Chapter 12. Manually rolling out Elasticsearch
OpenShift Container Platform supports the Elasticsearch rolling cluster restart. A rolling restart applies appropriate changes to the Elasticsearch cluster without down time (if three masters are configured). The Elasticsearch cluster remains online and operational, with nodes taken offline one at a time.
12.1. Performing an Elasticsearch rolling cluster restart
Perform a rolling restart when you change the elasticsearch configmap or any of the elasticsearch-* deployment configurations.
Also, a rolling restart is recommended if the nodes on which an Elasticsearch pod runs requires a reboot.
Prerequisite
- Cluster logging and Elasticsearch must be installed.
Procedure
To perform a rolling cluster restart:
Change to the
openshift-loggingproject:$ oc project openshift-logging
Use the following command to extract the CA certificate from Elasticsearch and write to the admin-ca file:
$ oc extract secret/elasticsearch --to=. --keys=admin-ca admin-ca
Perform a shard synced flush to ensure there are no pending operations waiting to be written to disk prior to shutting down:
$ oc exec <any_es_pod_in_the_cluster> -c elasticsearch -- curl -s --cacert /etc/elasticsearch/secret/admin-ca --cert /etc/elasticsearch/secret/admin-cert --key /etc/elasticsearch/secret/admin-key -XPOST 'https://localhost:9200/_flush/synced'
For example:
oc exec -c elasticsearch-cdm-5ceex6ts-1-dcd6c4c7c-jpw6 -- curl -s --cacert /etc/elasticsearch/secret/admin-ca --cert /etc/elasticsearch/secret/admin-cert --key /etc/elasticsearch/secret/admin-key -XPOST 'https://localhost:9200/_flush/synced'
Prevent shard balancing when purposely bringing down nodes using the OpenShift Container Platform es_util tool:
$ oc exec <any_es_pod_in_the_cluster> -c elasticsearch -- es_util --query=_cluster/settings -XPUT 'https://localhost:9200/_cluster/settings' -d '{ "transient": { "cluster.routing.allocation.enable" : "none" } }'For example:
$ oc exec elasticsearch-cdm-5ceex6ts-1-dcd6c4c7c-jpw6 -c elasticsearch -- es_util --query=_cluster/settings?pretty=true -XPUT 'https://localhost:9200/_cluster/settings' -d '{ "transient": { "cluster.routing.allocation.enable" : "none" } }' { "acknowledged" : true, "persistent" : { }, "transient" : { "cluster" : { "routing" : { "allocation" : { "enable" : "none" } } } }Once complete, for each deployment you have for an ES cluster:
By default, the OpenShift Container Platform Elasticsearch cluster blocks rollouts to their nodes. Use the following command to allow rollouts and allow the pod to pick up the changes:
$ oc rollout resume deployment/<deployment-name>
For example:
$ oc rollout resume deployment/elasticsearch-cdm-0-1 deployment.extensions/elasticsearch-cdm-0-1 resumed
A new pod is deployed. Once the pod has a ready container, you can move on to the next deployment.
$ oc get pods | grep elasticsearch-* NAME READY STATUS RESTARTS AGE elasticsearch-cdm-5ceex6ts-1-dcd6c4c7c-jpw6k 2/2 Running 0 22h elasticsearch-cdm-5ceex6ts-2-f799564cb-l9mj7 2/2 Running 0 22h elasticsearch-cdm-5ceex6ts-3-585968dc68-k7kjr 2/2 Running 0 22h
Once complete, reset the pod to disallow rollouts:
$ oc rollout pause deployment/<deployment-name>
For example:
$ oc rollout pause deployment/elasticsearch-cdm-0-1 deployment.extensions/elasticsearch-cdm-0-1 paused
Check that the Elasticsearch cluster is in
greenstate:$ oc exec <any_es_pod_in_the_cluster> -c elasticsearch -- es_util --query=_cluster/health?pretty=true
NoteIf you performed a rollout on the Elasticsearch pod you used in the previous commands, the pod no longer exists and you need a new pod name here.
For example:
$ oc exec elasticsearch-cdm-5ceex6ts-1-dcd6c4c7c-jpw6 -c elasticsearch -- es_util --query=_cluster/health?pretty=true { "cluster_name" : "elasticsearch", "status" : "green", 1 "timed_out" : false, "number_of_nodes" : 3, "number_of_data_nodes" : 3, "active_primary_shards" : 8, "active_shards" : 16, "relocating_shards" : 0, "initializing_shards" : 0, "unassigned_shards" : 1, "delayed_unassigned_shards" : 0, "number_of_pending_tasks" : 0, "number_of_in_flight_fetch" : 0, "task_max_waiting_in_queue_millis" : 0, "active_shards_percent_as_number" : 100.0 }- 1
- Make sure this parameter is
greenbefore proceeding.
- If you changed the Elasticsearch configuration map, repeat these steps for each Elasticsearch pod.
Once all the deployments for the cluster have been rolled out, re-enable shard balancing:
$ oc exec <any_es_pod_in_the_cluster> -c elasticsearch -- es_util --query=_cluster/settings -XPUT 'https://localhost:9200/_cluster/settings' -d '{ "transient": { "cluster.routing.allocation.enable" : "none" } }'For example:
$ oc exec elasticsearch-cdm-5ceex6ts-1-dcd6c4c7c-jpw6 -c elasticsearch -- es_util --query=_cluster/settings?pretty=true -XPUT 'https://localhost:9200/_cluster/settings' -d '{ "transient": { "cluster.routing.allocation.enable" : "all" } }' { "acknowledged" : true, "persistent" : { }, "transient" : { "cluster" : { "routing" : { "allocation" : { "enable" : "all" } } } } }
