langfuse / langfuse-js Goto Github PK

Hi all, since many of the features overlap across the core application and the client sdks, we centralize issues in the main application repo: langfuse/langfuse (filter by Javascript SDK)

Describe the solution you'd like

Add Langchain Integration to the JS/TS SDKs which currently only exists in the Python SDKs.

Why is this important? Reducing the integration effort is key to help more people use Langfuse for their project. The Langchain intgeration (Python only) is currently the fastest way to integrate. It would be awesome if this was also usable for JS/TS Langchain projects.

I'm happy to support on this, dm on Discord

Additional context

• Langchain Callbacks: https://js.langchain.com/docs/modules/callbacks/
• Langfuse Python implementation (probably a lot can be copied/ported)
  • Docs: https://langfuse.com/docs/integrations/langchain
  • Callback handler: https://github.com/langfuse/langfuse-python/blob/main/langfuse/callback.py
  • Tests: https://github.com/langfuse/langfuse-python/blob/main/tests/test_langchain.py

_{From SyncLinear.com | LFJ-2}

Currently, the Langfuse SDK is not able to take environment variables for configuration. Instead, it relies on options on the constructor.

We want to have one function, which takes params: { publicKey?: string; secretKey?: string } & LangfuseCoreOptions and returns the same type.

• This function should have the following behavior:
  • check if values for publicKey, secretKey, or variables within LangfuseCoreOptions were provided.
  • If not, check the environment variables and take values from there.
  • If still no variable was defined, log an error if the input param was required but not provided by either the constructor or the env variable. No exception is thrown.
• use existing getEnv utility to access environment variables
• the following variables are available:
  • LANGFUSE_RELEASE
  • LANGFUSE_PUBLIC_KEY
  • LANGFUSE_SECRET_KEY
  • LANGFUSE_DEBUG
  • LANGFUSE_HOST
• Please adjust all environment variables in the CI and tests to reflect the change.
• The function should be called as first action in the two Langfuse objects (

  langfuse-js/langfuse/src/langfuse.ts

  Line 20 in 04a75b4

  export class Langfuse extends LangfuseCore {

  , https://github.com/langfuse/langfuse-js/blob/04a75b406010368326bf3e12336f2a9bb9d4c210/langfuse-node/src/langfuse-node.ts#L28) and LangfuseWeb (

  langfuse-js/langfuse/src/langfuse.ts

  Lines 76 to 77 in 04a75b4

  	export class LangfuseWeb extends LangfuseWebStateless {
  	private _storage: LangfuseStorage;

  )
  • As of there, the values returned from that function will be used internally

Overview over all constructors:

• Langfuse: constructor(params: { publicKey: string; secretKey: string } & LangfuseOptions)

  • langfuse-js/langfuse/src/langfuse.ts

    Line 20 in 04a75b4

    export class Langfuse extends LangfuseCore {

  • extends LangfuseCore and is the object exposed to SDK users for the backend
• Langfuse (node): constructor(params: { publicKey: string; secretKey: string } & LangfuseOptions)

  • langfuse-js/langfuse-node/src/langfuse-node.ts

    Line 28 in 04a75b4

    constructor(params: { publicKey: string; secretKey: string } & LangfuseOptions) {

  • Backend SDK for users on old node versions, also extends LangfuseCore
• LangfuseCore: constructor(params: { publicKey: string; secretKey: string } & LangfuseCoreOptions)
  • extends LangfuseCoreStateless
  • Contains additional logic to the LangfuseCoreStateless class to improve developer experience
• LangfuseWeb: constructor(params: { publicKey: string } & LangfuseOptions)

  • langfuse-js/langfuse/src/langfuse.ts

    Lines 76 to 77 in 04a75b4

    	export class LangfuseWeb extends LangfuseWebStateless {
    	private _storage: LangfuseStorage;

  • extends LangfuseWebStateless
  • This is the SDK which our users can use in react applications
• LangfuseWebStateless: constructor(params: { publicKey: string } & LangfuseCoreOptions)
  • extends LangfuseCoreStateless
• LangfuseCoreStateless: constructor(params: { publicKey: string; secretKey?: string } & LangfuseCoreOptions)

  • langfuse-js/langfuse-core/src/index.ts

    Line 100 in 04a75b4

    constructor(params: { publicKey: string; secretKey?: string } & LangfuseCoreOptions) {

  • LangfuseCoreStateless is extended by LangfuseCore
  • LangfuseCoreStateless contains all API calls to our server