script to deploy kube-dns (#89)

update readme
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Sandeep Rajan 2018-08-20 15:26:26 -04:00 committed by Chris O'Haver
parent 8ad15e969e
commit 5b8ae1cda0
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@ -41,3 +41,21 @@ $ kubectl delete --namespace=kube-system deployment kube-dns
For non-RBAC deployments, you'll need to edit the resulting yaml before applying it:
1. Remove the line `serviceAccountName: coredns` from the `Deployment` section.
2. Remove the `ServiceAccount`, `ClusterRole`, and `ClusterRoleBinding` sections.
## Rollback to kube-dns
In case one wants to revert a Kubernetes cluster running CoreDNS back to kube-dns,
the `rollback.sh` script generates the kube-dns manifest to install kube-dns.
This uses the existing service, there is no disruption in servicing requests.
The script doesn't delete the CoreDNS deployment or replication controller - you'll have to
do that manually, after deploying kube-dns.
These commands will deploy kube-dns replacing CoreDNS:
~~~
$ ./rollback.sh | kubectl apply -f -
$ kubectl delete --namespace=kube-system deployment coredns
~~~
**NOTE:** You will need to delete the CoreDNS deployment (as above) since while CoreDNS and kube-dns are running at the same time, queries may randomly hit either one.

46
kubernetes/rollback.sh Normal file
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#!/bin/bash
# Roll back kube-dns to the cluster which has CoreDNS installed.
show_help () {
cat << USAGE
usage: $0 [ -i DNS-IP ] [ -d CLUSTER-DOMAIN ]
-i : Specify the cluster DNS IP address. If not specificed, the IP address of
the existing "kube-dns" service is used, if present.
-d : Specify the Cluster Domain. Default is "cluster.local"
USAGE
exit 0
}
curl -L https://raw.githubusercontent.com/kubernetes/kubernetes/master/cluster/addons/dns/kube-dns/kube-dns.yaml.base > `pwd`/kube-dns.yaml.sed
# Simple Defaults
CLUSTER_DOMAIN=cluster.local
YAML_TEMPLATE=`pwd`/kube-dns.yaml.sed
# Get Opts
while getopts "hi:d:" opt; do
case "$opt" in
h) show_help
;;
i) CLUSTER_DNS_IP=$OPTARG
;;
d) CLUSTER_DOMAIN=$OPTARG
;;
esac
done
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 [ $? -ne 0 ]; then
>&2 echo "Error! The IP address for DNS service couldn't be determined automatically. Please specify the DNS-IP with the '-i' option."
exit 2
fi
fi
sed -e s/__PILLAR__DNS__SERVER__/${CLUSTER_DNS_IP}/g -e s/__PILLAR__DNS__DOMAIN__/${CLUSTER_DOMAIN}/g ${YAML_TEMPLATE}