Permit use of wheel mirrors in pypi element.

pypi-mirror creates a separate mirror index for wheels (one per OS
that mirrors are built on). To be able to use it one then needs to be
able to export multiple mirrors for inclusion in pip.conf. As a drive
by I made it possible to disable the use of the pypi.python.org index
without using --offline (as --offline has larger impact).

Change-Id: I3e85a8069b18cafd7eae4cd0591821acc3b5a739

elements/pypi/README.md

@@ -8,11 +8,25 @@ temporarily overwrites /root/.pip.conf and .pydistutils.cfg to use it.
 When online, the official pypi.python.org pypi index is supplied as an
 extra-url, so uncached dependencies will still be available. When offline, only
 the mirror is used - be warned that a stale mirror will cause build failures.
+To disable the pypi.python.org index without using --offline (e.g. when working
+behind a corporate firewall that prohibits pypi.python.org) set
+DIB\_NO\_PYPI\_PIP to any non-empty value.
 
 To use an arbitrary mirror set PYPI\_MIRROR\_URL=http[s]://somevalue/
 
-[pypi-mirror](https://git.openstack.org/cgit/openstack-infra/pypi-mirror) can be useful in making a
-partial PyPI mirror suitable for building images. For instance:
+Additional mirrors can be added by exporting PYPI\_MIRROR\_URL\_1=... etc. Only
+the one mirror can be used by easy-install, but since wheels need to be in the
+first mirror to be used, the last listed mirror is used as the pydistutils
+index. NB: The sort order for these variables is a simple string sort - if
+you have more than 9 additional mirrors, some care will be needed.
+
+A typical use of this element is thus:
+export PYPI\_MIRROR\_URL=http://site/pypi/Ubuntu-13.10
+export PYPI\_MIRROR\_URL\_1=http://site/pypi/
+
+[pypi-mirror](https://git.openstack.org/cgit/openstack-infra/pypi-mirror) can
+be useful in making a partial PyPI mirror suitable for building images. For
+instance:
 
  * sudo apt-get install  libxml2-dev libxslt-dev libmysqlclient-dev libpq-dev \
    libnspr4-dev pkg-config libsqlite3-dev libzmq-dev libffi-dev libldap2-dev \

elements/pypi/pre-install.d/00-configure-pypi-mirror

@@ -1,32 +1,45 @@
-#!/bin/bash
+#!/usr/bin/env python
 
-set -eu
+import os.path
 
-PYPIURL=${PYPI_MIRROR_URL:-'file:///tmp/pypi'}
-mkdir -p ~/.pip
+def main():
+    home = os.path.expanduser("~")
+    backup_configs(home)
+    indices = []
+    if os.environ.get('PYPI_MIRROR_URL'):
+        candidates = [k for k in os.environ if k.startswith('PYPI_MIRROR_URL')]
+        indices = list(map(os.environ.get, sorted(candidates)))
+    else:
+        indices = ['file:///tmp/pypi']
+    easy_index = indices[-1]
+    use_pypi_python_org = True
+    if os.environ.get('DIB_OFFLINE'):
+        use_pypi_python_org = False
+    if os.environ.get('DIB_NO_PYPI_PIP'):
+        use_pypi_python_org = False
+    if use_pypi_python_org:
+        indices.append('https://pypi.python.org/simple')
+    with file(home + '/.pip/pip.conf', 'wt') as output:
+        output.write('[global]\n')
+        output.write('log = %s/pip.log\n' % (home,))
+        output.write('index-url = %s\n' % (indices[0],))
+        for index in indices[1:]:
+            output.write('extra-index-url = %s\n' % (index,))
+    with file(home + '/.pydistutils.cfg', 'wt') as output:
+        output.write('[easy_install]\n')
+        output.write('index_url = %s\n' % (easy_index,))
 
-if [ -e ~/.pip/pip.conf ]; then
-    mv ~/.pip/pip.conf{,.orig}
-fi
 
-if [ -e ~/.pydistutils.cfg ]; then
-    mv ~/.pydistutils.cfg{,.orig}
-fi
+def backup_configs(home):
+    pip_dir = home + '/.pip'
+    if not os.path.exists(pip_dir):
+        os.mkdir(pip_dir)
+    if os.path.exists(pip_dir + '/pip.conf'):
+        os.rename(pip_dir + '/pip.conf', pip_dir + '/pip.conf.orig')
+    if os.path.exists(home + '/.pydistutils.cfg'):
+        os.rename(home + '/.pydistutils.cfg', home + '/.pydistutils.cfg.orig')
 
-if [ -z $DIB_OFFLINE ]; then
-    ONLINE="extra-index-url = https://pypi.python.org/simple"
-else
-    ONLINE=""
-fi
 
-cat <<EOF > ~/.pip/pip.conf
-[global]
-index-url = $PYPIURL
-$ONLINE
-log = $HOME/pip.log
-EOF
+if __name__ == '__main__':
+    main()
 
-cat <<EOF > ~/.pydistutils.cfg
-[easy_install]
-index_url = $PYPIURL
-EOF