Merge pull request #20 from singularityhub/add/resolv.conf

Adding creation of resolv.conf

Author: vsoch

CHANGELOG.md

@@ -14,6 +14,7 @@ and **Merged pull requests**. Critical items to know are:
 The versions coincide with releases on pypi.
 
 ## [0.0.x](https://github.com/singularityhub/singularity-compose/tree/master) (0.0.x)
+ - resolv.conf needs to bind by default (0.0.16)
  - adding run command (0.0.15)
  - ensuring that builds are streamed (0.0.14)
  - adding more build options to build as build-flags (0.0.13)

docs/commands.md

@@ -21,6 +21,37 @@ If the build requires sudo (if you've defined sections in the config that warran
 setting up networking with sudo) the build will instead give you an instruction
 to run with sudo.
 
+## Up
+
+If you want to both build and bring them up, you can use "up." Note that for
+builds that require sudo, this will still stop and ask you to build with sudo.
+
+```bash
+$ singularity-compose up
+```
+
+### resolv.conf
+
+By default, singularity-compose will generate a resolv.conf for you to bind
+to the container, instead of using the host. It's a simple template
+that uses Google nameservers:
+
+```
+# This is resolv.conf generated by singularity-compose. It is provided
+# to provide Google nameservers. If you don't want to have it generated
+# and bound by default, use the up --no-resolv argument.
+
+nameserver 8.8.8.8
+nameserver 8.8.4.4
+```
+
+If you want to disable this:
+
+```bash
+$ singularity-compose up --no-resolv
+Creating app
+```
+
 ## Create
 
 Given that you have built your containers with `singularity-compose build`,
@@ -30,16 +61,25 @@ you can create your instances as follows:
 $ singularity-compose create
 ```
 
-## Up
+Akin to "up," you can also disable the generation of the resolv.conf.
+
+```bash
+$ singularity-compose create --no-resolv
+Creating app
+```
 
-If you want to both build and bring them up, you can use "up." Note that for
-builds that require sudo, this will still stop and ask you to build with sudo.
+
+## restart
+
+Restart is provided as a convenience to run "down" and then "up." You can
+specify most of the same arguments as create or up.
 
 ```bash
-$ singularity-compose up
+$ singularity-compose restart --no-resolv
+Stopping app
+Creating app
 ```
 
-Up is typically the command that you want to use to bring containers up and down.
 
 ## ps
 

scompose/client/__init__.py

@@ -97,6 +97,10 @@ def get_parser():
                          help="disable the instance from writing to tmp", 
                          default=False, action='store_true')
 
+        sub.add_argument('--no-resolv', dest="no_resolv", 
+                         help="do not generate and bind a resolv.conf", 
+                         default=False, action='store_true')
+
         sub.add_argument("--bridge", default="10.22.0.0/16", 
                          dest='bridge', type=str,
                          help='the address of the bridge to derive others from.')

scompose/client/create.py

@@ -33,4 +33,5 @@ def main(args, parser, extra):
     # Create instances, and if none specified, create all
     project.create(args.names, 
                    writable_tmpfs=not args.read_only,
-                   bridge=args.bridge)
+                   bridge=args.bridge,
+                   no_resolv=args.no_resolv)

scompose/client/restart.py

@@ -36,4 +36,5 @@ def main(args, parser, extra):
     # Create instances, and if none specified, create all
     project.up(args.names, 
                writable_tmpfs=not args.read_only,
-               bridge=args.bridge)
+               bridge=args.bridge,
+               no_resolv=args.no_resolv)

scompose/client/up.py

@@ -33,4 +33,5 @@ def main(args, parser, extra):
     # Create instances, and if none specified, create all
     project.up(args.names, 
                writable_tmpfs=not args.read_only,
-               bridge=args.bridge)
+               bridge=args.bridge,
+               no_resolv=args.no_resolv)

scompose/project/project.py

@@ -254,7 +254,17 @@ def create_hosts(self, lookup):
         # Add the host file to be mounted
         write_file(hosts_file, template)
         return hosts_file
- 
+
+
+    def generate_resolv_conf(self):
+        '''generate a resolv.conf file to bind to the containers.
+           We use the template provided by scompose.
+        '''
+        resolv_conf = os.path.join(self.working_dir, 'resolv.conf')
+        if not os.path.exists(resolv_conf):
+            template = read_file(get_template('resolv.conf'))
+            write_file(resolv_conf, template)
+        return resolv_conf
 
 # Commands
 
@@ -370,22 +380,36 @@ def down(self, names=None):
 
 # Create
 
-    def create(self, names=None, writable_tmpfs=True, bridge="10.22.0.0/16"):
+    def create(self, names=None,
+               writable_tmpfs=True,
+               bridge="10.22.0.0/16",
+               no_resolv=False):
+
         '''call the create function, which defaults to the command instance.create()
         '''
-        return self._create(names, writable_tmpfs=writable_tmpfs)
+        return self._create(names,
+                            writable_tmpfs=writable_tmpfs, 
+                            no_resolv=no_resolv)
+
+    def up(self, names=None, 
+           writable_tmpfs=True,
+           bridge="10.22.0.0/16",
+           no_resolv=False):
 
-    def up(self, names=None, writable_tmpfs=True, bridge="10.22.0.0/16"):
         '''call the up function, instance.up(), which will build before if
            a container binary does not exist.
         '''
-        return self._create(names, command="up", writable_tmpfs=writable_tmpfs)
+        return self._create(names, 
+                            command="up",
+                            writable_tmpfs=writable_tmpfs,
+                            no_resolv=no_resolv)
 
     def _create(self, 
                 names, 
                 command="create",
                 writable_tmpfs=True,
-                bridge="10.22.0.0/16"):
+                bridge="10.22.0.0/16",
+                no_resolv=False):
 
         '''create one or more instances. "Command" determines the sub function
            to call for the instance, which should be "create" or "up".
@@ -400,6 +424,8 @@ def _create(self,
            bridge: the bridge ip address to use for networking, and generating
                    addresses for the individual containers.
                    see /usr/local/etc/singularity/network/00_bridge.conflist 
+           no_resolv: if True, don't create and bind a resolv.conf with Google
+                      nameservers.
         '''
         # If no names provided, we create all
         names = names or self.get_instance_names()
@@ -431,9 +457,13 @@ def _create(self,
 
                 if do_create:
 
-                    instance.volumes.append('%s:/etc/hosts' % hosts_file)
+                    # Generate a resolv.conf to bind to the container
+                    if not no_resolv:
+                        resolv = self.generate_resolv_conf()
+                        instance.volumes.append('%s:/etc/resolv.conf' % resolv)
 
                     # Create a hosts file for the instance based, add as volume
+                    instance.volumes.append('%s:/etc/hosts' % hosts_file)
 
                     # If we get here, execute command and add to list
                     create_func = getattr(instance, command)

scompose/templates/resolv.conf

@@ -0,0 +1,7 @@
+# This is resolv.conf generated by singularity-compose. It is provided
+# to provide Google nameservers. If you don't want to have it generated
+# and bound by default, use the up --no-resolv argument.
+
+nameserver 8.8.8.8
+nameserver 8.8.4.4
+

scompose/tests/test_client.py

@@ -42,6 +42,7 @@ def test_commands(tmp_path):
     print('Testing up')
     project.up()
     assert 'etc.hosts' in os.listdir()
+    assert 'resolv.conf' in os.listdir()
 
     print('Waiting for instance to start')
     sleep(10)

scompose/version.py

@@ -17,7 +17,7 @@
 
 '''
 
-__version__ = "0.0.15"
+__version__ = "0.0.16"
 AUTHOR = 'Vanessa Sochat'
 AUTHOR_EMAIL = '[email protected]'
 NAME = 'singularity-compose'