Switch to using argparse for commandline parsing

Is cleaner and less hacky than using Traitlets. We still
use traitlets for configuration, and accept a config file
for configuring detectors and what not.

Also implements allowing arbitrary commands from the commandline,
so we can do things like build and test a container!

repo2docker/app.py

@@ -13,6 +13,7 @@ import time
 import logging
 import uuid
 import shutil
+import argparse
 from pythonjsonlogger import jsonlogger
 import escapism
 
@@ -47,51 +48,10 @@ class Repo2Docker(Application):
     version = __version__
     description = __doc__
 
-    config_file = Unicode(
-        'repo2docker_config.py',
-        config=True,
-        help="""
-        Path to read traitlets configuration file from.
-        """
-    )
-
     @default('log_level')
     def _default_log_level(self):
         return logging.INFO
 
-    repo = Unicode(
-        os.getcwd(),
-        allow_none=True,
-        config=True,
-        help="""
-        The git repository to clone.
-
-        Could be a git URL or a file path.
-        """
-    )
-
-    ref = Unicode(
-        'master',
-        allow_none=True,
-        config=True,
-        help="""
-        The git ref in the git repository to build.
-
-        Can be a tag, ref or branch.
-        """
-    )
-
-    output_image_spec = Unicode(
-        None,
-        allow_none=True,
-        config=True,
-        help="""
-        The spec of the image to build.
-
-        Should be the same as the value passed to `-t` param of docker build.
-        """
-    )
-
     git_workdir = Unicode(
         "/tmp",
         config=True,
@@ -149,27 +109,6 @@ class Repo2Docker(Application):
         DANGEROUS WHEN DONE IN A CLOUD ENVIRONMENT! ONLY USE LOCALLY!
         """
     )
-    json_logs = Bool(
-        False,
-        config=True,
-        help="""
-        Enable JSON logging for easier consumption by external services.
-        """
-    )
-
-    aliases = Dict({
-        'repo': 'Repo2Docker.repo',
-        'ref': 'Repo2Docker.ref',
-        'image': 'Repo2Docker.output_image_spec',
-        'f': 'Repo2Docker.config_file',
-    })
-
-    flags = Dict({
-        'no-clean': ({'Repo2Docker': {'cleanup_checkout': False}}, 'Do not clean up git checkout'),
-        'no-run': ({'Repo2Docker': {'run': False}}, 'Do not run built container image'),
-        'push': ({'Repo2Docker': {'push': True}}, 'Push built image to a docker registry'),
-        'json-logs': ({'Repo2Docker': {'json_logs': True}}, 'Enable JSON logging'),
-    })
 
     def fetch(self, url, ref, checkout_path):
         try:
@@ -180,19 +119,74 @@ class Repo2Docker(Application):
             self.log.error('Failed to clone repository!', extra=dict(phase='failed'))
             sys.exit(1)
 
-        try:
-            for line in execute_cmd(['git', 'reset', '--hard', ref], cwd=checkout_path,
-                                    capture=self.json_logs):
-                self.log.info(line, extra=dict(phase='fetching'))
-        except subprocess.CalledProcessError:
-            self.log.error('Failed to check out ref %s', ref, extra=dict(phase='failed'))
-            sys.exit(1)
+        if ref:
+            try:
+                for line in execute_cmd(['git', 'reset', '--hard', ref], cwd=checkout_path,
+                                        capture=self.json_logs):
+                    self.log.info(line, extra=dict(phase='fetching'))
+            except subprocess.CalledProcessError:
+                self.log.error('Failed to check out ref %s', ref, extra=dict(phase='failed'))
+                sys.exit(1)
 
-    def initialize(self, *args, **kwargs):
-        super().initialize(*args, **kwargs)
-        self.load_config_file(self.config_file)
+    def get_argparser(self):
+        argparser = argparse.ArgumentParser()
+        argparser.add_argument(
+            '--config',
+            default='repo2docker_config.py',
+            help="Path to config file for repo2docker"
+        )
 
-        if self.json_logs:
+        argparser.add_argument(
+            '--json-logs',
+            default=False,
+            action='store_true',
+            help='Emit JSON logs instead of human readable logs'
+        )
+
+        argparser.add_argument(
+            'repo',
+            help='Path to repository that should be built'
+        )
+
+        argparser.add_argument(
+            '--image-name',
+            help='Name of image to be built. If unspecified will be autogenerated'
+        )
+
+        argparser.add_argument(
+            '--push',
+            dest='push',
+            action='store_true',
+            help='Push docker image to repository'
+        )
+
+        argparser.add_argument(
+            '--no-run',
+            dest='run',
+            action='store_false',
+            help='Do not run container after it has been built'
+        )
+
+        argparser.add_argument(
+            'cmd',
+            nargs='*',
+            help='Custom command to run after building container'
+        )
+
+        return argparser
+
+    def initialize(self):
+        args = self.get_argparser().parse_args()
+
+        self.load_config_file(args.config)
+
+        if '@' in args.repo:
+            self.repo, self.ref = args.repo.split('@', 1)
+        else:
+            self.repo = args.repo
+            self.ref = None
+
+        if args.json_logs:
             # Need to reset existing handlers, or we repeat messages
             logHandler = logging.StreamHandler()
             formatter = jsonlogger.JsonFormatter()
@@ -208,18 +202,18 @@ class Repo2Docker(Application):
             # We don't want a [Repo2Docker] on all messages
             self.log.handlers[0].formatter = logging.Formatter(fmt='%(message)s')
 
-        if len(self.extra_args) == 1:
-            # accept repo as a positional arg
-            self.repo = self.extra_args[0]
-        elif len(self.extra_args) > 1:
-            print("%s accepts at most one positional argument." % self.name, file=sys.stderr)
-            print("See python -m repo2docker --help for usage", file=sys.stderr)
-            self.exit(1)
-
-        if self.output_image_spec is None:
+        if args.image_name:
+            self.output_image_spec = args.image_name
+        else:
             # Attempt to set a sane default!
             # HACK: Provide something more descriptive?
-            self.output_image_spec = escapism.escape(self.repo).lower() + ':' + self.ref.lower()
+            self.output_image_spec = 'image-' + escapism.escape(self.repo).lower()
+
+        self.push = args.push
+        self.run = args.run
+        self.json_logs = args.json_logs
+
+        self.run_cmd = args.cmd
 
 
     def push_image(self):
@@ -245,11 +239,18 @@ class Repo2Docker(Application):
     def run_image(self):
         client = docker.from_env(version='auto')
         port = self._get_free_port()
+        if not self.run_cmd:
+            port = str(self._get_free_port())
+            run_cmd = ['jupyter', 'notebook', '--ip', '0.0.0.0', '--port', port]
+            ports={'%s/tcp' % port: port}
+        else:
+            run_cmd = self.run_cmd
+            ports = {}
         container = client.containers.run(
             self.output_image_spec,
-            ports={'%s/tcp' % port: port},
+            ports={},
             detach=True,
-            command=['jupyter', 'notebook', '--ip', '0.0.0.0', '--port', str(port)],
+            command=run_cmd
         )
         while container.status == 'created':
             time.sleep(0.5)
@@ -259,8 +260,10 @@ class Repo2Docker(Application):
             for line in container.logs(stream=True):
                 self.log.info(line.decode('utf-8'), extra=dict(phase='running'))
         finally:
+            # FIXME: We should pass the container's exit code back out!
             self.log.info('Stopping container...\n', extra=dict(phase='running'))
-            container.kill()
+            if container.status == 'running':
+                container.kill()
             container.remove()
 
     def _get_free_port(self):