ARSN-617: clean-read filter hiding non-localized versions by DarkIsDude · Pull Request #2688 · scality/Arsenal

DarkIsDude · 2026-08-19T14:00:19Z

Context

https://scality.atlassian.net/browse/ARSN-617

In a clean room, metadata is replicated before the object data is copied locally: until then the version's dataStoreName still points at the remote production site. Such a version is non-localized and must not be visible to clients.

What this adds

A per-call hideNonLocalizedVersions flag on the metadata read and listing APIs (getObject, getObjects, getBucketAndObject, listObject, listMultipartUploads).

Notes for ARSN-618

ARSN-618 answers the same "which version is current" question at write time, unconditionally, and can reuse the condition helpers and the getLatestVersion filter parameter added here. Read-time resolution stays necessary for entries that never traverse the write path (mongodump/mongorestore bootstrap and re-bootstrap loads); since the design rejected read-time master filtering, the design and ARSN-618 should record that it now exists. We can also decide to drop it as this use case should not exist in a DR architecture.

Issue: ARSN-617

Add a per-call `cleanRead` flag on the metadata read and listing APIs, hiding the object versions whose data still lives on a remote source site (`locations[objMD.dataStoreName].isCRR`), as needed by the clean-room D/R deployments. MongoClientInterface implements it in the MongoDB query itself, so that listing limits and truncation stay correct, and MetadataWrapper sets the flag on every read and listing call when the deployment enables it. Issue: ARSN-617

bert-e · 2026-08-19T14:00:24Z

Hello darkisdude,

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bert-e · 2026-08-19T14:00:29Z

Incorrect fix version

The Fix Version/s in issue ARSN-617 contains:

None

Considering where you are trying to merge, I ignored possible hotfix versions and I expected to find:

8.5.15

Please check the Fix Version/s of ARSN-617, or the target
branch of this pull request.

codecov · 2026-08-19T14:07:13Z

Codecov Report

❌ Patch coverage is 90.13158% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.77%. Comparing base (d6ef4ed) to head (cad4307).
⚠️ Report is 3 commits behind head on development/8.5.

Files with missing lines	Patch %	Lines
lib/storage/metadata/mongoclient/readStream.js	73.07%	7 Missing ⚠️
lib/algos/list/delimiterMaster.ts	90.74%	5 Missing ⚠️
...orage/metadata/mongoclient/MongoClientInterface.ts	94.11%	3 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##           development/8.5    #2688      +/-   ##
===================================================
+ Coverage            74.66%   74.77%   +0.11%     
===================================================
  Files                  227      227              
  Lines                18606    18650      +44     
  Branches              3880     3892      +12     
===================================================
+ Hits                 13892    13946      +54     
+ Misses                4709     4699      -10     
  Partials                 5        5

☔ View full report in Codecov by Harness.
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Issue: ARSN-617

bert-e · 2026-08-24T09:25:47Z

Incorrect fix version

The Fix Version/s in issue ARSN-617 contains:

None

Considering where you are trying to merge, I ignored possible hotfix versions and I expected to find:

8.5.16

Please check the Fix Version/s of ARSN-617, or the target
branch of this pull request.

Rename the per-call flag to `hideNonLocalizedVersions`, keep the callback as the last argument of `getLatestVersion`, and trim the comments down to the non-obvious ones. Issue: ARSN-617

Issue: ARSN-617

A master pointing at a non-localized version is no longer hidden: the master key is resolved on the way out of the listing stream, exposing the newest localized version of the object — the same resolution a PHD key goes through, and the same one getObject already performs, so a listing and a GET agree. Only an object with no localized version at all is dropped. Issue: ARSN-617

bert-e · 2026-08-27T15:10:28Z

Incorrect fix version

The Fix Version/s in issue ARSN-617 contains:

8.5.15

Considering where you are trying to merge, I ignored possible hotfix versions and I expected to find:

8.5.16

Please check the Fix Version/s of ARSN-617, or the target
branch of this pull request.

bert-e · 2026-08-27T16:00:57Z

Waiting for approval

The following approvals are needed before I can proceed with the merge:

the author
2 peers

maeldonn · 2026-08-31T12:52:46Z

Please remove the footer Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> from your commits 🙏

francoisferrand · 2026-08-31T12:18:41Z

        this.replicationGroupId = replicationGroupId;
        this.database = database;
        this.isLocationTransient = isLocationTransient;
+        this.getLocationConstraints = getLocationConstraints;


this does not look the a list of "location constraints" : but really the actual list/map of locations.

("Location constraint" is a parameter of a bucket, which indicates in AWS in which region the bucket is; and which we use instead to track the default data location for the bucket)

francoisferrand · 2026-08-31T12:21:08Z

+        if (!hide) {
+            return null;
+        }
+        const excluded = this.nonLocalizedLocations();


list of locations do not change, best to compute this list just once in constructor

francoisferrand · 2026-08-31T12:23:21Z

+        // when the master keys are resolved, the stream must keep the
+        // non-localized masters so that they can be replaced by the newest
+        // localized version of their object


not needed : c.f. design and next ticket ARSN-618, the master is not updated when inserting a non-localized version... so only versions need filtering.

or is there something which was missed in the design?

francoisferrand · 2026-08-31T12:37:17Z

+`getLocationConstraints` parameter, evaluated on each call so that
+configuration updates are picked up.


configuration cannot be updated dynamically. The locations are defined in a config file, and service is restarted when the list changes.

francoisferrand · 2026-08-31T12:40:48Z

+  stream, the same way a PHD key is resolved. An object with no localized
+  version at all is dropped from the listing;
+- `getObject` resolves a hidden master the same way, so a listing and a `GET`
+  agree on which version is current;


The current version IS the localized version (the non-localized version in an "internal" version, so to say):

getObject should only point to latest localized version

GetObjectVersion returns the version, whether it is localized or not

Backbeat needs (internally) be able to see all the versions, but I don't think it needs the master: thinking of the use cases, maybe it is actually safer if even backbeat does not list these objets:

Lifecycle must not delete these objects (or delete the next "non-current" versions),

Bucket notification acts on versions, no listing or master access - so not affected

Replication cannot (yet) replicate the objects, so should ignore them

Pull-replication does not perform listing or access master, but must be able to both read and update the metadata of any version

Listing versions may be needed for tooling (e.g. finding non-localized objects), but this should not affect listing of masters

Some filtering will be done in backbeat indeed, and we probably need to "strict" when answering to external client (i.e. reject reading object/version if not localized) ; but we should avoid complexfying the code for path which do not need it (e.g. listing master or resolving non-localized master): are there situations where do you think this is needed?

Read-time resolution stays necessary for entries that never traverse the write path (mongodump/mongorestore bootstrap and re-bootstrap loads)

Bootstrap should no copy master either (since they are not localized), and thus master resolution is not needed: the master is only created when the ObjMD is finally "localized" - which happens regular arsenal calls and would be handled by ARSN-618

Not at all, as explained in the description. I was not really sure if I should be strict or not, you seems to have the answer. I'll then remove that and have a less defensive code 🙏

francoisferrand · 2026-08-31T12:41:34Z

+  and are therefore never hidden;
+- a master listing (`DelimiterMaster`) keeps the objects whose current version
+  is not localized, and lists them with their newest localized version — the
+  master key is resolved through `getLatestVersion` on the way out of the


the master should always point to a localized version, per the design : next (arsenal) ticket is about making sure putObject handles this

francoisferrand · 2026-08-31T13:50:06Z

+                return false;
+            }
+            try {
+                return nonLocalizedLocations.includes(JSON.parse(obj.value).dataStoreName);


this can be quite costly: JSON parse() call (object MD can be large, esp. for bug MPUs) + linear search (though not sure how many CRR locations we would have)

DarkIsDude added 2 commits August 19, 2026 15:54

🎨 prettier reformat files touched by ARSN-617

565f989

Issue: ARSN-617

🎨 prettier format the clean-read tests

6f78334

Issue: ARSN-617

DarkIsDude self-assigned this Aug 24, 2026

DarkIsDude added 3 commits August 27, 2026 16:21

♻️ address review: name the flag after what it hides

01ecfc7

Rename the per-call flag to `hideNonLocalizedVersions`, keep the callback as the last argument of `getLatestVersion`, and trim the comments down to the non-obvious ones. Issue: ARSN-617

🎨 prettier reformat the mongoclient specs touched by ARSN-617

3e99bb3

Issue: ARSN-617

DarkIsDude marked this pull request as ready for review August 31, 2026 09:11

DarkIsDude requested review from a team, SylvainSenechal, delthas and maeldonn August 31, 2026 09:11

DarkIsDude force-pushed the improvement/ARSN-617/clean-read-filter branch from ae474fa to cad4307 Compare August 31, 2026 13:02

francoisferrand reviewed Aug 31, 2026

View reviewed changes

		`getLocationConstraints` parameter, evaluated on each call so that
		configuration updates are picked up.

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DarkIsDude commented Aug 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Context

What this adds

Notes for ARSN-618

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bert-e commented Aug 19, 2026

Hello darkisdude,

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bert-e commented Aug 19, 2026

Incorrect fix version

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codecov Bot commented Aug 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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bert-e commented Aug 24, 2026

Incorrect fix version

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bert-e commented Aug 27, 2026

Incorrect fix version

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bert-e commented Aug 27, 2026

Waiting for approval

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maeldonn commented Aug 31, 2026

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DarkIsDude commented Aug 19, 2026 •

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