A number of environment variables can be used to configure the behavior of the library. There are also functions to configure this behavior in code. The environment variables are convenient when troubleshooting problems.
Endpoint Overrides
GOOGLE_CLOUD_CPP_IAM_CREDENTIALS_ENDPOINT=... overrides the EndpointOption (which defaults to "iamcredentials.googleapis.com") used by MakeIAMCredentialsConnection().
GOOGLE_CLOUD_CPP_IAM_ENDPOINT=... overrides the EndpointOption (which defaults to "iam.googleapis.com") used by MakeIAMConnection().
GOOGLE_CLOUD_CPP_IAM_POLICY_ENDPOINT=... overrides the EndpointOption (which defaults to "iam-meta-api.googleapis.com") used by MakeIAMPolicyConnection().
GOOGLE_CLOUD_CPP_POLICIES_ENDPOINT=... overrides the EndpointOption (which defaults to "iam.googleapis.com") used by MakePoliciesConnection().
GOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc: turns on tracing for most gRPC calls. The library injects an additional Stub decorator that prints each gRPC request and response. Unless you have configured your own logging backend, you should also set GOOGLE_CLOUD_CPP_ENABLE_CLOG to produce any output on the program's console.
See Also
google::cloud::LoggingComponentsOptionGOOGLE_CLOUD_CPP_TRACING_OPTIONS=...: modifies the behavior of gRPC tracing, including whether messages will be output on multiple lines, or whether string/bytes fields will be truncated.
See Also
google::cloud::GrpcTracingOptionsOptionGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes: turns on logging in the library, basically the library always "logs" but the logging infrastructure has no backend to actually print anything until the application sets a backend or they set this environment variable.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-09 UTC."],[[["This page provides documentation for various versions of the C++ IAM library, ranging from version 2.11.0 up to the latest release candidate 2.37.0-rc."],["The behavior of the C++ IAM library can be configured using several environment variables, useful for troubleshooting and adjusting library settings."],["Endpoint overrides are available for different services via environment variables like `GOOGLE_CLOUD_CPP_IAM_CREDENTIALS_ENDPOINT`, allowing customization of the service endpoints."],["Logging and tracing can be enabled and configured with variables such as `GOOGLE_CLOUD_CPP_ENABLE_TRACING` and `GOOGLE_CLOUD_CPP_TRACING_OPTIONS` to help with debugging."],["The `GOOGLE_CLOUD_PROJECT` variable is documented for use within examples and tests, but is noted to have no effect on library configuration."]]],[]]
