Create tools/install_prereqs.sh

* Factor system package prereq installs out to tools/install_prereqs.sh
* Set minimum time between runs with PREREQ_RERUN_HOURS
  default = 2 hours
* Create re_export_proxy_variables

Change-Id: I4a182b1da685f403d6abdd8540d2114796c01682

functions

@@ -710,6 +710,27 @@ function restart_service() {
 }
 
 
+# HTTP and HTTPS proxy servers are supported via the usual environment variables [1]
+# ``http_proxy``, ``https_proxy`` and ``no_proxy``. They can be set in
+# ``localrc`` or on the command line if necessary::
+#
+# [1] http://www.w3.org/Daemon/User/Proxies/ProxyClients.html
+#
+#     http_proxy=http://proxy.example.com:3128/ no_proxy=repo.example.net ./stack.sh
+
+function re_export_proxy_variables() {
+    if [[ -n "$http_proxy" ]]; then
+        export http_proxy=$http_proxy
+    fi
+    if [[ -n "$https_proxy" ]]; then
+        export https_proxy=$https_proxy
+    fi
+    if [[ -n "$no_proxy" ]]; then
+        export no_proxy=$no_proxy
+    fi
+}
+
+
 # Helper to launch a service in a named screen
 # screen_it service "command-line"
 function screen_it {

stack.sh

@@ -644,25 +644,7 @@ set -o xtrace
 
 # Install package requirements
 echo_summary "Installing package prerequisites"
-if is_ubuntu; then
-    install_package $(get_packages $FILES/apts)
-elif is_fedora; then
-    install_package $(get_packages $FILES/rpms)
-elif is_suse; then
-    install_package $(get_packages $FILES/rpms-suse)
-else
-    exit_distro_not_supported "list of packages"
-fi
-
-if [[ $SYSLOG != "False" ]]; then
-    if is_ubuntu || is_fedora; then
-        install_package rsyslog-relp
-    elif is_suse; then
-        install_package rsyslog-module-relp
-    else
-        exit_distro_not_supported "rsyslog-relp installation"
-    fi
-fi
+$TOP_DIR/tools/install_prereqs.sh
 
 if is_service_enabled rabbit; then
     # Install rabbitmq-server

tools/install_prereqs.sh

@@ -0,0 +1,78 @@
+#!/usr/bin/env bash
+
+# **install_prereqs.sh**
+
+# Install system package prerequisites
+#
+# install_prereqs.sh [-f]
+#
+# -f        Force an install run now
+
+
+if [[ -n "$1" &&  "$1" = "-f" ]]; then
+    FORCE=1
+fi
+
+# Keep track of the devstack directory
+TOP_DIR=$(cd $(dirname "$0")/.. && pwd)
+
+# Import common functions
+source $TOP_DIR/functions
+
+# Determine what system we are running on.  This provides ``os_VENDOR``,
+# ``os_RELEASE``, ``os_UPDATE``, ``os_PACKAGE``, ``os_CODENAME``
+# and ``DISTRO``
+GetDistro
+
+# Needed to get ``ENABLED_SERVICES``
+source $TOP_DIR/stackrc
+
+# Prereq dirs are here
+FILES=$TOP_DIR/files
+
+# Minimum wait time
+PREREQ_RERUN_MARKER=${PREREQ_RERUN_MARKER:-$TOP_DIR/.prereqs}
+PREREQ_RERUN_HOURS=${PREREQ_RERUN_HOURS:-2}
+PREREQ_RERUN_SECONDS=$((60*60*$PREREQ_RERUN_HOURS))
+
+NOW=$(date "+%s")
+LAST_RUN=$(head -1 $PREREQ_RERUN_MARKER 2>/dev/null || echo "0")
+DELTA=$(($NOW - $LAST_RUN))
+if [[ $DELTA -lt $PREREQ_RERUN_SECONDS && -z "$FORCE" ]]; then
+    echo "Re-run time has not expired ($(($PREREQ_RERUN_SECONDS - $DELTA)) seconds remaining); exiting..."
+    exit 0
+fi
+
+# Make sure the proxy config is visible to sub-processes
+re_export_proxy_variables
+
+# Install Packages
+# ================
+
+# Install package requirements
+if is_ubuntu; then
+    install_package $(get_packages $FILES/apts)
+elif is_fedora; then
+    install_package $(get_packages $FILES/rpms)
+elif is_suse; then
+    install_package $(get_packages $FILES/rpms-suse)
+else
+    exit_distro_not_supported "list of packages"
+fi
+
+if [[ -n "$SYSLOG" && "$SYSLOG" != "False" ]]; then
+    if is_ubuntu || is_fedora; then
+        install_package rsyslog-relp
+    elif is_suse; then
+        install_package rsyslog-module-relp
+    else
+        exit_distro_not_supported "rsyslog-relp installation"
+    fi
+fi
+
+
+# Mark end of run
+# ---------------
+
+date "+%s" >$PREREQ_RERUN_MARKER
+date >>$PREREQ_RERUN_MARKER