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Elastic Search Rolling Upgrade

Overview

This page provides comprehensive documentation and instructions for implementing a rolling upgrade strategy for your Elasticsearch cluster.

Steps

Note: During the rolling upgrade, it is anticipated that there will be some downtime. Additionally, ensure to take an elasticdump of the Elasticsearch data using the script provided below in the playground pod.

Copy the below script and save it as es-dump.sh. Replace the elasticsearch URL and the indices names in the script.

Run the below commands in the terminal.

Now, run the below command inside the playground pod.

Rolling upgrade from v6.6.2 to v7.17.15

Steps

List the elasticsearch pods and enter into any of the elasticsearch pod shells.

Scale down the replica count of elasticsearch master and data from 3 to 0.

Edit the Statefulset of elasticsearch master by replacing the docker image removing deprecated environment variables and adding compatible environment variables. Replace the elasticsearch image tag from 6.6.2 to 7.17.15. The below code provides the depraced environment variables and compatible environment variables.

Edit elasticsearch-master values.yaml file

Edit the Statefulset of elasticsearch data by replacing the docker image removing deprecated environment variables and adding compatible environment variables. Replace the elasticsearch image tag from 6.6.2 to 7.17.15.

Edit elasticsearch-data values.yaml file.

After making the changes, scale up the statefulsets of elasticsearch data and master.

After all pods are in running state, re-enable shard allocation and check cluster health.

# Enter into elasticsearch pod
kubectl exec -it <elasticsearch_data_pod_name> -n es-cluster  bash

#Run below curl commands
curl -X PUT "<elasticsearch_url>:9200/_cluster/settings?pretty" -H 'Content-Type: application/json' -d'
{
  "persistent": {
    "cluster.routing.allocation.enable": null
  }
}
'

curl -X GET "<elasticsearch_url>:9200/_cat/health?v=true&pretty"

You have successfully upgraded the elasticsearch cluster from v6.6.2 to v7.17.15 :)

ReIndexing the Indices:

After successfully upgrading the elasticsearch, reindex the indices present in elasticsearch using below script which are created in v6.6.2 or earlier.

Copy the below script and save it as es-reindex.sh. Replace the elasticsearch URL in the script.

#!/bin/bash

ELASTICSEARCH_URL="<Elasticsearch URL>:9200"
TMP="_tmp"

FILENAME="elasticsearch-indexes.txt"
INDICES=()
while IFS= read -r index; do
    INDICES+=("$index")
done < "$FILENAME"

# do for all abc elastic indices
for INDEX in "${INDICES[@]}"; do
    sleep 5
    echo -e "Reindex process starting for index: $INDEX\n"
    tmp_index=$INDEX${TMP}
    echo "Starting reindexing elastic data from original index:$INDEX to temporary index:$tmp_index"
    output=$(curl -X POST "${ELASTICSEARCH_URL}/_reindex" --max-time 3600 -H 'Content-Type: application/json' -d'
    {
      "source": {
        "index": "'"$INDEX"'"
      },
      "dest": {
        "index": "'"$tmp_index"'"
      }
    }
    ')
    sleep 5
    echo -e "Reindexing completed from original index:$INDEX to temporary index:$tmp_index with output: $output\n"
    echo -e "Deleting $INDEX\n"
    output=$(curl -X DELETE "${ELASTICSEARCH_URL}/$INDEX")
    echo -e "$INDEX deleted with status: $output\n"
    echo "Starting reindexing elastic data from temporary index:$tmp_index to original index:$INDEX"
    output=$(curl -X POST "${ELASTICSEARCH_URL}/_reindex" --max-time 3600 -H 'Content-Type: application/json' -d'
    {
      "source": {
        "index": "'"$tmp_index"'"
      },
      "dest": {
        "index": "'"$INDEX"'"
      }
    }
    ')
    echo -e "Reindexing completed from temporary index:$tmp_index to original index:$INDEX with output: $output\n"
    echo -e "Deleting $tmp_index\n"
    output=$(curl -X DELETE "${ELASTICSEARCH_URL}/$tmp_index")
    echo -e "$tmp_index deleted with status: $output\n\n\n"
done

Run the below commands in the terminal.

export KUBECONFIG=<path_to_your_kubeconfig>
kubectl get pods -n playground
kubectl cp <path_to_script_in_your_machine>/es-reindex.sh playground/<playground_name>:<path_in_playground_pod>/es-dump.sh

Now, run the below command inside the playground pod.

# Run the script which reinex the indicesc of your elasticsearch data using below command
kubectl exec -it <playground_pod_name> -n playground  bash
cd <path_to_script_inside_playground_pod>
chmod +x es-reindex.sh
./es-reindex.sh

NOTE: Make Sure to delete jaeger indices as mapping is not supported in v8.11.3 and the indices which are created before v7.17.15 by reindexing. If the indices which are created in v6.6.2 or earlier are present then the upgradation from v7.17.15 to v8.11.3 may fail.

Rolling upgrade from v7.17.15 to v8.11.3 & security is disabled

Steps

Scale down the replica count of elasticsearch master and data from 3 to 0.

kubectl get statefulsets -n es-cluster
kubectl scale statefulsets <elasticsearch_master> -n es-cluster --replicas=0
kubectl scale statefulsets <elasticsearch_data> -n es-cluster --replicas=0

Edit the Statefulset of elasticsearch master by replacing the docker image removing deprecated environment variables and adding compatible environment variables. Replace the elasticsearch image tag from 7.17.15 to 8.11.3. The below code provides the compatible environment variables and if you are following a rolling upgrade then there are no deprecated environment variables from v7.17.15 to v8.11.3.

# Compatible environment variables
# Security is disabled for elasticsearch, by default security is enabled.
- env:
  - name: cluster.initial_master_nodes
    value: elasticsearch-master-v1-0,elasticsearch-master-v1-1,elasticsearch-master-v1-2 
  - name: xpack.security.enabled
    value: false 
  - name: discovery.seed_hosts
    value: elasticsearch-master-v1-headless
  - name: node.roles
    value: master

Edit the Statefulset of elasticsearch data by replacing the docker image removing deprecated environment variables and adding compatible environment variables. Replace the elasticsearch image tag from 7.17.15 to 8.11.3.

# Compatible environment variables
# security is disabled for elasticsearch, by default security is enabled.
- env:
  - name: cluster.initial_master_nodes
    value: elasticsearch-master-v1-0,elasticsearch-master-v1-1,elasticsearch-master-v1-2 
  - name: discovery.seed_hosts
    value: elasticsearch-master-v1-headless
  - name: node.roles
    value: data,ingest
  - name: xpack.security.enabled
    value: false

After making the changes, scale up the statefulsets of elasticsearch data and master.

kubectl scale statefulsets <elasticsearch_master> -n es-cluster --replicas=3
kubectl scale statefulsets <elasticsearch_data> -n es-cluster --replicas=3

After all pods are in running state, re-enable shard allocation and check cluster health.

# Enter into elasticsearch pod
kubectl exec -it <elasticsearch_data_pod_name> -n es-cluster  bash

#Run below curl commands
curl -X PUT "<elasticsearch_url>:9200/_cluster/settings?pretty" -H 'Content-Type: application/json' -d'
{
  "persistent": {
    "cluster.routing.allocation.enable": null
  }
}
'

curl -X GET "<elasticsearch_url>:9200/_cat/health?v=true&pretty"

You have successfully upgraded the elasticsearch cluster from v7.17.15 to v8.11.3 👏