Bundled Libraries

Claude Code ships with libraries inside its program. These libraries read their own environment variables, and Claude Code itself does not use them. A variable here only works when the library code runs. Setting one can change behavior in a way Claude Code does not plan for.

This page lists 126 variables. The effect depends on the library and the feature that runs it. Set them in your shell.

Example

export GRPC_VERBOSITY=DEBUG
claude

The bundled gRPC library prints more log lines. This helps when an OTEL gRPC exporter fails.

Variables

The table is sorted by name. See Environment Variables for what each column and badge means.

Variable	Status	Library	What it does
APP_URL	Undocumented	cloud detector	A bundled cloud detector treats a value that contains ondigitalocean.app as the DigitalOcean App Platform.
AWS_ACCOUNT_ID	Undocumented	AWS SDK	The bundled AWS SDK env credential provider reads it with the key, secret, token, expiry, and scope vars.
AWS_AUTH_SCHEME_PREFERENCE	Undocumented	AWS SDK	The bundled AWS SDK reads it as a comma list of preferred auth schemes.
AWS_CONTAINER_AUTHORIZATION_TOKEN	Undocumented	AWS SDK	The bundled AWS SDK sends it as the auth value to the container credentials endpoint.
AWS_CONTAINER_AUTHORIZATION_TOKEN_FILE	Undocumented	AWS SDK	The bundled AWS SDK reads the container credentials auth token from this file path.
AWS_CREDENTIAL_EXPIRATION	Documented	AWS SDK	The bundled AWS SDK env credential provider reads it as the expiry time of the env credentials.
AWS_DEFAULTS_MODE	Undocumented	AWS SDK	The bundled AWS SDK reads it as the SDK defaults mode.
AWS_EC2_METADATA_DISABLED	Undocumented	AWS SDK	Turns off the EC2 instance metadata lookup in the bundled AWS SDK credential chain and region defaults.
AWS_EC2_METADATA_SERVICE_ENDPOINT	Undocumented	AWS SDK	Sets the EC2 metadata service URL for the bundled AWS SDK.
AWS_EC2_METADATA_SERVICE_ENDPOINT_MODE	Undocumented	AWS SDK	Picks IPv4 or IPv6 for the EC2 metadata service address in the bundled AWS SDK.
AWS_EC2_METADATA_V1_DISABLED	Undocumented	AWS SDK	Blocks the IMDSv1 fallback in the bundled AWS SDK, so only token-based IMDSv2 is used.
AWS_ENDPOINT_URL_SSO	Undocumented	AWS SDK	Overrides the AWS SSO endpoint in the bundled AWS SDK.
AWS_ENDPOINT_URL_SSO_OIDC	Undocumented	AWS SDK	Overrides the AWS SSO OIDC endpoint in the bundled AWS SDK.
AWS_LAMBDA_MAX_CONCURRENCY	Undocumented	AWS SDK	Selects the concurrent-aware store in the bundled AWS Lambda InvokeStore when present.
AWS_LOGIN_CACHE_DIRECTORY	Undocumented	AWS SDK	Sets the cache folder for the AWS SDK login_session credential provider (aws login).
AWS_MAX_ATTEMPTS	Undocumented	AWS SDK	Sets the maximum retry attempts of the bundled AWS SDK clients.
AWS_RETRY_MODE	Undocumented	AWS SDK	Sets the retry mode of the bundled AWS SDK clients.
AWS_ROLE_SESSION_NAME	Undocumented	AWS SDK	Sets the session name for AWS web identity role assumption in the bundled AWS SDK.
AWS_SDK_UA_APP_ID	Undocumented	AWS SDK	Adds an app/<id> part to the user agent of the bundled AWS SDK calls.
AWS_USE_DUALSTACK_ENDPOINT	Undocumented	AWS SDK	Turns on AWS dual-stack endpoints in the AWS SDK.
AZURE_ADDITIONALLY_ALLOWED_TENANTS	Undocumented	Azure SDK	Lists extra tenant IDs the bundled Azure identity library may use.
AZURE_AUTHORITY_HOST	Undocumented	Azure SDK	Sets the Microsoft Entra authority URL of the bundled Azure identity library.
AZURE_CLIENT_CERTIFICATE_PASSWORD	Undocumented	Azure SDK	Gives the password of the client certificate for the Azure EnvironmentCredential.
AZURE_CLIENT_CERTIFICATE_PATH	Undocumented	Azure SDK	Gives the client certificate path for the Azure EnvironmentCredential.
AZURE_CLIENT_ID	Documented	Azure SDK	Gives the Azure app client ID for the bundled Azure identity credentials.
AZURE_CLIENT_SECRET	Undocumented	Azure SDK	Gives the Azure app client secret for the Azure EnvironmentCredential.
AZURE_CLIENT_SEND_CERTIFICATE_CHAIN	Undocumented	Azure SDK	Makes the Azure client certificate credential send the full certificate chain.
AZURE_FEDERATED_TOKEN_FILE	Undocumented	Azure SDK	Gives the federated token file for Azure workload identity login.
AZURE_IDENTITY_DISABLE_MULTITENANTAUTH	Undocumented	Azure SDK	Turns off multi-tenant token requests in the Azure identity library, so the configured tenant is always used.
AZURE_LOG_LEVEL	Undocumented	Azure SDK	Sets the log level of the bundled Azure SDK logger.
AZURE_PASSWORD	Undocumented	Azure SDK	Gives the password for the Azure username and password credential.
AZURE_POD_IDENTITY_AUTHORITY_HOST	Undocumented	Azure SDK	Sets the Azure pod identity authority host for managed identity login in the bundled MSAL library.
AZURE_REGIONAL_AUTHORITY_NAME	Undocumented	Azure SDK	Sets the regional authority name for MSAL token requests.
AZURE_TENANT_ID	Documented	Azure SDK	Gives the Azure tenant ID for the bundled Azure identity credentials.
AZURE_TOKEN_CREDENTIALS	Undocumented	Azure SDK	Picks which Azure credential chain DefaultAzureCredential uses.
AZURE_USERNAME	Undocumented	Azure SDK	Gives the username for the Azure username and password credential.
BUF_BIGINT_DISABLE	Undocumented	protobuf	Turns off native BigInt use in the bundled protobuf library, so it uses its fallback int64 code.
BUN_DISABLE_DYNAMIC_CHUNK_SIZE	Undocumented	Bun runtime	Turns off dynamic chunk size tuning for native readable streams in the Bun runtime.
BUN_FEATURE_FLAG_VERBOSE_WARNINGS	Undocumented	Bun runtime	Shows the Bun runtime warning for unsupported async_hooks use.
BUN_INSPECT_NOTIFY	Undocumented	Bun runtime	Tells the Bun inspector where to report that it listens.
BUN_PORT	Undocumented	Bun runtime	Gives a fallback port for the Bun dev server when the default port is busy.
CHOKIDAR_INTERVAL	Undocumented	chokidar	Sets the poll interval for the bundled chokidar file watcher when polling is on.
CHOKIDAR_USEPOLLING	Undocumented	chokidar	Forces the bundled chokidar file watcher to use polling or not.
CLOUD_RUN_JOB	Undocumented	Google auth	Marks a Google Cloud Run job.
DATABASE_URL	Documented	Bun SQL	Gives the default connection URL to the embedded Bun SQL client.
DATABASEURL	Undocumented	Bun SQL	Is a second spelling of DATABASE_URL for the embedded Bun SQL client.
DEBUG_AUTH	Undocumented	Google auth	Prints GCP metadata detection errors with console.info.
DETECT_GCP_RETRIES	Undocumented	Google auth	Sets the number of retries for GCP metadata server detection.
FUNCTION_NAME	Undocumented	Google auth	Marks a Google Cloud Functions runtime in the bundled Google auth library.
FUNCTION_TARGET	Undocumented	Google auth	Marks a Google Cloud Functions runtime in the bundled Google auth library.
GAE_MODULE_NAME	Undocumented	Google auth	Marks a Google App Engine runtime in the bundled Google auth library.
GAE_SERVICE	Undocumented	Google auth	Marks a Google App Engine runtime in the bundled Google auth library.
GCE_METADATA_HOST	Undocumented	Google auth	Sets the host of the Compute Engine metadata server for the bundled Google auth library.
GCE_METADATA_IP	Undocumented	Google auth	Sets the address of the Compute Engine metadata server for the bundled Google auth library.
GOOGLE_API_CERTIFICATE_CONFIG	Undocumented	Google auth	Path of the certificate config for mTLS in the bundled Google auth library.
GOOGLE_CLOUD_QUOTA_PROJECT	Undocumented	Google auth	Sets the quota project of the credential in the bundled Google auth library.
GRACEFUL_FS_PLATFORM	Undocumented	graceful-fs	Overrides the platform name that the bundled graceful-fs patches use.
GRPC_DEFAULT_SSL_ROOTS_FILE_PATH	Undocumented	gRPC	Path of a root certificate file that the bundled gRPC library loads as its TLS roots.
GRPC_EXPERIMENTAL_ENABLE_OUTLIER_DETECTION	Undocumented	gRPC	Turns the gRPC outlier detection load balancer on or off.
GRPC_NODE_TRACE	Undocumented	gRPC	Lists the gRPC tracers to turn on.
GRPC_NODE_USE_ALTERNATIVE_RESOLVER	Undocumented	gRPC	Makes the gRPC DNS resolver use the alternative path when it is true.
GRPC_NODE_VERBOSITY	Undocumented	gRPC	Sets the gRPC log level.
GRPC_SSL_CIPHER_SUITES	Undocumented	gRPC	Sets the TLS cipher suites of the bundled gRPC library.
GRPC_TRACE	Undocumented	gRPC	Lists the gRPC tracers to turn on.
GRPC_VERBOSITY	Undocumented	gRPC	Sets the gRPC log level.
LRU_CACHE_IGNORE_AC_WARNING	Undocumented	lru-cache	Set to 1 to hide the lru-cache warning about a missing AbortController.
MARIADB_DATABASE	Undocumented	Bun SQL	Sets the database of the MariaDB connection of the embedded Bun SQL client.
MARIADB_HOST	Undocumented	Bun SQL	Sets the host of the MariaDB connection of the embedded Bun SQL client.
MARIADB_PASSWORD	Undocumented	Bun SQL	Sets the password of the MariaDB connection of the embedded Bun SQL client.
MARIADB_PORT	Undocumented	Bun SQL	Sets the port of the MariaDB connection of the embedded Bun SQL client.
MARIADB_URL	Undocumented	Bun SQL	Gives the default MariaDB connection URL to the embedded Bun SQL client.
MARIADB_USER	Undocumented	Bun SQL	Sets the user of the MariaDB connection of the embedded Bun SQL client.
MARIADBDATABASE	Undocumented	Bun SQL	Is another spelling of MARIADB_DATABASE.
MARIADBHOST	Undocumented	Bun SQL	Is another spelling of MARIADB_HOST.
MARIADBPASSWORD	Undocumented	Bun SQL	Is another spelling of MARIADB_PASSWORD.
MARIADBPORT	Undocumented	Bun SQL	Is another spelling of MARIADB_PORT.
MARIADBURL	Undocumented	Bun SQL	Is another spelling of MARIADB_URL for the embedded Bun SQL client.
MARIADBUSER	Undocumented	Bun SQL	Is another spelling of MARIADB_USER.
MYSQL_DATABASE	Undocumented	Bun SQL	Sets the database of the MySQL connection of the embedded Bun SQL client.
MYSQL_HOST	Undocumented	Bun SQL	Sets the host of the MySQL connection of the embedded Bun SQL client.
MYSQL_PASSWORD	Undocumented	Bun SQL	Sets the password of the MySQL connection of the embedded Bun SQL client.
MYSQL_PORT	Undocumented	Bun SQL	Sets the port of the MySQL connection of the embedded Bun SQL client.
MYSQL_URL	Undocumented	Bun SQL	Gives the default MySQL connection URL to the embedded Bun SQL client.
MYSQL_USER	Undocumented	Bun SQL	Sets the user of the MySQL connection of the embedded Bun SQL client.
MYSQLDATABASE	Undocumented	Bun SQL	Is another spelling of MYSQL_DATABASE.
MYSQLHOST	Undocumented	Bun SQL	Is another spelling of MYSQL_HOST.
MYSQLPASSWORD	Undocumented	Bun SQL	Is another spelling of MYSQL_PASSWORD.
MYSQLPORT	Undocumented	Bun SQL	Is another spelling of MYSQL_PORT.
MYSQLURL	Undocumented	Bun SQL	Is another spelling of MYSQL_URL for the embedded Bun SQL client.
MYSQLUSER	Undocumented	Bun SQL	Is another spelling of MYSQL_USER.
NODE_CHANNEL_FD	Undocumented	Bun runtime	Bun runtime: if set, the process has an IPC channel and send and disconnect are stubbed in workers.
NODE_CLUSTER_SCHED_POLICY	Undocumented	Bun runtime	Bun runtime cluster: rr or none picks the scheduling policy.
NODE_DEBUG	Undocumented	Bun runtime	Bun runtime: enables debuglog sections by name.
NODE_DISABLE_COLORS	Undocumented	Bun runtime	Bun runtime: a non-empty value sets terminal color depth to one color.
NODE_NO_READLINE	Undocumented	Bun runtime	Bun REPL: a number that parses to non-zero turns off terminal mode.
NODE_PORT	Undocumented	Bun runtime	Bun dev server: fallback port after PORT and BUN_PORT when the port is in use.
NODE_REPL_EXTERNAL_MODULE	Undocumented	Bun runtime	Bun REPL: path of a module to load in place of the built-in REPL.
NODE_REPL_HISTORY	Undocumented	Bun runtime	Bun REPL: file path for persistent history.
NODE_REPL_HISTORY_SIZE	Undocumented	Bun runtime	Bun REPL: history size.
NODE_REPL_MODE	Undocumented	Bun runtime	Bun REPL: strict or sloppy mode.
NODE_UNIQUE_ID	Undocumented	Bun runtime	Bun runtime cluster: gives the worker id of a forked worker and is deleted after use.
OSTYPE	Undocumented	which	The bundled which code treats cygwin or msys as a Windows-style path list.
PASSWORD	Documented	Bun SQL	Gives a fallback password to the embedded Bun SQL client.
PG_DATABASE	Undocumented	Bun SQL	Sets the database of the Postgres connection of the embedded Bun SQL client.
PG_HOST	Undocumented	Bun SQL	Sets the host of the Postgres connection of the embedded Bun SQL client.
PG_PASSWORD	Undocumented	Bun SQL	Sets the password of the Postgres connection of the embedded Bun SQL client.
PG_PORT	Undocumented	Bun SQL	Sets the port of the Postgres connection of the embedded Bun SQL client.
PG_SSLMODE	Undocumented	Bun SQL	Sets the TLS mode of the Postgres connection of the embedded Bun SQL client.
PG_URL	Undocumented	Bun SQL	Is a third spelling of POSTGRES_URL for the embedded Bun SQL client.
PG_USER	Undocumented	Bun SQL	Sets the user of the Postgres connection of the embedded Bun SQL client.
PGDATABASE	Undocumented	Bun SQL	Is another spelling of PG_DATABASE.
PGHOST	Undocumented	Bun SQL	Is another spelling of PG_HOST.
PGPASSWORD	Undocumented	Bun SQL	Is another spelling of PG_PASSWORD.
PGPORT	Undocumented	Bun SQL	Is another spelling of PG_PORT.
PGSSLMODE	Undocumented	Bun SQL	Is another spelling of PG_SSLMODE.
PGURL	Undocumented	Bun SQL	Is another spelling of POSTGRES_URL for the embedded Bun SQL client.
PGUSER	Undocumented	Bun SQL	Is another spelling of PG_USER.
POSTGRES_URL	Undocumented	Bun SQL	Gives the default Postgres connection URL to the embedded Bun SQL client.
SQLITE_URL	Undocumented	Bun SQL	Gives the default SQLite connection URL to the embedded Bun SQL client.
SQLITEURL	Undocumented	Bun SQL	Is another spelling of SQLITE_URL for the embedded Bun SQL client.
TEAMCITY_VERSION	Undocumented	color support	TeamCity CI variable.
TLS_DATABASE_URL	Undocumented	Bun SQL	Gives a default URL and turns on TLS for the embedded Bun SQL client.
TLS_MARIADB_DATABASE_URL	Undocumented	Bun SQL	Gives the MariaDB URL and turns on TLS for the embedded Bun SQL client.
TLS_MYSQL_DATABASE_URL	Undocumented	Bun SQL	Gives the MySQL URL and turns on TLS for the embedded Bun SQL client.
TLS_POSTGRES_DATABASE_URL	Undocumented	Bun SQL	Gives the Postgres URL and turns on TLS for the embedded Bun SQL client.
VERBOSE_SSR	Undocumented	Bun runtime	Bun's server-side rendering debug flag.

How It Works

The names were found by scanning strings in the program, so the list can miss names built at run time. Rows describe what the library does with the name, not what Claude Code does.

Related Pages

• Environment Variables: how Claude Code reads variables and which value wins.
• System and Third-Party
• Telemetry and Debug
• Undocumented Items: every item that only the program shows.

Source: the program (variable names found in the 2.1.304 binary) and the Environment Variables page of the official docs.