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 the EndpointOption (which defaults to "vision.googleapis.com") used by MakeImageAnnotatorConnection().
GOOGLE_CLOUD_CPP_PRODUCT_SEARCH_ENDPOINT=... overrides the EndpointOption (which defaults to "vision.googleapis.com") used by MakeProductSearchConnection().
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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis document outlines environment variables and configuration options for the C++ Vision library, covering versions from 2.11.0 up to 2.36.0, with a link to the release candidate of version 2.37.0.\u003c/p\u003e\n"],["\u003cp\u003eYou can override default endpoints for image annotation and product search functionalities by using the \u003ccode\u003eGOOGLE_CLOUD_CPP_IMAGE_ANNOTATOR_ENDPOINT\u003c/code\u003e and \u003ccode\u003eGOOGLE_CLOUD_CPP_PRODUCT_SEARCH_ENDPOINT\u003c/code\u003e environment variables respectively.\u003c/p\u003e\n"],["\u003cp\u003eThe environment variable \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc\u003c/code\u003e enables tracing for gRPC calls, and when combined with \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG\u003c/code\u003e, it produces the tracing output to the program's console.\u003c/p\u003e\n"],["\u003cp\u003eUsing the \u003ccode\u003eGOOGLE_CLOUD_CPP_TRACING_OPTIONS\u003c/code\u003e environment variable allows modifications to gRPC tracing behaviors, such as formatting and field truncation, and \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes\u003c/code\u003e activates logging within the library.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGOOGLE_CLOUD_PROJECT\u003c/code\u003e environment variable is utilized in examples and integration tests for project configuration, but it does not directly impact the library's functionality.\u003c/p\u003e\n"]]],[],null,["Version 2.36.0keyboard_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."]]
