Allow installation of sync gateway on 18.04

Author: yorinasub17

modules/install-couchbase-server/install-couchbase-server

@@ -45,7 +45,7 @@ function print_usage {
   echo
   echo "Usage: install-couchbase-server [options]"
   echo
-  echo "This script can be used to install Couchbase Server and its dependencies. This script has been tested with Ubuntu 16.04 and Amazon Linux 2."
+  echo "This script can be used to install Couchbase Server and its dependencies. This script has been tested with Ubuntu 16.04, 18.04, and Amazon Linux 2."
   echo
   echo "Options:"
   echo
@@ -147,7 +147,7 @@ function disable_transparent_huge_pages {
   elif os_is_amazon_linux; then
     sudo chkconfig disable-thp on
   else
-    log_error "This script only supports Ubuntu 16.04 and Amazon Linux 2."
+    log_error "This script only supports Ubuntu 16.04, 18.04, and Amazon Linux 2."
     exit 1
   fi
 }

modules/install-sync-gateway/install-sync-gateway

@@ -48,7 +48,7 @@ function print_usage {
   echo
   echo "Usage: install-sync-gateway [options]"
   echo
-  echo "This script can be used to install Couchbase Sync Gateway and its dependencies. This script has been tested with Ubuntu 16.04 and Amazon Linux 2."
+  echo "This script can be used to install Couchbase Sync Gateway and its dependencies. This script has been tested with Ubuntu 16.04, 18.04, and Amazon Linux 2."
   echo
   echo "Options:"
   echo
@@ -257,12 +257,12 @@ function install {
 
   log_info "Starting Sync Gateway install..."
 
-  if os_is_ubuntu "16.04"; then
+  if os_is_ubuntu "16.04" || os_is_ubuntu "18.04"; then
     install_sync_gateway_on_ubuntu "$edition" "$version" "$checksum" "$checksum_type"
   elif os_is_amazon_linux "2"; then
     install_sync_gateway_on_amazon_linux "$edition" "$version" "$checksum" "$checksum_type"
   else
-    log_error "This script only supports Ubuntu 16.04 and Amazon Linux 2."
+    log_error "This script only supports Ubuntu 16.04, 18.04, and Amazon Linux 2."
     exit 1
   fi