[docker] disable APM by default, document changes (DataDog#1268)

Dockerfiles/agent/Dockerfile

@@ -49,7 +49,11 @@ ARG WITH_JMX
 ENV DOCKER_DD_AGENT=yes \
     PATH=/opt/datadog-agent/bin/agent/:/opt/datadog-agent/embedded/bin/:$PATH \
     CURL_CA_BUNDLE=/opt/datadog-agent/embedded/ssl/certs/cacert.pem \
-    TERM=xterm \
+    # Disable dsd, apm and logs listening until user decides so, to avoid unknown open ports
+    DD_DOGSTATSD_NON_LOCAL_TRAFFIC=false \
+    DD_APM_ENABLED=false \
+    DD_APM_NON_LOCAL_TRAFFIC=true \
+    DD_LOGS_ENABLED=false \
     # Pass envvar variables to agents
     S6_KEEP_ENV=1 \
     # Direct all agent logs to stdout

Dockerfiles/agent/README.md

@@ -28,9 +28,11 @@ The agent is highly customizable, here are the most used environment variables:
 
 ##### Optional collection agents
 
+These features are disabled by default for security or performance reasons, you need to explicitly enable them:
+
 - `DD_APM_ENABLED`: run the trace-agent along with the infrastructure agent, allowing the container to accept traces on 8126/tcp
-- `DD_PROCESS_AGENT_ENABLED`: run the [process-agent](https://docs.datadoghq.com/graphing/infrastructure/process/) along with the infrastructure agent, feeding data to the Live Process View and Live Containers View
 - `DD_LOGS_ENABLED`: run the [log-agent](https://docs.datadoghq.com/logs/) along with the infrastructure agent. [See below for details](#log-collection)
+- `DD_PROCESS_AGENT_ENABLED`: enable live process collection in the [process-agent](https://docs.datadoghq.com/graphing/infrastructure/process/). The Live Container View is already enabled by default if the Docker socket is available
 
 ##### Dogstatsd (custom metrics)
 

docs/agent/changes.md

@@ -193,7 +193,12 @@ The APM agent (also known as _trace agent_) is shipped by default with the
 Agent 6 in the Linux, MacOS and Windows packages.
 
 Similar to the Agent 5, the APM agent is enabled by default. To disable it, set
-`apm_enabled` to `false` in the main agent configuration (`datadog.yaml`).
+`apm_enabled` to `false` in the main agent configuration (`datadog.yaml`). It only
+listens to localhost by default. You can set `apm_config.apm_non_local_traffic = true`
+to enable listening on the network.
+
+In the Docker image, the APM agent is disabled by default. You can enable it by setting
+the `DD_APM_ENABLED` envvar to `true`. It will listen to all interfaces by default.
 
 _Optional_: If you need to use apm-specific configuration options (i.e. options that would be
 specified under the `[trace.config]`, `[trace.sampler]` and `[trace.receiver]` in

releasenotes/notes/disable-apm-default-f32eaa7cb3d7f157.yaml

@@ -0,0 +1,9 @@
+---
+upgrade:
+  - |
+    Normal installations: APM now listens to localhost only by default, you need to set
+    `apm_config.apm_non_local_traffic = true` to enable listening on the network
+  - |
+    Docker image: APM is now disabled by default, you need to set `DD_APM_ENABLED=true`
+    to run the trace agent. It listens on all interfaces by default when running, you can
+    set `DD_APM_NON_LOCAL_TRAFFIC=false` to only listen on localhost