Tag Archives: Elasticsearch

Getting ElasticSearch Node Versions

Kibana doesn’t tell you what version your nodes are currently running which can be frustrating if you get distracted during an upgrade process. Here is a simple PowerShell script that gets all the nodes and their current version.

$cred = Get-Credential
$nodes_raw = Invoke-RestMethod -Method Get -Uri "http://elasticsearch:9200/_nodes" -Credential $cred

#get the names of each node
$node_names = $nodes_raw.nodes | Get-Member -MemberType NoteProperty | Select -ExpandProperty Name

#convert from object properties to an array of objects
$nodes = foreach ($node_name in $node_names) {
    $nodes_raw.nodes."$node_name"   
}

# Select desired info about the node
$nodes | select name, version

Grafana Elasticsearch Moving Averages

Adding moving averages to a graph of Elasticsearch data in grafana is pretty easy, but not well documented

  1. Add a new metric
  2. Choose MovingFunction and pick the metric you want an average on
  3. Expand the options, set Window to the number of samples you want to have your moving function on
  4. Script should be one of the following:
    1. MovingFunctions.max(values)
    2. MovingFunctions.min(values)
    3. MovingFunctions.sum(values)
    4. MovingFunctions.unweightedAvg(values)
    5. MovingFunctions.linearWeightedAvg(values)

Reference: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-pipeline-movfn-aggregation.html#:~:text=The%20Moving%20Function%20aggregation%20allows,script%20in%20the%20values%20variable.

Reducing the number of replicas in Elasticsearch

Sometimes you just want to run a single Elasticsearch node and not have it constantly alert that it has no were to write its replicas. Since Elasticsearch and more templates default to at least 1 replica we have to make changes to Elasticsearch and to the templates. First change the default:

curl -XPUT 'localhost:9200/_settings' -d '
{
    "index" : {
        "number_of_replicas" : 0
    }
}
'

Then we can list all the templates and figure out which ones need updates as well

curl -XGET -H 'Content-Type: application/json' 'localhost:9200/_template/*?pretty'

Then for each of the templates you want to update. For instance to update a Logstash template use the following:

curl -XPUT -H 'Content-Type: application/json' 'localhost:9200/logstash-*/_settings' -d '{ "number_of_replicas" : 0 } }'