Policy Simulator is a collection of endpoints for creating, running, and viewing aReplay. AReplayis a type of simulation that lets you see how your members' access to resources might change if you changed your IAM policy.
During aReplay, Policy Simulator re-evaluates, or replays, past access attempts under both the current policy and your proposed policy, and compares those results to determine how your members' access might change under the proposed policy.
While this library isGA, please note that the Google Cloud C++ client libraries donotfollowSemantic Versioning.
Quickstart
The following shows the code that you'll run in thegoogle/cloud/policysimulator/quickstart/directory, which should give you a taste of the Policy Simulator API C++ client library API.
[[["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 page provides documentation for the C++ client library for the Policy Simulator API, which allows users to simulate how changes to IAM policies might impact resource access.\u003c/p\u003e\n"],["\u003cp\u003eThe latest release candidate version is 2.37.0-rc, and the page lists versions down to 2.15.1, with each link leading to the specific documentation for that version.\u003c/p\u003e\n"],["\u003cp\u003eThe library's main class is \u003ccode\u003epolicysimulator_v1::SimulatorClient\u003c/code\u003e, which exposes all RPCs as member functions and offers helpers for configuration and testing.\u003c/p\u003e\n"],["\u003cp\u003eThe Policy Simulator API allows creation and examination of replays, where past access attempts are re-evaluated under both current and proposed policies.\u003c/p\u003e\n"],["\u003cp\u003eWhile this library is considered generally available (GA), it is important to be aware that the Google Cloud C++ client libraries do not adhere to Semantic Versioning.\u003c/p\u003e\n"]]],[],null,["Version 2.24.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/policysimulator/latest)\n- [2.41.0](/cpp/docs/reference/policysimulator/2.41.0)\n- [2.40.0](/cpp/docs/reference/policysimulator/2.40.0)\n- [2.39.0](/cpp/docs/reference/policysimulator/2.39.0)\n- [2.38.0](/cpp/docs/reference/policysimulator/2.38.0)\n- [2.37.0](/cpp/docs/reference/policysimulator/2.37.0)\n- [2.36.0](/cpp/docs/reference/policysimulator/2.36.0)\n- [2.35.0](/cpp/docs/reference/policysimulator/2.35.0)\n- [2.34.0](/cpp/docs/reference/policysimulator/2.34.0)\n- [2.33.0](/cpp/docs/reference/policysimulator/2.33.0)\n- [2.32.0](/cpp/docs/reference/policysimulator/2.32.0)\n- [2.31.0](/cpp/docs/reference/policysimulator/2.31.0)\n- [2.30.0](/cpp/docs/reference/policysimulator/2.30.0)\n- [2.29.0](/cpp/docs/reference/policysimulator/2.29.0)\n- [2.28.0](/cpp/docs/reference/policysimulator/2.28.0)\n- [2.27.0](/cpp/docs/reference/policysimulator/2.27.0)\n- [2.26.0](/cpp/docs/reference/policysimulator/2.26.0)\n- [2.25.1](/cpp/docs/reference/policysimulator/2.25.1)\n- [2.24.0](/cpp/docs/reference/policysimulator/2.24.0)\n- [2.23.0](/cpp/docs/reference/policysimulator/2.23.0)\n- [2.22.1](/cpp/docs/reference/policysimulator/2.22.1)\n- [2.21.0](/cpp/docs/reference/policysimulator/2.21.0)\n- [2.20.0](/cpp/docs/reference/policysimulator/2.20.0)\n- [2.19.0](/cpp/docs/reference/policysimulator/2.19.0)\n- [2.18.0](/cpp/docs/reference/policysimulator/2.18.0)\n- [2.17.0](/cpp/docs/reference/policysimulator/2.17.0)\n- [2.16.0](/cpp/docs/reference/policysimulator/2.16.0)\n- [2.15.1](/cpp/docs/reference/policysimulator/2.15.1) \n\nPolicy Simulator API C++ Client Library\n=======================================\n\nAn idiomatic C++ client library for the [Policy Simulator API](https://cloud.google.com/policy-intelligence/docs/iam-simulator-overview)\n\nPolicy Simulator is a collection of endpoints for creating, running, and viewing a `Replay`. A `Replay` is a type of simulation that lets you see how your members' access to resources might change if you changed your IAM policy.\n\nDuring a `Replay`, Policy Simulator re-evaluates, or replays, past access attempts under both the current policy and your proposed policy, and compares those results to determine how your members' access might change under the proposed policy.\n\nWhile this library is **GA** , please note that the Google Cloud C++ client libraries do **not** follow [Semantic Versioning](https://semver.org/).\n\n### Quickstart\n\nThe following shows the code that you'll run in the `google/cloud/policysimulator/quickstart/` directory, which should give you a taste of the Policy Simulator API C++ client library API. \n\n #include \"google/cloud/policysimulator/v1/simulator_client.h\"\n #include \"google/cloud/location.h\"\n #include \u003ciostream\u003e\n #include \u003cstring\u003e\n\n int main(int argc, char* argv[]) try {\n if (argc != 3) {\n std::cerr\n \u003c\u003c \"Usage: \" \u003c\u003c argv[0] \u003c\u003c \" project-id resource-name\\n\"\n \u003c\u003c \"See https://cloud.google.com/iam/docs/full-resource-names for \"\n \"examples of fully qualified resource names.\\n\";\n return 1;\n }\n\n auto const location = google::cloud::Location(argv[1], \"global\");\n auto const resource_name = std::string{argv[2]};\n\n namespace policysimulator = ::google::cloud::policysimulator_v1;\n auto client = policysimulator::SimulatorClient(\n policysimulator::MakeSimulatorConnection());\n\n google::cloud::policysimulator::v1::Replay r;\n auto& overlay = *r.mutable_config()-\u003emutable_policy_overlay();\n overlay[resource_name] = [] {\n google::iam::v1::Policy p;\n auto& binding = *p.add_bindings();\n binding.set_role(\"storage.buckets.get\");\n binding.add_members(\"user@example.com\");\n return p;\n }();\n\n auto replay = client.CreateReplay(location.FullName(), r).get();\n if (!replay) throw std::move(replay).status();\n std::cout \u003c\u003c replay-\u003eDebugString() \u003c\u003c \"\\n\";\n\n return 0;\n } catch (google::cloud::Status const& status) {\n std::cerr \u003c\u003c \"google::cloud::Status thrown: \" \u003c\u003c status \u003c\u003c \"\\n\";\n return 1;\n }\n\n### Main classes\n\nThe main class in this library is [`policysimulator_v1::SimulatorClient`](/cpp/docs/reference/policysimulator/2.24.0/classgoogle_1_1cloud_1_1policysimulator__v1_1_1SimulatorClient). All RPCs are exposed as member functions of this class. Other classes provide helpers, configuration parameters, and infrastructure to mock [`policysimulator_v1::SimulatorClient`](/cpp/docs/reference/policysimulator/2.24.0/classgoogle_1_1cloud_1_1policysimulator__v1_1_1SimulatorClient) when testing your application.\n\n### More Information\n\n- [Error Handling](https://cloud.google.com/cpp/docs/reference/common/latest/common-error-handling.html) - describes how the library reports errors.\n- [How to Override the Default Endpoint](/cpp/docs/reference/policysimulator/2.24.0/policysimulator-override-endpoint) - describes how to override the default endpoint.\n- [How to Override the Authentication Credentials](/cpp/docs/reference/policysimulator/2.24.0/policysimulator-override-authentication) - describes how to change the authentication credentials used by the library.\n- [Override Retry, Backoff, and Idempotency Policies](/cpp/docs/reference/policysimulator/2.24.0/policysimulator-override-retry) - describes how to change the default retry policies.\n- [Environment Variables](/cpp/docs/reference/policysimulator/2.24.0/policysimulator-env) - describes environment variables that can configure the behavior of the library."]]