docker_swarm_service_info: Read information about swarm services (#55008)

* Add docker_swarm_service_info module

* Remove unused import

* Limit to retrieving info about one service

* Add exists return value

* Add yaml 3-dash

Co-Authored-By: hannseman <hannes@5monkeys.se>

* Document return value as jinja `none´

Co-Authored-By: hannseman <hannes@5monkeys.se>

* Name is required

test/integration/targets/docker_swarm_service_info/aliases

@@ -0,0 +1,7 @@
+shippable/posix/group3
+skip/osx
+skip/freebsd
+destructive
+skip/docker  # The tests sometimes make docker daemon unstable; hence,
+             # we skip all docker-based CI runs to avoid disrupting
+             # the whole CI system.

test/integration/targets/docker_swarm_service_info/meta/main.yml

@@ -0,0 +1,3 @@
+---
+dependencies:
+  - setup_docker

test/integration/targets/docker_swarm_service_info/tasks/main.yml

@@ -0,0 +1,6 @@
+---
+- include_tasks: test_docker_swarm_service_info.yml
+  when: docker_py_version is version('2.0.0', '>=') and docker_api_version is version('1.24', '>=')
+
+- fail: msg="Too old docker / docker-py version to run docker_swarm_service_info tests!"
+  when: not(docker_py_version is version('2.0.0', '>=') and docker_api_version is version('1.24', '>=')) and (ansible_distribution != 'CentOS' or ansible_distribution_major_version|int > 6)

test/integration/targets/docker_swarm_service_info/tasks/test_docker_swarm_service_info.yml

@@ -0,0 +1,76 @@
+---
+
+- name: Generate service base name
+  set_fact:
+    service_base_name: "{{ 'ansible-test-%0x' % ((2**32) | random) }}"
+
+- name: Registering service names
+  set_fact:
+    service_name: "{{ service_base_name ~ '-1' }}"
+
+- block:
+  - name: Make sure we're not already using Docker swarm
+    docker_swarm:
+      state: absent
+      force: true
+
+  - name: Try to get docker_swarm_service_info when docker is not running in swarm mode
+    docker_swarm_service_info:
+      name: "{{ service_name }}"
+    ignore_errors: yes
+    register: output
+
+  - name: assert failure when called when swarm is not in use or not run on manager node
+    assert:
+      that:
+        - 'output is failed'
+        - 'output.msg == "Error running docker swarm module: must run on swarm manager node"'
+
+  - name: Create a Swarm cluster
+    docker_swarm:
+      state: present
+    register: output
+
+  - name: Create services
+    docker_swarm_service:
+      name: "{{ service_name }}"
+      image: alpine:3.8
+
+  - name: Try to get docker_swarm_service_info for a single service
+    docker_swarm_service_info:
+      name: "{{ service_name }}"
+    register: output
+
+  - name: assert reading reading service info
+    assert:
+      that:
+        - 'output.exists == true'
+        - 'output.service.ID is string'
+        - 'output.service.Spec.Name == service_name'
+
+  - name: Create random name
+    set_fact:
+      random_service_name: "{{ 'random-service-%0x' % ((2**32) | random) }}"
+
+  - name: Try to get docker_swarm_service_info using random service name as parameter
+    docker_swarm_service_info:
+      name: "{{ random_service_name }}"
+    register: output
+
+  - name: assert reading reading service info
+    assert:
+      that:
+        - 'output.service is none'
+        - 'output.exists == false'
+
+  always:
+    - name: Remove services
+      docker_swarm_service:
+        name: "{{ service_name }}"
+        state: absent
+      ignore_errors: yes
+
+    - name: Remove swarm
+      docker_swarm:
+        state: absent
+        force: true