Update index options for global search in Elasticsearch

Production Change - Criticality 3 C3

Change Objective	Describe the objective of the change
Change Type	ConfigurationChange
Services Impacted	Elasticsearch global search cluster
Change Team Members	@DylanGriffith
Change Severity	C3
Change Reviewer or tested in staging	Will be tested on staging first
Dry-run output
Due Date	2020-03-18 02:00 UTC
Time tracking

Prep

1. Perform all change steps on staging

Detailed steps for the change

1. Ping SRE on call in #production: @sre-oncall we are about to make this minor Elasticsearch settings change for the global search cluster prod-gitlab-com indexing https://gitlab.com/gitlab-com/gl-infra/production/-/issues/1758. This is unlikely to impact any other settings but will ideally reduce load on the cluster and slightly reduce storage used over time.
2. Make the settings change with the following request to the cluster

   curl -H 'Content-Type: application/json' -XPUT "$ES_CLUSTER_HOST/gitlab-production/_mapping" -d '{
    "properties": {
      "blob": {
        "properties": {
          "content": {
            "type": "text",
            "index_options": "positions",
            "analyzer": "code_analyzer",
            "search_analyzer": "code_search_analyzer"
         }
        }
       }
      }
     }'

3. Create a new file in any indexed project
4. Search for the newly created file and validate that it appears in the search results (may take a couple of minutes for the indexing job to complete)

Rollback steps

1. Make the settings change with the following request to the cluster

   curl -H 'Content-Type: application/json' -XPUT "$ES_CLUSTER_HOST/gitlab-production/_mapping" -d '{
    "properties": {
      "blob": {
        "properties": {
          "content": {
            "type": "text",
            "index_options": "offsets",
            "analyzer": "code_analyzer",
            "search_analyzer": "code_search_analyzer"
         }
        }
       }
      }
     }'

2. Create a new file any indexed project
3. Search for the newly created file and validate that it appears in the search results (may take a couple of minutes for the indexing job to complete)

Changes checklist

• Detailed steps and rollback steps have been filled prior to commencing work
• Person on-call has been informed prior to change being rolled out