feat: add Function (FunctionRegistry) client by eaddingtonwhite · Pull Request #1618 · momentohq/client-sdk-javascript

eaddingtonwhite · 2026-06-17T22:48:38Z

Adds a PreviewFunctionClient for managing Momento Functions, mirroring PreviewLeaderboardClient (a preview, data-plane client on the cache endpoint).

const fns = new PreviewFunctionClient({credentialProvider});
await fns.putFunction(cacheName, name, wasmBytes, {description, environmentVariables}); // -> PutFunction.Success.functionId()
await fns.listFunctions(cacheName);            // -> ListFunctions.Success.getFunctions(): FunctionInfo[]
await fns.listFunctionVersions(functionId);    // -> ListFunctionVersions.Success.getVersions(): FunctionVersionInfo[]
await fns.deleteFunction(cacheName, name);

Requires @gomomento/generated-types 0.133.0 — the first release that includes the FunctionRegistry service (added in momentohq/client-protos#340).

Notes / decisions worth a look:

nodejs only for now — no web parity yet. The immediate consumer is a Node/Lambda CDK construct; happy to follow up with a client-sdk-web implementation if we want parity before release.
listFunctions/listFunctionVersions are server-streaming; they use streaming interceptors without the retry interceptor. putFunction/deleteFunction aren't in the retry allowlist, so mutations are never auto-retried.
deleteFunction on a missing function returns Error (NOT_FOUND), like deleteCache — not idempotent.
putFunction sends a 32 MB max-message override (wasm ships inline) and uses a 60s deadline.
Integration test (test/integration/function/) runs in the normal sweep when MOMENTO_API_KEY is set, via CredentialProvider.fromEnvVarV2(). It puts/lists/deletes a real function using a small committed wasm-component fixture.

Tested: unit tests for construction + validation; a live integration test against the alpha cell (put → list → listFunctionVersions → delete) passes.

Opening as a draft to get feedback on the web-parity question and the design notes above before finalizing.

Adds PreviewFunctionClient for managing Momento Functions (putFunction, deleteFunction, listFunctions, listFunctionVersions), mirroring PreviewLeaderboardClient (a preview, data-plane client on the cache endpoint). Requires @gomomento/generated-types 0.133.0, the first release that includes the FunctionRegistry service. nodejs only for now (no web parity yet).

Copilot

Pull request overview

Adds a new preview, Node.js-only client for managing Momento Functions via the new FunctionRegistry data-plane service on the cache endpoint, along with the corresponding core response types and metadata models.

Changes:

Introduces core Function response types/enums and FunctionInfo / FunctionVersionInfo models, plus an internal IFunctionClient interface.
Adds PreviewFunctionClient + internal gRPC implementation (streaming list operations, 32MB message size override, Function-specific configuration defaults).
Adds unit + live integration tests and bumps @gomomento/generated-types to 0.133.0.

Reviewed changes

Copilot reviewed 22 out of 24 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/core/src/messages/responses/function/put-function.ts	Adds PutFunction response types (Success/Error).
packages/core/src/messages/responses/function/list-functions.ts	Adds ListFunctions response types (Success/Error) returning `FunctionInfo[]`.
packages/core/src/messages/responses/function/list-function-versions.ts	Adds ListFunctionVersions response types (Success/Error) returning `FunctionVersionInfo[]`.
packages/core/src/messages/responses/function/delete-function.ts	Adds DeleteFunction response types (Success/Error).
packages/core/src/messages/responses/function/index.ts	Barrels Function response exports.
packages/core/src/messages/responses/enums/function/index.ts	Adds enums for Function response type discrimination.
packages/core/src/messages/responses/enums/index.ts	Exposes Function enums alongside existing response enums.
packages/core/src/messages/function-info.ts	Adds `FunctionInfo` / `FunctionVersionInfo` metadata models used by list operations.
packages/core/src/internal/clients/function/IFunctionClient.ts	Defines internal function client interface + options (`PutFunctionOptions`).
packages/core/src/internal/clients/function/index.ts	Barrels internal function client exports.
packages/core/src/internal/clients/index.ts	Exposes function client module from internal clients index.
packages/core/src/index.ts	Exposes Function response types and metadata models from sdk-core entrypoint.
packages/client-sdk-nodejs/src/config/function-configuration.ts	Introduces FunctionClient configuration interface + implementation.
packages/client-sdk-nodejs/src/config/function-configurations.ts	Adds default “Laptop” Function configuration (60s deadline).
packages/client-sdk-nodejs/src/function-client-props.ts	Adds Node SDK props type for Function client construction.
packages/client-sdk-nodejs/src/internal/function-client-all-props.ts	Adds internal “all props” type for Function client instantiation.
packages/client-sdk-nodejs/src/internal/function-client.ts	Implements gRPC client for FunctionRegistry (put/delete unary, list streaming).
packages/client-sdk-nodejs/src/preview-function-client.ts	Adds public PreviewFunctionClient wrapper that mirrors PreviewLeaderboardClient pattern.
packages/client-sdk-nodejs/src/index.ts	Re-exports Function client, configuration, and core response/model types from Node SDK entrypoint.
packages/client-sdk-nodejs/test/unit/function-client.test.ts	Adds constructor + basic argument-validation unit tests.
packages/client-sdk-nodejs/test/integration/function/function-client.test.ts	Adds live integration test (put → list → list versions → delete).
packages/client-sdk-nodejs/package.json	Bumps generated-types dependency and adds integration-test-function script.
packages/client-sdk-nodejs/package-lock.json	Locks generated-types bump to `0.133.0` with resolved tarball metadata.

Files not reviewed (1)

packages/client-sdk-nodejs/package-lock.json: Generated file

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Addresses code review feedback: putFunction/deleteFunction now validate the function name (and putFunction rejects empty wasm) like other resource APIs; listFunctionVersions validates the function id; and a ListFunctionVersions row missing id/wasm_id is now surfaced as an error instead of a degraded result. Adds validateFunctionName/validateFunctionId to core.

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Copilot reviewed 23 out of 25 changed files in this pull request and generated 3 comments.

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packages/client-sdk-nodejs/package-lock.json: Generated file

Code review round 2: import IFunctionClient/PutFunctionOptions from the public @gomomento/sdk-core entrypoint instead of the internal dist path; fix the addMiddleware JSDoc (it prepends, not appends).

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Copilot reviewed 23 out of 25 changed files in this pull request and generated 5 comments.

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packages/client-sdk-nodejs/package-lock.json: Generated file

… from putFunction FunctionInfo now exposes getCurrentVersion() (resolves the pinned/latest oneof, as the Rust SDK does) and getLastUpdatedAt(). PutFunction.Success now carries the full FunctionInfo the server already returns (getFunction()) instead of only id+name.

@returns

Code review round 3: public client interfaces belong under core/src/clients (like ILeaderboardClient), so move IFunctionClient + PutFunctionOptions out of internal/clients/function. Correct the function-configuration JSDoc @returns to FunctionConfiguration.

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Copilot reviewed 21 out of 23 changed files in this pull request and generated 1 comment.

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packages/client-sdk-nodejs/package-lock.json: Generated file

Code review round 4: the shared CacheServiceErrorMapper renders a NOT_FOUND as a cache-flavored CacheNotFoundError. Add FunctionNotFoundError (+ a FUNCTION_NOT_FOUND_ERROR code) and remap NOT_FOUND in the function client so a missing function surfaces the correct error. Verified live.

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packages/client-sdk-nodejs/package-lock.json: Generated file

Code review round 5: FunctionInfo is now returned by putFunction (PutFunction.Success) as well as listFunctions; update the class docstring.

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anitarua

lgtm!

malandis

No blockers from me. I wasn't aware the various functions lifecycle methods were data plane? Seems like control plane but 👍

malandis · 2026-06-18T20:41:03Z

+    // Deploying a function uploads the wasm artifact inline, so the deadline is more generous than the
+    // cache-data defaults.


malandis · 2026-06-18T20:41:34Z

+// Wasm artifacts ship inline in the PutFunction request and can be large, so raise the gRPC message-size
+// caps above the data-plane defaults (which are tuned for small cache items).
+const MAX_MESSAGE_SIZE_BYTES = 32 * 1024 * 1024;


malandis · 2026-06-18T20:58:29Z

+  public getFunction(): FunctionInfo {
+    return this._function;
+  }


getFunctionInfo?

eaddingtonwhite requested review from anitarua, Copilot and tylerburdsall June 17, 2026 22:51

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Comment thread packages/client-sdk-nodejs/src/internal/function-client.ts

Comment thread packages/client-sdk-nodejs/src/internal/function-client.ts

Comment thread packages/client-sdk-nodejs/src/internal/function-client.ts Outdated

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Comment thread packages/client-sdk-nodejs/src/preview-function-client.ts

Comment thread packages/client-sdk-nodejs/src/internal/function-client.ts

Comment thread packages/client-sdk-nodejs/src/config/function-configuration.ts

fix: import public sdk-core types + correct addMiddleware doc

3e407cb

Code review round 2: import IFunctionClient/PutFunctionOptions from the public @gomomento/sdk-core entrypoint instead of the internal dist path; fix the addMiddleware JSDoc (it prepends, not appends).

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eaddingtonwhite added 2 commits June 17, 2026 16:23

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Comment thread packages/core/src/messages/function-info.ts

docs: FunctionInfo is returned by putFunction too

0aca283

Code review round 5: FunctionInfo is now returned by putFunction (PutFunction.Success) as well as listFunctions; update the class docstring.

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eaddingtonwhite marked this pull request as ready for review June 18, 2026 00:33

tylerburdsall approved these changes Jun 18, 2026

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eaddingtonwhite merged commit 30fa5d2 into main Jun 18, 2026
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eaddingtonwhite deleted the feat/function-client branch June 18, 2026 21:02

		// Deploying a function uploads the wasm artifact inline, so the deadline is more generous than the
		// cache-data defaults.

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