Merge pull request #398 from yarikoptic/opt-imports-lazy

reproman/distributions/debian.py

@@ -14,7 +14,7 @@
 
 import attr
 from collections import defaultdict
-
+# OPT: requests is imported at the point of use
 
 import pytz
 
@@ -25,8 +25,6 @@
 
 import logging
 
-import requests
-
 from reproman.support.distributions.debian import \
     parse_apt_cache_show_pkgs_output, parse_apt_cache_policy_pkgs_output, \
     parse_apt_cache_policy_source_info, get_apt_release_file_names, \
@@ -184,6 +182,7 @@ def _init_apt_sources(self, session,
                 date.strftime("%Y%m%dT%H%M%SZ"),
                 source.codename
             )
+            import requests  # OPT
             r = requests.get(url)
             m = re.search(
                 '<a href="/archive/\w*debian/(\w+)/dists/\w+/">next change</a>',

reproman/resource/docker_container.py

@@ -13,8 +13,8 @@
 import io
 import json
 import os
-import requests
 import tarfile
+
 from reproman import utils
 from ..cmd import Runner
 from ..support.exceptions import CommandError, ResourceError
@@ -66,10 +66,11 @@ def is_engine_running(base_url=None):
         -------
         boolean
         """
+        from requests.exceptions import ConnectionError
         try:
             session = docker.Client(base_url=base_url)
             session.info()
-        except (requests.exceptions.ConnectionError,
+        except (ConnectionError,
                 docker.errors.DockerException):
             return False
         return True

reproman/resource/ssh.py

@@ -9,11 +9,9 @@
 
 import attr
 import getpass
-import invoke
 import uuid
-from fabric import Connection
 from ..log import LoggerHelper
-from paramiko import AuthenticationException
+# OPT: invoke, fabric and paramiko is imported at the point of use
 
 import logging
 lgr = logging.getLogger('reproman.resource.ssh')
@@ -71,6 +69,8 @@ def connect(self, password=None):
         """
         # Convert key_filename to a list
         # See: https://github.com/ReproNim/reproman/commit/3807f1287c39ea2393bae26803e6da8122ac5cff
+        from fabric import Connection
+        from paramiko import AuthenticationException
         key_filename = None
         if self.key_filename:
             key_filename = [self.key_filename]
@@ -96,7 +96,6 @@ def connect(self, password=None):
                   self._connection.user, self._connection.host,
                   self._connection.port,  # Fabric defaults to 22.
                   auth)
-
         try:
             self._connection.open()
         except AuthenticationException:
@@ -170,6 +169,7 @@ class SSHSession(POSIXSession):
     def _execute_command(self, command, env=None, cwd=None, handle_permission_denied=True):
         # TODO -- command_env is not used etc...
         # command_env = self.get_updated_env(env)
+        from invoke.exceptions import UnexpectedExit
         command = command_as_string(command)
         if env:
             command = ' '.join(['%s=%s' % k for k in env.items()]) \
@@ -180,7 +180,7 @@ def _execute_command(self, command, env=None, cwd=None, handle_permission_denied
 
         try:
             result = self.connection.run(command, hide=True)
-        except invoke.exceptions.UnexpectedExit as e:
+        except UnexpectedExit as e:
             if 'permission denied' in e.result.stderr.lower() and handle_permission_denied:
                 # Issue warning once
                 if not getattr(self, '_use_sudo_warning', False):

reproman/support/jobs/template.py

@@ -12,7 +12,8 @@
 import os.path as op
 import logging
 
-import jinja2
+# jinja2 is imported at the point of use for faster startup
+
 from shlex import quote as shlex_quote
 
 lgr = logging.getLogger("reproman.support.jobs.template")
@@ -31,6 +32,7 @@ def __init__(self, **kwds):
         self.kwds = kwds
 
     def _render(self, template_name, subdir):
+        import jinja2
         lgr.debug("Using template %s", template_name)
         env = jinja2.Environment(
             loader=jinja2.FileSystemLoader(

reproman/tests/test_api.py

@@ -7,10 +7,14 @@
 ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ### ##
 '''Unit tests for Python API functionality.'''
 
+import os
 import re
-from reproman.utils import getargspec
-import pytest
+import sys
+
+from ..utils import getargspec
+from ..cmd import Runner
 
+import pytest
 from .utils import assert_true, assert_false, eq_
 
 
@@ -59,3 +63,26 @@ def test_consistent_order_of_args(intf, spec_posargs):
     if not spec_posargs:
         pytest.skip("no positional args")
     eq_(set(args[:len(spec_posargs)]), spec_posargs)
+
+
+def test_no_heavy_imports():
+
+    def get_modules(extra=''):
+        out, err = Runner().run([
+            sys.executable,
+            '-c',
+            'import os, sys%s; print(os.linesep.join(sys.modules))' % extra
+        ])
+        return set(out.split(os.linesep))
+
+    # Establish baseline
+    modules0 = get_modules()  # e.g. currently ~60
+
+    # new modules brought by import of our .api
+    modules = get_modules(', reproman.api').difference(modules0)
+    assert 'requests' not in modules
+    assert 'boto' not in modules
+    assert 'jinja2' not in modules
+    assert 'paramiko' not in modules
+    # and catch it all!  Raise the boundary as needed
+    assert len(modules) < 230  # currently 203