example: k8s patch script

patch_redis.sh

#!/bin/bash
# get all deployments with name `redis-sentinel-manager` or `redis-cluster-manager`
# and patch these deploy with a nodeSelector with name similar to group-<ns>: <ns>

read -r -d '' tmpl <<'EOF'
kubectl -n i_ns patch deploy i_deploy --type='json' -p='[{"op": "add", "path": "/spec/template/spec/nodeSelector/group-i_ns", "value": "i_ns" }]'
EOF

# redis
ns_deploy=$(kubectl get deploy --all-namespaces|grep -E 'redis-.*-manager' | awk '{printf "%s+%s ", $1,$2}')
echo > patch_redis_1.sh
for i in ${ns_deploy}
do
  i_ns=$(echo $i | tr '+' ' '|awk '{print $1}')
  i_deploy=$(echo $i | tr '+' ' '|awk '{print $2}')
  # backup existing yaml
  kubectl -n ${i_ns} get deploy ${i_deploy} -o yaml > ${i_ns}_${i_deploy}_$(date +%Y%m%d).yaml
  echo "${tmpl}" | sed "s|i_ns|${i_ns}|g"  | sed "s|i_deploy|${i_deploy}|g"  >> patch_redis_1.sh
done
echo "Run `bash patch_redis_1.sh`"