fixup: tidy up deployment

1 files changed, 79 insertions, 24 deletions

diff --git a/morphlib/plugins/deploy_plugin.py b/morphlib/plugins/deploy_plugin.py
index f68d004a..9c2782e6 100644
--- a/morphlib/plugins/deploy_plugin.py
+++ b/morphlib/plugins/deploy_plugin.py
@@ -27,6 +27,14 @@ import morphlib
 from morphlib.artifactcachereference import ArtifactCacheReference
 
 
+class NotYetBuiltError(morphlib.Error):
+
+    def __init__(self, name):
+        self.msg = ('Deployment failed as %s is not yet built.\n'
+                    'Please ensure the system is built before deployment.'
+                    % name)
+
+
 class DeployPlugin(cliapp.Plugin):
 
     def enable(self):
@@ -542,6 +550,20 @@ class DeployPlugin(cliapp.Plugin):
             pass
 
     def checkout_stratum(self, path, artifact, lac, rac):
+        """Pull the chunks in a stratum, and checkout them into `path`.
+
+        This reads a stratum artifact and pulls the chunks it contains from
+        the remote into the local artifact cache if they are not already
+        cached locally. Each of these chunks is then checked out into `path`.
+
+        Also download the stratum metadata into the local cache, then place
+        it in the /baserock directory of the system checkout indicated by
+        `path`.
+
+        If any of the chunks have not been cached either locally or remotely,
+        a morphlib.remoteartifactcache.GetError is raised.
+
+        """
         with open(lac.get(artifact), 'r') as stratum:
             chunks = [ArtifactCacheReference(c) for c in json.load(stratum)]
         morphlib.builder.download_depends(chunks, lac, rac)
@@ -556,14 +578,69 @@ class DeployPlugin(cliapp.Plugin):
                 shutil.copyfileobj(meta_src, meta_dst)
 
     def checkout_strata(self, path, artifact, lac, rac):
+        """Pull the dependencies of `artifact` and checkout them into `path`.
+
+        This assumes that `artifact` is a system artifact. If any of the
+        dependencies aren't cached remotely or locally, this raises a
+        morphlib.remoteartifactcache.GetError.
+
+        """
         deps = artifact.source.dependencies
         morphlib.builder.download_depends(deps, lac, rac)
         for stratum in deps:
             self.checkout_stratum(path, stratum, lac, rac)
         morphlib.builder.ldconfig(self.app.runcmd, path)
 
+    def checkout_system(self, build_command, artifact, path):
+        """Checkout a system into `path`.
+
+        This checks out each of the strata into the directory given by `path`,
+        then checks out the system artifact into the same directory. This uses
+        OSTree's `union` checkout mode to overwrite duplicate files but not
+        need an empty directory. Artifacts which aren't cached locally are
+        fetched from the remote cache.
+
+        Raises a NotYetBuiltError if either the system artifact or any of the
+        chunk artifacts in the strata which make up the system aren't cached
+        either locally or remotely.
+
+        """
+        # Check if the system artifact is in the local or remote cache.
+        # If it isn't, we don't need to bother checking out strata before
+        # we fail.
+        if not (build_command.lac.has(artifact)
+                or build_command.rac.has(artifact)):
+            raise NotYetBuiltError(artifact.name)
+
+        # Checkout the strata involved in the artifact into a tempdir
+        self.app.status(msg='Checking out strata in system')
+        try:
+            self.checkout_strata(path, artifact,
+                                 build_command.lac, build_command.rac)
+
+            self.app.status(msg='Checking out system for configuration')
+            build_command.cache_artifacts_locally([artifact])
+            build_command.lac.get(artifact, path)
+        except (morphlib.ostreeartifactcache.NotCachedError,
+                morphlib.remoteartifactcache.GetError):
+            raise NotYetBuiltError(artifact.name)
+
+        self.app.status(
+            msg='System checked out at %(system_tree)s',
+            system_tree=path)
+
     def setup_deploy(self, build_command, deploy_tempdir, root_repo_dir, ref,
                      artifact, deployment_type, location, env):
+        """Checkout the artifact, create metadata and return the location.
+
+        This checks out the system into a temporary directory, and then mounts
+        this temporary directory alongside a different temporary directory
+        using a union filesystem. This allows changes to be made without
+        touching the checked out artifacts. The deployment metadata file is
+        created and then the directory at which the two temporary directories
+        are mounted is returned.
+
+        """
         # deployment_type, location and env are only used for saving metadata
 
         deployment_dir = tempfile.mkdtemp(dir=deploy_tempdir)
@@ -583,26 +660,7 @@ class DeployPlugin(cliapp.Plugin):
         deploy_tree = os.path.join(deployment_dir,
                                    'overlay-deploy-%s' % artifact.name)
         try:
-            # Checkout the strata involved in the artifact into a tempdir
-            self.app.status(msg='Checking out strata in system')
-            self.checkout_strata(system_tree, artifact,
-                                 build_command.lac, build_command.rac)
-
-            self.app.status(msg='Checking out system for configuration')
-            if build_command.lac.has(artifact):
-                build_command.lac.get(artifact, system_tree)
-            elif build_command.rac.has(artifact):
-                build_command.cache_artifacts_locally([artifact])
-                build_command.lac.get(artifact, system_tree)
-            else:
-                raise cliapp.AppException('Deployment failed as system is'
-                                          ' not yet built.\nPlease ensure'
-                                          ' the system is built before'
-                                          ' deployment.')
-
-            self.app.status(
-                msg='System checked out at %(system_tree)s',
-                system_tree=system_tree)
+            self.checkout_system(build_command, artifact, system_tree)
 
             union_filesystem = self.app.settings['union-filesystem']
             morphlib.fsutils.overlay_mount(self.app.runcmd,
@@ -625,10 +683,7 @@ class DeployPlugin(cliapp.Plugin):
         except Exception:
             if deploy_tree and os.path.exists(deploy_tree):
                 morphlib.fsutils.unmount(self.app.runcmd, deploy_tree)
-                shutil.rmtree(deploy_tree)
-            shutil.rmtree(system_tree)
-            shutil.rmtree(overlay_dir)
-            shutil.rmtree(work_dir)
+            shutil.rmtree(deployment_dir)
             raise
 
     def run_deploy_commands(self, deploy_tempdir, env, artifact, root_repo_dir,