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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-07-02 UTC."],[[["This page provides documentation for various versions of the C++ IAM library, ranging from version 2.11.0 up to the release candidate 2.37.0-rc."],["Environment variables are detailed for configuring the library's behavior, such as overriding endpoints and enabling logging or tracing."],["Several endpoint override variables exist, including `GOOGLE_CLOUD_CPP_IAM_CREDENTIALS_ENDPOINT`, `GOOGLE_CLOUD_CPP_IAM_ENDPOINT`, `GOOGLE_CLOUD_CPP_IAM_POLICY_ENDPOINT`, and `GOOGLE_CLOUD_CPP_POLICIES_ENDPOINT`, that can be set to change the default endpoint for various connections."],["Tracing can be enabled using `GOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc`, and further modified with the `GOOGLE_CLOUD_CPP_TRACING_OPTIONS` variable, with `GOOGLE_CLOUD_CPP_ENABLE_CLOG=yes` enabling output to the console."]]],[]]
