prometheus / prometheus/prometheus

[Remote Write] WAL watching best-effort start from a checkpoint instead of time.Now

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component/remote storage help wanted not-as-easy-as-it-looks
Dominant language
Go
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Description

Right now remote write starts sending samples with a timestamp after time.Now() when Prometheus started (more or less). On restart or config reload if remote write wasn't able to flush it's pending samples cleanly or was behind for some reason there will be samples missing in the remote storage. If remote write always starts from a checkpoint in some kind of checkpoint file for it's queue name/config hash we can avoid that situation.

see: https://github.com/prometheus/prometheus/pull/7710

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reading the remote write and WAL behavior described in the issue, then inspect the referenced pull request 7710 for existing context. Work out how a checkpoint keyed by queue name and config hash could support restarts and config reloads; done means pending samples are not missed when remote write cannot flush cleanly.

Written by the indexing model from the issue text.

Assessment

Tech stack
go
Domain
backend, data
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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