json[l] callback: add parameter to set JSON prettyprint indent level

Add ANSIBLE_JSON_INDENT parameter to both the json and jsonl callback
plugins.  The default values are different between the two modules to
maintain their existing behavior:

* json: indent==4, causing a prettyprint output
* jsonl: indent==0, causing a 1-line output

One specific use-case that is enabled by this feature: if a user
chooses to use the jsonl plugin so that they still get output at the
end of each task (vs. only at the end of the play), they may also want
human-readable output so that they can monitor the status of their
play.  For example, setting the jsonl indent level to 4 gives a)
output at the end of each task, and b) making that output be both
machine readable and human readable.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

changelogs/fragments/441-json-add-indent-parameter.yaml

@@ -0,0 +1,2 @@
+minor_changes:
+  - json and jsonl - Add the ``ANSIBLE_JSON_INDENT`` parameter

plugins/callback/json.py

@@ -25,6 +25,16 @@ DOCUMENTATION = '''
           - key: show_custom_stats
             section: defaults
         type: bool
+      json_indent:
+        name: Use indenting for the JSON output
+        description: 'If specified, use this many spaces for indenting in the JSON output. If <= 0, write to a single line.'
+        default: 4
+        env:
+          - name: ANSIBLE_JSON_INDENT
+        ini:
+          - key: json_indent
+            section: defaults
+        type: integer
     notes:
       - When using a strategy such as free, host_pinned, or a custom strategy, host results will
         be added to new task results in ``.plays[].tasks[]``. As such, there will exist duplicate
@@ -61,6 +71,12 @@ class CallbackModule(CallbackBase):
         self._task_map = {}
         self._is_lockstep = False
 
+        self.set_options()
+
+        self._json_indent = self.get_option('json_indent')
+        if self._json_indent <= 0:
+            self._json_indent = None
+
     def _new_play(self, play):
         self._is_lockstep = play.strategy in LOCKSTEP_CALLBACKS
         return {
@@ -143,7 +159,7 @@ class CallbackModule(CallbackBase):
             'global_custom_stats': global_custom_stats,
         }
 
-        self._display.display(json.dumps(output, cls=AnsibleJSONEncoder, indent=4, sort_keys=True))
+        self._display.display(json.dumps(output, cls=AnsibleJSONEncoder, indent=self._json_indent, sort_keys=True))
 
     def _record_task_result(self, on_info, result, **kwargs):
         """This function is used as a partial to add failed/skipped info in a single method"""

plugins/callback/jsonl.py

@@ -26,6 +26,16 @@ DOCUMENTATION = '''
           - key: show_custom_stats
             section: defaults
         type: bool
+      json_indent:
+        name: Use indenting for the JSON output
+        description: 'If specified, use this many spaces for indenting in the JSON output. If not specified or <= 0, write to a single line.'
+        default: 0
+        env:
+          - name: ANSIBLE_JSON_INDENT
+        ini:
+          - key: json_indent
+            section: defaults
+        type: integer
     notes:
       - When using a strategy such as free, host_pinned, or a custom strategy, host results will
         be added to new task results in ``.plays[].tasks[]``. As such, there will exist duplicate
@@ -63,6 +73,12 @@ class CallbackModule(CallbackBase):
         self._task_map = {}
         self._is_lockstep = False
 
+        self.set_options()
+
+        self._json_indent = self.get_option('json_indent')
+        if self._json_indent <= 0:
+            self._json_indent = None
+
     def _new_play(self, play):
         self._is_lockstep = play.strategy in LOCKSTEP_CALLBACKS
         return {
@@ -156,7 +172,7 @@ class CallbackModule(CallbackBase):
     def _write_event(self, event_name, output):
         output['_event'] = event_name
         output['_timestamp'] = current_time()
-        self._display.display(json.dumps(output, cls=AnsibleJSONEncoder, separators=',:', sort_keys=True))
+        self._display.display(json.dumps(output, cls=AnsibleJSONEncoder, indent=self._json_indent, separators=',:', sort_keys=True))
 
     def _record_task_result(self, event_name, on_info, result, **kwargs):
         """This function is used as a partial to add failed/skipped info in a single method"""