configure-resolvers.service

[Unit]
Description=Configure resolvers
Requires=network-online.target
After=network-online.target

[Service]
Type=oneshot
User=root
Group=root
ExecStart=/usr/local/libexec/configure_resolvers

[Install]
WantedBy=multi-user.target

configure_resolvers

#!/usr/bin/env bash

# Adds 127.0.0.1 as the first name server to use. This is where Consul's DNS server runs in the VM.
# Obtains the rest of the DNS servers from Triton.

# Fetch all resolvers from Triton.
while : ${i:=-1}; ((i++)); SERVER=$(mdata-get sdc:resolvers.${i}); [ ${SERVER} ]; do
  RESOLVERS=(${RESOLVERS[@]} ${SERVER})
done

DNS_DOMAIN=$(mdata-get sdc:dns_domain)

# Configure new resolvers in '/etc/resolve.conf'.
(
/bin/sed '/nameserver/d' /etc/resolv.conf 2>/dev/null
echo "nameserver 127.0.0.1"
for HOST in ${RESOLVERS[@]}; do
  echo "nameserver ${HOST}"
done
echo "search $DNS_DOMAIN"
) > /etc/resolv.conf.new
mv /etc/resolv.conf{.new,}