feat: WASI target support for func (build + deploy) by cardil · Pull Request #3560 · knative/func

cardil · 2026-04-01T18:16:52Z

Adds an alternative build/deployment mode for func that uses WASI modules instead of container images.

What it does

func create --runtime rust-wasi or func create --runtime go-wasi creates WASI function projects
func build compiles to wasm32-wasip2 and pushes OCI WASM artifacts to registry
func deploy creates WasmModule CRs (from knative-serving-wasm) with readiness polling
func list, func describe, func delete work with WasmModule resources
Builder/deployer auto-inferred from *-wasi runtime suffix
Compatibility validation prevents invalid runtime/builder/deployer combinations

Key components

pkg/wasm/ — Builder, deployer, lister, remover, describer, OCI artifact pusher
templates/rust-wasi/http/ — Rust WASI HTTP function template (wasi:http/proxy)
templates/go-wasi/http/ — Go WASI HTTP function template (TinyGo + WIT bindings)
pkg/functions/registry.go — Self-registering builder/deployer system with constraints
pkg/functions/compatibility.go — Runtime/builder/deployer compatibility validation
hack/cluster.sh — E2e cluster setup with knative-serving-wasm controller
E2e tests covering build, deploy, describe, delete for both runtimes

Supported runtimes

rust-wasi, go-wasi (others return "not yet implemented")

Dependencies

github.com/cardil/knative-serving-wasm v0.2.0 (WasmModule CRD types)
Requires cargo + wasm32-wasip2 target for Rust, tinygo for Go

Jira: SRVOCF-750

Assisted-by: 🤖 Claude Opus/Sonnet 4.6

Initial design proposal for WASI/WebAssembly support in func CLI. Covers build pipeline, deploy pipeline, WasmModule CRD integration, and func.yaml schema changes. Assisted-by: 🤖 Claude Opus/Sonnet 4.5

- Remove explicit --builder/--deployer flags from diagram (auto-inferred) - Replace 'Runtime Detection' with 'Runtime Selection' section - Clarify runtime is chosen at func create time, not auto-detected Assisted-by: 🤖 Claude Sonnet 4.5

…ation

Implements foundational WASM support infrastructure: - Add github.com/cardil/knative-serving-wasm dependency - Create pkg/wasm/ package with: - Constants for builder, deployer, and OCI media type - WASI runtime identifiers (rust-wasi, go-wasi, etc.) - IsWasiRuntime() helper function - Type aliases for WasmModule CRD network configuration - Add Wasm constant to pkg/builders/builders.go - Include unit tests with 83.3% coverage - Fix trailing whitespace in design document All tests pass (make test) and linting passes (make check). Phase 1 focuses on core types and constants. Builder and Deployer implementations will follow in subsequent phases. Assisted-by: 🤖 Claude Opus/Sonnet 4.5

… checks Self-registering builders and deployers via explicit Registry struct; WASI runtimes auto-infer wasm builder/deployer; incompatible combinations rejected at build/deploy time with wrapped ErrIncompatibility. Assisted-by: 🤖 Claude Sonnet 4.5

- Add templates/rust-wasi/http/ with Cargo.toml, src/lib.rs, README.md - Add templates/go-wasi/http/ with go.mod, function.go, function_test.go, README.md - Fix yaml.Decoder EOF bug in repository.go: comment-only manifest.yaml is valid - Update test expected lists to include go-wasi and rust-wasi runtimes - Regenerate embedded FS Assisted-by: 🤖 Claude Sonnet 4.6

Add build and deploy support for go-wasi and rust-wasi runtimes. Builder dispatch (pkg/wasm/builder.go) routes to TinyGo (go-wasi) or cargo (rust-wasi). TinyGo uses -no-debug to strip debug info (1.4MB→438KB). OCI push packs .wasm as a wasm/wasi layer (pkg/wasm/oci.go). Self-registration hooks builder and deployer into the registry. Fix inference never running: builder/deployer were always non-empty due to viper static defaults, making InferBuilder/InferDeployer dead code. Track explicit origin (flag or func.yaml) via BuilderExplicit/DeployerExplicit before Configure() overwrites with the static default. Fix func.yaml pollution: inferred values (e.g. 'wasm') are not written back to func.yaml. Restore the pre-Configure value before f.Write() when inference was used. Traditional runtimes still persist 'pack'/'knative'. e2e tests cover rust-wasi and go-wasi builds (renamed from e2e_wasm_test.go to avoid the GOARCH=wasm Go build constraint on _wasm_ filenames). First build uses --verbose; second build verifies func.yaml is not polluted. Assisted-by: 🤖 Claude Sonnet 4.6

…enerator gitignore - cmd/client.go: wire wasm remover, describer, lister in NewClient() - pkg/wasm: rename API fields TcpSpec→TCPSpec, UdpSpec→UDPSpec, AllowIpNameLookup→AllowIPNameLookup (.Tcp→.TCP, .Udp→.UDP) - bump github.com/cardil/knative-serving-wasm to latest (env var fix) - generate/templates/main.go: respect .gitignore in embedded FS generator (pass trailing slash for dirs so 'target/' pattern matches correctly) - pkg/filesystem/filesystem_test.go: apply same gitignore filtering to loadLocalFiles, initOSFS, initGitFS so they match the embedded FS - regenerate zz_filesystem_generated.go (drops rust-wasi/http/target/) - e2e: deployer tests, cluster.sh improvements - docs: regenerated reference pages

- Remove types.go (unused type aliases) - Rename types_test.go -> wasm_test.go (stale name) - Convert deployer_test.go to package wasm_test (black-box) - Export BuildNetworkSpec for external test access - Add t.Parallel() to compatibility_test.go tests - serving_wasm() uses stable kubectl apply from release manifest - Add KnativeServingWasm to component-versions

- Deployer readiness polling mirrors Knative deployer pattern - Pod watcher goroutine detects CrashLoopBackOff/ImagePullBackOff fast - ServiceUnavailable treated as transient (not terminal) - In-cluster registry (Deployment+NodePort) replaces external container - Insecure registry ConfigMap for WASM runner pods - Podman PID limit raised to 8192 (Knative+wasmtime needs >2048) - E2e liveness checks with withContentMatch for WASI templates - Update serving-wasm to v0.2.0 (insecure registries + terminal failures) Assisted-by: 🤖 Claude Opus/Sonnet 4.6

- Add pkg/wasm/wit.go: ProvisionWIT downloads WIT deps from OCI into wit/<key>/ using wasm-tools, compares wit/.versions to skip unchanged entries, writes per-subdir .gitignore to prevent accidental commits - Add pkg/wasm/wit_test.go: unit tests for diffVersions, load/save versions, writeGitignore, and ProvisionWIT no-op cases - Update pkg/wasm/builder.go: call ProvisionWIT before compiler when build.builderImages is non-empty - Update pkg/wasm/builder_go.go: recursive+parallel hasGoGenerateDirective, run go generate when //go:generate found; add -wit-package/-wit-world boson tinygo flags when wit/ dir present - Add templates/go-wasi/http/wit/world.wit: static source WIT world (package boson:function; world boson includes wasi:http/proxy@0.2.3) - Rewrite templates/go-wasi/http/function.go: WIT bindings handler via wit-bindgen-go generated bindings; pure greet() helper for testability - Rewrite templates/go-wasi/http/function_test.go: test greet() directly - Update templates/go-wasi/http/go.mod: go 1.24, tool directive for go.bytecodealliance.org/cmd/wit-bindgen-go - Add templates/go-wasi/http/.gitignore: ignore gen/ and module.wasm - Update e2e/e2e_wasi_test.go: GoDeploy now expects success with liveness - Update docs/design/wasi-integration.md: document WIT build pipeline Assisted-by: 🤖 Claude Sonnet 4.6

Replace atomic.Int32 + manual done channel with sync.WaitGroup to prevent double-close panic when goroutines finish between WalkDir callbacks. Move semaphore release inside the acquired path to prevent deadlock on context cancellation. Add builder_go_test.go with unit tests for hasGoGenerateDirective and fileHasGoGenerate, including stress tests exercising the concurrent fan-out with the race detector. Assisted-by: 🤖 Claude Opus/Sonnet 4.6

….2.3 wit.go — rewrite WIT provisioning pipeline: - Download OCI artifacts to temp dir, restructure into flat wit/deps/<pkg>/ - restructureWITDeps: main packages always overwrite, transitive deps skip existing dirs (prevents HTTP's stub cli.wit from clobbering full CLI package) - Add copyFile helper; pre-allocate provisioned slice builder_go.go — fix build pipeline: - Add runGoModTidy before go generate (template ships without go.sum) - Fix tinygo -o flag: use relative 'module.wasm' not absolute wasmPath (cmd.Dir=root makes -o relative to root, avoiding double-nesting) manifest.yaml — add builderImages for WASI deps: - cli: ghcr.io/webassembly/wasi/cli:0.2.3 - http: ghcr.io/webassembly/wasi/http:0.2.3 world.wit — define composite world for TinyGo: - include wasi:http/proxy@0.2.3 (HTTP handler export) - include wasi:cli/imports@0.2.3 (TinyGo runtime needs environment, filesystem, sockets beyond what proxy provides) function.go — fix wit-bindgen-go code generation: - go:generate flags: --world boson --out gen --package-root function/gen - Fix cm API: Value() not Unwrap(), cm.None/cm.OK not types.None/Ok, intermediate vars for pointer receivers, cm.ToList for byte slices, ResourceDrop() not Drop() builder_go_test.go — fix lint: check error returns in test helpers Regenerated embedded FS and docs. Assisted-by: 🤖 Claude Opus/Sonnet 4.6

The versionsScriptTemplate was missing knative_serving_wasm_version. The shell script had stale v0.1.0 while component-versions.json said v0.2.0, causing the cluster to deploy a controller without config-runner insecure registries support. Assisted-by: 🤖 Claude Opus/Sonnet 4.6

- Sort builderImages keys for deterministic iteration order - Track direct deps to prevent transitive overrides - Add __WASI_WIT_PROVIDER_MODE config in builderImages - strict (default): byte-diff is fatal error - forgiving: same-size skip, larger wins (with warnings) - Enable forgiving mode for go-wasi template - Detect auto-fetched vs user-vendored dep dirs Assisted-by: 🤖 Claude Opus/Sonnet 4.6

On systems with podman-docker installed, /usr/bin/docker is a shell wrapper that exec's podman. The previous default (CONTAINER_ENGINE=docker) caused the PID limit fix in cluster.sh to never fire, leading to PID exhaustion and containerd crashes under WASM workloads. Now common.sh detects the actual runtime via 'docker --version' output and falls back to podman when docker is absent. Assisted-by: 🤖 Claude Opus/Sonnet 4.6

Assisted-by: 🤖 Claude Opus/Sonnet 4.6

- Add Args []string to RunSpec in pkg/functions/function.go - Map f.Run.Args to spec.Args in pkg/wasm/deployer.go buildWasmModuleSpec - Add TestDeploy_Args and TestDeploy_Args_Empty to deployer_test.go - Regenerate schema/func_yaml-schema.json (adds args, NetworkSpec, TcpNetworkSpec, UdpNetworkSpec) - Document run.args in docs/reference/func_yaml.md Assisted-by: 🤖 Claude Sonnet 4.6

knative-prow · 2026-04-01T18:16:58Z

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: cardil
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cardil · 2026-04-01T18:19:16Z

/hold

This should all be already working, but I need to run a review of all the changes.

cardil · 2026-04-01T18:20:15Z

go.mod

 	github.com/alecthomas/jsonschema v0.0.0-20220216202328-9eeeec9d044b
 	github.com/blang/semver/v4 v4.0.0
 	github.com/buildpacks/pack v0.38.2
+	github.com/cardil/knative-serving-wasm v0.2.0


Rely on my personal WASI runner.

TBD what to do with it...

codecov · 2026-04-01T18:27:41Z

Codecov Report

❌ Patch coverage is 57.44337% with 789 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.05%. Comparing base (67c3fd2) to head (cecff33).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/wasm/wit.go	16.25%	299 Missing and 5 partials ⚠️
pkg/wasm/deployer.go	64.58%	108 Missing and 17 partials ⚠️
pkg/wasm/builder_go.go	36.94%	96 Missing and 3 partials ⚠️
pkg/wasm/oci.go	55.76%	35 Missing and 11 partials ⚠️
pkg/wasm/builder_rust.go	52.94%	35 Missing and 5 partials ⚠️
pkg/functions/registry.go	81.81%	22 Missing and 8 partials ⚠️
pkg/wasm/remover.go	60.78%	16 Missing and 4 partials ⚠️
pkg/wasm/describer.go	70.96%	15 Missing and 3 partials ⚠️
pkg/wasm/builder.go	74.62%	14 Missing and 3 partials ⚠️
pkg/wasm/lister.go	69.81%	12 Missing and 4 partials ⚠️
... and 15 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3560      +/-   ##
==========================================
- Coverage   56.13%   54.05%   -2.09%     
==========================================
  Files         180      202      +22     
  Lines       20465    22220    +1755     
==========================================
+ Hits        11489    12010     +521     
- Misses       7781     9033    +1252     
+ Partials     1195     1177      -18

Flag	Coverage Δ
e2e	`34.64% <22.24%> (-1.47%)`	⬇️
e2e go	`31.44% <22.45%> (-1.11%)`	⬇️
e2e node	`27.60% <21.54%> (-0.77%)`	⬇️
e2e python	`31.77% <22.45%> (-1.15%)`	⬇️
e2e quarkus	`27.71% <21.54%> (-0.78%)`	⬇️
e2e rust	`27.15% <20.35%> (-0.76%)`	⬇️
e2e springboot	`25.62% <19.22%> (-0.74%)`	⬇️
e2e typescript	`27.70% <21.54%> (-0.80%)`	⬇️
e2e-wasi	`22.12% <39.64%> (?)`
integration	`?`
unit macos-14	`42.53% <34.47%> (-0.84%)`	⬇️
unit macos-latest	`42.53% <34.47%> (-0.84%)`	⬇️
unit ubuntu-24.04-arm	`42.81% <35.38%> (-0.76%)`	⬇️
unit ubuntu-latest	`43.35% <34.47%> (-0.91%)`	⬇️
unit windows-latest	`42.55% <34.47%> (-0.83%)`	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

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…ation # Conflicts: # go.mod # go.sum

Use json.Decoder token parsing to verify key ordering from raw JSON bytes instead of iterating a map (non-deterministic in Go). Assisted-by: 🤖 Claude Opus/Sonnet 4.6

The Knative Configuration may not have created its first Revision yet during cold-start, reporting Ready=False with Reason=RevisionMissing. This is a transient condition (like ServiceUnavailable) that resolves once the backing ksvc boots. Treating it as terminal causes false deploy failures in CI. Assisted-by: 🤖 Claude Opus/Sonnet 4.6

knative-prow-robot · 2026-04-03T15:20:12Z

PR needs rebase.

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cardil added 19 commits February 17, 2026 18:20

Add WASI integration architecture design document

a0ee767

Initial design proposal for WASI/WebAssembly support in func CLI. Covers build pipeline, deploy pipeline, WasmModule CRD integration, and func.yaml schema changes. Assisted-by: 🤖 Claude Opus/Sonnet 4.5

Merge remote-tracking branch 'upstream/main' into feature/wasi-integr…

a151f70

…ation

chore: regenerate embedded FS and docs

8a4ab89

Assisted-by: 🤖 Claude Opus/Sonnet 4.6

Merge upstream/main into feature/wasi-integration

1521ff1

knative-prow bot requested review from dsimansk and jrangelramos April 1, 2026 18:16

knative-prow bot added the size/XXL 🤖 PR changes 1000+ lines, ignoring generated files. label Apr 1, 2026

knative-prow bot added the do-not-merge/hold 🤖 PR should not merge because someone has issued a /hold command. label Apr 1, 2026

cardil commented Apr 1, 2026

View reviewed changes

cardil added 3 commits April 1, 2026 20:31

fix: update docs codegen and remove insensitive word in test

d6d6cfe

fix: sort builder/deployer names for deterministic docs

50d8950

ci: add WASI e2e test job and make target

bd55961

cardil added 3 commits April 2, 2026 11:10

Merge remote-tracking branch 'upstream/main' into feature/wasi-integr…

4c4dd6b

…ation # Conflicts: # go.mod # go.sum

fix: flaky TestSaveVersions_SortedOutput due to map iteration order

10cf58e

Use json.Decoder token parsing to verify key ordering from raw JSON bytes instead of iterating a map (non-deterministic in Go). Assisted-by: 🤖 Claude Opus/Sonnet 4.6

knative-prow-robot added the needs-rebase Cannot be merged due to conflicts with HEAD. label Apr 3, 2026

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feat: WASI target support for func (build + deploy)#3560

feat: WASI target support for func (build + deploy)#3560
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