Migrate google/btree to k8s util #336

pjsharath28 · 2025-12-17T15:01:53Z

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

The github.com/google/btree library used by k8s and etcd has been archived and is no longer maintained. This raises long-term concerns around security fixes and CVEs.

We discussed multiple options to address this in the issue. Given that we only rely on a single source file from the library, we concluded that copying the code into k8s.io/utils is the simplest option. This avoids introducing or maintaining a separate fork while preserving identical behaviour.

Which issue(s) this PR is related to:

Discussion issue: etcd-io/etcd#20991

Special notes for your reviewer:

Upstream Google attribution is preserved and the file header follows Kubernetes conventions while remaining Apache-2.0 compliant.

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

k8s-ci-robot · 2025-12-17T15:02:05Z

Welcome @pjsharath28!

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aojea · 2025-12-17T16:00:19Z

/assign @dims

side note @dims, it seems the github actions are waiting for manual approval, you can change that option in in the repo settings IIRC so they always run

skitt · 2025-12-19T14:11:09Z

btree/btree_generic.go

+// In Go 1.18 and beyond, a BTreeG generic is created, and BTree is a specific
+// instantiation of that generic for the Item interface, with a backwards-
+// compatible API.  Before go1.18, generics are not supported,
+// and BTree is just an implementation based around the Item interface.
+


This isn’t relevant and should be removed.

skitt · 2025-12-19T14:13:32Z

btree/btree_generic.go

+// There are two implementations; those suffixed with 'G' are generics, usable
+// for any type, and require a passed-in "less" function to define their ordering.
+// Those without this prefix are specific to the 'Item' interface, and use
+// its 'Less' function for ordering.


k/k only uses the generic implementation, do we need to keep both in utils?

Ideally not needed, I removed the non-generic implementation

pjsharath28 · 2025-12-22T07:31:18Z

/retest

k8s-ci-robot · 2025-12-22T07:31:39Z

@pjsharath28: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

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skitt · 2025-12-22T08:42:50Z

btree/btree.go

+// BTree has its own FreeList, but multiple BTrees can share the same
+// FreeList, in particular when they're created with Clone.
+// Two Btrees using the same freelist are safe for concurrent write access.
+type FreeListG[T any] struct {


Since we’re only keeping the generic variant, the G suffix isn’t necessary; please remove it throughout.

skitt · 2025-12-24T15:05:37Z

btree/btree.go

+type ItemIterator[T any] func(item T) bool
+
+// Ordered represents the set of types for which the '<' operator work.
+type Ordered interface {


Ah, I missed this previously, sorry — please use cmp.Ordered instead.

Good catch, thanks
I've resolved it as well

pjsharath28 · 2025-12-28T04:09:14Z

@skitt, @dims, I've addressed all comments.
Please review when you're back. Thanks.

dims · 2025-12-29T13:59:16Z

@pjsharath28 can you please move the code to third_party/forked so it is pretty clear where we got this from?

see the existing code in there and the additional files that give it context (we have one in there forked from golang)

skitt · 2026-01-05T09:46:56Z

/lgtm

Thanks! cmp.Less could be used instead of functions returned by Less but at a slight additional cost (related to NaN handling), but it’s not particularly important IMO and changes the API slightly compared to the original project.

dims · 2026-01-05T13:47:55Z

please add LICENSE - https://github.com/google/btree/blob/master/LICENSE

dims · 2026-01-05T13:54:44Z

hmmm 68cb205 is not a license :)

dims · 2026-01-05T13:57:54Z

@pjsharath28 please squash and we are good to goo

dims · 2026-01-05T14:55:08Z

/approve
/lgtm

/hold

@pohly please remove hold when happy :)

pohly · 2026-01-05T18:55:45Z

please squash and we are good to go

Hmm, now there's only a single commit, but quite a bit was changed:

$ diff -r third_party/forked/golang/btree /tmp/btree | diffstat
 .git                  |only
 .github               |only
 LICENSE               |    2 -
 README.md             |   11 +++--
 btree.go              |  481 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----------------------------------------------------------------------------------------------------------------
 btree_generic.go      |only
 btree_generic_test.go |only
 btree_mem.go          |only
 btree_test.go         |  462 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------------------------------------------------------------------------------------------------------------
 go.mod                |only
 10 files changed, 508 insertions(+), 448 deletions(-)

I think it would be nicer if the first commit had just a verbatim copy of the upstream code that we want (i.e. removing files that we don't care about is fine) and the second commit contains our changes.

pohly · 2026-01-06T09:25:29Z

The update has some comment changes, but those seem benign except that we now have "See http://godoc.org/github.com/google/btree for documentation." again. I think that should be removed in the second commit.

The commits now allow reviewing the history of the code: 👍

pohly · 2026-01-06T10:50:28Z

/lgtm

Based on #336 (comment) and only one minor diff compared to the already approved version.

Not sure whether that's worth fixing?

pohly · 2026-01-06T11:20:47Z

@pjsharath28: thanks for your patience!

/lgtm
/hold cancel

k8s-ci-robot · 2026-01-06T11:20:57Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dims, pjsharath28, pohly, skitt

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

~~OWNERS~~ [dims]

Approvers can indicate their approval by writing /approve in a comment
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k8s-ci-robot added the kind/cleanup Categorizes issue or PR as related to cleaning up code, process, or technical debt. label Dec 17, 2025

k8s-ci-robot requested review from danwinship and dims December 17, 2025 15:01

k8s-ci-robot added the cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. label Dec 17, 2025

k8s-ci-robot added the size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. label Dec 17, 2025

pjsharath28 mentioned this pull request Dec 17, 2025

Migrate google/btree usage to k8s util package kubernetes/kubernetes#135793

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k8s-ci-robot assigned dims Dec 17, 2025

pjsharath28 mentioned this pull request Dec 19, 2025

golint in CI blocks valid generic code; discuss replacement or scoped exclusions #339

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skitt reviewed Dec 19, 2025

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pjsharath28 force-pushed the migrate-btree-to-k8s-util branch from d458954 to af10f52 Compare December 22, 2025 07:19

pjsharath28 requested a review from skitt December 22, 2025 07:32

skitt reviewed Dec 22, 2025

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pjsharath28 requested a review from skitt December 23, 2025 09:54

skitt reviewed Dec 24, 2025

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pjsharath28 requested a review from skitt December 24, 2025 15:41

k8s-ci-robot assigned skitt Jan 5, 2026

k8s-ci-robot added the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Jan 5, 2026

k8s-ci-robot removed the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Jan 5, 2026

pjsharath28 force-pushed the migrate-btree-to-k8s-util branch from 0a3a1ef to aa383d1 Compare January 5, 2026 14:29

k8s-ci-robot added do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. lgtm "Looks good to me", indicates that a PR is ready to be merged. approved Indicates a PR has been approved by an approver from all required OWNERS files. labels Jan 5, 2026

third_party/forked/btree: add upstream google/btree code

4ac6739

pjsharath28 force-pushed the migrate-btree-to-k8s-util branch from aa383d1 to f2dbb5e Compare January 6, 2026 08:12

k8s-ci-robot removed the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Jan 6, 2026

pjsharath28 force-pushed the migrate-btree-to-k8s-util branch from f2dbb5e to d87c826 Compare January 6, 2026 10:29

k8s-ci-robot assigned pohly Jan 6, 2026

k8s-ci-robot added the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Jan 6, 2026

third_party/forked/btree: adapt forked google/btree for Kubernetes usage

cec797e

pjsharath28 force-pushed the migrate-btree-to-k8s-util branch from d87c826 to cec797e Compare January 6, 2026 10:56

k8s-ci-robot removed the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Jan 6, 2026

k8s-ci-robot added lgtm "Looks good to me", indicates that a PR is ready to be merged. and removed do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. labels Jan 6, 2026

k8s-ci-robot merged commit 0fe9cd7 into kubernetes:master Jan 6, 2026
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pjsharath28 mentioned this pull request Jan 9, 2026

REQUEST: New membership for pjsharath28 kubernetes/org#6050

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Migrate google/btree to k8s util #336

Migrate google/btree to k8s util #336

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pjsharath28 commented Dec 17, 2025

What type of PR is this?

What this PR does / why we need it:

Which issue(s) this PR is related to:

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pjsharath28 commented Dec 28, 2025

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