Implement environment singleton to be accessed throughout the code

Load and parse environment file from working dir

Signed-off-by: Joffrey F <joffrey@docker.com>

compose/cli/command.py

@@ -21,7 +21,7 @@ log = logging.getLogger(__name__)
 def project_from_options(project_dir, options):
     return get_project(
         project_dir,
-        get_config_path_from_options(options),
+        get_config_path_from_options(project_dir, options),
         project_name=options.get('--project-name'),
         verbose=options.get('--verbose'),
         host=options.get('--host'),
@@ -29,12 +29,13 @@ def project_from_options(project_dir, options):
     )
 
 
-def get_config_path_from_options(options):
+def get_config_path_from_options(base_dir, options):
     file_option = options.get('--file')
     if file_option:
         return file_option
 
-    config_files = os.environ.get('COMPOSE_FILE')
+    environment = config.environment.get_instance(base_dir)
+    config_files = environment.get('COMPOSE_FILE')
     if config_files:
         return config_files.split(os.pathsep)
     return None
@@ -57,8 +58,9 @@ def get_project(project_dir, config_path=None, project_name=None, verbose=False,
     config_details = config.find(project_dir, config_path)
     project_name = get_project_name(config_details.working_dir, project_name)
     config_data = config.load(config_details)
+    environment = config.environment.get_instance(project_dir)
 
-    api_version = os.environ.get(
+    api_version = environment.get(
         'COMPOSE_API_VERSION',
         API_VERSIONS[config_data.version])
     client = get_client(
@@ -73,7 +75,8 @@ def get_project_name(working_dir, project_name=None):
     def normalize_name(name):
         return re.sub(r'[^a-z0-9]', '', name.lower())
 
-    project_name = project_name or os.environ.get('COMPOSE_PROJECT_NAME')
+    environment = config.environment.get_instance(working_dir)
+    project_name = project_name or environment.get('COMPOSE_PROJECT_NAME')
     if project_name:
         return normalize_name(project_name)
 

compose/cli/main.py

@@ -222,7 +222,7 @@ class TopLevelCommand(object):
             --services      Print the service names, one per line.
 
         """
-        config_path = get_config_path_from_options(config_options)
+        config_path = get_config_path_from_options(self.project_dir, config_options)
         compose_config = config.load(config.find(self.project_dir, config_path))
 
         if options['--quiet']:

compose/config/__init__.py

@@ -2,6 +2,7 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 
+from . import environment
 from .config import ConfigurationError
 from .config import DOCKER_CONFIG_KEYS
 from .config import find

compose/config/config.py

@@ -17,6 +17,7 @@ from cached_property import cached_property
 from ..const import COMPOSEFILE_V1 as V1
 from ..const import COMPOSEFILE_V2_0 as V2_0
 from ..utils import build_string_dict
+from .environment import Environment
 from .errors import CircularReference
 from .errors import ComposeFileNotFound
 from .errors import ConfigurationError
@@ -211,7 +212,8 @@ def find(base_dir, filenames):
     if filenames == ['-']:
         return ConfigDetails(
             os.getcwd(),
-            [ConfigFile(None, yaml.safe_load(sys.stdin))])
+            [ConfigFile(None, yaml.safe_load(sys.stdin))],
+        )
 
     if filenames:
         filenames = [os.path.join(base_dir, f) for f in filenames]
@@ -221,7 +223,8 @@ def find(base_dir, filenames):
     log.debug("Using configuration files: {}".format(",".join(filenames)))
     return ConfigDetails(
         os.path.dirname(filenames[0]),
-        [ConfigFile.from_filename(f) for f in filenames])
+        [ConfigFile.from_filename(f) for f in filenames],
+    )
 
 
 def validate_config_version(config_files):
@@ -288,6 +291,10 @@ def load(config_details):
     """
     validate_config_version(config_details.config_files)
 
+    # load environment in working dir for later use in interpolation
+    # it is done here to avoid having to pass down working_dir
+    Environment.get_instance(config_details.working_dir)
+
     processed_files = [
         process_config_file(config_file)
         for config_file in config_details.config_files
@@ -302,9 +309,8 @@ def load(config_details):
         config_details.config_files, 'get_networks', 'Network'
     )
     service_dicts = load_services(
-        config_details.working_dir,
-        main_file,
-        [file.get_service_dicts() for file in config_details.config_files])
+        config_details, main_file,
+    )
 
     if main_file.version != V1:
         for service_dict in service_dicts:
@@ -348,14 +354,16 @@ def load_mapping(config_files, get_func, entity_type):
     return mapping
 
 
-def load_services(working_dir, config_file, service_configs):
+def load_services(config_details, config_file):
     def build_service(service_name, service_dict, service_names):
         service_config = ServiceConfig.with_abs_paths(
-            working_dir,
+            config_details.working_dir,
             config_file.filename,
             service_name,
             service_dict)
-        resolver = ServiceExtendsResolver(service_config, config_file)
+        resolver = ServiceExtendsResolver(
+            service_config, config_file
+        )
         service_dict = process_service(resolver.run())
 
         service_config = service_config._replace(config=service_dict)
@@ -383,6 +391,10 @@ def load_services(working_dir, config_file, service_configs):
             for name in all_service_names
         }
 
+    service_configs = [
+        file.get_service_dicts() for file in config_details.config_files
+    ]
+
     service_config = service_configs[0]
     for next_config in service_configs[1:]:
         service_config = merge_services(service_config, next_config)
@@ -462,8 +474,8 @@ class ServiceExtendsResolver(object):
         extends_file = ConfigFile.from_filename(config_path)
         validate_config_version([self.config_file, extends_file])
         extended_file = process_config_file(
-            extends_file,
-            service_name=service_name)
+            extends_file, service_name=service_name
+        )
         service_config = extended_file.get_service(service_name)
 
         return config_path, service_config, service_name
@@ -476,7 +488,8 @@ class ServiceExtendsResolver(object):
                 service_name,
                 service_dict),
             self.config_file,
-            already_seen=self.already_seen + [self.signature])
+            already_seen=self.already_seen + [self.signature],
+        )
 
         service_config = resolver.run()
         other_service_dict = process_service(service_config)
@@ -824,10 +837,11 @@ def parse_ulimits(ulimits):
 
 
 def resolve_env_var(key, val):
+    environment = Environment.get_instance()
     if val is not None:
         return key, val
-    elif key in os.environ:
-        return key, os.environ[key]
+    elif key in environment:
+        return key, environment[key]
     else:
         return key, None
 

compose/config/environment.py

@@ -0,0 +1,69 @@
+from __future__ import absolute_import
+from __future__ import unicode_literals
+
+import logging
+import os
+
+from .errors import ConfigurationError
+
+log = logging.getLogger(__name__)
+
+
+class BlankDefaultDict(dict):
+    def __init__(self, *args, **kwargs):
+        super(BlankDefaultDict, self).__init__(*args, **kwargs)
+        self.missing_keys = []
+
+    def __getitem__(self, key):
+        try:
+            return super(BlankDefaultDict, self).__getitem__(key)
+        except KeyError:
+            if key not in self.missing_keys:
+                log.warn(
+                    "The {} variable is not set. Defaulting to a blank string."
+                    .format(key)
+                )
+                self.missing_keys.append(key)
+
+            return ""
+
+
+class Environment(BlankDefaultDict):
+    __instance = None
+
+    @classmethod
+    def get_instance(cls, base_dir='.'):
+        if cls.__instance:
+            return cls.__instance
+
+        instance = cls(base_dir)
+        cls.__instance = instance
+        return instance
+
+    @classmethod
+    def reset(cls):
+        cls.__instance = None
+
+    def __init__(self, base_dir):
+        super(Environment, self).__init__()
+        self.load_environment_file(os.path.join(base_dir, '.env'))
+        self.update(os.environ)
+
+    def load_environment_file(self, path):
+        if not os.path.exists(path):
+            return
+        mapping = {}
+        with open(path, 'r') as f:
+            for line in f.readlines():
+                line = line.strip()
+                if '=' not in line:
+                    raise ConfigurationError(
+                        'Invalid environment variable mapping in env file. '
+                        'Missing "=" in "{0}"'.format(line)
+                    )
+                mapping.__setitem__(*line.split('=', 1))
+        self.update(mapping)
+
+
+def get_instance(base_dir=None):
+    return Environment.get_instance(base_dir)

compose/config/interpolation.py

@@ -2,17 +2,17 @@ from __future__ import absolute_import
 from __future__ import unicode_literals
 
 import logging
-import os
 from string import Template
 
 import six
 
+from .environment import Environment
 from .errors import ConfigurationError
 log = logging.getLogger(__name__)
 
 
 def interpolate_environment_variables(config, section):
-    mapping = BlankDefaultDict(os.environ)
+    mapping = Environment.get_instance()
 
     def process_item(name, config_dict):
         return dict(
@@ -60,25 +60,6 @@ def interpolate(string, mapping):
         raise InvalidInterpolation(string)
 
 
-class BlankDefaultDict(dict):
-    def __init__(self, *args, **kwargs):
-        super(BlankDefaultDict, self).__init__(*args, **kwargs)
-        self.missing_keys = []
-
-    def __getitem__(self, key):
-        try:
-            return super(BlankDefaultDict, self).__getitem__(key)
-        except KeyError:
-            if key not in self.missing_keys:
-                log.warn(
-                    "The {} variable is not set. Defaulting to a blank string."
-                    .format(key)
-                )
-                self.missing_keys.append(key)
-
-            return ""
-
-
 class InvalidInterpolation(Exception):
     def __init__(self, string):
         self.string = string