LangGraph.js: Troubleshooting `onRunCreated` Locally

by Sebastian Müller 53 views

Introduction

Hey guys! Today, we're diving deep into a quirky issue some of us have been facing with LangGraph.js: the onRunCreated callback not firing in local development environments. It's one of those things that works perfectly in production but throws a wrench in the gears when we're trying to test things locally. So, let’s unravel this mystery and figure out how to get our local setups behaving correctly.

When you're building with LangGraph.js, the onRunCreated callback is super handy for capturing the run ID the moment a new run is initiated. This is crucial for tracking and managing your graph executions, especially in complex applications. Imagine you're setting up a system that needs to log each run, trigger notifications, or perform some other action as soon as a new run starts. The onRunCreated callback is your go-to tool for this. But what happens when this nifty feature decides to take a break in your local environment? That's exactly what we're tackling today. We'll explore the potential causes, dig into the code, and, most importantly, find solutions to get this callback working consistently across all environments. Think of this as your ultimate guide to making onRunCreated play nice, whether you're in the cloud or coding from your cozy home setup. Let's get started and ensure our local development mirrors the reliability of our production systems. After all, a smooth local development experience is the key to efficient and stress-free coding!

Problem Report

Issue Summary

I've noticed that the onRunCreated callback, which is supposed to trigger when a new run is created in LangGraph.js, isn't being called in my local development environment. This is quite a contrast to our production environment, where it works flawlessly. To give you a clearer picture, I've set up a simple piece of code to illustrate this. The goal is to capture the run_id using the onRunCreated callback, but it seems like this callback is never executed when I'm running things locally. This makes it tricky to debug and test certain features that rely on this callback. Has anyone else run into this, and if so, how did you guys manage to solve it? I'm keen to hear your experiences and any advice you might have. It's a bit of a head-scratcher, especially since everything seems to be set up correctly, and there are no error messages popping up. It's just that the callback stubbornly refuses to be called. This is more than just a minor inconvenience; it's a roadblock that prevents me from fully testing and ensuring the reliability of my LangGraph.js applications in a local setting. So, any insights or suggestions would be greatly appreciated. Let's work together to crack this nut and make our local development environments as robust as our production setups.

Code Example

Here’s a snippet of the code I’m using. It's pretty straightforward: I'm using the client.runs.wait function and passing in an onRunCreated callback. This callback should, in theory, assign the run_id from the parameters to a variable. However, in my local environment, this callback never gets triggered, leaving runId as null. This is particularly puzzling because the same code works perfectly fine when deployed to our production environment. I've made sure that all the necessary services are running locally and that there are no obvious configuration differences that might be causing this. The fact that the issue is isolated to the local environment suggests that it might be related to how the LangGraph.js client interacts with the local development server or some other environment-specific setting. I've tried various debugging techniques, including logging and stepping through the code, but I haven't been able to pinpoint the exact cause. It's one of those issues that makes you scratch your head and wonder if you're missing something obvious. So, I'm hoping that by sharing this code and the problem I'm facing, someone in the community might have some insights or suggestions that can help me resolve this. Let's take a look at the code:

let runId: string | null = null;
const state = await client.runs.wait(null, "assistant-id", {
 input: {},
 onRunCreated: (params) => {
 // never called in local env
 runId = params.run_id;
 },
});

Observations

As you can see from the code, the onRunCreated function is intended to capture the run_id when a new run is initiated. However, in my local setup, this just doesn't happen. The callback simply isn't triggered. This is quite perplexing, especially since there are no error messages or warnings to guide me. It's like the function is being completely ignored. I've double-checked the documentation and examples, and everything seems to be set up correctly. This leads me to believe that there might be some subtle difference in how LangGraph.js behaves in a local environment compared to production. Perhaps there's a configuration setting that I'm missing, or maybe there's a dependency that's not being properly initialized in my local setup. I've also considered the possibility that there might be a bug in the LangGraph.js library itself, although I'm hoping that's not the case. The fact that this issue is only happening locally makes it particularly challenging to diagnose. It's like trying to find a needle in a haystack, especially when you're not even sure what the haystack looks like. So, I'm really counting on the community's expertise to help me shed some light on this issue and get the onRunCreated callback working as expected in my local development environment.

Investigation

I even went digging into the LangGraph.js schema and the LangGraph Python SDK to see if I could find any clues. I checked the schema definition in the LangGraph.js repository, specifically looking for the onRunCreated parameter. I wanted to ensure that it was correctly defined and that there were no obvious discrepancies that could be causing the issue. Similarly, I explored the LangGraph Python SDK, examining the client-side implementation related to run creation and callback handling. My goal was to trace the execution flow and identify any potential bottlenecks or misconfigurations that might be preventing the callback from being triggered in the local environment. It was a bit like detective work, piecing together different parts of the code to form a complete picture. Unfortunately, despite my efforts, I didn't find anything conclusive. The schema seemed to be correctly defined, and the Python SDK implementation appeared to be in order. This led me to believe that the issue might be more subtle, perhaps related to how the local development server handles callbacks or some other environment-specific factor. But let's look at the specific links I checked:

Environment Details

For those of you who are curious about the versions I'm running, here’s my system info. I'm using @langchain/langgraph version 0.4.1, @langchain/langgraph-sdk version 0.0.105, and @langchain/langgraph-cli version 0.0.55. Knowing the specific versions can sometimes help in identifying compatibility issues or known bugs that might be causing the problem. I've made sure to keep my dependencies up to date, but it's always possible that a recent update has introduced a regression or some other issue that's affecting the onRunCreated callback. I've also checked the release notes and changelogs for these packages, but I haven't found any mention of known issues related to this callback. This makes the problem even more puzzling, as it suggests that it might be a more nuanced issue that's specific to my setup or a combination of factors. Providing this information is part of my effort to give you guys as complete a picture as possible of my environment and the problem I'm facing. The more details we have, the better our chances of finding a solution. So, if you spot anything in these version numbers that might be relevant, please let me know. I'm all ears for any suggestions or insights you might have.

@langchain/langgraph 0.4.1
@langchain/langgraph-sdk 0.0.105
@langchain/langgraph-cli 0.0.55

Possible Causes and Solutions

Okay, let’s brainstorm some potential reasons why onRunCreated might be ghosting us in local development. We know it works in production, so the core logic should be sound. This points to environmental differences as the likely culprit. Here’s a breakdown of what might be happening and some steps we can take to troubleshoot. It's crucial to remember that local development environments often have different configurations and settings compared to production environments. This can lead to unexpected behavior, especially when dealing with callbacks and event-driven systems. The key is to systematically examine the potential differences and identify the root cause of the issue. This might involve checking environment variables, server configurations, and even the way the local development server handles asynchronous operations. It's also worth considering whether there might be any network-related issues that are preventing the callback from being triggered. For example, if the local development server is not properly configured to handle WebSocket connections, this could interfere with the callback mechanism. So, let's put on our detective hats and start exploring the various possibilities.

1. Environment Variables

First off, let’s talk about environment variables. Sometimes, local setups miss crucial environment variables that the production environment has. These variables can dictate how LangGraph.js communicates with its backend or other services. Think of environment variables as the secret sauce that makes your application run smoothly. They often contain sensitive information, such as API keys, database credentials, and other configuration settings that should not be hardcoded directly into your code. In the context of LangGraph.js, environment variables might be used to specify the URL of the LangGraph server, the authentication credentials, or other parameters that affect the behavior of the onRunCreated callback. If these variables are not correctly set in your local development environment, it can lead to unexpected issues, such as the callback not being triggered. So, it's essential to double-check your environment variables and ensure that they are properly configured. This might involve setting the variables directly in your terminal, adding them to a .env file, or using a tool like Docker Compose to manage your environment. The key is to make sure that your local environment closely mirrors your production environment in terms of configuration and settings. This will help you avoid many common pitfalls and ensure that your application behaves consistently across all environments.

Solution: Double-check that all necessary environment variables are set in your local environment. Compare your local .env file (if you have one) with the environment variables set in your production environment. Ensure any API keys, URLs, or other critical settings are present and correct. This simple step can often resolve mysterious issues like this, as missing or incorrect environment variables can silently break functionality.

2. Server Configuration

Next up, the server configuration itself. Are you running a local LangGraph server, and is it configured correctly? This is a big one because if the server isn't set up right, the callback might never get the signal to fire. The server plays a crucial role in handling requests and responses, and if it's not properly configured, it can lead to various issues, including callbacks not being triggered. In the context of LangGraph.js, the server is responsible for managing the execution of graphs and notifying clients when certain events occur, such as the creation of a new run. If the server is not listening for these events or is not properly configured to send notifications, the onRunCreated callback will not be triggered. This can happen for a variety of reasons, such as incorrect port settings, firewall restrictions, or misconfigured routing rules. So, it's essential to carefully review your server configuration and ensure that it's set up to handle the callbacks correctly. This might involve checking the server logs for any error messages, verifying the network settings, and ensuring that the server is running the correct version of LangGraph.js. It's also worth considering whether there might be any conflicts with other services or applications that are running on the same server. By systematically examining your server configuration, you can often identify and resolve issues that are preventing the onRunCreated callback from being triggered.

Solution: Verify that your local LangGraph server is running and properly configured. Check the server logs for any errors or warnings. Ensure that the server is listening on the correct port and that there are no firewall issues preventing communication. If you're using a reverse proxy, make sure it's configured to forward requests to the LangGraph server correctly. A misconfigured server can silently drop events, preventing the callback from ever being invoked.

3. Asynchronous Issues

Let's talk about asynchronous issues. Callbacks are inherently asynchronous, meaning they don't fire immediately. If there’s a problem with how your local environment handles asynchronous operations, it could explain why onRunCreated isn't being triggered. Asynchronous operations are a fundamental part of modern web development, allowing applications to perform tasks in the background without blocking the main thread. This is crucial for maintaining a responsive user interface and ensuring that long-running operations don't freeze the application. However, asynchronous operations can also introduce complexity, especially when dealing with callbacks. Callbacks are functions that are executed when an asynchronous operation completes, and if there's a problem with how these callbacks are handled, it can lead to unexpected behavior. In the case of LangGraph.js, the onRunCreated callback is triggered when a new run is created asynchronously. If there's an issue with the asynchronous event loop or the way promises are being resolved, the callback might not be triggered at the expected time, or it might not be triggered at all. This can be particularly challenging to debug, as asynchronous issues often manifest themselves in subtle and unpredictable ways. So, it's essential to have a good understanding of how asynchronous operations work and to use debugging tools and techniques to trace the execution flow and identify any potential problems.

Solution: Ensure your local environment correctly handles asynchronous operations. Check for any issues with your event loop or promise resolution. Try adding some logging within the onRunCreated callback and also immediately before and after the client.runs.wait call. This can help you determine if the callback is ever reached and if the asynchronous operation is completing as expected. If you're using any task queues or background processing libraries, make sure they are properly configured and running in your local environment.

4. Version Mismatch

Could there be a version mismatch? Sometimes, discrepancies between the versions of LangGraph.js, its SDK, or other related packages can cause unexpected behavior. This is a common pitfall in software development, especially when dealing with complex libraries and frameworks. Version mismatches can occur for a variety of reasons, such as using different versions of packages in different environments, failing to update dependencies correctly, or accidentally installing incompatible versions. In the context of LangGraph.js, a version mismatch between the core library, the SDK, or the CLI tools can lead to issues with the onRunCreated callback. For example, a newer version of the SDK might introduce changes that are not compatible with an older version of the core library, or vice versa. This can result in the callback not being triggered, or it might lead to other unexpected errors. So, it's crucial to ensure that all the LangGraph.js packages in your project are running the same version, or at least compatible versions. This might involve checking your package.json file, running npm install or yarn install to update your dependencies, or using a tool like npm outdated or yarn outdated to identify any outdated packages. It's also a good practice to consult the LangGraph.js documentation or release notes to understand the compatibility requirements between different versions of the packages.

Solution: Double-check the versions of @langchain/langgraph, @langchain/langgraph-sdk, and @langchain/langgraph-cli in your local environment. Make sure they match the versions you're using in production, or at least that they are compatible. Run npm list or yarn list to verify the installed versions. If there are discrepancies, update or downgrade the packages as necessary to ensure consistency. Version mismatches are a common source of bugs, so keeping your dependencies aligned is crucial.

5. Local Environment Quirks

Finally, let’s consider local environment quirks. Sometimes, the issue isn’t a specific configuration problem but rather a peculiarity of your local development setup. This could be anything from how your operating system handles network requests to how your IDE manages background processes. Local development environments are often highly customized and can vary significantly from one machine to another. This can introduce subtle differences in behavior that are difficult to predict and troubleshoot. For example, a firewall setting on your local machine might be blocking the communication between the LangGraph.js client and the server, preventing the onRunCreated callback from being triggered. Or, a specific configuration of your IDE might be interfering with the asynchronous event loop, causing delays or other issues. It's also worth considering whether there might be any resource constraints on your local machine that are affecting the performance of LangGraph.js. For example, if your machine is running low on memory or CPU, this could lead to timeouts or other errors that prevent the callback from being triggered. So, it's essential to be aware of the unique characteristics of your local environment and to consider how these might be affecting the behavior of LangGraph.js. This might involve experimenting with different settings, trying different debugging techniques, or even running your application on a different machine to see if the issue persists.

Solution: Try running your LangGraph.js application in a different local environment, such as a Docker container or a virtual machine. This can help isolate the issue and determine if it's specific to your local setup. Check for any unusual configurations in your operating system, IDE, or other development tools that might be interfering with LangGraph.js. Sometimes, a fresh environment can provide a clean slate and resolve issues that are difficult to track down in a customized setup.

Conclusion

So, there you have it, folks! We’ve journeyed through the potential pitfalls of getting onRunCreated to behave in our local LangGraph.js setups. Remember, the key is methodical troubleshooting: check your environment variables, server configurations, asynchronous handling, version consistencies, and those sneaky local environment quirks. By systematically ruling out each possibility, you'll be well on your way to a smooth local development experience. And hey, if you stumble upon a solution that we haven’t covered here, don’t be a stranger! Share your wisdom with the community. After all, we’re all in this together, building awesome things with LangGraph.js. Keep coding, keep exploring, and most importantly, keep those callbacks firing!