debian-install: put pagespeed-libraries.conf where it will be loaded

The way you used to install apache2 configuration on Debian-based systems
was to put it in /etc/apache2/conf.d/, but starting with Ubuntu 14 LTS
there's a new system where you install it to /etc/apache2/conf-available/ and
then run a2enconf to symlink it to /etc/apache2/conf-enabled.  On these
systems we weren't installing pagespeed-libraries.conf in a way that made
it usable, because when we put it in conf.d it just was never loaded.

Switch to installing to /etc/apache2/conf-available/, and then use a2enconf
if it's available.  If a2enconf isn't available, manually symlink to conf.d.

Fixes: https://github.com/pagespeed/mod_pagespeed/issues/1389

install/debian/build.sh

@@ -46,7 +46,7 @@ prep_staging_debian() {
   prep_staging_common
   install -m 755 -d "${STAGEDIR}/DEBIAN" \
     "${STAGEDIR}/etc/cron.daily" \
-    "${STAGEDIR}/etc/apache2/conf.d" \
+    "${STAGEDIR}${APACHE_CONF_AVAILABLE_DIR}" \
     "${STAGEDIR}/usr/bin"
 }
 
@@ -80,7 +80,7 @@ stage_install_debian() {
   chmod 644 "${STAGEDIR}${APACHE_CONFDIR}/pagespeed.conf"
   install -m 644 \
     "${BUILDDIR}/../../net/instaweb/genfiles/conf/pagespeed_libraries.conf" \
-    "${STAGEDIR}${APACHE_CONF_D_DIR}/pagespeed_libraries.conf"
+    "${STAGEDIR}${APACHE_CONF_AVAILABLE_DIR}/pagespeed_libraries.conf"
 }
 
 # Build the deb file within a fakeroot.
@@ -248,12 +248,14 @@ export DEBEMAIL="${MAINTMAIL}"
 # Make everything happen in the OUTPUTDIR.
 cd "${OUTPUTDIR}"
 
-COMMON_DEPS="apache2.2-common|apache2-api-20120211"
+# Modules shouldn't generally depend on apache2, but to install ourselves we use
+# a2enmod etc which are in the apache2 package.
+COMMON_DEPS="apache2"
 COMMON_PREDEPS="dpkg (>= 1.14.0)"
 
 APACHE_MODULEDIR="/usr/lib/apache2/modules"
 APACHE_CONFDIR="/etc/apache2/mods-available"
-APACHE_CONF_D_DIR="/etc/apache2/conf.d"
+APACHE_CONF_AVAILABLE_DIR="/etc/apache2/conf-available"
 MOD_PAGESPEED_CACHE="/var/cache/mod_pagespeed"
 MOD_PAGESPEED_LOG="/var/log/pagespeed"
 APACHE_USER="www-data"

install/debian/conffiles

@@ -1,3 +1,3 @@
 /etc/apache2/mods-available/pagespeed.load
 /etc/apache2/mods-available/pagespeed.conf
-/etc/apache2/conf.d/pagespeed_libraries.conf
+/etc/apache2/conf-available/pagespeed_libraries.conf

install/debian/postinst

@@ -19,6 +19,26 @@ case "$1" in
 
         test ! -e /etc/apache2/mods-enabled/pagespeed.load && \
             a2enmod pagespeed
+
+        # Enable pagespeed-libraries.conf.  On recent systems you install config
+        # files into /etc/apache2/conf-available and then use a2enconf to
+        # symlink it into /etc/apache2/conf-enabled.  On older systems there's
+        # just /etc/apache2/conf.d/, so we manually symlink it there instead.
+        # See https://github.com/pagespeed/mod_pagespeed/issues/1389
+        if hash a2enconf 2> /dev/null; then
+          # a2enconf is available; use it.
+          a2enconf pagespeed_libraries
+        elif [ -d /etc/apache2/conf.d/ ]; then
+          # this ubuntu is too old for that; manually symlink it
+          if [ -e /etc/apache2/conf.d/pagespeed_libraries.conf ]; then
+            echo "Not symlinking on top of existing pagespeed_libraries.conf"
+          else
+            ln -s ../conf-available/pagespeed_libraries.conf \
+                  /etc/apache2/conf.d/
+          fi
+        else
+          echo "failed to configure pagespeed_libraries.conf" >&2
+        fi
     ;;
     abort-upgrade|abort-remove|abort-deconfigure)
     ;;

install/debian/prerm

@@ -3,6 +3,16 @@
 case "$1" in
     remove)
         test -e /etc/apache2/mods-enabled/pagespeed.load && a2dismod pagespeed
+        if hash a2disconf 2> /dev/null; then
+          # a2disconf is available; use it.
+          test -L /etc/apache2/conf-enabled/pagespeed_libraries.conf && \
+            a2disconf pagespeed_libraries
+        else
+          # If we don't have a2disconf, then the symlink is in conf.d instead of
+          # conf-enabled.
+          test -L /etc/apache2/conf.d/pagespeed_libraries.conf && \
+               rm /etc/apache2/conf.d/pagespeed_libraries.conf
+        fi
     ;;
     upgrade|deconfigure|failed-upgrade)
     ;;