shell: add a way to set environment variables (#50)

* shell: add a way to set environment variables

Add a new config dictionary in the `shell` key: `environment`. All
values in this dictionary are passed to LXD's config under the
"environment.*" config type.

We set this config when `shell` is called, which is a bit at odds with
the rest of the container config, which is usually set at creation time.
We do this so that a user who fiddles with her `lxdock.yml` file doesn't
have to restart/recreate her container to benefit from the change she's
just made. They will be effective on the next `lxdock shell` call.

* Change shell-env test's container name in test_container

It apparently prevents it from passing.

* shell-env: coerce env values into strings

Otherwise, we can set env variables to values like "42" without
explicitly quoting them in our yaml.

* Widen the scope of the "environment" config

Rather than being specific to `shell`, `environment` is now a top-level
configuration and it now affects both `provision` and `shell`.

docs/conf.rst

@@ -47,6 +47,20 @@ containers, as follows:
     - name: test01
     - name: test02
 
+environment
+-----------
+
+A mapping of environment variables to override in the container when executing commands. This will
+affect ``lxdock shell`` and ``lxdock provision`` operations.
+
+.. code-block:: yaml
+
+  name: myproject
+  image: ubuntu/xenial
+
+  environment:
+    LC_ALL: en_US.utf8
+
 hostnames
 ---------
 
@@ -211,8 +225,11 @@ of shared items. Each shared item should define a ``source`` (a path on your hos
 shell
 -----
 
-The ``shell`` option allows you to define the user to use when doing a ``lxdock shell``. This allows
-you to have a shell for a specific user/home directory when doing ``lxdock shell``:
+The ``shell`` option alters the behavior of the ``lxdock shell`` command. It's a map of these
+sub-options:
+
+* ``user``: Default user to open the shell under.
+* ``home``: Path to open the shell under.
 
 .. code-block:: yaml
 

lxdock/conf/schema.py

@@ -1,11 +1,12 @@
-from voluptuous import All, Any, In, IsDir, Length, Required, Schema, Url
+from voluptuous import All, Any, Coerce, Extra, In, IsDir, Length, Required, Schema, Url
 
 from ..provisioners import Provisioner
 
 from .validators import Hostname, LXDIdentifier
 
 
 _top_level_and_containers_common_options = {
+    'environment': {Extra: Coerce(str)},
     'hostnames': [Hostname(), ],
     'image': str,
     'mode': In(['local', 'pull', ]),

lxdock/container.py

@@ -77,6 +77,9 @@ def halt(self):
     @must_be_running
     def provision(self, barebone=None):
         """ Provisions the container. """
+        # We run this in case our lxdock.yml config was modified since our last `lxdock up`.
+        self._setup_env()
+
         if barebone is None:  # None == only if the container isn't provisioned.
             barebone = not self.is_provisioned
 
@@ -104,6 +107,9 @@ def provision(self, barebone=None):
     @must_be_running
     def shell(self, username=None):
         """ Opens a new interactive shell in the container. """
+        # We run this in case our lxdock.yml config was modified since our last `lxdock up`.
+        self._setup_env()
+
         # For now, it's much easier to call `lxc`, but eventually, we might want to contribute
         # to pylxd so it supports `interactive = True` in `exec()`.
         shellcfg = self.options.get('shell', {})
@@ -145,6 +151,9 @@ def up(self):
         # Setup shares if applicable.
         self._setup_shares()
 
+        # Override environment variables
+        self._setup_env()
+
         # Provisions the container if applicable.
         if not self.is_provisioned:
             self.provision(barebone=True)
@@ -291,6 +300,14 @@ def _perform_barebones_setup(self):
         else:
             logger.warning('SSH pubkey was not found. Provisioning tools may not work correctly...')
 
+    def _setup_env(self):
+        """ Add environment overrides from the conf to our container config. """
+        env_override = self.options.get('environment')
+        if env_override:
+            for key, value in env_override.items():
+                self._container.config['environment.{}'.format(key)] = str(value)
+            self._container.save(wait=True)
+
     def _setup_hostnames(self, ip):
         """ Configure the potential hostnames associated with the container. """
         hostnames = self.options.get('hostnames', [])

tests/integration/test_container.py

@@ -95,6 +95,19 @@ def test_can_open_a_shell_for_a_specific_shelluser(self, mocked_call):
         assert mocked_call.call_args[0][0] == \
             'lxc exec {} --env HOME=/opt -- su -m test'.format(container.lxd_name)
 
+    @unittest.mock.patch('subprocess.call')
+    def test_can_set_shell_environment_variables(self, mocked_call):
+        # Environment variables in the shell can be set through configuration.
+        container_options = {
+            'name': self.containername('shell-env'), 'image': 'ubuntu/xenial',
+            'environment': {'FOO': 'bar', 'BAR': 42},
+        }
+        container = Container('myproject', THIS_DIR, self.client, **container_options)
+        container.up()
+        container.shell()
+        assert container._container.config['environment.FOO'] == 'bar'
+        assert container._container.config['environment.BAR'] == '42'
+
     def test_can_tell_if_a_container_exists_or_not(self, persistent_container):
         unknown_container = Container('myproject', THIS_DIR, self.client, **{
             'name': self.containername('unknown'), 'image': 'ubuntu/xenial', 'mode': 'pull', })