balancer: expose endpoint weight and hostname as experimental APIs by hpathak01 · Pull Request #9074 · grpc/grpc-go

hpathak01 · 2026-04-17T08:34:02Z

Description

This PR exposes two new experimental public APIs so that custom load balancing policies can access endpoint attributes that were previously only available via internal packages:

google.golang.org/grpc/balancer/weight — Set, FromEndpoint, EndpointInfo
google.golang.org/grpc/balancer/hostname — Set, FromEndpoint, FromAddress

These attributes (especially weight) are required by custom balancers such as deterministic aperture / P2C that need EDS-provided endpoint details like weights etc.

Changes

New public package balancer/hostname with full experimental notices.
Moved internal/balancer/weight to public balancer/weight via git mv, added experimental notices.
Internal callers (ringhash, pickfirst, cdsbalancer, clusterimpl, xdsresource) updated to use the public packages directly.
Removed SetHostname and Hostname wrappers from xdsresource; callers now use hostname.Set and hostname.FromAddress directly.
Added table-driven unit tests for both new public packages.

Related Issues

Fixes #8971

Testing

All tests pass (go test -count=1 ./...)

Notes for Reviewers

The new APIs follow the exact same experimental pattern used by resolver/ringhash.
The "Dependency Changes" check fails because this PR intentionally adds two new public packages (balancer/weight and balancer/hostname).

RELEASE NOTES: none

linux-foundation-easycla · 2026-04-17T08:34:10Z

The committers listed above are authorized under a signed CLA.

✅ login: hpathak01 / name: Harsh Pathak (0132067, 1b58d32, 3b06903, 5ed3447, 777e7f6, 83417df, 9fa484c, cad2a5f, d39465e, f30c259)

codecov · 2026-04-17T08:37:17Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.14%. Comparing base (06fc26a) to head (565012e).
⚠️ Report is 30 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9074      +/-   ##
==========================================
+ Coverage   80.52%   83.14%   +2.62%     
==========================================
  Files         413      418       +5     
  Lines       33543    33649     +106     
==========================================
+ Hits        27012    27979     +967     
+ Misses       4316     4248      -68     
+ Partials     2215     1422     -793

Files with missing lines	Coverage Δ
balancer/pickfirst/pickfirst.go	`89.76% <ø> (ø)`
balancer/ringhash/ringhash.go	`94.11% <ø> (ø)`
experimental/balancer/hostname/hostname.go	`100.00% <100.00%> (ø)`
experimental/balancer/weight/weight.go	`100.00% <ø> (ø)`
internal/xds/balancer/cdsbalancer/configbuilder.go	`91.11% <100.00%> (ø)`
internal/xds/balancer/clusterimpl/clusterimpl.go	`88.25% <100.00%> (ø)`
...nternal/xds/xdsclient/xdsresource/unmarshal_eds.go	`96.07% <100.00%> (+4.30%)`	⬆️

... and 58 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

…rpc#8971) - Add new public packages balancer/weight and balancer/hostname with Set/FromEndpoint and Set/Hostname/HostnameFromAddress helpers. - Mark all new APIs as # Experimental with the standard notice. - Update internal callers (ringhash, pickfirst, cdsbalancer, xdsresource) to use the public packages. - Remove dead hostnameKeyType from xdsresource and delegate legacy Hostname() to the public API (fixes Authority_Rewrite_Mismatch test). - Keep deprecated internal/balancer/weight package for transition. - Add tests for the new public packages. - Verified end-to-end with custom DAPerture balancer.

easwars · 2026-04-20T05:26:02Z

The "Dependency Changes" check fails because this PR intentionally adds two new public packages (balancer/weight and balancer/hostname).

Yes, that is expected.

easwars · 2026-04-20T05:26:24Z

@Pranjali-2501 : Could you please do a first pass.

Pranjali-2501

Hi @hpathak01, thanks for raising the PR.
I have added some comments, please take a look.

Pranjali-2501 · 2026-04-22T06:44:05Z

@hpathak01 , please fix Testing / static checks (latest-1) (pull_request).

hpathak01 · 2026-04-22T07:38:30Z

@hpathak01 , please fix Testing / static checks (latest-1) (pull_request).

hi @Pranjali-2501 done

Pranjali-2501

LGTM.

hpathak01 · 2026-05-06T03:58:41Z

Hi @easwars , just checking in — I've addressed all the review comments. Would you have a chance to take a look when you get a moment? Thanks!

easwars

Apologies for the delay in reviewing this.

…rpc#9074) ### Description This PR exposes two new **experimental** public APIs so that custom load balancing policies can access endpoint attributes that were previously only available via internal packages: - `google.golang.org/grpc/balancer/weight` — `Set`, `FromEndpoint`, `EndpointInfo` - `google.golang.org/grpc/balancer/hostname` — `Set`, `FromEndpoint` These attributes (especially `weight`) are required by custom balancers such as deterministic aperture / P2C that need EDS-provided endpoint details like weights etc. Fixes grpc#8971 RELEASE NOTES: - experimental/balancer/hostname: New APIs to access endpoint hostname attributes - experimental/balancer/weight: New APIs to access endpoint weight attributes

hpathak01 force-pushed the hpathak01/issue-8971-expose-xds-attr branch from 7e7f078 to 5ed3447 Compare April 17, 2026 08:39

hpathak01 added 3 commits April 17, 2026 16:52

[balancer] fix import ordering in test and xdsresource files

d39465e

[ci] fix import ordering for goimports check

83417df

[ci] run goimports on all changed files

1b58d32

hpathak01 marked this pull request as ready for review April 20, 2026 03:45

easwars added the Type: Feature New features or improvements in behavior label Apr 20, 2026

easwars added this to the 1.82 Release milestone Apr 20, 2026

easwars added the Area: Resolvers/Balancers Includes LB policy & NR APIs, resolver/balancer/picker wrappers, LB policy impls and utilities. label Apr 20, 2026

easwars changed the title ~~[balancer] expose endpoint weight and hostname as experimental APIs (…~~ balancer: expose endpoint weight and hostname as experimental APIs Apr 20, 2026

easwars requested a review from Pranjali-2501 April 20, 2026 05:26

easwars assigned Pranjali-2501 Apr 20, 2026

Pranjali-2501 reviewed Apr 21, 2026

View reviewed changes

Pranjali-2501 assigned hpathak01 and unassigned Pranjali-2501 Apr 21, 2026

Pranjali-2501 added the Status: Requires Reporter Clarification label Apr 21, 2026

hpathak01 added 3 commits April 21, 2026 17:38

balancer: address review comments for weight/hostname APIs

0132067

balancer: address review comments for weight/hostname APIs (2)

3b06903

balancer: remove empty line in import

cad2a5f

Pranjali-2501 reviewed Apr 22, 2026

View reviewed changes

Comment thread internal/xds/xdsclient/xdsresource/unmarshal_eds.go

Comment thread internal/xds/xdsclient/xdsresource/unmarshal_eds_test.go Outdated

Comment thread internal/xds/xdsclient/xdsresource/unmarshal_eds.go Outdated

Comment thread balancer/hostname/hostname_test.go Outdated

hpathak01 added 2 commits April 22, 2026 15:09

balancer: review comments addressed

9fa484c

balancer: revert unintentional import change

777e7f6

Pranjali-2501 approved these changes Apr 23, 2026

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Pranjali-2501 reviewed Apr 23, 2026

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Comment thread balancer/hostname/hostname.go Outdated

Pranjali-2501 assigned easwars and unassigned hpathak01 Apr 23, 2026

Pranjali-2501 requested a review from easwars April 23, 2026 05:04

balancer/hostname: wrap doc comment at 80 cols

f30c259

Pranjali-2501 removed the Status: Requires Reporter Clarification label Apr 27, 2026

easwars reviewed May 20, 2026

View reviewed changes

easwars assigned hpathak01 and unassigned easwars May 20, 2026

hpathak01 added 3 commits May 21, 2026 15:02

balancer: address review comments for weight/hostname APIs (3)

b18c038

balancer: reorder methods in unmarshal_eds.go

aa7a1a1

balancer: reorder imports

565012e

easwars approved these changes May 27, 2026

View reviewed changes

easwars merged commit 429e6e0 into grpc:master May 27, 2026
13 of 14 checks passed

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