script.sh

#!/usr/bin/env bash

set -e

function __is_pod_ready() {
  [[ "$(kubectl get po "$1" -o 'jsonpath={.status.conditions[?(@.type=="Ready")].status}')" == 'True' ]]
}

function __pods_ready() {
  local pod

  [[ "$#" == 0 ]] && return 0

  for pod in $pods; do
    __is_pod_ready "$pod" || return 1
  done

  return 0
}

function __wait-until-pods-ready() {
  local period interval i pods

  if [[ $# != 2 ]]; then
    echo "Usage: wait-until-pods-ready PERIOD INTERVAL" >&2
    echo "" >&2
    echo "This script waits for all pods to be ready in the current namespace." >&2

    return 1
  fi

  period="$1"
  interval="$2"

  for ((i=0; i<$period; i+=$interval)); do
    pods="$(kubectl get po -o 'jsonpath={.items[*].metadata.name}')"
    if __pods_ready $pods; then
      return 0
    fi

    echo "Waiting for pods to be ready..."
    sleep "$interval"
  done

  echo "Waited for $period seconds, but all pods are not ready yet."
  return 1
}

function __getVolumeDebuggerPod(){

cat << EOP
kind: Pod
apiVersion: v1
metadata:
  name: volume-debugger
spec:
  volumes:
    - name: volume-to-debug
      persistentVolumeClaim:
       claimName: $1
  containers:
    - name: debugger
      image: busybox
      command: ['sleep', '3600']
      volumeMounts:
        - mountPath: "/data"
          name: volume-to-debug
EOP

}

function __copyFirstData(){
    
    if [ -d "data" ]; then
        echo "data directory already exists exiting"
        return 1
    fi

    # switch cluster to $sourceClusterName
    gcloud container clusters get-credentials $sourceClusterName --zone $sourceZone --project $sourceProject

    currentNs=$(kubectl config get-contexts $(kubectl config current-context) --no-headers | awk '{ print $5 }')
    kubectl config set-context $(kubectl config current-context) --namespace=$sourceNamespace

    # get the volume claim name from the pod
    sourceClaimName=$(kubectl get pods $sourcePod -o 'jsonpath={.spec.volumes[].persistentVolumeClaim.claimName}')
    # get the statefulset name
    sourceControllerName=$(kubectl get pods $sourcePod -o 'jsonpath={.metadata.ownerReferences[].name}')

    # scale down $sourceClusterName to zero pods and copy data
    kubectl scale statefulset $sourceControllerName --replicas 0

    # create the pod to copy data from
    __getVolumeDebuggerPod $sourceClaimName | kubectl create -f -
    __wait-until-pods-ready 300 2
    kubectl cp $sourceNamespace/volume-debugger:data data
    kubectl delete pod volume-debugger --grace-period=0

    kubectl config set-context $(kubectl config current-context) --namespace=$currentNs

    # switch to production-us-central1 copy data 
    gcloud container clusters get-credentials $destClusterName --zone $destZone --project $destProject

    currentNs=$(kubectl config get-contexts $(kubectl config current-context) --no-headers | awk '{ print $5 }')
    kubectl config set-context $(kubectl config current-context) --namespace=$destNamespace

    # get the volume claim name from the pod
    destClaimName=$(kubectl get pods $destPod -o 'jsonpath={.spec.volumes[].persistentVolumeClaim.claimName}')
    # get the statefulset name
    destControllerName=$(kubectl get pods $destPod -o 'jsonpath={.metadata.ownerReferences[].name}')

    # scale down production-us-central1 to zero pods
    kubectl scale statefulset $destControllerName --replicas 0

    __getVolumeDebuggerPod $destClaimName | kubectl create -f - 
    __wait-until-pods-ready 300 2
    kubectl cp data $destNamespace/volume-debugger:/
    kubectl delete pod volume-debugger --grace-period=0

    rm -rf data

    kubectl scale statefulset $destControllerName --replicas 1

    kubectl config set-context $(kubectl config current-context) --namespace=$currentNs
}


function __copyFirstDataFromOldToNew(){

    sourcePod=test-cc-fdc-nashville-0
    sourceNamespace=firstdata-test
    sourceClusterName=gke-production-us-central1
    sourceZone=us-central1-a
    sourceProject=prj-shared-services

    destPod=firstdata-authorizations-test-0	
    destNamespace=firstdata-test
    destClusterName=production-us-central1
    destZone=us-central1
    destProject=prj-shared-services

    # copy from pod to pod
    __copyFirstData

}

function __copyFirstDataFromNewToOld(){

    sourcePod=firstdata-authorizations-test-0	
    sourceNamespace=firstdata-test
    sourceClusterName=production-us-central1
    sourceZone=us-central1
    sourceProject=prj-shared-services

    destPod=test-cc-fdc-nashville-0
    destNamespace=firstdata-test
    destClusterName=gke-production-us-central1
    destZone=us-central1-a
    destProject=prj-shared-services

    # copy from pod to pod
    __copyFirstData

}


__copyFirstDataFromNewToOld()