---
title: Wandb Callback Handler
 | LlamaIndex OSS Documentation
---

[Weights & Biases Prompts](https://docs.wandb.ai/guides/prompts) is a suite of LLMOps tools built for the development of LLM-powered applications.

The `WandbCallbackHandler` is integrated with W\&B Prompts to visualize and inspect the execution flow of your index construction, or querying over your index and more. You can use this handler to persist your created indices as W\&B Artifacts allowing you to version control your indices.

```
%pip install llama-index-callbacks-wandb
%pip install llama-index-llms-openai
```

```
import os
from getpass import getpass


if os.getenv("OPENAI_API_KEY") is None:
    os.environ["OPENAI_API_KEY"] = getpass(
        "Paste your OpenAI key from:"
        " https://platform.openai.com/account/api-keys\n"
    )
assert os.getenv("OPENAI_API_KEY", "").startswith(
    "sk-"
), "This doesn't look like a valid OpenAI API key"
print("OpenAI API key configured")
```

```
OpenAI API key configured
```

```
from llama_index.core.callbacks import CallbackManager
from llama_index.core.callbacks import LlamaDebugHandler
from llama_index.callbacks.wandb import WandbCallbackHandler
from llama_index.core import (
    VectorStoreIndex,
    SimpleDirectoryReader,
    SimpleKeywordTableIndex,
    StorageContext,
)
from llama_index.llms.openai import OpenAI
```

## Setup LLM

```
from llama_index.core import Settings


Settings.llm = OpenAI(model="gpt-4", temperature=0)
```

## W\&B Callback Manager Setup

**Option 1**: Set Global Evaluation Handler

```
import llama_index.core
from llama_index.core import set_global_handler


set_global_handler("wandb", run_args={"project": "llamaindex"})
wandb_callback = llama_index.core.global_handler
```

**Option 2**: Manually Configure Callback Handler

Also configure a debugger handler for extra notebook visibility.

```
llama_debug = LlamaDebugHandler(print_trace_on_end=True)


# wandb.init args
run_args = dict(
    project="llamaindex",
)


wandb_callback = WandbCallbackHandler(run_args=run_args)


Settings.callback_manager = CallbackManager([llama_debug, wandb_callback])
```

> After running the above cell, you will get the W\&B run page URL. Here you will find a trace table with all the events tracked using [Weights and Biases’ Prompts](https://docs.wandb.ai/guides/prompts) feature.

## 1. Indexing

Download Data

```
!mkdir -p 'data/paul_graham/'
!wget 'https://raw.githubusercontent.com/run-llama/llama_index/main/docs/examples/data/paul_graham/paul_graham_essay.txt' -O 'data/paul_graham/paul_graham_essay.txt'
```

```
docs = SimpleDirectoryReader("./data/paul_graham/").load_data()
```

```
index = VectorStoreIndex.from_documents(docs)
```

```
**********
Trace: index_construction
    |_node_parsing ->  0.295179 seconds
      |_chunking ->  0.293976 seconds
    |_embedding ->  0.494492 seconds
    |_embedding ->  0.346162 seconds
**********




wandb: Logged trace tree to W&B.
```

### 1.1 Persist Index as W\&B Artifacts

```
wandb_callback.persist_index(index, index_name="simple_vector_store")
```

```
wandb: Adding directory to artifact (/Users/loganmarkewich/llama_index/docs/examples/callbacks/wandb/run-20230801_152955-ds93prxa/files/storage)... Done. 0.0s
```

### 1.2 Download Index from W\&B Artifacts

```
from llama_index.core import load_index_from_storage


storage_context = wandb_callback.load_storage_context(
    artifact_url="ayut/llamaindex/simple_vector_store:v0"
)


# Load the index and initialize a query engine
index = load_index_from_storage(
    storage_context,
)
```

```
wandb:   3 of 3 files downloaded.




**********
Trace: index_construction
**********
```

## 2. Query Over Index

```
query_engine = index.as_query_engine()
response = query_engine.query("What did the author do growing up?")
print(response, sep="\n")
```

```
**********
Trace: query
    |_query ->  2.695958 seconds
      |_retrieve ->  0.806379 seconds
        |_embedding ->  0.802871 seconds
      |_synthesize ->  1.8893 seconds
        |_llm ->  1.842434 seconds
**********




wandb: Logged trace tree to W&B.




The text does not provide information on what the author did growing up.
```

## Close W\&B Callback Handler

When we are done tracking our events we can close the wandb run.

```
wandb_callback.finish()
```