from PR review, clarify pre-check logging, minor docs additions

awx/main/tasks.py

@@ -1569,17 +1569,6 @@ def should_use_proot(self, job):
         '''
         return getattr(settings, 'AWX_PROOT_ENABLED', False)
 
-    def copy_folders(self, project_path, galaxy_install_path, private_data_dir):
-        if project_path is None:
-            raise RuntimeError('project does not supply a valid path')
-        elif not os.path.exists(project_path):
-            raise RuntimeError('project path %s cannot be found' % project_path)
-        runner_project_folder = os.path.join(private_data_dir, 'project')
-        copy_tree(project_path, runner_project_folder)
-        if galaxy_install_path:
-            galaxy_run_path = os.path.join(private_data_dir, 'project', 'roles')
-            copy_tree(galaxy_install_path, galaxy_run_path)
-
     def pre_run_hook(self, job, private_data_dir):
         if job.inventory is None:
             error = _('Job could not start because it does not have a valid inventory.')
@@ -1596,8 +1585,6 @@ def pre_run_hook(self, job, private_data_dir):
             job = self.update_model(job.pk, status='failed', job_explanation=msg)
             raise RuntimeError(msg)
 
-        galaxy_install_path = None
-        git_repo = None
         project_path = job.project.get_project_path(check_if_exists=False)
         job_revision = job.project.scm_revision
         needs_sync = True
@@ -1606,21 +1593,20 @@ def pre_run_hook(self, job, private_data_dir):
             needs_sync = False
         elif not os.path.exists(project_path):
             logger.debug('Performing fresh clone of {} on this instance.'.format(job.project))
-            needs_sync = True
+        elif job.project.scm_revision:
+            logger.debug('Revision not known for {}, will sync with remote'.format(job.project))
         elif job.project.scm_type == 'git':
             git_repo = git.Repo(project_path)
-            if job.scm_branch and job.scm_branch != job.project.scm_branch and git_repo:
-                try:
-                    commit = git_repo.commit(job.scm_branch)
-                    job_revision = commit.hexsha
-                    logger.info('Skipping project sync for {} because commit is locally available'.format(job.log_format))
-                    needs_sync = False  # requested commit is already locally available
-                except (ValueError, BadGitName):
-                    pass
-            else:
-                if git_repo.head.commit.hexsha == job.project.scm_revision:
-                    logger.info('Source tree for for {} is already up to date'.format(job.log_format))
-                    needs_sync = False
+            try:
+                desired_revision = job.project.scm_revision
+                if job.scm_branch and job.scm_branch != job.project.scm_branch:
+                    desired_revision = job.scm_branch  # could be commit or not, but will try as commit
+                commit = git_repo.commit(desired_revision)
+                job_revision = commit.hexsha
+                logger.info('Skipping project sync for {} because commit is locally available'.format(job.log_format))
+                needs_sync = False
+            except (ValueError, BadGitName):
+                logger.debug('Needed commit for {} not in local source tree, will sync with remote'.format(job.log_format))
         # Galaxy requirements are not supported for manual projects
         if not needs_sync and job.project.scm_type:
             # see if we need a sync because of presence of roles
@@ -1629,6 +1615,7 @@ def pre_run_hook(self, job, private_data_dir):
                 logger.debug('Running project sync for {} because of galaxy role requirements.'.format(job.log_format))
                 needs_sync = True
 
+        galaxy_install_path = None
         if needs_sync:
             pu_ig = job.instance_group
             pu_en = job.execution_node

docs/clustering.md

@@ -268,12 +268,13 @@ As Tower instances are brought online, it effectively expands the work capacity
 
 It's important to note that not all instances are required to be provisioned with an equal capacity.
 
-Project updates behave differently than they did before. Previously they were ordinary jobs that ran on a single instance. It's now important that they run successfully on any instance that could potentially run a job. Projects will now sync themselves to the correct version on the instance immediately prior to running the job.
+If an Instance Group is configured but all instances in that group are offline or unavailable, any jobs that are launched targeting only that group will be stuck in a waiting state until instances become available. Fallback or backup resources should be provisioned to handle any work that might encounter this scenario.
 
-When the sync happens, it is recorded in the database as a project update with a `launch_type` of "sync" and a `job_type` of "run". Project syncs will not change the status or version of the project; instead, they will update the source tree _only_ on the instance where they run. The only exception to this behavior is when the project is in the "never updated" state (meaning that no project updates of any type have been run), in which case a sync should fill in the project's initial revision and status, and subsequent syncs should not make such changes.
+#### Project synchronization behavior
 
-If an Instance Group is configured but all instances in that group are offline or unavailable, any jobs that are launched targeting only that group will be stuck in a waiting state until instances become available. Fallback or backup resources should be provisioned to handle any work that might encounter this scenario.
+Project updates behave differently than they did before. Previously they were ordinary jobs that ran on a single instance. It's now important that they run successfully on any instance that could potentially run a job. Projects will sync themselves to the correct version on the instance immediately prior to running the job. If the needed revision is already locally available and galaxy or collections updates are not needed, then a sync may not be performed.
 
+When the sync happens, it is recorded in the database as a project update with a `launch_type` of "sync" and a `job_type` of "run". Project syncs will not change the status or version of the project; instead, they will update the source tree _only_ on the instance where they run. The only exception to this behavior is when the project is in the "never updated" state (meaning that no project updates of any type have been run), in which case a sync should fill in the project's initial revision and status, and subsequent syncs should not make such changes.
 
 #### Controlling where a particular job runs
 

docs/prompting.md

@@ -20,6 +20,7 @@ The standard pattern applies to fields
  - `limit`
  - `diff_mode`
  - `verbosity`
+ - `scm_branch`
 
 ##### Non-Standard Cases (Credentials Changing in Tower 3.3)