Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
executable file 133 lines (110 sloc) 3.7 KB
#!/bin/bash
# Deploys CoreDNS to a cluster currently running Kube-DNS.
show_help () {
cat << USAGE
usage: $0 [ -r REVERSE-CIDR ] [ -i DNS-IP ] [ -d CLUSTER-DOMAIN ] [ -t YAML-TEMPLATE ]
-r : Define a reverse zone for the given CIDR. You may specify this option more
than once to add multiple reverse zones. If no reverse CIDRs are defined,
then the default is to handle all reverse zones (i.e. in-addr.arpa and ip6.arpa)
-i : Specify the cluster DNS IP address. If not specified, the IP address of
the existing "kube-dns" service is used, if present.
-s : Skips the translation of kube-dns configmap to the corresponding CoreDNS Corefile configuration.
USAGE
exit 0
}
# Simple Defaults
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null && pwd )"
CLUSTER_DOMAIN=cluster.local
YAML_TEMPLATE="$DIR/coredns.yaml.sed"
STUBDOMAINS=""
UPSTREAM=\\/etc\\/resolv\.conf
FEDERATIONS=""
# Translates the kube-dns ConfigMap to equivalent CoreDNS Configuration.
function translate-kube-dns-configmap {
kube-dns-federation-to-coredns
kube-dns-upstreamnameserver-to-coredns
kube-dns-stubdomains-to-coredns
}
function kube-dns-federation-to-coredns {
fed=$(kubectl -n kube-system get configmap kube-dns -ojsonpath='{.data.federations}' 2> /dev/null | jq . | tr -d '":,')
if [[ ! -z ${fed} ]]; then
FEDERATIONS=$(sed -e '1s/^/federation /' -e 's/^/ /' -e '1i\\' <<< "${fed}") # add federation to the stanza
fi
}
function kube-dns-upstreamnameserver-to-coredns {
up=$(kubectl -n kube-system get configmap kube-dns -ojsonpath='{.data.upstreamNameservers}' 2> /dev/null | tr -d '[",]')
if [[ ! -z ${up} ]]; then
UPSTREAM=${up}
fi
}
function kube-dns-stubdomains-to-coredns {
STUBDOMAIN_TEMPLATE='
SD_DOMAIN:53 {
errors
cache 30
loop
forward . SD_DESTINATION
}'
function dequote {
str=${1#\"} # delete leading quote
str=${str%\"} # delete trailing quote
echo ${str}
}
function parse_stub_domains() {
sd=$1
# get keys - each key is a domain
sd_keys=$(echo -n $sd | jq keys[])
# For each domain ...
for dom in $sd_keys; do
dst=$(echo -n $sd | jq '.['$dom'][0]') # get the destination
dom=$(dequote $dom)
dst=$(dequote $dst)
sd_stanza=${STUBDOMAIN_TEMPLATE/SD_DOMAIN/$dom} # replace SD_DOMAIN
sd_stanza=${sd_stanza/SD_DESTINATION/$dst} # replace SD_DESTINATION
echo "$sd_stanza"
done
}
sd=$(kubectl -n kube-system get configmap kube-dns -ojsonpath='{.data.stubDomains}' 2> /dev/null)
STUBDOMAINS=$(parse_stub_domains "$sd")
}
# Get Opts
while getopts "hsr:i:d:t:k:" opt; do
case "$opt" in
h) show_help
;;
s) SKIP=1
;;
r) REVERSE_CIDRS="$REVERSE_CIDRS $OPTARG"
;;
i) CLUSTER_DNS_IP=$OPTARG
;;
d) CLUSTER_DOMAIN=$OPTARG
;;
t) YAML_TEMPLATE=$OPTARG
;;
esac
done
# Conditional Defaults
if [[ -z $REVERSE_CIDRS ]]; then
REVERSE_CIDRS="in-addr.arpa ip6.arpa"
fi
if [[ -z $CLUSTER_DNS_IP ]]; then
# Default IP to kube-dns IP
CLUSTER_DNS_IP=$(kubectl get service --namespace kube-system kube-dns -o jsonpath="{.spec.clusterIP}")
if [ $? -ne 0 ]; then
>&2 echo "Error! The IP address for DNS service couldn't be determined automatically. Please specify the DNS-IP with the '-i' option."
exit 2
fi
fi
if [[ "${SKIP}" -ne 1 ]] ; then
translate-kube-dns-configmap
fi
orig=$'\n'
replace=$'\\\n'
sed -e "s/CLUSTER_DNS_IP/$CLUSTER_DNS_IP/g" \
-e "s/CLUSTER_DOMAIN/$CLUSTER_DOMAIN/g" \
-e "s?REVERSE_CIDRS?$REVERSE_CIDRS?g" \
-e "s@STUBDOMAINS@${STUBDOMAINS//$orig/$replace}@g" \
-e "s@FEDERATIONS@${FEDERATIONS//$orig/$replace}@g" \
-e "s/UPSTREAMNAMESERVER/$UPSTREAM/g" \
"${YAML_TEMPLATE}"
You can’t perform that action at this time.