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_APPLICATIONS_ENDPOINT=...overrides theEndpointOption(which defaults to "appengine.googleapis.com") used byMakeApplicationsConnection().
GOOGLE_CLOUD_CPP_AUTHORIZED_CERTIFICATES_ENDPOINT=...overrides theEndpointOption(which defaults to "appengine.googleapis.com") used byMakeAuthorizedCertificatesConnection().
GOOGLE_CLOUD_CPP_AUTHORIZED_DOMAINS_ENDPOINT=...overrides theEndpointOption(which defaults to "appengine.googleapis.com") used byMakeAuthorizedDomainsConnection().
GOOGLE_CLOUD_CPP_DOMAIN_MAPPINGS_ENDPOINT=...overrides theEndpointOption(which defaults to "appengine.googleapis.com") used byMakeDomainMappingsConnection().
GOOGLE_CLOUD_CPP_FIREWALL_ENDPOINT=...overrides theEndpointOption(which defaults to "appengine.googleapis.com") used byMakeFirewallConnection().
GOOGLE_CLOUD_CPP_INSTANCES_ENDPOINT=...overrides theEndpointOption(which defaults to "appengine.googleapis.com") used byMakeInstancesConnection().
GOOGLE_CLOUD_CPP_SERVICES_ENDPOINT=...overrides theEndpointOption(which defaults to "appengine.googleapis.com") used byMakeServicesConnection().
GOOGLE_CLOUD_CPP_VERSIONS_ENDPOINT=...overrides theEndpointOption(which defaults to "appengine.googleapis.com") used byMakeVersionsConnection().
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 the most recent stable release being 2.36.0, and the page contains a list of versions dating back to 2.11.0.\u003c/p\u003e\n"],["\u003cp\u003eEnvironment variables can be utilized to override default endpoints for various services, like Applications, AuthorizedCertificates, and more, all defaulting to "appengine.googleapis.com".\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING\u003c/code\u003e activates gRPC call tracing, and when paired with \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG\u003c/code\u003e, directs output to the console.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGOOGLE_CLOUD_PROJECT\u003c/code\u003e environment variable is used in the library's examples and tests to set the GCP project but does not have any impact on the behavior of the library itself.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG\u003c/code\u003e activates the library's logging, allowing messages to be printed to the program's console when paired with a logging backend.\u003c/p\u003e\n"]]],[],null,["Version 2.28.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/appengine/latest/appengine-env)\n- [2.41.0](/cpp/docs/reference/appengine/2.41.0/appengine-env)\n- [2.40.0](/cpp/docs/reference/appengine/2.40.0/appengine-env)\n- [2.39.0](/cpp/docs/reference/appengine/2.39.0/appengine-env)\n- [2.38.0](/cpp/docs/reference/appengine/2.38.0/appengine-env)\n- [2.37.0](/cpp/docs/reference/appengine/2.37.0/appengine-env)\n- [2.36.0](/cpp/docs/reference/appengine/2.36.0/appengine-env)\n- [2.35.0](/cpp/docs/reference/appengine/2.35.0/appengine-env)\n- [2.34.0](/cpp/docs/reference/appengine/2.34.0/appengine-env)\n- [2.33.0](/cpp/docs/reference/appengine/2.33.0/appengine-env)\n- [2.32.0](/cpp/docs/reference/appengine/2.32.0/appengine-env)\n- [2.31.0](/cpp/docs/reference/appengine/2.31.0/appengine-env)\n- [2.30.0](/cpp/docs/reference/appengine/2.30.0/appengine-env)\n- [2.29.0](/cpp/docs/reference/appengine/2.29.0/appengine-env)\n- [2.28.0](/cpp/docs/reference/appengine/2.28.0/appengine-env)\n- [2.27.0](/cpp/docs/reference/appengine/2.27.0/appengine-env)\n- [2.26.0](/cpp/docs/reference/appengine/2.26.0/appengine-env)\n- [2.25.1](/cpp/docs/reference/appengine/2.25.1/appengine-env)\n- [2.24.0](/cpp/docs/reference/appengine/2.24.0/appengine-env)\n- [2.23.0](/cpp/docs/reference/appengine/2.23.0/appengine-env)\n- [2.22.1](/cpp/docs/reference/appengine/2.22.1/appengine-env)\n- [2.21.0](/cpp/docs/reference/appengine/2.21.0/appengine-env)\n- [2.20.0](/cpp/docs/reference/appengine/2.20.0/appengine-env)\n- [2.19.0](/cpp/docs/reference/appengine/2.19.0/appengine-env)\n- [2.18.0](/cpp/docs/reference/appengine/2.18.0/appengine-env)\n- [2.17.0](/cpp/docs/reference/appengine/2.17.0/appengine-env)\n- [2.16.0](/cpp/docs/reference/appengine/2.16.0/appengine-env)\n- [2.15.1](/cpp/docs/reference/appengine/2.15.1/appengine-env)\n- [2.14.0](/cpp/docs/reference/appengine/2.14.0/appengine-env)\n- [2.13.0](/cpp/docs/reference/appengine/2.13.0/appengine-env)\n- [2.12.0](/cpp/docs/reference/appengine/2.12.0/appengine-env)\n- [2.11.0](/cpp/docs/reference/appengine/2.11.0/appengine-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_APPLICATIONS_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"appengine.googleapis.com\") used by `MakeApplicationsConnection()`.\n- `GOOGLE_CLOUD_CPP_AUTHORIZED_CERTIFICATES_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"appengine.googleapis.com\") used by `MakeAuthorizedCertificatesConnection()`.\n- `GOOGLE_CLOUD_CPP_AUTHORIZED_DOMAINS_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"appengine.googleapis.com\") used by `MakeAuthorizedDomainsConnection()`.\n- `GOOGLE_CLOUD_CPP_DOMAIN_MAPPINGS_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"appengine.googleapis.com\") used by `MakeDomainMappingsConnection()`.\n- `GOOGLE_CLOUD_CPP_FIREWALL_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"appengine.googleapis.com\") used by `MakeFirewallConnection()`.\n- `GOOGLE_CLOUD_CPP_INSTANCES_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"appengine.googleapis.com\") used by `MakeInstancesConnection()`.\n- `GOOGLE_CLOUD_CPP_SERVICES_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"appengine.googleapis.com\") used by `MakeServicesConnection()`.\n- `GOOGLE_CLOUD_CPP_VERSIONS_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"appengine.googleapis.com\") used by `MakeVersionsConnection()`.\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."]]
