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_IMAGE_ANNOTATOR_ENDPOINT=...overrides theEndpointOption(which defaults to "vision.googleapis.com") used byMakeImageAnnotatorConnection().
GOOGLE_CLOUD_CPP_PRODUCT_SEARCH_ENDPOINT=...overrides theEndpointOption(which defaults to "vision.googleapis.com") used byMakeProductSearchConnection().
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, with a comprehensive list of prior versions available, ranging from 2.36.0 down to 2.11.0, providing users with access to a wide range of historical documentation.\u003c/p\u003e\n"],["\u003cp\u003eEnvironment variables like \u003ccode\u003eGOOGLE_CLOUD_CPP_IMAGE_ANNOTATOR_ENDPOINT\u003c/code\u003e and \u003ccode\u003eGOOGLE_CLOUD_CPP_PRODUCT_SEARCH_ENDPOINT\u003c/code\u003e allow for overriding default endpoint options, offering flexibility in configuring the library's behavior.\u003c/p\u003e\n"],["\u003cp\u003eThe library's gRPC call tracing can be enabled using \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc\u003c/code\u003e, which logs each gRPC request and response, and it is suggested to set \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG\u003c/code\u003e for console output unless another logging backend is configured.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGOOGLE_CLOUD_CPP_TRACING_OPTIONS\u003c/code\u003e environment variable offers options to customize the behavior of gRPC tracing, such as controlling output formatting and field truncation.\u003c/p\u003e\n"],["\u003cp\u003eLogging functionality within the library can be activated with \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes\u003c/code\u003e, which enables the logging infrastructure to output messages to the console when no other logging backend has been set.\u003c/p\u003e\n"]]],[],null,["Version 2.27.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/vision/latest/vision-env)\n- [2.41.0](/cpp/docs/reference/vision/2.41.0/vision-env)\n- [2.40.0](/cpp/docs/reference/vision/2.40.0/vision-env)\n- [2.39.0](/cpp/docs/reference/vision/2.39.0/vision-env)\n- [2.38.0](/cpp/docs/reference/vision/2.38.0/vision-env)\n- [2.37.0](/cpp/docs/reference/vision/2.37.0/vision-env)\n- [2.36.0](/cpp/docs/reference/vision/2.36.0/vision-env)\n- [2.35.0](/cpp/docs/reference/vision/2.35.0/vision-env)\n- [2.34.0](/cpp/docs/reference/vision/2.34.0/vision-env)\n- [2.33.0](/cpp/docs/reference/vision/2.33.0/vision-env)\n- [2.32.0](/cpp/docs/reference/vision/2.32.0/vision-env)\n- [2.31.0](/cpp/docs/reference/vision/2.31.0/vision-env)\n- [2.30.0](/cpp/docs/reference/vision/2.30.0/vision-env)\n- [2.29.0](/cpp/docs/reference/vision/2.29.0/vision-env)\n- [2.28.0](/cpp/docs/reference/vision/2.28.0/vision-env)\n- [2.27.0](/cpp/docs/reference/vision/2.27.0/vision-env)\n- [2.26.0](/cpp/docs/reference/vision/2.26.0/vision-env)\n- [2.25.1](/cpp/docs/reference/vision/2.25.1/vision-env)\n- [2.24.0](/cpp/docs/reference/vision/2.24.0/vision-env)\n- [2.23.0](/cpp/docs/reference/vision/2.23.0/vision-env)\n- [2.22.1](/cpp/docs/reference/vision/2.22.1/vision-env)\n- [2.21.0](/cpp/docs/reference/vision/2.21.0/vision-env)\n- [2.20.0](/cpp/docs/reference/vision/2.20.0/vision-env)\n- [2.19.0](/cpp/docs/reference/vision/2.19.0/vision-env)\n- [2.18.0](/cpp/docs/reference/vision/2.18.0/vision-env)\n- [2.17.0](/cpp/docs/reference/vision/2.17.0/vision-env)\n- [2.16.0](/cpp/docs/reference/vision/2.16.0/vision-env)\n- [2.15.1](/cpp/docs/reference/vision/2.15.1/vision-env)\n- [2.14.0](/cpp/docs/reference/vision/2.14.0/vision-env)\n- [2.13.0](/cpp/docs/reference/vision/2.13.0/vision-env)\n- [2.12.0](/cpp/docs/reference/vision/2.12.0/vision-env)\n- [2.11.0](/cpp/docs/reference/vision/2.11.0/vision-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_IMAGE_ANNOTATOR_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"vision.googleapis.com\") used by `MakeImageAnnotatorConnection()`.\n- `GOOGLE_CLOUD_CPP_PRODUCT_SEARCH_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"vision.googleapis.com\") used by `MakeProductSearchConnection()`.\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."]]
