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 webpage provides documentation for the Policy Simulator API C++ client library, which allows users to simulate IAM policy changes and analyze their impact on member access.\u003c/p\u003e\n"],["\u003cp\u003eThe Policy Simulator API lets you create and run simulations, known as "Replays," to compare past access attempts under current and proposed policies.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version available for the Policy Simulator API C++ client library is \u003ccode\u003e2.37.0-rc\u003c/code\u003e, with multiple other available versions ranging down to version \u003ccode\u003e2.15.1\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe main class for interacting with the Policy Simulator API is \u003ccode\u003epolicysimulator_v1::SimulatorClient\u003c/code\u003e, which exposes all RPCs as member functions.\u003c/p\u003e\n"],["\u003cp\u003eThis documentation covers various topics including error handling, overriding default endpoints and authentication, modifying retry policies, and using environment variables to configure the library.\u003c/p\u003e\n"]]],[],null,["Version 2.16.0keyboard_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 \u003ciostream\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 namespace policysimulator = ::google::cloud::policysimulator_v1;\n auto client = policysimulator::SimulatorClient(\n policysimulator::MakeSimulatorConnection());\n\n auto const parent = std::string{\"projects/\"} + argv[1] + \"/locations/global\";\n auto const resource_name = std::string{argv[2]};\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(parent, 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/2.16.0/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/2.16.0/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/2.16.0/policysimulator-override-endpoint) - describes how to override the default endpoint.\n- [How to Override the Authentication Credentials](/cpp/docs/reference/policysimulator/2.16.0/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/2.16.0/policysimulator-override-retry) - describes how to change the default retry policies.\n- [Environment Variables](/cpp/docs/reference/policysimulator/2.16.0/policysimulator-env) - describes environment variables that can configure the behavior of the library."]]