feature: add chroot-pip helper

Dockerfile.alpine

@@ -21,6 +21,7 @@ ENV BUILD_ROOT=$BUILD_ROOT \
     _chroot="chroot $BUILD_ROOT"
 
 ADD --chmod=0755 chroot-apk.sh /usr/local/bin/chroot-apk
+ADD --chmod=0755 chroot-pip.sh /usr/local/bin/chroot-pip
 ADD --chmod=0755 remove-py-if-pyc-exists.sh /usr/local/bin/remove-py-if-pyc-exists
 RUN set -eu ; \
     python -m pip install -U pip setuptools ; \

chroot-pip.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env sh
+
+if [ "x$CACHE_ROOT" = 'x' ] || [ "x$BUILD_ROOT" = 'x' ]; then
+    >&2 echo "CACHE_ROOT (${CACHE_ROOT:-not-set}) and/or BUILD_ROOT (${BUILD_ROOT:-not-set}) is not set!"
+    exit 1
+fi
+
+set -e
+set -o pipefail
+
+setup () {
+    return 0
+}
+
+fini () {
+    python -m compileall -b $BUILD_ROOT/usr/local/lib/python$PYTHON_VERSION/site-packages
+    export ALLOW_SITE_PACKAGES=1
+    find $BUILD_ROOT/usr/local/lib/python$PYTHON_VERSION/site-packages \
+        -type f -name '*.py' -exec sh -c "remove-py-if-pyc-exists {}" \; ;\
+    return $?
+}
+
+trap fini EXIT
+setup
+export PYTHONPATH=$BUILD_ROOT/usr/local/lib/python$PYTHON_VERSION/site-packages
+export PIP_PREFIX=$BUILD_ROOT/usr/local
+
+set -x
+python -m pip $@

remove-py-if-pyc-exists.sh

@@ -1,7 +1,9 @@
 #!/usr/bin/env sh
 
+ALLOW_SITE_PACKAGES=${ALLOW_SITE_PACKAGES:-0}
+
 if [ -f "${1}c" ]; then
-    if ! case "$1" in *site-packages/*) false ;; *) true ;; esac ; then
+    if [ "x$ALLOW_SITE_PACKAGES" = 'x0' ] && ! case "$1" in *site-packages/*) false ;; *) true ;; esac ; then
         echo 'Skipping optimization of '"$1"
         exit 0
     fi