Add support for environment variables

README.md

@@ -75,6 +75,19 @@ You can fetch a logger named "storage" from it, too:
 
     logger = StorageConfig.get_logger()
 
+### Bootstrap Configuration ###
+
+By default, mandrel looks for a bootstrap file named 'Mandrel.py' in the search path, as described above.
+In most cases this works well and the default behaviour is exactly what you need.
+There are rare exceptions though where you don't want Mandrel to throw an exception if the
+bootstrap file isn't found or don't want to the default search path to be the current working directory.
+
+Mandrel supports two environment variables for these specific cases:
+`MANDREL_ROOT = The root directory from which to start looking for the bootstrap file`
+`MANDREL_BOOTSTRAP_NAME = The name of the bootstrap file to look for in the search path`
+
+These environment variables can be set independently of each other and do not have to both be set.
+
 # License #
 
 Mandrel is free software and is released under the terms

changelog.md

@@ -1,4 +1,9 @@
-2.0.0
+TBD
+
+* Issue #8: Allow mandrel root to be specified via an environment variable
+* Issue #13: Allow bootstrap basename to be specified via an environment variable
+
+0.2.0
 
 * mandrel-runner uses return value of callable as the exit code.
 

mandrel/bootstrap.py

@@ -5,7 +5,7 @@
 from mandrel import exception
 from mandrel import util
 
-__BOOTSTRAP_BASENAME = 'Mandrel.py'
+__BOOTSTRAP_BASENAME = os.getenv('MANDREL_BOOTSTRAP_NAME', 'Mandrel.py')
 
 LOGGING_CONFIG_BASENAME = 'logging.cfg'
 DEFAULT_LOGGING_LEVEL = logging.INFO
@@ -105,12 +105,16 @@ def get_logger(name=None):
 
 
 def _find_bootstrap_base():
-    current = os.path.realpath('.')
-    while not os.path.isfile(os.path.join(current, __BOOTSTRAP_BASENAME)):
-        parent = os.path.dirname(current)
-        if parent == current:
-            raise exception.MissingBootstrapException, 'Cannot find %s file in directory hierarchy' % __BOOTSTRAP_BASENAME
-        current = parent
+    if os.getenv('MANDREL_ROOT'):
+        current = os.getenv('MANDREL_ROOT')
+    else:
+        current = os.path.realpath('.')
+
+        while not os.path.isfile(os.path.join(current, __BOOTSTRAP_BASENAME)):
+            parent = os.path.dirname(current)
+            if parent == current:
+                raise exception.MissingBootstrapException, 'Cannot find %s file in directory hierarchy' % __BOOTSTRAP_BASENAME
+            current = parent
 
     return current, os.path.join(current, __BOOTSTRAP_BASENAME)
 
@@ -129,9 +133,10 @@ def parse_bootstrap_file():
     This makes it easy for the BOOTSTRAP_FILE to configure mandrel settings
     without performing further imports.
     """
-    with open(BOOTSTRAP_FILE, 'rU') as source:
-        code = compile(source.read(), BOOTSTRAP_FILE, 'exec')
-        eval(code, {'bootstrap': sys.modules[__name__], 'config': config})
+    if os.path.exists(BOOTSTRAP_FILE):
+        with open(BOOTSTRAP_FILE, 'rU') as source:
+            code = compile(source.read(), BOOTSTRAP_FILE, 'exec')
+            eval(code, {'bootstrap': sys.modules[__name__], 'config': config})
 
 (ROOT_PATH, BOOTSTRAP_FILE) = _find_bootstrap_base()
 SEARCH_PATHS = util.TransformingList(normalize_path)

mandrel/test/bootstrap/bootstrap_file_test.py

@@ -3,6 +3,7 @@
 import unittest
 import mandrel.exception
 from mandrel.test import utils
+from test.test_support import EnvironmentVarGuard
 
 class TestBootstrapFile(utils.TestCase):
     def testNoFile(self):
@@ -43,3 +44,99 @@ def testDefaultLoggingConfig(self):
             utils.refresh_bootstrapper()
             self.assertEqual('logging.cfg', mandrel.bootstrap.LOGGING_CONFIG_BASENAME)
 
+    def testNoOSEnv(self):
+        """
+        Base case: neither variable is defined (the original behaviors)
+        """
+        with EnvironmentVarGuard() as env:
+            with utils.bootstrap_scenario(dir='~') as spec:
+                utils.refresh_bootstrapper()
+                self.assertEqual(spec[0], mandrel.bootstrap.ROOT_PATH)
+                self.assertEqual(spec[1], mandrel.bootstrap.BOOTSTRAP_FILE)
+
+    def testBothOSEnv(self):
+        """
+        Root is specified, bootstrapper is specified, the specified file does not exist in the specified root
+        """
+        with EnvironmentVarGuard() as env:
+            env.set('MANDREL_ROOT', '/blah')
+            env.set('MANDREL_BOOTSTRAP_NAME', 'bootstrapper.py')
+
+            utils.refresh_bootstrapper()
+            self.assertEqual(os.getenv('MANDREL_ROOT'), mandrel.bootstrap.ROOT_PATH)
+            expected = os.path.join(os.getenv('MANDREL_ROOT'), os.getenv('MANDREL_BOOTSTRAP_NAME'))
+            self.assertEqual(expected, mandrel.bootstrap.BOOTSTRAP_FILE)
+            self.assertEqual(['/blah'], mandrel.bootstrap.SEARCH_PATHS._list)
+
+    def testBothOSEnvFileExists(self):
+        """
+        Root is specified, bootstrapper is specified, the specified file exists in the specified root
+        """
+        with EnvironmentVarGuard() as env:
+            env.set('MANDREL_BOOTSTRAP_NAME', 'bootstrapper.py')
+            with utils.bootstrap_scenario(text='bootstrap.SEARCH_PATHS.append("/blah/myconf")', dir='~') as spec:
+                env.set('MANDREL_ROOT', spec[0])
+
+                utils.refresh_bootstrapper()
+                self.assertEqual(spec[0], mandrel.bootstrap.ROOT_PATH)
+                expected = os.path.join(spec[0], os.getenv('MANDREL_BOOTSTRAP_NAME'))
+                self.assertEqual(expected, mandrel.bootstrap.BOOTSTRAP_FILE)
+                self.assertEqual([spec[0], '/blah/myconf'], mandrel.bootstrap.SEARCH_PATHS._list)
+
+    def testOSEnvNoBootstrapName(self):
+        """
+        Root is specified, bootstrapper is not, Mandrel.py is not present in specified root (should get basic defaults)
+        """
+        with EnvironmentVarGuard() as env:
+            env.set('MANDREL_ROOT', '/blah')
+
+            utils.refresh_bootstrapper()
+            self.assertEqual(os.getenv('MANDREL_ROOT'), mandrel.bootstrap.ROOT_PATH)
+            expected = os.path.join(os.getenv('MANDREL_ROOT'), 'Mandrel.py')
+            self.assertEqual(expected, mandrel.bootstrap.BOOTSTRAP_FILE)
+            self.assertEqual(['/blah'], mandrel.bootstrap.SEARCH_PATHS._list)
+
+    def testOSEnvNoBootstrapNameFileExists(self):
+        """
+        Root is specified, bootstrapper is not, Mandrel.py is present in specified root (should parse the file it finds)
+        """
+        with EnvironmentVarGuard() as env:
+            with utils.bootstrap_scenario(text='bootstrap.SEARCH_PATHS.append("/blah/myconf")', dir='~') as spec:
+                env.set('MANDREL_ROOT', spec[0])
+                utils.refresh_bootstrapper()
+                self.assertEqual(os.getenv('MANDREL_ROOT'), mandrel.bootstrap.ROOT_PATH)
+                self.assertEqual(spec[1], mandrel.bootstrap.BOOTSTRAP_FILE)
+                self.assertEqual([spec[0], '/blah/myconf'], mandrel.bootstrap.SEARCH_PATHS._list)
+
+    def testOSEnvNoMandrelRoot(self):
+        """
+        Root is not specified, bootstrapper is specified,
+        the specified file does not exist within the file system hierarchy
+        """
+        with EnvironmentVarGuard() as env:
+            env.set('MANDREL_BOOTSTRAP_NAME', 'bootstrapper.py')
+            with utils.workdir(dir='~') as path:
+                self.assertRaises(mandrel.exception.MissingBootstrapException, utils.refresh_bootstrapper)
+
+    def testOSEnvNoMandrelRootFileExists(self):
+        """
+        Root is not specified, bootstrapper is specified, the specified file exists
+        """
+        with EnvironmentVarGuard() as env:
+            env.set('MANDREL_BOOTSTRAP_NAME', 'bootstrapper.py')
+            with utils.bootstrap_scenario(text='bootstrap.SEARCH_PATHS.append("/blah/myconf")', dir='~') as spec:
+                utils.refresh_bootstrapper()
+                self.assertEqual(spec[0], mandrel.bootstrap.ROOT_PATH)
+                expected = os.path.join(spec[0], os.getenv('MANDREL_BOOTSTRAP_NAME'))
+                self.assertEqual(expected, mandrel.bootstrap.BOOTSTRAP_FILE)
+                self.assertEqual([spec[0], '/blah/myconf'], mandrel.bootstrap.SEARCH_PATHS._list)
+
+            # Create a folder structure such that starting search path is several levels
+            # below where the bootstrap file exists.
+            # Make sure that the bootstrap file is found and parsed
+            with utils.nested_bootstrap_scenario(text='bootstrap.SEARCH_PATHS.append("/blah/myconf")', dir='~') as spec:
+                utils.refresh_bootstrapper()
+                self.assertEqual(spec[0], mandrel.bootstrap.ROOT_PATH)
+                expected = os.path.join(spec[0], os.getenv('MANDREL_BOOTSTRAP_NAME'))
+                self.assertEqual(expected, mandrel.bootstrap.BOOTSTRAP_FILE)
+                self.assertEqual([spec[0], '/blah/myconf'], mandrel.bootstrap.SEARCH_PATHS._list)

mandrel/test/utils.py

@@ -48,12 +48,23 @@ def refresh_bootstrapper():
     else:
         __import__('mandrel.bootstrap')
 
-BOOTSTRAP_FILE = 'Mandrel.py'
+
 @contextlib.contextmanager
 def bootstrap_scenario(text="", dir=None):
+    BOOTSTRAP_FILE = os.getenv('MANDREL_BOOTSTRAP_NAME', 'Mandrel.py')
     with workdir(dir=dir) as path:
         bootstrapper = os.path.join(path, BOOTSTRAP_FILE)
         with open(bootstrapper, 'w') as f:
             f.write(text)
         yield path, bootstrapper
 
+@contextlib.contextmanager
+def nested_bootstrap_scenario(text="", dir=None):
+    BOOTSTRAP_FILE = os.getenv('MANDREL_BOOTSTRAP_NAME', 'Mandrel.py')
+    with workdir(dir=dir) as path0:
+        with workdir(dir=path0) as path1:
+            with workdir(dir=path1) as path2:
+                bootstrapper = os.path.join(path0, BOOTSTRAP_FILE)
+                with open(bootstrapper, 'w') as f:
+                    f.write(text)
+                yield path0, bootstrapper