Merge pull request #2647 from shin-/preexisting_volume_detection_rb1

Support for external volumes

compose/config/config.py

@@ -273,6 +273,13 @@ def load_volumes(config_files):
     for config_file in config_files:
         for name, volume_config in config_file.config.get('volumes', {}).items():
             volumes.update({name: volume_config})
+            external = volume_config.get('external')
+            if external:
+                if isinstance(external, dict):
+                    volume_config['external_name'] = external.get('name')
+                else:
+                    volume_config['external_name'] = name
+
     return volumes
 
 

compose/config/fields_schema_v2.json

@@ -32,17 +32,32 @@
   "definitions": {
     "volume": {
       "id": "#/definitions/volume",
-      "type": "object",
-      "properties": {
-        "driver": {"type": "string"},
-        "driver_opts": {
-          "type": "object",
-          "patternProperties": {
-            "^.+$": {"type": ["string", "number"]}
-          },
-          "additionalProperties": false
-        }
-      }
+      "oneOf": [{
+        "type": "object",
+        "properties": {
+          "driver": {"type": "string"},
+          "driver_opts": {
+            "type": "object",
+            "patternProperties": {
+              "^.+$": {"type": ["string", "number"]}
+            },
+            "additionalProperties": false
+          }
+        },
+        "additionalProperties": false
+      }, {
+        "type": "object",
+        "properties": {
+          "external": {
+            "type": ["boolean", "object"],
+            "properties": {
+              "name": {"type": "string"}
+            },
+            "additionalProperties": false
+          }
+        },
+        "additionalProperties": false
+      }]
     }
   },
   "additionalProperties": false

compose/project.py

@@ -77,7 +77,9 @@ class Project(object):
                 project.volumes.append(
                     Volume(
                         client=client, project=name, name=vol_name,
-                        driver=data.get('driver'), driver_opts=data.get('driver_opts')
+                        driver=data.get('driver'),
+                        driver_opts=data.get('driver_opts'),
+                        external_name=data.get('external_name')
                     )
                 )
         return project
@@ -235,6 +237,21 @@ class Project(object):
     def initialize_volumes(self):
         try:
             for volume in self.volumes:
+                if volume.external:
+                    log.debug(
+                        'Volume {0} declared as external. No new '
+                        'volume will be created.'.format(volume.name)
+                    )
+                    if not volume.exists():
+                        raise ConfigurationError(
+                            'Volume {name} declared as external, but could'
+                            ' not be found. Please create the volume manually'
+                            ' using `{command}{name}` and try again.'.format(
+                                name=volume.full_name,
+                                command='docker volume create --name='
+                            )
+                        )
+                    continue
                 volume.create()
         except NotFound:
             raise ConfigurationError(

compose/volume.py

@@ -1,14 +1,18 @@
 from __future__ import absolute_import
 from __future__ import unicode_literals
 
+from docker.errors import NotFound
+
 
 class Volume(object):
-    def __init__(self, client, project, name, driver=None, driver_opts=None):
+    def __init__(self, client, project, name, driver=None, driver_opts=None,
+                 external_name=None):
         self.client = client
         self.project = project
         self.name = name
         self.driver = driver
         self.driver_opts = driver_opts
+        self.external_name = external_name
 
     def create(self):
         return self.client.create_volume(
@@ -21,6 +25,19 @@ class Volume(object):
     def inspect(self):
         return self.client.inspect_volume(self.full_name)
 
+    def exists(self):
+        try:
+            self.inspect()
+        except NotFound:
+            return False
+        return True
+
+    @property
+    def external(self):
+        return bool(self.external_name)
+
     @property
     def full_name(self):
+        if self.external_name:
+            return self.external_name
         return '{0}_{1}'.format(self.project, self.name)