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 theEndpointOption(which defaults to "iamcredentials.googleapis.com") used byMakeIAMCredentialsConnection().
GOOGLE_CLOUD_CPP_IAM_ENDPOINT=...overrides theEndpointOption(which defaults to "iam.googleapis.com") used byMakeIAMConnection().
GOOGLE_CLOUD_CPP_IAM_POLICY_ENDPOINT=...overrides theEndpointOption(which defaults to "iam-meta-api.googleapis.com") used byMakeIAMPolicyConnection().
GOOGLE_CLOUD_CPP_POLICIES_ENDPOINT=...overrides theEndpointOption(which defaults to "iam.googleapis.com") used byMakePoliciesConnection().
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 setGOOGLE_CLOUD_CPP_ENABLE_CLOGto 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"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThis 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.\u003c/p\u003e\n"],["\u003cp\u003eEnvironment variables are detailed for configuring the library's behavior, such as overriding endpoints and enabling logging or tracing.\u003c/p\u003e\n"],["\u003cp\u003eSeveral endpoint override variables exist, including \u003ccode\u003eGOOGLE_CLOUD_CPP_IAM_CREDENTIALS_ENDPOINT\u003c/code\u003e, \u003ccode\u003eGOOGLE_CLOUD_CPP_IAM_ENDPOINT\u003c/code\u003e, \u003ccode\u003eGOOGLE_CLOUD_CPP_IAM_POLICY_ENDPOINT\u003c/code\u003e, and \u003ccode\u003eGOOGLE_CLOUD_CPP_POLICIES_ENDPOINT\u003c/code\u003e, that can be set to change the default endpoint for various connections.\u003c/p\u003e\n"],["\u003cp\u003eTracing can be enabled using \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc\u003c/code\u003e, and further modified with the \u003ccode\u003eGOOGLE_CLOUD_CPP_TRACING_OPTIONS\u003c/code\u003e variable, with \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes\u003c/code\u003e enabling output to the console.\u003c/p\u003e\n"]]],[],null,["Version 2.29.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/iam/latest/iam-env)\n- [2.41.0](/cpp/docs/reference/iam/2.41.0/iam-env)\n- [2.40.0](/cpp/docs/reference/iam/2.40.0/iam-env)\n- [2.39.0](/cpp/docs/reference/iam/2.39.0/iam-env)\n- [2.38.0](/cpp/docs/reference/iam/2.38.0/iam-env)\n- [2.37.0](/cpp/docs/reference/iam/2.37.0/iam-env)\n- [2.36.0](/cpp/docs/reference/iam/2.36.0/iam-env)\n- [2.35.0](/cpp/docs/reference/iam/2.35.0/iam-env)\n- [2.34.0](/cpp/docs/reference/iam/2.34.0/iam-env)\n- [2.33.0](/cpp/docs/reference/iam/2.33.0/iam-env)\n- [2.32.0](/cpp/docs/reference/iam/2.32.0/iam-env)\n- [2.31.0](/cpp/docs/reference/iam/2.31.0/iam-env)\n- [2.30.0](/cpp/docs/reference/iam/2.30.0/iam-env)\n- [2.29.0](/cpp/docs/reference/iam/2.29.0/iam-env)\n- [2.28.0](/cpp/docs/reference/iam/2.28.0/iam-env)\n- [2.27.0](/cpp/docs/reference/iam/2.27.0/iam-env)\n- [2.26.0](/cpp/docs/reference/iam/2.26.0/iam-env)\n- [2.25.1](/cpp/docs/reference/iam/2.25.1/iam-env)\n- [2.24.0](/cpp/docs/reference/iam/2.24.0/iam-env)\n- [2.23.0](/cpp/docs/reference/iam/2.23.0/iam-env)\n- [2.22.1](/cpp/docs/reference/iam/2.22.1/iam-env)\n- [2.21.0](/cpp/docs/reference/iam/2.21.0/iam-env)\n- [2.20.0](/cpp/docs/reference/iam/2.20.0/iam-env)\n- [2.19.0](/cpp/docs/reference/iam/2.19.0/iam-env)\n- [2.18.0](/cpp/docs/reference/iam/2.18.0/iam-env)\n- [2.17.0](/cpp/docs/reference/iam/2.17.0/iam-env)\n- [2.16.0](/cpp/docs/reference/iam/2.16.0/iam-env)\n- [2.15.1](/cpp/docs/reference/iam/2.15.1/iam-env)\n- [2.14.0](/cpp/docs/reference/iam/2.14.0/iam-env)\n- [2.13.0](/cpp/docs/reference/iam/2.13.0/iam-env)\n- [2.12.0](/cpp/docs/reference/iam/2.12.0/iam-env)\n- [2.11.0](/cpp/docs/reference/iam/2.11.0/iam-env) \n\nEnvironment Variables\n=====================\n\nA 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.\n\nEndpoint Overrides\n------------------\n\n- `GOOGLE_CLOUD_CPP_IAM_CREDENTIALS_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"iamcredentials.googleapis.com\") used by `MakeIAMCredentialsConnection()`.\n- `GOOGLE_CLOUD_CPP_IAM_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"iam.googleapis.com\") used by `MakeIAMConnection()`.\n- `GOOGLE_CLOUD_CPP_IAM_POLICY_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"iam-meta-api.googleapis.com\") used by `MakeIAMPolicyConnection()`.\n- `GOOGLE_CLOUD_CPP_POLICIES_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"iam.googleapis.com\") used by `MakePoliciesConnection()`.\n\n###### See Also\n\n[`google::cloud::EndpointOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1EndpointOption.html)\n\nLogging\n-------\n\n`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.\n\n###### See Also\n\n[`google::cloud::LoggingComponentsOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1LoggingComponentsOption.html)`GOOGLE_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.\n\n###### See Also\n\n[`google::cloud::GrpcTracingOptionsOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1GrpcTracingOptionsOption.html)`GOOGLE_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.\n\n###### See Also\n\n[`google::cloud::LogBackend`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1LogBackend.html)\n\n###### See Also\n\n[`google::cloud::LogSink`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1LogSink.html)\n\nSetting the Default Project\n---------------------------\n\n`GOOGLE_CLOUD_PROJECT=...`: is used in examples and integration tests to configure the GCP project. This has no effect in the library."]]
