Fix environment variable fallbacks for plugins. (#1299)

changelogs/fragments/1299-env.yml

@@ -0,0 +1,3 @@
+bugfixes:
+  - "docker_api connection plugin - the environment fallbacks for ``docker_host``, ``tls_hostname``, ``api_version``, ``timeout``, ``tls``, and ``validate_certs`` now finally work (https://github.com/ansible-collections/community.docker/issues/1298, https://github.com/ansible-collections/community.docker/pull/1299)."
+  - "docker_containers inventory plugin - the environment fallbacks for ``docker_host``, ``tls_hostname``, ``api_version``, ``timeout``, ``tls``, and ``validate_certs`` now finally work (https://github.com/ansible-collections/community.docker/issues/1298, https://github.com/ansible-collections/community.docker/pull/1299)."

plugins/connection/docker_api.py

@@ -19,6 +19,7 @@ notes:
     with Python's C(SSLSocket)s. See U(https://github.com/ansible-collections/community.docker/issues/605) for more information.
 extends_documentation_fragment:
   - community.docker._docker.api_documentation
+  - community.docker._docker.api_environment_documentation
   - community.docker._docker.var_names
 options:
   remote_user:

plugins/doc_fragments/_docker.py

@@ -387,3 +387,25 @@ notes:
   - This module does B(not) use the L(Docker SDK for Python,https://docker-py.readthedocs.io/en/stable/) to
     communicate with the Docker daemon. It directly calls the Docker CLI program.
 """
+
+    API_ENVIRONMENT_DOCUMENTATION = r"""
+options:
+  docker_host:
+    env:
+      - name: DOCKER_HOST
+  tls_hostname:
+    env:
+      - name: DOCKER_TLS_HOSTNAME
+  api_version:
+    env:
+      - name: DOCKER_API_VERSION
+  timeout:
+    env:
+      - name: DOCKER_TIMEOUT
+  tls:
+    env:
+      - name: DOCKER_TLS
+  validate_certs:
+    env:
+      - name: DOCKER_TLS_VERIFY
+"""

plugins/inventory/docker_containers.py

@@ -17,6 +17,7 @@ author:
 extends_documentation_fragment:
   - ansible.builtin.constructed
   - community.docker._docker.api_documentation
+  - community.docker._docker.api_environment_documentation
   - community.library_inventory_filtering_v1.inventory_filter
 description:
   - Reads inventories from the Docker API.