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_FLEET_ROUTING_ENDPOINT=...overrides theEndpointOption(which defaults to "cloudoptimization.googleapis.com") used byMakeFleetRoutingConnection().
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 provides a comprehensive list of C++ optimization library versions, ranging from the latest release candidate, 2.37.0-rc, down to version 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eEnvironment variables can be leveraged to adjust the library's operation, and corresponding in-code functions are available for similar configurations, which is useful for troubleshooting.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGOOGLE_CLOUD_CPP_FLEET_ROUTING_ENDPOINT\u003c/code\u003e variable can override the default endpoint used by \u003ccode\u003eMakeFleetRoutingConnection()\u003c/code\u003e, allowing for custom endpoint settings.\u003c/p\u003e\n"],["\u003cp\u003eTracing for gRPC calls can be enabled using the \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc\u003c/code\u003e variable, which outputs request and response data, and in conjunction with \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG\u003c/code\u003e it outputs to the console.\u003c/p\u003e\n"],["\u003cp\u003eThe logging infrastructure, although always present, requires the \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes\u003c/code\u003e environment variable to actually print any information.\u003c/p\u003e\n"]]],[],null,["Version 2.12.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/optimization/latest/optimization-env)\n- [2.41.0](/cpp/docs/reference/optimization/2.41.0/optimization-env)\n- [2.40.0](/cpp/docs/reference/optimization/2.40.0/optimization-env)\n- [2.39.0](/cpp/docs/reference/optimization/2.39.0/optimization-env)\n- [2.38.0](/cpp/docs/reference/optimization/2.38.0/optimization-env)\n- [2.37.0](/cpp/docs/reference/optimization/2.37.0/optimization-env)\n- [2.36.0](/cpp/docs/reference/optimization/2.36.0/optimization-env)\n- [2.35.0](/cpp/docs/reference/optimization/2.35.0/optimization-env)\n- [2.34.0](/cpp/docs/reference/optimization/2.34.0/optimization-env)\n- [2.33.0](/cpp/docs/reference/optimization/2.33.0/optimization-env)\n- [2.32.0](/cpp/docs/reference/optimization/2.32.0/optimization-env)\n- [2.31.0](/cpp/docs/reference/optimization/2.31.0/optimization-env)\n- [2.30.0](/cpp/docs/reference/optimization/2.30.0/optimization-env)\n- [2.29.0](/cpp/docs/reference/optimization/2.29.0/optimization-env)\n- [2.28.0](/cpp/docs/reference/optimization/2.28.0/optimization-env)\n- [2.27.0](/cpp/docs/reference/optimization/2.27.0/optimization-env)\n- [2.26.0](/cpp/docs/reference/optimization/2.26.0/optimization-env)\n- [2.25.1](/cpp/docs/reference/optimization/2.25.1/optimization-env)\n- [2.24.0](/cpp/docs/reference/optimization/2.24.0/optimization-env)\n- [2.23.0](/cpp/docs/reference/optimization/2.23.0/optimization-env)\n- [2.22.1](/cpp/docs/reference/optimization/2.22.1/optimization-env)\n- [2.21.0](/cpp/docs/reference/optimization/2.21.0/optimization-env)\n- [2.20.0](/cpp/docs/reference/optimization/2.20.0/optimization-env)\n- [2.19.0](/cpp/docs/reference/optimization/2.19.0/optimization-env)\n- [2.18.0](/cpp/docs/reference/optimization/2.18.0/optimization-env)\n- [2.17.0](/cpp/docs/reference/optimization/2.17.0/optimization-env)\n- [2.16.0](/cpp/docs/reference/optimization/2.16.0/optimization-env)\n- [2.15.1](/cpp/docs/reference/optimization/2.15.1/optimization-env)\n- [2.14.0](/cpp/docs/reference/optimization/2.14.0/optimization-env)\n- [2.13.0](/cpp/docs/reference/optimization/2.13.0/optimization-env)\n- [2.12.0](/cpp/docs/reference/optimization/2.12.0/optimization-env)\n- [2.11.0](/cpp/docs/reference/optimization/2.11.0/optimization-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_FLEET_ROUTING_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"cloudoptimization.googleapis.com\") used by `MakeFleetRoutingConnection()`.\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."]]
