pip module improvements

- Do not silently ignore malformed pip requirements files.
- Properly reports changed when removing packages.
- "latest" i.e. --upgrade is *not* incompatible with requirements files.
- Less branchy, simpler logic.
- Removed pointless variable "initializations", Python doesn't need that.
  Other code simplifications.
- Fun fact; pip install is (kind of) case insensitive, pip freeze is not.
  So, 'sqlalchemy' will be reported as installed by install, but missing
  by freeze.

The perhaps controversial change and the one that led to finding /
fixing above issues...

Instead of adding command parameters 'index', and 'find', and 'mirrors',
and etc.  Added 'extra_args' which are passed onto pip.

The use case for --index-url is having a private pypi repo, like
http://pypi.python.org/pypi/localshop, to which you publish private
packages.  I'm sure most every pip option has a use case for someone.
extra_args handles all those. Can reserve ansible command parameters for
the most common.

Tested with pip 1.1.

pip

@@ -62,23 +62,32 @@ options:
     required: false
     default: present
     choices: [ "present", "absent", "latest" ]
+  extra_args:
+    description:
+      - Extra arguments passed to pip.
+    required: false
+    default: null
+    version_added: "1.0"
 examples:
    - code: "pip: name=flask"
      description: Install I(flask) python package.
    - code: "pip: name=flask version=0.8"
      description: Install I(flask) python package on version 0.8.
-   - code: "pip: name=flask virtualenv=/srv/webapps/my_app/venv"
+   - code: "pip: name=flask virtualenv=/my_app/venv"
      description: "Install I(Flask) (U(http://flask.pocoo.org/)) into the specified I(virtualenv)"
-   - code: "pip: requirements=/srv/webapps/my_app/src/requirements.txt"
+   - code: "pip: requirements=/my_app/requirements.txt"
      description: Install specified python requirements.
-   - code: "pip: requirements=/srv/webapps/my_app/src/requirements.txt virtualenv=/srv/webapps/my_app/venv"
+   - code: "pip: requirements=/my_app/requirements.txt virtualenv=/my_app/venv"
      description: Install specified python requirements in indicated I(virtualenv).
+   - code: "pip: requirements=/my_app/requirements.txt extra_args='-i https://example.com/pypi/simple'"
+     description: Install specified python requirements and custom Index URL.
 notes:
    - Please note that U(http://www.virtualenv.org/, virtualenv) must be installed on the remote host if the virtualenv parameter is specified.
 requirements: [ "virtualenv", "pip" ]
 author: Matt Wright
 '''
 
+
 def _get_full_name(name, version=None):
     if version is None:
         resp = name
@@ -86,28 +95,23 @@ def _get_full_name(name, version=None):
         resp = name + '==' + version
     return resp
 
-def _ensure_virtualenv(module, env, virtualenv):
-    if os.path.exists(os.path.join(env, 'bin', 'activate')):
-        return 0, '', ''
-    else:
-        return _run('%s %s' % (virtualenv, env))
-
-
-def _is_package_installed(name, pip, version=None, requirements=None):
-    cmd = '%s freeze' % pip
-    if requirements is not None:
-        cmd += ' -r %s' % requirements
-    rc, status_stdout, status_stderr = _run(cmd)
-    if requirements is not None:
-        if 'not installed' in status_stderr:
-            return False
-        else:
-            return True
-    return _get_full_name(name, version).lower() in status_stdout.lower()
-
 
-def _did_install(out):
+def _get_pip(module, env):
-    return 'Successfully installed' in out
+    # On Debian and Ubuntu, pip is pip.
+    # On Fedora18 and up, pip is python-pip.
+    # On Fedora17 and below, CentOS and RedHat 6 and 5, pip is pip-python.
+    # On Fedora, CentOS, and RedHat, the exception is in the virtualenv.
+    # There, pip is just pip.
+    # Try pip with the virtualenv directory first.
+    pip = module.get_bin_path('pip', False, ['%s/bin' % env])
+    for p in ['python-pip', 'pip-python']:
+        if not pip:
+            pip = module.get_bin_path(p, False, ['%s/bin' % env])
+    # pip should have been found by now.  The final call to get_bin_path
+    # will trigger fail_json.
+    if not pip:
+        pip = module.get_bin_path('pip', True, ['%s/bin' % env])
+    return pip
 
 
 def _run(cmd):
@@ -118,128 +122,88 @@ def _run(cmd):
     return (process.returncode, stdout, stderr)
 
 
+def _fail(module, cmd, out, err):
+    msg = ''
+    if out:
+        msg += "stdout: %s" % (out, )
+    if err:
+        msg += "\n:stderr: %s" % (err, )
+    module.fail_json(cmd=cmd, msg=msg)
+
+
 def main():
-    pip = None
+    state_map = dict(
-    virtualenv = None
+        present='install',
-    env = None
+        absent='uninstall -y',
-
+        latest='install -U',
-    arg_spec = dict(
-        state=dict(default='present', choices=['absent', 'present', 'latest']),
-        name=dict(default=None, required=False),
-        version=dict(default=None, required=False),
-        requirements=dict(default=None, required=False),
-        virtualenv=dict(default=None, required=False),
-        use_mirrors=dict(default='yes', choices=BOOLEANS)
     )
 
     module = AnsibleModule(
-        argument_spec=arg_spec,
+        argument_spec=dict(
-        required_one_of=[['name','requirements']],
+            state=dict(default='present', choices=state_map.keys()),
-        mutually_exclusive=[['name','requirements']],
+            name=dict(default=None, required=False),
+            version=dict(default=None, required=False),
+            requirements=dict(default=None, required=False),
+            virtualenv=dict(default=None, required=False),
+            use_mirrors=dict(default='yes', choices=BOOLEANS),
+            extra_args=dict(default=None, required=False),
+        ),
+        required_one_of=[['name', 'requirements']],
+        mutually_exclusive=[['name', 'requirements']],
     )
 
-    rc = 0
-    err = ''
-    out = ''
-
-    env = module.params['virtualenv']
-
-    if env:
-        virtualenv = module.get_bin_path('virtualenv', True)
-
-        rc_venv, out_venv, err_venv = _ensure_virtualenv(module, env, virtualenv)
-
-        rc += rc_venv
-        out += out_venv
-        err += err_venv
-
-    # On Debian and Ubuntu, pip is pip.
-    # On Fedora18 and up, pip is python-pip.
-    # On Fedora17 and below, CentOS and RedHat 6 and 5, pip is pip-python.
-    # On Fedora, CentOS, and RedHat, the exception is in the virtualenv.
-    # There, pip is just pip.
-    # Try pip with the virtualenv directory first.
-    pip = module.get_bin_path('pip', False, ['%s/bin' % env])
-
-    for p in ['python-pip', 'pip-python']:
-        if not pip:
-            pip = module.get_bin_path(p, False, ['%s/bin' % env])
-
-    # pip should have been found by now.  The final call to get_bin_path
-    # will trigger fail_json.
-    if not pip:
-        pip = module.get_bin_path('pip', True, ['%s/bin' % env])
-
     state = module.params['state']
     name = module.params['name']
     version = module.params['version']
     requirements = module.params['requirements']
     use_mirrors = module.boolean(module.params['use_mirrors'])
-    command_map = dict(present='install', absent='uninstall', latest='install')
+    extra_args = module.params['extra_args']
 
     if state == 'latest' and version is not None:
         module.fail_json(msg='version is incompatible with state=latest')
+    if name and '=' in name:
+        module.fail_json(msg='version must be specified in the version parameter')
 
-    if state == 'latest' and requirements is not None:
+    err = ''
-        module.fail_json(msg='requirements is incompatible with state=latest')
+    out = ''
-
-    if name is not None and '=' in name:
-        module.fail_json(msg='versions must be specified in the version= parameter')
-
-    cmd = None
-    installed = None
 
-    if name and state == 'latest':
+    env = module.params['virtualenv']
 
-        cmd = '%s %s %s --upgrade' % (pip, command_map[state], name)
+    if env:
-        rc_pip, out_pip, err_pip = _run(cmd)
+        virtualenv = module.get_bin_path('virtualenv', True)
+        if not os.path.exists(os.path.join(env, 'bin', 'activate')):
+            cmd = '%s %s' % (virtualenv, env)
+            rc, out_venv, err_venv = _run(cmd)
+            out += out_venv
+            err += err_venv
+            if rc != 0:
+                _fail(module, cmd, out, err)
+
+    pip = _get_pip(module, env)
+
+    cmd = '%s %s' % (pip, state_map[state])
+    if state != 'absent' and use_mirrors:
+        cmd += ' --use-mirrors'
+    if extra_args:
+        cmd += ' %s' % extra_args
+    if name:
+        cmd += ' %s' % _get_full_name(name, version)
+    elif requirements:
+        cmd += ' -r %s' % requirements
 
-        rc += rc_pip
+    rc, out_pip, err_pip = _run(cmd)
-        out += out_pip
+    out += out_pip
-        err += err_pip
+    err += err_pip
+    if rc == 1 and state == 'absent' and 'not installed' in out_pip:
+        pass  # rc is 1 when attempting to uninstall non-installed package
+    elif rc != 0:
+        _fail(module, cmd, out, err)
 
+    if state == 'absent':
+        changed = 'Successfully uninstalled' in out_pip
+    else:
         changed = 'Successfully installed' in out_pip
 
-    elif name or requirements:
-
-        installed = _is_package_installed(name, pip, version, requirements)
-        changed = ((installed and state == 'absent') or
-                   (not installed and state == 'present'))
-
-        if changed:
-            cmd = '%s %s ' % (pip, command_map[state])
-            if name:
-                if state == 'present':
-                    full_name = _get_full_name(name, version)
-                else:
-                    full_name = name
-                cmd += '%s' % full_name
-            elif requirements:
-                cmd += ' -r %s' % requirements
-
-            if state == 'absent':
-                cmd = cmd + ' -y'
-            elif use_mirrors:
-                cmd = cmd + ' --use-mirrors'
-
-            rc_pip, out_pip, err_pip = _run(cmd)
-            rc  += rc_pip
-            out += out_pip
-            err += err_pip
-
-            if requirements:
-                changed = ((_did_install(out) and state == 'present') or
-                           (not _did_install(out) and state == 'absent'))
-
-    if rc != 0:
-        if not out:
-            msg = err
-        elif not err:
-            msg = out
-        else:
-            msg = "stdout: %s\n:stderr: %s" % (out, err)
-        module.fail_json(msg=msg, cmd=cmd)
-
     module.exit_json(changed=changed, cmd=cmd, name=name, version=version,
                      state=state, requirements=requirements, virtualenv=env)