Delete old system log data from the Elasticsearch cluster

The elasticsearch cluster on banco.internal.softwareheritage.org contains

• old system log data
• test data injected by error from my laptop

It would be nice to delete unneeded documents at some point.

Proposed request to clean up test data:

curl -i -H'Content-Type: application/json' -XPOST "http://localhost:9200/_all/_delete_by_query/?pretty=true" -d '
{
    "query" : {
	"match" : { "hostname" : "hplaptopft0" }}
    }
}'

Proposed request to clean up old system log data:

curl -i -H'Content-Type: application/json' -XPOST "http://localhost:9200/_all/_delete_by_query/?pretty=true" -d '
{
    "query" : {
	"bool": {
	    "must_not": [{ "match" : { "systemd_unit" : "swh-worker@" } }],
	    "must": { "range" : { "@timestamp" : { "lt" : "now-3M" }}}
	}
    }
}'

Remark: closed Elasticsearch indices are not processed. In order to delete documents from closed indices, we have to reopen them first.

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Migrated from T977 (view on Phabricator)