zuul-stream : don't write out logfile for tasks in loops

In zuul_stream.py:v2_playbook_on_task_start() it checks for
"task.loop" and exits if the task is part of a loop.

However the library/command.py override still writes out the console
log despite it never being read.  To avoid leaving this file around,
mark a sentinel uuid in the action plugin if the command is part of a
loop.  In that case, for simplicity we just write to /dev/null -- that
way no other assumptions in the library/command.py have to change; it
just doesn't leave a file on disk.

This is currently difficult to test as the infrastructure zuul_console
leaves /tmp/console-* files and we do not know what comes from that,
or testing.  After this and the related change
I823156dc2bcae91bd6d9770bd1520aa55ad875b4 are deployed to the
infrastructure executors, we can make a simple and complete test for
the future by just ensuring no /tmp/console-* files are left behind
afer testing.  I have tested this locally and do not see files from
loops, which I was before this change.

Change-Id: I4f4660c3c0b0f170561c14940cc159dc43eadc79

zuul/ansible/2.8/library/command.py

@@ -168,7 +168,15 @@ _log_lines = []
 
 class Console(object):
     def __init__(self, log_uuid):
-        self.logfile_name = LOG_STREAM_FILE.format(log_uuid=log_uuid)
+        # The streamer currently will not ask us for output from
+        # loops.  This flag uuid was set in the action plugin if this
+        # call was part of a loop.  This avoids us leaving behind
+        # files that will never be read, but also means no other
+        # special-casing for any of this path.
+        if log_uuid == 'in-loop-ignore':
+            self.logfile_name = os.devnull
+        else:
+            self.logfile_name = LOG_STREAM_FILE.format(log_uuid=log_uuid)
 
     def __enter__(self):
         self.logfile = open(self.logfile_name, 'ab', buffering=0)

zuul/ansible/2.9/library/command.py

@@ -168,7 +168,15 @@ _log_lines = []
 
 class Console(object):
     def __init__(self, log_uuid):
-        self.logfile_name = LOG_STREAM_FILE.format(log_uuid=log_uuid)
+        # The streamer currently will not ask us for output from
+        # loops.  This flag uuid was set in the action plugin if this
+        # call was part of a loop.  This avoids us leaving behind
+        # files that will never be read, but also means no other
+        # special-casing for any of this path.
+        if log_uuid == 'in-loop-ignore':
+            self.logfile_name = os.devnull
+        else:
+            self.logfile_name = LOG_STREAM_FILE.format(log_uuid=log_uuid)
 
     def __enter__(self):
         self.logfile = open(self.logfile_name, 'ab', buffering=0)

zuul/ansible/base/action/command.py

@@ -25,15 +25,21 @@ class ActionModule(command.ActionModule):
         if self._task.action in (
                 'command', 'shell',
                 'ansible.builtin.command', 'ansible.builtin.shell'):
-            # Get a unique key for ZUUL_LOG_ID_MAP.  ZUUL_LOG_ID_MAP
-            # is read-only since we are forked.  Use it to add a
-            # counter to the log id so that if we run the same task
-            # more than once, we get a unique log file.  See comments
-            # in paths.py for details.
-            log_host = paths._sanitize_filename(
-                task_vars.get('inventory_hostname'))
-            key = "%s-%s" % (self._task._uuid, log_host)
-            count = paths.ZUUL_LOG_ID_MAP.get(key, 0)
-            self._task.args['zuul_log_id'] = "%s-%s-%s" % (
-                self._task._uuid, count, log_host)
+            # This is a bit lame, but we do not log loops in the
+            # zuul_stream.py callback.  This allows us to not write
+            # out command.py output to files that will never be read.
+            if 'ansible_loop_var' in task_vars:
+                self._task.args['zuul_log_id'] = 'in-loop-ignore'
+            else:
+                # Get a unique key for ZUUL_LOG_ID_MAP.  ZUUL_LOG_ID_MAP
+                # is read-only since we are forked.  Use it to add a
+                # counter to the log id so that if we run the same task
+                # more than once, we get a unique log file.  See comments
+                # in paths.py for details.
+                log_host = paths._sanitize_filename(
+                    task_vars.get('inventory_hostname'))
+                key = "%s-%s" % (self._task._uuid, log_host)
+                count = paths.ZUUL_LOG_ID_MAP.get(key, 0)
+                self._task.args['zuul_log_id'] = "%s-%s-%s" % (
+                    self._task._uuid, count, log_host)
         return super(ActionModule, self).run(tmp, task_vars)

zuul/ansible/base/library/command.py

@@ -263,7 +263,15 @@ _log_lines = []
 
 class Console(object):
     def __init__(self, log_uuid):
-        self.logfile_name = LOG_STREAM_FILE.format(log_uuid=log_uuid)
+        # The streamer currently will not ask us for output from
+        # loops.  This flag uuid was set in the action plugin if this
+        # call was part of a loop.  This avoids us leaving behind
+        # files that will never be read, but also means no other
+        # special-casing for any of this path.
+        if log_uuid == 'in-loop-ignore':
+            self.logfile_name = os.devnull
+        else:
+            self.logfile_name = LOG_STREAM_FILE.format(log_uuid=log_uuid)
 
     def __enter__(self):
         self.logfile = open(self.logfile_name, 'ab', buffering=0)