Don't call sys.exit from inside the class

Instead, we raise exceptions that can be caught and
handled by calling code instead

repo2docker/__main__.py

@@ -1,6 +1,7 @@
 import argparse
 import sys
 import os
+import docker
 from .app import Repo2Docker
 from . import __version__
 from .utils import validate_and_generate_port_mapping
@@ -314,8 +315,18 @@ def make_r2d(argv=None):
 def main():
     r2d = make_r2d()
     r2d.initialize()
+    try:
         r2d.start()
-
+    except docker.errors.BuildError as e:
+        # This is only raised by us
+        if r2d.debug:
+            r2d.log.exception(e)
+        sys.exit(1)
+    except docker.errors.ImageLoadError as e:
+        # This is only raised by us
+        if r2d.debug:
+            r2d.log.exception(e)
+        sys.exit(1)
 
 if __name__ == '__main__':
     main()

repo2docker/app.py

@@ -415,7 +415,7 @@ class Repo2Docker(Application):
             progress = json.loads(line.decode('utf-8'))
             if 'error' in progress:
                 self.log.error(progress['error'], extra=dict(phase='failed'))
-                sys.exit(1)
+                raise docker.errors.ImageLoadError(progress['error'])
             if 'id' not in progress:
                 continue
             if 'progressDetail' in progress and progress['progressDetail']:
@@ -545,12 +545,8 @@ class Repo2Docker(Application):
                 api_client = docker.APIClient(version='auto',
                                               **kwargs_from_env())
             except DockerException as e:
-                print("Docker client initialization error. Check if docker is"
+                self.log.exception(e)
-                      " running on the host.")
+                raise
-                print(e)
-                if self.log_level == logging.DEBUG:
-                    raise e
-                sys.exit(1)
         # If the source to be executed is a directory, continue using the
         # directory. In the case of a local directory, it is used as both the
         # source and target. Reusing a local directory seems better than
@@ -572,7 +568,7 @@ class Repo2Docker(Application):
                 if not os.path.isdir(checkout_path):
                     self.log.error('Subdirectory %s does not exist',
                                    self.subdir, extra=dict(phase='failure'))
-                    sys.exit(1)
+                    raise FileNotFoundError(f'Could not find {checkout_path}')
 
             with chdir(checkout_path):
                 for BP in self.buildpacks:
@@ -608,7 +604,7 @@ class Repo2Docker(Application):
                                           extra=dict(phase='building'))
                         elif 'error' in l:
                             self.log.info(l['error'], extra=dict(phase='failure'))
-                            sys.exit(1)
+                            raise docker.errors.BuildError(l['error'])
                         elif 'status' in l:
                                 self.log.info('Fetching base image...\r',
                                               extra=dict(phase='building'))

repo2docker/contentproviders/git.py

@@ -38,7 +38,7 @@ class Git(ContentProvider):
             if hash is None:
                 self.log.error('Failed to check out ref %s', ref,
                                extra=dict(phase='failed'))
-                sys.exit(1)
+                raise ValueError(f'Failed to check out ref {ref}')
             # If the hash is resolved above, we should be able to reset to it
             for line in execute_cmd(['git', 'reset', '--hard', hash],
                                     cwd=output_dir,