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This is the process for in-place upgrades of Elasticsearch (ES), using an existing Search feed and index data.

Info

Required

Upgrading Elasticsearch by

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Script

On each node in an Elasticsearch cluster, follow this process and run the files from the Swarm download bundle:

  1. Before upgrading, query the Elasticsearch cluster for the list of nodes.

    Code Block
    languagebash
    curl -i http://ELASTICSEARCH:9200/_cat/nodes
    Note which node is starred; that 
    Example output:
    [root@elasticsearch Elasticsearch]# curl -i http://<ip-address>:9200/_cat/nodes
    HTTP/1.1 200 OK
    content-type: text/plain; charset=UTF-8
    content-length: 300
    <ip-node1> 14 99 1 0.02 0.14 0.15 dilm - <hostname-node1>
    <ip-node2>  1 71 1 0.01 0.09 0.08 dilm - <hostname-node2>
    <ip-node3> 72 99 0 0.08 0.06 0.08 dilm - <hostname-node3>
    <ip-node4> 50 99 0 0.03 0.04 0.05 dilm * <hostname-node4>
    <ip-node5> 47 99 1 0.08 0.14 0.22 dilm - <hostname-node5>
    The node with the * is the Elasticsearch master node, which . It is recommended to upgrade the node last to avoid problems electing a new onemaster node.
  2. Backup the existing elasticsearch.yml, existing configurations so a record exists of any customizations made exists. Run /root/dist/indexer./techsupport-bundle-grab.sh and gather stats for support from your Support tools directory to do this, making sure to upgrade your support tools prior to running the script. Instructions are here.
  3. Start by installing the latest Swarm Search, which is the caringo-elasticsearch-search RPM.
     Code Block
    languagebash
    yum install caringo-elasticsearch-search-VERSION.noarch.rpm
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  1. Run the script that installs and configures the upgrade.
    If the script detects that Elasticsearch is installed and configured, it runs with --upgrade instead of configuring a new cluster, automating the Elasticsearch rolling upgrade steps (https://www.elastic.co/guide/en/elasticsearch/reference/7.17/rolling-upgrades.html).
 Code Block
languagebash
/usr/share/caringo-elasticsearch-search/bin/configure_elasticsearch_with_swarm_search.py
 Infowarning
Important
The upgrade requires Internet access to download the Elasticsearch rpm. Place elasticsearch-7.17.*.rpm in the current directory if Internet access is unavailable.
 Note
Warning
The configure script currently requires node.name to be set in /etc/elasticsearch/elasticsearch.yml. This is not the case with an Swarm Cluster Installer (SCI) deployed VM; uncomment the setting and set it to the default value of ${HOSTNAME}.
  1. Compare the backup file to the newly created elasticsearch.yml and add back any customizations needed , such as node.attr.rack and systemctl restart elasticsearch if the configuration was modified.
Note
thread_pool.write.queue_size: 1000, xpack.ml.enabled, xpack.security.enabled, and prometheus.indices are no longer required.
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 Info
Troubleshooting
Change permissions if the Elasticsearch service fails and journalctl -u elasticsearch shows access is denied (BootstrapException/AccessDeniedException): 
chown elasticsearch /etc/elasticsearch
 Info
Important
Type Ctrl-C once when the upgrade script is stuck in retrying status checks and proceed to the next node after the script finishes if the cluster loses master during the upgrade process and does not recover. Review /etc/elasticsearch/elasticsearch.yml and tail -F /var/log/elasticsearch/<cluster-name>.log for configuration errors.
The nodes elect the master and recover once all nodes have started on Elasticsearch 7.5.2. Health status goes yellow, then eventually green. Re-enable shard allocation, otherwise /_cat/health?v stops at 50% with health status yellow.
Upgrading Elasticsearch 
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Manually
These are the steps the script automates if you need to upgrade manually:
  1. It fixes /etc/sysconfig/elasticsearch to the correct ES6 version (the same as ES7).
  2. It increases the systemd timeout in /etc/systemd/system/elasticsearch.service.d/override.conf (see github.com/elastic/elasticsearch/issues/60140)
  3. A prompt to continue with the yum upgrade to 7.5.2 appears after refreshing the config files for Elasticsearch 6.
  4. It disables shard allocation and does a POST synced-flush for safer rolling upgrades. 
 Info
...
Important
Disabling shard allocation or sync-flush can fail to contact the node, but do not proceed to upgrade the next node until the cluster health is green again.
  1. It uninstalls the Prometheus Exporter plugin if it exists.
  2. It shells out to yum to install the Elasticsearch 7 RPM in the current directory or from artifacts.elastic.co, if unavailable.
  3. It updates elasticsearch.yml for version 7 compatibility, including discovery.initial_master_nodes instead of discovery.zen.unicast.hosts, and jvm.options.
  4. It starts the upgraded Elasticsearch 7 and waits for it to be ready.
  5. The cluster re-enables shard allocation and prompts to repeat these two steps on the next node if the cluster health is green or yellow.