Update mirror-image

  * Allign to offline-build example

Change-Id: I96448007b75ef98dd8f658b0be14c0b56c8117ba
diff --git a/mirror-image/scripts/base.sh b/mirror-image/scripts/base.sh
index a070f10..1487f42 100644
--- a/mirror-image/scripts/base.sh
+++ b/mirror-image/scripts/base.sh
@@ -1,16 +1,21 @@
 #!/bin/bash -xe
+
+UBUNTU_BASEURL="${UBUNTU_BASEURL:-"mirror://mirrors.ubuntu.com/mirrors.txt"}"
+
 ## Base packages and setup
 export DEBIAN_FRONTEND=noninteractive
 echo "exit 101" > /usr/sbin/policy-rc.d
 chmod +x /usr/sbin/policy-rc.d
 
 echo "Acquire::CompressionTypes::Order gz;" >/etc/apt/apt.conf.d/99compression-workaround-salt
+echo "Acquire::EnableSrvRecords false;" >/etc/apt/apt.conf.d/99enablesrvrecords-false
 
+sysctl -w fs.file-max=100000
 # Overwrite default mirrors
-echo "deb mirror://mirrors.ubuntu.com/mirrors.txt xenial main restricted multiverse universe" > /etc/apt/sources.list
-echo "deb mirror://mirrors.ubuntu.com/mirrors.txt xenial-updates main restricted multiverse universe" >> /etc/apt/sources.list
-echo "deb mirror://mirrors.ubuntu.com/mirrors.txt xenial-security main restricted multiverse universe" >> /etc/apt/sources.list
-echo "deb mirror://mirrors.ubuntu.com/mirrors.txt xenial-backports main restricted multiverse universe" >> /etc/apt/sources.list
+echo "deb [arch=amd64] ${UBUNTU_BASEURL} xenial main restricted multiverse universe" > /etc/apt/sources.list
+echo "deb [arch=amd64] ${UBUNTU_BASEURL} xenial-updates main restricted multiverse universe" >> /etc/apt/sources.list
+echo "deb [arch=amd64] ${UBUNTU_BASEURL} xenial-security main restricted multiverse universe" >> /etc/apt/sources.list
+#echo "deb [arch=amd64] ${UBUNTU_BASEURL} xenial-backports main restricted multiverse universe" >> /etc/apt/sources.list
 
 apt-get clean
 apt-get update
@@ -21,12 +26,9 @@
 apt-get -y install apt-transport-https libmnl0 python-apt python-m2crypto python-psutil
 
 # Cleanup old kernels, ensure latest is installed via virtual package
-apt-get purge -y linux-image-* linux-headers-*
 if [ ! -f /tmp/no_install_kernel ]; then
-    # Use HWE kernel
-    ## Temporary disable latest hwe due to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe-edge/+bug/1679823
-    #apt-get install -y linux-image-generic-hwe-16.04
-    apt-get install -y linux-image-4.8.0-41-generic linux-image-extra-4.8.0-41-generic
+    apt-get purge -y linux-image-* linux-headers-*
+    apt-get install -y linux-image-virtual-lts-xenial linux-image-extra-virtual-lts-xenial
 
     # Update grub cmdline
     sed -i 's|GRUB_CMDLINE_LINUX_DEFAULT=.*|GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=ttyS0,115200n8"|g' /etc/default/grub