2022-09-23: Remove ILM allocation settings and rely on ES to manage them

Production Change

Change Summary

We currently set the hot allocation settings in index templates and the warm allocation settings in the ILM policies. We are currently using the require.data allocation setting in index templates and then we update this when in the warm phase. This has led to issues in the past as ES also sets the _tier_preference allocation setting (which is the preferred method) and there has been cases where some indices had the tier preference set to data_warm,data_hot but the require.data setting was set to hot so the indices never got migrated to the warm nodes.

To simplify our configuration and align with what ES recommend, we're removing the setting of require.data ourselves and instead relying on ES to set the _tier_preference when entering the hot/warm phase, which will move shards accordingly.

This has already been rolled out in staging --> gitlab-com/runbooks!4971 (merged)

Change Details

  1. Services Impacted - ServiceLogging
  2. Change Technician - @gsgl
  3. Change Reviewer - @msmiley
  4. Time tracking - unknown
  5. Downtime Component - none

Detailed steps for the change

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - Estimated Time to Complete in Minutes

  • Set label changein-progress /label ~change::in-progress

  • Merge gitlab-com/runbooks!5009 (merged)

  • Wait until the CI pipeline runs and deploys the changes

  • Update index settings of existing indices:

    • Set ES URL:

      ES_URL="https://user:pass@<prod ES cluster>:9243"

    HOT

    • Get list of indices that are in the hot phase:

      curl -sSL -H 'Content-Type: application/json' -X GET "$ES_URL/_all/_ilm/explain" | jq -r '.indices | to_entries | .[].value | select(.phase == "hot") | .index' | sort -V > ~/tmp/hot-indices.txt

    • Split file into chunks of 20 lines:

      split -l 20 ~/tmp/hot-indices.txt ~/tmp/hot-indices-

    • Update index settings:

      for i in ~/tmp/hot-indices-*; do
  INDICES="$(cat $i | paste -sd, -)"
  echo "--> Pushing index settings to: ${INDICES}"
  curl -sSL -H 'Content-Type: application/json' -X PUT "${ES_URL}/${INDICES}/_settings" -d '{ "index.routing.allocation.require.data" : null, "index.routing.allocation.include._tier_preference": "data_content" }'
  echo
done

    WARM

    • Get list of indices that are in the warm phase:

      curl -sSL -H 'Content-Type: application/json' -X GET "$ES_URL/_all/_ilm/explain" | jq -r '.indices | to_entries | .[].value | select(.phase == "warm") | .index' | sort -V > ~/tmp/warm-indices.txt

    • Split file into chunks of 20 lines:

      split -l 20 ~/tmp/warm-indices.txt ~/tmp/warm-indices-

    • Update index settings:

      for i in ~/tmp/warm-indices-*; do
  INDICES="$(cat $i | paste -sd, -)"
  echo "--> Pushing index settings to: ${INDICES}"
  curl -sSL -H 'Content-Type: application/json' -X PUT "${ES_URL}/${INDICES}/_settings" -d '{ "index.routing.allocation.require.data" : null, "index.routing.allocation.include._tier_preference": "data_warm,data_hot" }'
  echo
done

  • Set label changecomplete /label ~change::complete

Rollback

Rollback steps - steps to be taken in the event of a need to rollback this change

Estimated Time to Complete (mins) - Estimated Time to Complete in Minutes

  • Revert gitlab-com/runbooks!5009 (merged)
  • Wait until the CI pipeline runs and deploys the changes
  • Update index settings of existing indices:

    • Set ES URL:

      ES_URL="https://user:pass@<prod ES cluster>:9243"

    • Update index settings for HOT indices:

      for i in ~/tmp/hot-indices-*; do
  INDICES="$(cat $i | paste -sd, -)"
  echo "--> Pushing index settings to: ${INDICES}"
  curl -sSL -H 'Content-Type: application/json' -X PUT "${ES_URL}/${INDICES}/_settings" -d '{ "index.routing.allocation.require.data" : "hot", "index.routing.allocation.include._tier_preference": "data_content" }'
  echo
done

    • Update index settings for WARM indices:

      for i in ~/tmp/warm-indices-*; do
  INDICES="$(cat $i | paste -sd, -)"
  echo "--> Pushing index settings to: ${INDICES}"
  curl -sSL -H 'Content-Type: application/json' -X PUT "${ES_URL}/${INDICES}/_settings" -d '{ "index.routing.allocation.require.data" : "warm", "index.routing.allocation.include._tier_preference": "data_warm,data_hot" }'
  echo
done
  • Set label changeaborted /label ~change::aborted

Monitoring

Key metrics to observe

  • Metric: Metric Name
    • Location: Dashboard URL
    • What changes to this metric should prompt a rollback: Describe Changes

Change Reviewer checklist

C4 C3 C2 C1:

  • Check if the following applies:
    • The scheduled day and time of execution of the change is appropriate.
    • The change plan is technically accurate.
    • The change plan includes estimated timing values based on previous testing.
    • The change plan includes a viable rollback plan.
    • The specified metrics/monitoring dashboards provide sufficient visibility for the change.

C2 C1:

  • Check if the following applies:
    • The complexity of the plan is appropriate for the corresponding risk of the change. (i.e. the plan contains clear details).
    • The change plan includes success measures for all steps/milestones during the execution.
    • The change adequately minimizes risk within the environment/service.
    • The performance implications of executing the change are well-understood and documented.
    • The specified metrics/monitoring dashboards provide sufficient visibility for the change.
      • If not, is it possible (or necessary) to make changes to observability platforms for added visibility?
    • The change has a primary and secondary SRE with knowledge of the details available during the change window.
    • The labels blocks deployments and/or blocks feature-flags are applied as necessary

Change Technician checklist

  • Check if all items below are complete:
    • The change plan is technically accurate.
    • This Change Issue is linked to the appropriate Issue and/or Epic
    • Change has been tested in staging and results noted in a comment on this issue.
    • A dry-run has been conducted and results noted in a comment on this issue.
    • The change execution window respects the Production Change Lock periods.
    • For C1 and C2 change issues, the change event is added to the GitLab Production calendar.
    • For C1 and C2 change issues, the SRE on-call has been informed prior to change being rolled out. (In #production channel, mention @sre-oncall and this issue and await their acknowledgement.)
    • For C1 and C2 change issues, the SRE on-call provided approval with the eoc_approved label on the issue.
    • For C1 and C2 change issues, the Infrastructure Manager provided approval with the manager_approved label on the issue.
    • Release managers have been informed (If needed! Cases include DB change) prior to change being rolled out. (In #production channel, mention @release-managers and this issue and await their acknowledgment.)
    • There are currently no active incidents that are severity1 or severity2
    • If the change involves doing maintenance on a database host, an appropriate silence targeting the host(s) should be added for the duration of the change.
Edited by Gonzalo Servat