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_APP_HUB_ENDPOINT=...overrides theEndpointOption(which defaults to "apphub.googleapis.com") used byMakeAppHubConnection().
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\u003eThe latest release candidate version is 2.37.0-rc, and the page provides documentation links for versions ranging from 2.23.0 to 2.36.0.\u003c/p\u003e\n"],["\u003cp\u003eEnvironment variables can be used to configure the library's behavior, including options for endpoint overrides, such as setting the \u003ccode\u003eGOOGLE_CLOUD_CPP_APP_HUB_ENDPOINT\u003c/code\u003e to define a custom endpoint.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING\u003c/code\u003e variable enables tracing for gRPC calls, and along with it \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG\u003c/code\u003e can also be used to provide an output to the console.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eGOOGLE_CLOUD_PROJECT\u003c/code\u003e environment variable sets the default GCP project for examples and integration tests.\u003c/p\u003e\n"]]],[],null,["Version 2.35.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/apphub/latest/apphub-env)\n- [2.41.0](/cpp/docs/reference/apphub/2.41.0/apphub-env)\n- [2.40.0](/cpp/docs/reference/apphub/2.40.0/apphub-env)\n- [2.39.0](/cpp/docs/reference/apphub/2.39.0/apphub-env)\n- [2.38.0](/cpp/docs/reference/apphub/2.38.0/apphub-env)\n- [2.37.0](/cpp/docs/reference/apphub/2.37.0/apphub-env)\n- [2.36.0](/cpp/docs/reference/apphub/2.36.0/apphub-env)\n- [2.35.0](/cpp/docs/reference/apphub/2.35.0/apphub-env)\n- [2.34.0](/cpp/docs/reference/apphub/2.34.0/apphub-env)\n- [2.33.0](/cpp/docs/reference/apphub/2.33.0/apphub-env)\n- [2.32.0](/cpp/docs/reference/apphub/2.32.0/apphub-env)\n- [2.31.0](/cpp/docs/reference/apphub/2.31.0/apphub-env)\n- [2.30.0](/cpp/docs/reference/apphub/2.30.0/apphub-env)\n- [2.29.0](/cpp/docs/reference/apphub/2.29.0/apphub-env)\n- [2.28.0](/cpp/docs/reference/apphub/2.28.0/apphub-env)\n- [2.27.0](/cpp/docs/reference/apphub/2.27.0/apphub-env)\n- [2.26.0](/cpp/docs/reference/apphub/2.26.0/apphub-env)\n- [2.25.1](/cpp/docs/reference/apphub/2.25.1/apphub-env)\n- [2.24.0](/cpp/docs/reference/apphub/2.24.0/apphub-env)\n- [2.23.0](/cpp/docs/reference/apphub/2.23.0/apphub-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_APP_HUB_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"apphub.googleapis.com\") used by `MakeAppHubConnection()`.\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."]]
