Check the compose templates at startup

Depsolve the packages included in the templates and report any errors
using the /api/status 'msgs' field. This should help narrow down
problems with package sources not being setup correctly.

src/pylorax/api/compose.py

@@ -46,13 +46,41 @@ from pyanaconda.simpleconfig import SimpleConfigFile
 from pykickstart.parser import KickstartParser
 from pykickstart.version import makeVersion, RHEL7
 
-from pylorax.api.projects import projects_depsolve_with_size, dep_nevra
+from pylorax.api.projects import projects_depsolve, projects_depsolve_with_size, dep_nevra
 from pylorax.api.projects import ProjectsError
 from pylorax.api.recipes import read_recipe_and_id
 from pylorax.imgutils import default_image_name
 from pylorax.sysutils import joinpaths
 
 
+def test_templates(yb, share_dir):
+    """ Try depsolving each of the the templates and report any errors
+
+    :param yb: yum base object
+    :type yb: YumBase
+    :returns: List of template types and errors
+    :rtype: List of errors
+
+    Return a list of templates and errors encountered or an empty list
+    """
+    template_errors = []
+    for compose_type in compose_types(share_dir):
+        # Read the kickstart template for this type
+        ks_template_path = joinpaths(share_dir, "composer", compose_type) + ".ks"
+        ks_template = open(ks_template_path, "r").read()
+
+        # How much space will the packages in the default template take?
+        ks_version = makeVersion(RHEL7)
+        ks = KickstartParser(ks_version, errorsAreFatal=False, missingIncludeIsFatal=False)
+        ks.readKickstartFromString(ks_template+"\n%end\n")
+        pkgs = [(name, "*") for name in ks.handler.packages.packageList]
+        try:
+            _ = projects_depsolve(yb, pkgs)
+        except ProjectsError as e:
+            template_errors.append("Error depsolving %s: %s" % (compose_type, str(e)))
+
+    return template_errors
+
 def repo_to_ks(r, url="url"):
     """ Return a kickstart line with the correct args.
 

src/pylorax/api/server.py

@@ -65,13 +65,19 @@ def v0_status():
             "db_supported": true,
             "db_version": "0",
             "schema_version": "0",
-            "backend": "lorax-composer"}
+            "backend": "lorax-composer",
+            "msgs": []}
+
+    The 'msgs' field can be a list of strings describing startup problems or status that
+    should be displayed to the user. eg. if the compose templates are not depsolving properly
+    the errors will be in 'msgs'.
     """
     return jsonify(backend="lorax-composer",
                    build=vernum,
                    api="0",
                    db_version="0",
                    schema_version="0",
-                   db_supported=True)
+                   db_supported=True,
+                   msgs=server.config["TEMPLATE_ERRORS"])
 
 v0_api(server)

src/sbin/lorax-composer

@@ -37,6 +37,7 @@ from gevent.pywsgi import WSGIServer
 
 from pylorax import vernum
 from pylorax.api.config import configure, make_yum_dirs, make_queue_dirs
+from pylorax.api.compose import test_templates
 from pylorax.api.queue import start_queue_monitor
 from pylorax.api.recipes import open_or_create_repo, commit_recipe_directory
 from pylorax.api.server import server, GitLock, YumLock
@@ -280,6 +281,9 @@ if __name__ == '__main__':
     yb = get_base_object(server.config["COMPOSER_CFG"])
     server.config["YUMLOCK"] = YumLock(yb=yb, lock=Lock())
 
+    # Depsolve the templates and make a note of the failures for /api/status to report
+    server.config["TEMPLATE_ERRORS"] = test_templates(yb, server.config["COMPOSER_CFG"].get("composer", "share_dir"))
+
     # Setup access to the git repo
     server.config["REPO_DIR"] = opts.BLUEPRINTS
     repo = open_or_create_repo(server.config["REPO_DIR"])

tests/pylorax/test_server.py

@@ -61,6 +61,9 @@ class ServerTestCase(unittest.TestCase):
         yb = get_base_object(server.config["COMPOSER_CFG"])
         server.config["YUMLOCK"] = YumLock(yb=yb, lock=Lock())
 
+        # Include a message in /api/status output
+        server.config["TEMPLATE_ERRORS"] = ["Test message"]
+
         server.config['TESTING'] = True
         self.server = server.test_client()
         self.repo_dir = repo_dir
@@ -84,12 +87,16 @@ class ServerTestCase(unittest.TestCase):
 
     def test_01_status(self):
         """Test the /api/status route"""
-        status_fields = ["build", "api", "db_version", "schema_version", "db_supported", "backend"]
+        status_fields = ["build", "api", "db_version", "schema_version", "db_supported", "backend", "msgs"]
         resp = self.server.get("/api/status")
         data = json.loads(resp.data)
-        # Just make sure the fields are present
+        # Make sure the fields are present
         self.assertEqual(sorted(data.keys()), sorted(status_fields))
 
+        # Check for test message
+        self.assertEqual(data["msgs"], ["Test message"])
+
+
     def test_02_blueprints_list(self):
         """Test the /api/v0/blueprints/list route"""
         list_dict = {"blueprints":["atlas", "custom-base", "development", "glusterfs", "http-server",