Refactor Python API examples and docs

PR #70446: it's a follow-up for #70445.

It includes a merge of `examples/scripts/uptime.py` and a similar
code snippet from `docs/docsite/rst/dev_guide/developing_api.rst`.

This patch also changes the docs RST file to include contents of
the example file instead of holding a copy of a similar code.

1 files changed, 54 insertions, 28 deletions

diff --git a/examples/scripts/uptime.py b/examples/scripts/uptime.py
index 6542ff55b3..d2cb3b0c52 100755
--- a/examples/scripts/uptime.py
+++ b/examples/scripts/uptime.py
@@ -3,41 +3,58 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
+import json
+import shutil
+
+import ansible.constants as C
 from ansible.executor.task_queue_manager import TaskQueueManager
+from ansible.module_utils.common.collections import ImmutableDict
 from ansible.inventory.manager import InventoryManager
 from ansible.parsing.dataloader import DataLoader
 from ansible.playbook.play import Play
 from ansible.plugins.callback import CallbackBase
 from ansible.vars.manager import VariableManager
 from ansible import context
-from ansible.module_utils.common.collections import ImmutableDict
 
 
-# Create a callback object so we can capture the output
-class ResultsCollector(CallbackBase):
+# Create a callback plugin so we can capture the output
+class ResultsCollectorJSONCallback(CallbackBase):
+    """A sample callback plugin used for performing an action as results come in.
+
+    If you want to collect all results into a single object for processing at
+    the end of the execution, look into utilizing the ``json`` callback plugin
+    or writing your own custom callback plugin.
+    """
 
     def __init__(self, *args, **kwargs):
-        super(ResultsCollector, self).__init__(*args, **kwargs)
+        super(ResultsCollectorJSONCallback, self).__init__(*args, **kwargs)
         self.host_ok = {}
         self.host_unreachable = {}
         self.host_failed = {}
 
     def v2_runner_on_unreachable(self, result):
-        self.host_unreachable[result._host.get_name()] = result
+        host = result._host
+        self.host_unreachable[host.get_name()] = result
 
     def v2_runner_on_ok(self, result, *args, **kwargs):
-        self.host_ok[result._host.get_name()] = result
+        """Print a json representation of the result.
+
+        Also, store the result in an instance attribute for retrieval later
+        """
+        host = result._host
+        self.host_ok[host.get_name()] = result
+        print(json.dumps({host.name: result._result}, indent=4))
 
     def v2_runner_on_failed(self, result, *args, **kwargs):
-        self.host_failed[result._host.get_name()] = result
+        host = result._host
+        self.host_failed[host.get_name()] = result
 
 
 def main():
     host_list = ['localhost', 'www.example.com', 'www.google.com']
     # since the API is constructed for CLI it expects certain options to always be set in the context object
-    context.CLIARGS = ImmutableDict(connection='smart', module_path=['/usr/share/ansible'], forks=10, become=None,
+    context.CLIARGS = ImmutableDict(connection='smart', module_path=['/to/mymodules', '/usr/share/ansible'], forks=10, become=None,
                                     become_method=None, become_user=None, check=False, diff=False)
-
     # required for
     # https://github.com/ansible/ansible/blob/devel/lib/ansible/inventory/manager.py#L204
     sources = ','.join(host_list)
@@ -45,20 +62,19 @@ def main():
         sources += ','
 
     # initialize needed objects
-    loader = DataLoader()
-    passwords = dict()
+    loader = DataLoader()  # Takes care of finding and reading yaml, json and ini files
+    passwords = dict(vault_pass='secret')
 
-    # Instantiate our ResultsCollector for handling results as
-    # they come in. Ansible expects this to be one of its main
-    # display outlets.
-    callback = ResultsCollector()
+    # Instantiate our ResultsCollectorJSONCallback for handling results as they come in. Ansible expects this to be one of its main display outlets
+    results_callback = ResultsCollectorJSONCallback()
 
-    # create inventory and pass to var manager
+    # create inventory, use path to host config file as source or hosts in a comma separated string
     inventory = InventoryManager(loader=loader, sources=sources)
+
+    # variable manager takes care of merging all the different sources to give you a unified view of variables available in each context
     variable_manager = VariableManager(loader=loader, inventory=inventory)
 
-    # Instantiate task queue manager, which takes care of forking
-    # and setting up all objects to iterate over host list and tasks.
+    # instantiate task queue manager, which takes care of forking and setting up all objects to iterate over host list and tasks
     # IMPORTANT: This also adds library dirs paths to the module loader
     # IMPORTANT: and so it must be initialized before calling `Play.load()`.
     tqm = TaskQueueManager(
@@ -66,37 +82,47 @@ def main():
         variable_manager=variable_manager,
         loader=loader,
         passwords=passwords,
-        stdout_callback=callback,
+        stdout_callback=results_callback,  # Use our custom callback instead of the ``default`` callback plugin, which prints to stdout
     )
 
-    # create play with tasks
+    # create data structure that represents our play, including tasks, this is basically what our YAML loader does internally.
     play_source = dict(
         name="Ansible Play",
         hosts=host_list,
         gather_facts='no',
-        tasks=[dict(action=dict(module='command', args=dict(cmd='/usr/bin/uptime')))]
+        tasks=[
+            dict(action=dict(module='shell', args='ls'), register='shell_out'),
+            dict(action=dict(module='debug', args=dict(msg='{{shell_out.stdout}}'))),
+            dict(action=dict(module='command', args=dict(cmd='/usr/bin/uptime'))),
+        ]
     )
+
+    # Create play object, playbook objects use .load instead of init or new methods,
+    # this will also automatically create the task objects from the info provided in play_source
     play = Play().load(play_source, variable_manager=variable_manager, loader=loader)
 
-    # actually run it
+    # Actually run it
     try:
-        result = tqm.run(play)
+        result = tqm.run(play)  # most interesting data for a play is actually sent to the callback's methods
     finally:
-        if tqm is not None:
-            tqm.cleanup()
+        # we always need to cleanup child procs and the structures we use to communicate with them
+        tqm.cleanup()
         if loader:
             loader.cleanup_all_tmp_files()
 
+    # Remove ansible tmpdir
+    shutil.rmtree(C.DEFAULT_LOCAL_TMP, True)
+
     print("UP ***********")
-    for host, result in callback.host_ok.items():
+    for host, result in results_callback.host_ok.items():
         print('{0} >>> {1}'.format(host, result._result['stdout']))
 
     print("FAILED *******")
-    for host, result in callback.host_failed.items():
+    for host, result in results_callback.host_failed.items():
         print('{0} >>> {1}'.format(host, result._result['msg']))
 
     print("DOWN *********")
-    for host, result in callback.host_unreachable.items():
+    for host, result in results_callback.host_unreachable.items():
         print('{0} >>> {1}'.format(host, result._result['msg']))