Example of Cloud-init Vendor data to conditionally write a per-distro mirror configuration.

easy_vendor-data.sh

#cloud-boothook
#!/bin/sh

# Make sure that we can determine if this Ubuntu or Debian
lsbrelease="/usr/bin/lsb_release"
if [ ! -e "${lsbrelease}" ]; then
    exit 0
fi

# Find out if this Ubuntu
distro=$(lsb_release -i -s)

if [ "${distro}" != "Ubuntu" ]; then
    exit 0
fi

# Write a cloud-config
cat > /etc/cloud/cloud.cfg.d/99-configure-mirror.cfg <<EOF
# This was written via Vendor Data
system_info:
   distro: ubuntu
   package_mirrors:
     - arches: [i386, amd64]
       failsafe:
         primary: http://archive.ubuntu.com/ubuntu
         security: http://security.ubuntu.com/ubuntu
       search:
         primary:
           - http://%(region)s.utlemming.clouds.archive.ubuntu.com/ubuntu/
         security: []
     - arches: [armhf, armel, default]
       failsafe:
         primary: http://ports.ubuntu.com/ubuntu-ports
         security: http://ports.ubuntu.com/ubuntu-ports
EOF