allow config to manage python3 use explicitly

Add variables ENABLED_PYTHON3_PACKAGES and DISABLED_PYTHON3_PACKAGES to
work like ENABLED_SERVICES and DISABLED_SERVICES and to manage which
packages are installed using Python 3. Move the list of whitelisted
packages in pip_install to the default for ENABLED_PYTHON3_PACKAGES,
except swift which is not enabled by default for now.

Add enable_python3_package and disable_python3_package functions to make
editing the variables from local.conf easier.

Add python3_enabled_for and python3_disabled_for functions to check the
settings against packages being installed by pip.

Update pip_install to check if python3 is disabled for a service, then
see if it is explicitly enabled, and only then fall back to looking at
the classifiers in the packaging metadata.

Update pip_install messages to give more detail about why the choice
between python 2 and 3 is being made for a given package.

Change-Id: I69857d4e11f4767928614a3b637c894bcd03491f
Signed-off-by: Doug Hellmann <doug@doughellmann.com>
diff --git a/inc/python b/inc/python
index 5a9a9ed..1c581ba 100644
--- a/inc/python
+++ b/inc/python
@@ -97,6 +97,111 @@
     echo $classifier
 }
 
+# python3_enabled_for() checks if the service(s) specified as arguments are
+# enabled by the user in ``ENABLED_PYTHON3_PACKAGES``.
+#
+# Multiple services specified as arguments are ``OR``'ed together; the test
+# is a short-circuit boolean, i.e it returns on the first match.
+#
+# Uses global ``ENABLED_PYTHON3_PACKAGES``
+# python3_enabled_for dir [dir ...]
+function python3_enabled_for {
+    local xtrace
+    xtrace=$(set +o | grep xtrace)
+    set +o xtrace
+
+    local enabled=1
+    local dirs=$@
+    local dir
+    for dir in ${dirs}; do
+        [[ ,${ENABLED_PYTHON3_PACKAGES}, =~ ,${dir}, ]] && enabled=0
+    done
+
+    $xtrace
+    return $enabled
+}
+
+# python3_disabled_for() checks if the service(s) specified as arguments are
+# disabled by the user in ``DISABLED_PYTHON3_PACKAGES``.
+#
+# Multiple services specified as arguments are ``OR``'ed together; the test
+# is a short-circuit boolean, i.e it returns on the first match.
+#
+# Uses global ``DISABLED_PYTHON3_PACKAGES``
+# python3_disabled_for dir [dir ...]
+function python3_disabled_for {
+    local xtrace
+    xtrace=$(set +o | grep xtrace)
+    set +o xtrace
+
+    local enabled=1
+    local dirs=$@
+    local dir
+    for dir in ${dirs}; do
+        [[ ,${DISABLED_PYTHON3_PACKAGES}, =~ ,${dir}, ]] && enabled=0
+    done
+
+    $xtrace
+    return $enabled
+}
+
+# enable_python3_package() adds the repositories passed as argument to the
+# ``ENABLED_PYTHON3_PACKAGES`` list, if they are not already present.
+#
+# For example:
+#   enable_python3_package nova
+#
+# Uses global ``ENABLED_PYTHON3_PACKAGES``
+# enable_python3_package dir [dir ...]
+function enable_python3_package {
+    local xtrace
+    xtrace=$(set +o | grep xtrace)
+    set +o xtrace
+
+    local tmpsvcs="${ENABLED_PYTHON3_PACKAGES}"
+    local python3
+    for dir in $@; do
+        if [[ ,${DISABLED_PYTHON3_PACKAGES}, =~ ,${dir}, ]]; then
+            warn $LINENO "Attempt to enable_python3_package ${dir} when it has been disabled"
+            continue
+        fi
+        if ! python3_enabled_for $dir; then
+            tmpsvcs+=",$dir"
+        fi
+    done
+    ENABLED_PYTHON3_PACKAGES=$(_cleanup_service_list "$tmpsvcs")
+
+    $xtrace
+}
+
+# disable_python3_package() prepares the services passed as argument to be
+# removed from the ``ENABLED_PYTHON3_PACKAGES`` list, if they are present.
+#
+# For example:
+#   disable_python3_package swift
+#
+# Uses globals ``ENABLED_PYTHON3_PACKAGES`` and ``DISABLED_PYTHON3_PACKAGES``
+# disable_python3_package dir [dir ...]
+function disable_python3_package {
+    local xtrace
+    xtrace=$(set +o | grep xtrace)
+    set +o xtrace
+
+    local disabled_svcs="${DISABLED_PYTHON3_PACKAGES}"
+    local enabled_svcs=",${ENABLED_PYTHON3_PACKAGES},"
+    local dir
+    for dir in $@; do
+        disabled_svcs+=",$dir"
+        if python3_enabled_for $dir; then
+            enabled_svcs=${enabled_svcs//,$dir,/,}
+        fi
+    done
+    DISABLED_PYTHON3_PACKAGES=$(_cleanup_service_list "$disabled_svcs")
+    ENABLED_PYTHON3_PACKAGES=$(_cleanup_service_list "$enabled_svcs")
+
+    $xtrace
+}
+
 # Wrapper for ``pip install`` to set cache and proxy environment variables
 # Uses globals ``OFFLINE``, ``PIP_VIRTUAL_ENV``,
 # ``PIP_UPGRADE``, ``TRACK_DEPENDS``, ``*_proxy``,
@@ -149,16 +254,16 @@
                 # support for python3 in progress, but don't claim support
                 # in their classifier
                 echo "Check python version for : $package_dir"
-                if [[ ${package_dir##*/} == "nova" || ${package_dir##*/} == "glance" || \
-                        ${package_dir##*/} == "cinder" || ${package_dir##*/} == "swift" || \
-                        ${package_dir##*/} == "uwsgi" ]]; then
-                    echo "Using $PYTHON3_VERSION version to install $package_dir"
+                if python3_disabled_for ${package_dir##*/}; then
+                    echo "Explicitly using $PYTHON2_VERSION version to install $package_dir based on DISABLED_PYTHON3_PACKAGES"
+                elif python3_enabled_for ${package_dir##*/}; then
+                    echo "Explicitly using $PYTHON3_VERSION version to install $package_dir based on ENABLED_PYTHON3_PACKAGES"
                     sudo_pip="$sudo_pip LC_ALL=en_US.UTF-8"
                     cmd_pip=$(get_pip_command $PYTHON3_VERSION)
                 elif [[ -d "$package_dir" ]]; then
                     python_versions=$(get_python_versions_for_package $package_dir)
                     if [[ $python_versions =~ $PYTHON3_VERSION ]]; then
-                        echo "Using $PYTHON3_VERSION version to install $package_dir"
+                        echo "Automatically using $PYTHON3_VERSION version to install $package_dir based on classifiers"
                         sudo_pip="$sudo_pip LC_ALL=en_US.UTF-8"
                         cmd_pip=$(get_pip_command $PYTHON3_VERSION)
                     else
@@ -167,7 +272,7 @@
                         # a warning.
                         python3_classifier=$(check_python3_support_for_package_local $package_dir)
                         if [[ ! -z "$python3_classifier" ]]; then
-                            echo "Using $PYTHON3_VERSION version to install $package_dir"
+                            echo "Automatically using $PYTHON3_VERSION version to install $package_dir based on local package settings"
                             sudo_pip="$sudo_pip LC_ALL=en_US.UTF-8"
                             cmd_pip=$(get_pip_command $PYTHON3_VERSION)
                         fi
@@ -177,7 +282,7 @@
                     package=$(echo $package_dir | grep -o '^[.a-zA-Z0-9_-]*')
                     python3_classifier=$(check_python3_support_for_package_remote $package)
                     if [[ ! -z "$python3_classifier" ]]; then
-                        echo "Using $PYTHON3_VERSION version to install $package"
+                        echo "Automatically using $PYTHON3_VERSION version to install $package based on remote package settings"
                         sudo_pip="$sudo_pip LC_ALL=en_US.UTF-8"
                         cmd_pip=$(get_pip_command $PYTHON3_VERSION)
                     fi
diff --git a/stackrc b/stackrc
index 19f5b53..ae71772 100644
--- a/stackrc
+++ b/stackrc
@@ -102,9 +102,19 @@
     source $RC_DIR/.localrc.password
 fi
 
-# Control whether Python 3 should be used.
+# Control whether Python 3 should be used at all.
 export USE_PYTHON3=$(trueorfalse False USE_PYTHON3)
 
+# Control whether Python 3 is enabled for specific services by the
+# base name of the directory from which they are installed. See
+# enable_python3_package to edit this variable and use_python3_for to
+# test membership.
+export ENABLED_PYTHON3_PACKAGES="nova,glance,cinder,uwsgi"
+
+# Explicitly list services not to run under Python 3. See
+# disable_python3_package to edit this variable.
+export DISABLED_PYTHON3_PACKAGES=""
+
 # When Python 3 is supported by an application, adding the specific
 # version of Python 3 to this variable will install the app using that
 # version of the interpreter instead of 2.7.
diff --git a/tests/test_python.sh b/tests/test_python.sh
new file mode 100755
index 0000000..8652798
--- /dev/null
+++ b/tests/test_python.sh
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+
+# Tests for DevStack INI functions
+
+TOP=$(cd $(dirname "$0")/.. && pwd)
+
+source $TOP/functions-common
+source $TOP/inc/python
+
+source $TOP/tests/unittest.sh
+
+echo "Testing Python 3 functions"
+
+# Initialize variables manipulated by functions under test.
+export ENABLED_PYTHON3_PACKAGES=""
+export DISABLED_PYTHON3_PACKAGES=""
+
+assert_false "should not be enabled yet" python3_enabled_for testpackage1
+
+enable_python3_package testpackage1
+assert_equal "$ENABLED_PYTHON3_PACKAGES" "testpackage1"  "unexpected result"
+assert_true "should be enabled" python3_enabled_for testpackage1
+
+assert_false "should not be disabled yet" python3_disabled_for testpackage2
+
+disable_python3_package testpackage2
+assert_equal "$DISABLED_PYTHON3_PACKAGES" "testpackage2"  "unexpected result"
+assert_true "should be disabled" python3_disabled_for testpackage2
+
+report_results