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_TEXT_TO_SPEECH_ENDPOINT=...overrides theEndpointOption(which defaults to "texttospeech.googleapis.com") used byMakeTextToSpeechConnection().
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::TracingComponentsOptionGOOGLE_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 document outlines various versions of the Text-to-Speech C++ library, with version 2.37.0-rc as the latest release candidate and a history of versions going back to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eEnvironment variables can be utilized to modify the library's behavior, such as setting endpoint overrides with \u003ccode\u003eGOOGLE_CLOUD_CPP_TEXT_TO_SPEECH_ENDPOINT\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe document discusses enabling gRPC tracing via \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING\u003c/code\u003e and configuring tracing options with \u003ccode\u003eGOOGLE_CLOUD_CPP_TRACING_OPTIONS\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eLogging within the library can be activated by setting \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG\u003c/code\u003e to "yes", which makes the logging output to the programs console, though the logging infrastructure is always active.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eGOOGLE_CLOUD_PROJECT\u003c/code\u003e is an environment variable used for setting the default GCP project in examples and tests, but it does not affect the library's behavior.\u003c/p\u003e\n"]]],[],null,["Version 2.14.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/texttospeech/latest/texttospeech-env)\n- [2.41.0](/cpp/docs/reference/texttospeech/2.41.0/texttospeech-env)\n- [2.40.0](/cpp/docs/reference/texttospeech/2.40.0/texttospeech-env)\n- [2.39.0](/cpp/docs/reference/texttospeech/2.39.0/texttospeech-env)\n- [2.38.0](/cpp/docs/reference/texttospeech/2.38.0/texttospeech-env)\n- [2.37.0](/cpp/docs/reference/texttospeech/2.37.0/texttospeech-env)\n- [2.36.0](/cpp/docs/reference/texttospeech/2.36.0/texttospeech-env)\n- [2.35.0](/cpp/docs/reference/texttospeech/2.35.0/texttospeech-env)\n- [2.34.0](/cpp/docs/reference/texttospeech/2.34.0/texttospeech-env)\n- [2.33.0](/cpp/docs/reference/texttospeech/2.33.0/texttospeech-env)\n- [2.32.0](/cpp/docs/reference/texttospeech/2.32.0/texttospeech-env)\n- [2.31.0](/cpp/docs/reference/texttospeech/2.31.0/texttospeech-env)\n- [2.30.0](/cpp/docs/reference/texttospeech/2.30.0/texttospeech-env)\n- [2.29.0](/cpp/docs/reference/texttospeech/2.29.0/texttospeech-env)\n- [2.28.0](/cpp/docs/reference/texttospeech/2.28.0/texttospeech-env)\n- [2.27.0](/cpp/docs/reference/texttospeech/2.27.0/texttospeech-env)\n- [2.26.0](/cpp/docs/reference/texttospeech/2.26.0/texttospeech-env)\n- [2.25.1](/cpp/docs/reference/texttospeech/2.25.1/texttospeech-env)\n- [2.24.0](/cpp/docs/reference/texttospeech/2.24.0/texttospeech-env)\n- [2.23.0](/cpp/docs/reference/texttospeech/2.23.0/texttospeech-env)\n- [2.22.1](/cpp/docs/reference/texttospeech/2.22.1/texttospeech-env)\n- [2.21.0](/cpp/docs/reference/texttospeech/2.21.0/texttospeech-env)\n- [2.20.0](/cpp/docs/reference/texttospeech/2.20.0/texttospeech-env)\n- [2.19.0](/cpp/docs/reference/texttospeech/2.19.0/texttospeech-env)\n- [2.18.0](/cpp/docs/reference/texttospeech/2.18.0/texttospeech-env)\n- [2.17.0](/cpp/docs/reference/texttospeech/2.17.0/texttospeech-env)\n- [2.16.0](/cpp/docs/reference/texttospeech/2.16.0/texttospeech-env)\n- [2.15.1](/cpp/docs/reference/texttospeech/2.15.1/texttospeech-env)\n- [2.14.0](/cpp/docs/reference/texttospeech/2.14.0/texttospeech-env)\n- [2.13.0](/cpp/docs/reference/texttospeech/2.13.0/texttospeech-env)\n- [2.12.0](/cpp/docs/reference/texttospeech/2.12.0/texttospeech-env)\n- [2.11.0](/cpp/docs/reference/texttospeech/2.11.0/texttospeech-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_TEXT_TO_SPEECH_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"texttospeech.googleapis.com\") used by `MakeTextToSpeechConnection()`.\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::TracingComponentsOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1TracingComponentsOption.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."]]
