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Weave provides a set of environment variables to configure and optimize its behavior. This page is for developers using the Weave SDK who want to adjust runtime behavior such as tracing, logging, caching, and retries without modifying application code. You can set these variables in your shell or within scripts to control specific functionality. The following examples show two common ways to set Weave environment variables. Use the shell approach to configure Weave for an entire session, or the Python approach to set values from within your script. 
# Example of setting environment variables in the shell
export WEAVE_PARALLELISM=10  # Controls the number of parallel workers
export WEAVE_PRINT_CALL_LINK=false  # Disables call link output

# Example of setting environment variables in Python
import os

os.environ["WEAVE_PARALLELISM"] = "10"
os.environ["WEAVE_PRINT_CALL_LINK"] = "false"

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Available environment variables

The following table lists each supported environment variable, its type, default value, and the behavior it controls. For accepted values when setting boolean variables, see the note about boolean values.
VariableTypeDefaultDescription
WANDB_API_KEYstringNoneIf set, automatically logs you into W&B Weave without prompting for your API key. To generate an API key, log in to your W&B account and go to User Settings.
WEAVE_DISABLEDboolfalseWhen set to true, disables all Weave tracing. Weave ops behave like regular functions.
WEAVE_PRINT_CALL_LINKbooltrueControls whether to print a link to the Weave UI when calling a Weave op. You can also set this directly in your code by configuring the settings argument for weave.init() like this: weave.init("your-project-name", settings={"print_call_link": False})
WEAVE_LOG_LEVELstrINFOControls the log level of the Weave logger.
WEAVE_CAPTURE_CODEbooltrueControls whether to save code for ops so you can reload it for later use.
WEAVE_DEBUG_HTTPboolfalseWhen set to true, turns on HTTP request and response logging for debugging.
WEAVE_PARALLELISMint20In evaluations, controls the number of examples to evaluate in parallel. Set to 1 to run examples sequentially.
WEAVE_TRACE_LANGCHAINbooltrueControls global tracing for LangChain. Set to false to explicitly disable LangChain tracing.
WEAVE_USE_SERVER_CACHEbooltrueEnables server response caching. When enabled, Weave caches server responses to disk so repeated queries can be served from the cache instead of refetching from the server.
WEAVE_SERVER_CACHE_SIZE_LIMITint1,000,000,000Sets the maximum size limit for the server cache in bytes. When the cache reaches this size, Weave automatically removes older entries to make space for new ones. Important: the underlying implementation uses SQLite, which has a Write-Ahead Log (WAL) that grows to 4 MB regardless of this setting. Weave removes this WAL when the program exits.
WEAVE_SERVER_CACHE_DIRstrNoneSpecifies the directory where Weave stores cache files. If not set, Weave uses a temporary directory.
WEAVE_MAX_CALLS_QUEUE_SIZEint100000Sets the maximum size of the calls queue. Defaults to 100000. Setting a value of 0 lets the queue grow unbounded.
WEAVE_ENABLE_WALboolfalseEnables the Weave Write-Ahead Log (WAL). When set to true, Weave writes API requests to disk before sending them to the server, so requests can be recovered if the process exits before they are sent.
WEAVE_DISABLE_WAL_SENDERboolfalseDisables the Weave Write-Ahead Log (WAL) sender. When set to true, Weave writes requests to disk but doesn’t flush them to the server. Useful for debugging.
WEAVE_RETRY_MAX_ATTEMPTSint3Sets the maximum number of retry attempts for failed requests.
WEAVE_RETRY_MAX_INTERVALfloat300.0Sets the maximum interval between retry attempts in seconds.
WANDB_BASE_URLstringNoneSets the Weave host URL. Equivalent to entering the host URL when prompted by wandb.login(). You can specify WANDB_BASE_URL and WANDB_API_KEY before using weave.init() to automatically log in and authenticate to Weave.
All boolean environment variables accept the following values (case-insensitive):
  • true, 1, yes, on for True
  • false, 0, no, off for False