# EngineManagement

Manage your DAH child servers. With the `EngineManagement` action, you can dynamically (without restarting the DAH) bring child IDOL servers online or take them offline. You can also add a server, edit the host or port of an existing server, check the status of a child server, manage primary servers, and change the weight of a child server.

If you mark a child server as offline, the DAH sends no requests (even polling requests) to it, until you bring it back online again.

You specify the action to perform on the child server by setting EngineAction. Depending on the value of EngineAction, you might need to set additional parameters:

- When you set EngineAction to `PowerUp`, `PowerDown`, `ChangeWeight`, `EngineEdit`, `Ping`, or `SetPrimaryEngine`, you must set EngineID.
- When you set EngineAction to `ChangeWeight`, you must also set EngineWeight.
- When you set EngineAction to `EngineAdd`, you must also set EngineHost and EnginePort.
- When you set EngineAction to `EngineEdit`, you must also set at least one of EngineHost or EnginePort to edit the host and/or port of the engine.

TIP: When you have set UseEngineAlias to `True` in your configuration file, you can optionally use EngineName to identify your child servers, instead of EngineID.

NOTE: This is an administrative action that can be sent only by users that belong to an authorization role that allows the `Admin` standard role, or which enables the action explicitly. See Authorization Roles Configuration Parameters.

## Example

    http://localhost:9060/action=EngineManagement&EngineAction=PowerDown&EngineID=2,4

This action takes offline the child IDOL servers with IDs `2` and `4`.

`http://localhost:9060/action=EngineManagement&EngineAction=EngineEdit&EngineID=0&EngineHost=newhost`

This action changes the host name of the child server with ID `0`.

## Required Parameters

The following action parameters are required.

Parameter | Description
--- | ---
EngineAction | The action to take on the specified child servers.

Depending on the value of EngineAction, and your configuration, you might need to set one or more of the following parameters.

Parameter | Description
--- | ---
EngineHost | The host of the new server. This parameter is required when you set EngineAction to `EngineAdd`.
EngineID | The child servers to perform the specified action on.
EngineName | Specifies one or more aliases of child IDOL servers to mark as online or offline. This parameter is valid only when you configure UseEngineAlias.
EnginePort | The port of the new server. This parameter is required when you set EngineAction to `EngineAdd`.
EngineWeight | The new weight of a child server. This parameter is valid only when you set EngineAction to `ChangeWeight`.
PrimaryEngines | The IDs of the primary servers in child server groups. This parameter is valid only when you set EngineAction to `SetPrimaryEngines`, and you have configured DAH in non-mirror mode with child server groups.

## Optional Parameters

This action accepts the following standard ACI action parameters.

Parameter | Description
--- | ---
ActionID | A string to use to identify an ACI action.
EncryptResponse | Encrypt the output.
FileName | The file to write output to.
ForceTemplateRefresh | Forces the server to load the template from disk.
Output | Writes output to a file.
ResponseFormat | The format of the action output.
Template | The template to use for the action output.
TemplateParamCSVs | A list of variables to use for the specified template.

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