Agent to pull metrics from this test
 Copy `misbehaving-jmxfetch-conf.yaml` to `/etc/datadog-agent/conf.d/` and just run the `with-dependencies` jar created by Maven.
 You will need to restart the Agent to pick up the config.
 
+### Using Docker Compose
+
+```shell
+$ docker compose up
+```
+
+The Agent will auto discover the container and begin to collect metrics from it.
+
 ### Using Docker
 
-After building the `misbehaving-jmx-server` you can simply run:
+If your container's IP is directly
+accessible by your Agent, you can use the following run command and use AD.
 
 ```shell
 $ docker run \
@@ -66,10 +75,7 @@ misbehaving-jmx-server
 
 The Agent will auto discover the container and begin to collect metrics from it.
 
-### Using Docker Compose
+Note that this implicitly sets the `RMI_HOSTNAME` to `localhost` which is where
+the host port mapping comes into play. If this is giving you trouble, consider
+using the docker-compose setup above.
 
-```shell
-$ docker compose up
-```
-
-The Agent will auto discover the container and begin to collect metrics from it.

tools/misbehaving-jmx-server/docker-compose.yaml

@@ -2,11 +2,24 @@
 version: "3.9"
 
 services:
-
-  test-server:
+  # The docker compose service name is used as the hostname for the misbehaving-jmx-server
+  # Note it is in the entrypoint as the --rmi-host and in the AD label as the hostname
+  # that the Agent should reach out to.
+  jmx-test-server:
     build:
       context: .
+    # Override entrypoint to specify the docker-compose service name as the RMI host
+    entrypoint: ["java", "-cp", "misbehavingjmxserver-1.0-SNAPSHOT-jar-with-dependencies.jar", "org.datadog.misbehavingjmxserver.App", "--rmi-host", "jmx-test-server"]
     ports:
       - "1099:1099"
     labels:
-      com.datadoghq.ad.checks: '{"misbehaving":{"init_config":{"is_jmx":true},"instances":[{"host":"%%host%%","port":"1099","collect_default_jvm_metrics":false,"max_returned_metrics":300000,"conf":[{"include":{"domain":"Bohnanza"}}]}]}}'
+      com.datadoghq.ad.checks: '{"misbehaving":{"init_config":{"is_jmx":true},"instances":[{"host":"jmx-test-server","port":"1099","collect_default_jvm_metrics":false,"max_returned_metrics":300000,"conf":[{"include":{"domain":"Bohnanza"}}]}]}}'
+  datadog:
+    image: datadog/agent:7-jmx
+    pid: host
+    environment:
+     - DD_API_KEY=000000001
+    volumes:
+     - /var/run/docker.sock:/var/run/docker.sock
+     - /proc/:/host/proc/:ro
+     - /sys/fs/cgroup:/host/sys/fs/cgroup:ro