# Platform Variables The ONE Game Hosting service has a feature called Platform Variables, which can be used for configuration of your applications. Platform variables come in two types: * variables pre-defined by the platform * user defined variables These variables can be used inside the `startupParameters` property of an [ApplicationBuild](https://docs.i3d.net/game-hosting/elements/application/applicationbuild) and inside configuration files ([ApplicationBuildConfiguration](https://docs.i3d.net/game-hosting/elements/application/applicationbuildconfiguration) elements), submitted for an ApplicationBuild. Examples are provided near the end of this page. ## Platform defined variables The platform supplies a number of predefined variables: | Variable name | Description | | ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- | | VARSERVERID | The ID of the (physical or virtual) server an application is deployed on | | VARHOSTID | The ID of the host an application is deployed on | | VARHOSTNAME | The hostname of the host an application is deployed on | | VARPLAYERS | Maximum number of players allowed on a game server | | VARCONTINENT | The name of the continent in which the host is located | | VARCOUNTRYCODE | The ISO 3166-1 alpha-2 code of the country in which the host is located | | VARCOUNTRY | The full name of the country in which the host is located | | VARDCLOCATIONID | The ID of the data center location in which the host is located | | VARDCLOCATION | The name of the data center location in which the host is located | | VARDEPLOYMENTENVIRONMENTID | The ID of the DeploymentEnvironment of this ApplicationInstance | | VARDEPLOYMENTENVIRONMENTNAME | The name of the DeploymentEnvironment of this ApplicationInstance | | VARREGIONID | The identifier of the DeploymentRegion in which the host is located | | VARREGIONNAME | The name of the DeploymentRegion in which the host is located | | VARPROVIDER | The name of the owner of the (physical or virtual) server (e.g. i3D.net, GCP, AWS, etc.) | | VARFLEETID | The identifier of the Fleet in which the host is located | | VARFLEETNAME | The name of the Fleet in which the host is located | | VARAPPLICATIONID | The identifier of the Application element belonging to the ApplicationInstance that is being deployed | | VARAPPLICATIONBUILDID | The identifier of the ApplicationBuild element that is being deployed | | VARAPPLICATIONINSTANCEID | The ID of the ApplicationInstance that's being deployed | | VARIPV4PRIVATE | RFC-1918 IPv4 address of the host an application is deployed on | | VARIPV4PUBLIC | Public IPv4 address of the host an application is deployed on | | VARIPV4BINDING | IPv4 address that should be used by an application to bind on (e.g. a cloud VM will locally only see the host's private IP and not the public IP) | | VARIPV6 | IPv6 address of the host an application is deployed on | | VARIPV6BINDING | IPv6 address that should be used by an application to bind on (e.g. a cloud VM will locally only see the host's private IP and not the public IP) | Table 1: Platform defined VARiables ## User defined variables Alongside the platform defined VARiables, there are also custom ones that are derived from [ApplicationProperty](https://docs.i3d.net/game-hosting/elements/application/applicationproperty) elements. For each ApplicationProperty, a VARiable is generated. Some examples of this: For a property named `game_port`, a VARiable named `VAR_GAME_PORT` is generated. For a property named `managementport`, a VARiable named `VAR_MANAGEMENTPORT` is generated. For a property named `management_password`, a VARiable named `VAR_MANAGEMENT_PASSWORD` is generated. As you may already see, there is a visual difference between platform-defined VARiables and custom ones. The custom ones have the prefix `VAR_` (with an underscore), whereas the platform-defined ones lack the underscore. All VARiables are in upper case. Please note that startParameters VAR must have quotations surrounding it when using JSON: ``` { "startParameters": "dclocation: \\\"\\\" regionId:2434242" } ``` ## Examples An example of VAR usage inside [ApplicationBuild](https://docs.i3d.net/game-hosting/elements/application/applicationbuild).startupParameters: `-ip VARIPV4BINDING -port VAR_GAME_PORT -arcusport VAR_MANAGEMENTPORT -name "Bluewolf VAR_GAME_PORT" -applicationInstanceId VARAPPLICATIONINSTANCEID -maxplayers 8` An example of VAR usage inside [ApplicationBuildConfiguration](https://docs.i3d.net/game-hosting/elements/application/applicationbuildconfiguration).configContent: ``` // Server name hostname=Bluewolf VARAPPLICATIONINSTANCEID // Arcus management passsword arcus_password=VAR_MANAGEMENT_PASSWORD // Server password srv_password=VAR_SRVPASSWORD // etc ``` You can concatenate VARiables if you want - they do not have to be separated by a space: `-regionIdent VARREGIONNAME-VARAPPLICATIONINSTANCEID` It will even work without a glue character: `-regionIdent VARREGIONNAMEVARAPPLICATIONINSTANCEID` !!! Warning "Underscore is not a glue character" ``` Remember `_` is a character that can exist in a VAR name, so **this will not work**: `-regionIdent VARREGIONNAME_VARAPPLICATIONINSTANCEID` ```