storcon: verbose logs in rare case of shards not attached yet

[jcsp]

Problem

When we do a timeline CRUD operation, we check that the shards we need to mutate are currently attached to a pageserver, by reading generation and generation_pageserver from the database.

If any don't appear to be attached, we respond with a a 503 and "One or more shards in tenant is not yet attached".

This is happening more often than expected, and it's not obvious with current logging what's going on: specifically which shard has a problem, and exactly what we're seeing in these persistent generation columns.

(Aside: it's possible that we broke something with the change in #10011 which clears generation_pageserver when we detach a shard, although if so the mechanism isn't trivial: what should happen is that if we stamp on generation_pageserver if a reconciler is running, then it shouldn't matter because we're about to

Summary of changes

• When we are in Attached mode but find that generation_pageserver/generation are unset, output details while looping over shards.

[github-actions]

6450 tests run: 6166 passed, 0 failed, 284 skipped (full report)

---

Flaky tests (1)

Postgres 14

• test_timeline_offloading[True]: release-arm64

Code coverage* (full report)

• functions: 31.2% (8403 of 26940 functions)
• lines: 47.9% (66682 of 139101 lines)

* collected from Rust tests only

---

_{The comment gets automatically updated with the latest test results
362bdff at 2025-01-02T19:23:35.369Z :recycle:}