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::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"]],[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14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 provides a list of available versions for a C++ vision library, ranging from version 2.11.0 up to the latest release candidate, 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe library's behavior can be configured using environment variables, offering a convenient way to troubleshoot issues or modify the library without changing the code.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eGOOGLE_CLOUD_CPP_IMAGE_ANNOTATOR_ENDPOINT\u003c/code\u003e and \u003ccode\u003eGOOGLE_CLOUD_CPP_PRODUCT_SEARCH_ENDPOINT\u003c/code\u003e allow users to override the default endpoints for specific connection types.\u003c/p\u003e\n"],["\u003cp\u003eTracing for gRPC calls can be enabled using \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc\u003c/code\u003e, which will print each request and response for debugging and \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes\u003c/code\u003e can be set to produce output on the program's console.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eGOOGLE_CLOUD_PROJECT=...\u003c/code\u003e is a GCP project environment variable that is used in examples and integration tests, but doesn't affect the library itself.\u003c/p\u003e\n"]]],[],null,["Version 2.21.0keyboard_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::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."]]
