Add support for docker's client's --add-host command

docs/yml.md

@@ -70,6 +70,23 @@ external_links:
  - project_db_1:postgresql
 ```
 
+### extra_hosts
+
+Add hostname mappings. Use the same values as the docker client `--add-hosts` parameter.
+
+```
+extra_hosts:
+ - docker: 162.242.195.82
+ - fig: 50.31.209.229
+```
+
+An entry with the ip address and hostname will be created in `/etc/hosts` inside containers for this service, e.g:
+
+```
+162.242.195.82  docker
+50.31.209.229   fig
+```
+
 ### ports
 
 Expose ports. Either specify both ports (`HOST:CONTAINER`), or just the container port (a random host port will be chosen).

fig/service.py

@@ -27,6 +27,7 @@
     'entrypoint',
     'env_file',
     'environment',
+    'extra_hosts',
     'hostname',
     'image',
     'mem_limit',
@@ -43,6 +44,7 @@
 ]
 DOCKER_CONFIG_HINTS = {
     'cpu_share' : 'cpu_shares',
+    'add_host'  : 'extra_hosts',
     'link'      : 'links',
     'port'      : 'ports',
     'privilege' : 'privileged',
@@ -58,6 +60,7 @@
     'dns',
     'dns_search',
     'env_file',
+    'extra_hosts',
     'net',
     'privileged',
     'restart',
@@ -97,7 +100,6 @@ def __init__(self, name, client=None, project='default', links=None, external_li
 
         supported_options = DOCKER_CONFIG_KEYS + ['build', 'expose',
                                                   'external_links']
-
         for k in options:
             if k not in supported_options:
                 msg = "Unsupported config option for %s service: '%s'" % (name, k)
@@ -322,6 +324,8 @@ def start_container(self, container, intermediate_container=None, **override_opt
 
         restart = parse_restart_spec(options.get('restart', None))
 
+        extra_hosts = build_extra_hosts(options.get('extra_hosts', None))
+
         container.start(
             links=self._get_links(link_to_self=options.get('one_off', False)),
             port_bindings=port_bindings,
@@ -334,6 +338,7 @@ def start_container(self, container, intermediate_container=None, **override_opt
             restart_policy=restart,
             cap_add=cap_add,
             cap_drop=cap_drop,
+            extra_hosts=extra_hosts,
         )
         return container
 
@@ -629,6 +634,26 @@ def split_port(port):
     return internal_port, (external_ip, external_port or None)
 
 
+def build_extra_hosts(extra_hosts_config):
+    if extra_hosts_config is None:
+        return None
+
+    if isinstance(extra_hosts_config, basestring):
+        extra_hosts_config = [extra_hosts_config]
+
+    extra_hosts_dict = {}
+    for extra_hosts_line in extra_hosts_config:
+        if isinstance(extra_hosts_line, dict):
+            # already interpreted as a dict (depends on pyyaml version)
+            extra_hosts_dict.update(extra_hosts_line)
+        else:
+            # not already interpreted as a dict
+            host, ip = extra_hosts_line.split(':')
+            extra_hosts_dict.update({host.strip(): ip.strip()})
+
+    return extra_hosts_dict
+
+
 def merge_environment(options):
     env = {}
 

requirements.txt

@@ -1,5 +1,5 @@
 PyYAML==3.10
-docker-py==0.6.0
+docker-py==0.7.1
 dockerpty==0.3.2
 docopt==0.6.1
 requests==2.2.1

setup.py

@@ -30,7 +30,7 @@ def find_version(*file_paths):
     'requests >= 2.2.1, < 3',
     'texttable >= 0.8.1, < 0.9',
     'websocket-client >= 0.11.0, < 0.12',
-    'docker-py >= 0.6.0, < 0.7',
+    'docker-py >= 0.7.1, < 0.8',
     'dockerpty >= 0.3.2, < 0.4',
     'six >= 1.3.0, < 2',
 ]

tests/integration/service_test.py

@@ -5,6 +5,7 @@
 
 from fig import Service
 from fig.service import CannotBeScaledError
+from fig.service import build_extra_hosts
 from fig.container import Container
 from docker.errors import APIError
 from .testcases import DockerClientTestCase
@@ -106,6 +107,42 @@ def test_create_container_with_cpu_shares(self):
         service.start_container(container)
         self.assertEqual(container.inspect()['Config']['CpuShares'], 73)
 
+    def test_build_extra_hosts(self):
+        # string
+        self.assertEqual(build_extra_hosts("www.example.com: 192.168.0.17"),
+                         {'www.example.com': '192.168.0.17'})
+
+        # list of strings
+        self.assertEqual(build_extra_hosts(
+                          ["www.example.com: 192.168.0.17"]),
+                         {'www.example.com': '192.168.0.17'})
+        self.assertEqual(build_extra_hosts(
+                          ["www.example.com: 192.168.0.17",
+                           "api.example.com: 192.168.0.18"]),
+                         {'www.example.com': '192.168.0.17',
+                          'api.example.com': '192.168.0.18'})
+        # list of dictionaries
+        self.assertEqual(build_extra_hosts(
+                          [{'www.example.com': '192.168.0.17'},
+                           {'api.example.com': '192.168.0.18'}
+                          ]),
+                          {'www.example.com': '192.168.0.17',
+                           'api.example.com': '192.168.0.18'})
+
+    def test_create_container_with_extra_hosts_list(self):
+        extra_hosts = ['docker:162.242.195.82', 'fig:50.31.209.229']
+        service = self.create_service('db', extra_hosts=extra_hosts)
+        container = service.create_container()
+        service.start_container(container)
+        self.assertEqual(container.get('HostConfig.ExtraHosts'), extra_hosts)
+
+    def test_create_container_with_extra_hosts_string(self):
+        extra_hosts = 'docker:162.242.195.82'
+        service = self.create_service('db', extra_hosts=extra_hosts)
+        container = service.create_container()
+        service.start_container(container)
+        self.assertEqual(container.get('HostConfig.ExtraHosts'), [extra_hosts])
+
     def test_create_container_with_specified_volume(self):
         host_path = '/tmp/host-path'
         container_path = '/container-path'