BuildGraph Script Elements

BuildGraph scripts are written in XML. This document covers the types of data found within BuildGraph scripts, as well as their overall structure.

Elements

Elements describe the data that they contain, making them one of the basic building blocks of BuildGraph scripts. The following tables contain items that are provided as metadata, which are exported when running on the build system. Although they're not used directly by BuildGraph when executing tasks locally, they're tagged with [META].

Graph Structure

A BuildGraph script is typically defined with the following elements:

  • <Node>

  • <Aggregate>

  • <Agent>

  • <Trigger>

Node

<Node> is the smallest unit of execution in BuildGraph, having a set of inputs and outputs. Each <Node> consists of a sequence of tasks that are executed in order.

Attribute

Type

Required?

Description

Name

Name

Required

Name of the node.

Requires

Target List

Optional

List of nodes, aggregates, or tagged file sets produced by other nodes that this node requires to execute, separated by semicolons.

Produces

Tag List

Optional

Tagged file sets that this node makes available to other nodes, separated by semicolons.

After

Target List

Optional

List of nodes that this node should run after, if they are part of the current target (ignored if they are not). Separated by semicolons.

NotifyOnWarnings

Boolean

Optional

If false, this node will not produce notifications on warnings. Only used by build systems. Defaults to true. [META]

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Aggregate

<Aggregate> declares a named aggregate that can be used as a synonym for a set of other nodes (or produced tag sets).

Attribute

Type

Required?

Description

Name

Name

Required

Name of the aggregate.

Requires

Target List

Required

List of dependencies for this aggregate. May be nodes, tagged file sets, or agent groups.

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Agent

<Agent> defines requirements for an agent on nodes that will be executed in sequence (without cleaning intermediate directories). <Agent> requirements are ignored when building locally, but must be specified.

Attribute

Type

Required?

Description

Name

Name

Required

Name of the group.

Type

Identifier List

Optional

Type of agent to run on. The meaning of this string is inferred by the host build system; it does not have any intrinsic meaning. [META]

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Trigger

<Trigger> serves as a container for portions of the graph that should only be executed with explicit user intervention. To execute nodes behind a trigger, pass -Trigger=<Name> to the command line.

Attribute

Type

Required?

Description

Name

Name

Required

Name of the trigger.

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Property Manipulation

BuildGraph properties can be modified with the following elements:

  • <Property>

  • <Option>

  • <EnvVar>

Property

<Property> sets the value of a property. If a property in an outer scope has already been declared with the same name, <Property> overwrites it. Otherwise, a new property is declared at the current scope.

Attribute

Type

Required?

Description

Name

Name

Required

Name of the property to set.

Value

String

Required

New value for the property.

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Option

<Option> defines a user option that can be set from the command line. <Option> may only appear at a global scope.

Attribute

Type

Required?

Description

Name

Name

Required

Name of the option (and property) to initialize with the option's value.

Description

String

Required

Description for the option to display when running BuildGraph with the -ListOnly argument.

Restrict

Regex

Optional

Regex that matches valid values for this option (eg. [a-zA-Z]+, true | false).

DefaultValue

String

Required

Default value for the option if the user does not set it explicitly.

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

EnvVar

<EnvVar> declares a property to contain the contents of an environment variable (or an empty string if it's not set). <EnvVar> may only appear at a global scope.

Attribute

Type

Required?

Description

Name

Name

Required

Name of the environment variable to introduce as a property.

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Flow Control

You can control the flow of your BuildGraph scripts with the following elements:

  • <Include>

  • <Do>

  • <Switch>

  • <ForEach>

Include

<Include> processes the contents of another BuildGraph script as if it appeared within this file. <Include> may only appear at a global scope.

Attribute

Type

Required?

Description

Script

String

Required

Path to the script you wan to include (relative to the current script).

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Do

<Do> groups a sequence of elements and only processes them if a condition evaluates as true.

Attribute

Type

Required?

Description

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Switch

<Switch> is similar to a C switch statement because it evaluates the conditions on a sequence of branches, processing the first statement with a condition that evaluates as true.

Example <Switch> statement:

<Switch>
    <Case If=X>
        <Elements go here>
    </Case>
    <Case If=Y>
        <Elements go here>
    </Case>
    <Default>
        <Elements go here>
    </Default>
</Switch>

Attribute

Type

Required?

Description

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

ForEach

<ForEach> expands the body of the element with a given property assigned to each item in a list that is separated by semicolons.

Example <ForEach> statement:

<ForEach Name="Counter" Values="1;2;3;4;5">
    <Log Message="Counter=$(Counter)"/>
</ForEach>

Attribute

Type

Required?

Description

Name

Name

Required

Property to assign to each value in the list.

Values

String List

Required

List of values that are separated by semicolons.

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Diagnostics

You can perform diagnostics on your BuildGraph scripts with the following elements:

  • <Warning>

  • <Error>

Warning

<Warning> outputs a warning message before executing the graph. <Warning> may be included in nodes, agents, triggers, or at global scope. <Warning> will only provide an output if it's still part of the graph after it has been trimmed down to the target being executed.

Attribute

Type

Required?

Description

Message

String

Required

Text to be printed to the log.

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Error

<Error>outputs an error message. <Error> may be included in nodes, agents, triggers, or at global scope. <Error> will only provide an output if it's still part of the graph after it has been trimmed down to the target being executed.

Attribute

Type

Required?

Description

Message

String

Required

Text to be printed to the log.

If

Condition

Optional

Condition to be evaluated. The element is ignored unless the condition evaluates to true.

Tasks

Typically, project-specific utility scripts are implemented as AutomationTool BuildCommand classes. There are times, however, when you'll want to automate custom tasks for your project. This is where BuildGraph can help. BuildGraph can be extended with any number of tasks, enabling you to customize your build automation tasks in ways that suit your specific needs. The following section goes over ways of creating custom tasks using BuildGraph, including a listing of predefined tasks that'll give you a great starting point for creating custom tasks.

Custom Tasks

To create a new custom task, implement a class derived from the CustomTask class and apply the [TaskElement] attribute to it. The TaskElement constructor takes two arguments; the name of the XML element that it's represented by, and the type of class containing its parameters (which is passed to the constructor at load time).

If you want to read parameter class fields from an XML file, attach the [TaskParameter] attribute to the task. Attaching the TaskParameter attribute indicates if the parameter is required or optional, including additional validation that should be applied to the argument.

Predefined Tasks

If you'd like to have a starting point for creating tasks, we're providing a variety of predefined tasks as templates for you to work from. If you're looking for a simple predefined task to start from, we recommend using LogTask as a good starting point. If you want to keep up with our latest improvements to BuildGraph; bookmark this page, because the following list of predefined tasks will be updated periodically.

AgeStore

Task which strips symbols from a set of files. This task is named after the AGESTORE utility that comes with the Microsoft debugger tools SDK, but is actually a separate implementation. The main difference is that it uses the last modified time rather than last access time to determine which files to delete.

Platform

UnrealTargetPlatform

Required

The target platform to age symbols for.

StoreDir

String

Required

The symbol server directory.

Days

Int32

Required

Number of days worth of symbols to keep.

Filter

String

Optional

A substring to match in directory file names before deleting symbols. This allows the "age store" task to avoid deleting symbols from other builds in the case where multiple builds share the same symbol server. Specific use of the filter value is determined by the symbol server structure defined by the platform tool chain.

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Command

Invokes an AutomationTool child process to run the given command.

Name

String

Required

The command name to execute

Arguments

String

Optional

Arguments to be passed to the command

MergeTelemetryWithPrefix

String

Optional

If non-null, instructs telemetry from the command to be merged into the telemetry for this UAT instance with the given prefix. May be an empty (non-null) string.

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Commandlet

Spawns the editor to run a commandlet.

Name

String

Required

The commandlet name to execute

Project

File Spec

Optional

The project to run the editor with

Arguments

String

Optional

Arguments to be passed to the commandlet

EditorExe

File Name

Optional

The editor executable to use. Defaults to the development UE4Editor executable for the current platform.

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Compile

Compiles a target with UnrealBuildTool.

Target

String

Required

The target to compile

Configuration

UnrealTargetConfiguration

Required

The configuration to compile

Platform

UnrealTargetPlatform

Required

The platform to compile for

Arguments

String

Optional

Additional arguments for UnrealBuildTool

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Cook

Cook a selection of maps for a certain platform

Project

String

Required

Project file to be cooked

Platform

String

Required

The cook platform to target (eg. WindowsNoEditor)

Maps

String

Optional

List of maps to be cooked, separated by '+' characters

Versioned

Boolean

Optional

Additional arguments to be passed to the cooker

Arguments

String

Optional

Additional arguments to be passed to the cooker

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Copy

Copies files from one directory to another.

Files

File Spec

Optional

Filter to be applied to the list of input files. Optional.

From

File Spec

Required

The pattern(s) to copy from (eg. Engine/*.txt)

To

File Spec

Required

The directory or to copy to

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

CsCompile

Compiles C# project files, and their dependencies.

Project

String

Required

The C# project file to be compile. More than one project file can be specified by separating with semicolons.

Configuration

String

Optional

The configuration to compile

Platform

String

Optional

The platform to compile

Arguments

String

Optional

Additional options to pass to the compiler

EnumerateOnly

Boolean

Optional

Only enumerate build products; do not actually compile the projects.

Tag

Tag List

Optional

Tag to be applied to build products of this task

TagReferences

Tag List

Optional

Tag to be applied to any non-private references the projects have (i.e. those that are external and not copied into the output dir)

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Delete

Delete a set of files.

Files

File Spec

Required

List of file specifications separated by semicolons (eg. .cpp;Engine/.../.bat), or the name of a tag set

DeleteEmptyDirectories

Boolean

Optional

Whether to delete empty directories after deleting the files. Defaults to true.

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Log

Print a message (and other optional diagnostic information) to the output log

Message

String

Optional

Message to print out

Files

File Spec

Optional

If specified, causes the given list of files to be printed after the given message.

IncludeContents

Boolean

Optional

If specified, causes the contents of the given files to be printed out.

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Move

Moves files from one directory to another.

Files

File Spec

Optional

Filter to be applied to the list of input files. Optional.

From

File Spec

Required

The pattern(s) to copy from (eg. Engine/*.txt)

To

File Spec

Required

The directory or to copy to

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

PakFile

Creates a PAK file from a given set of files.

Files

File Spec

Required

List of files, wildcards and tag sets to add to the pak file, separated by ';' characters.

Output

File Name

Required

PAK file to output

ResponseFile

File Name

Optional

Path to a Response File that contains a list of files to add to the pak file, instead of specifying them individually

RebaseDir

Directory Name

Optional

Directories to rebase the files relative to. If specified, the shortest path under a listed directory will be used for each file.

Order

File Name

Optional

Script which gives the order of files

Sign

String

Optional

Encryption keys for this pak file

Compress

Boolean

Optional

Whether to compress files

Arguments

String

Optional

Additional arguments to be passed to UnrealPak

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Rename

Renames a file, or group of files.

Files

File Spec

Required

The file or files to rename

From

Directory Name

Optional

The current file name, or pattern to match (eg. *.txt). Should not include any path separators.

To

Directory Name

Required

The new name for the file(s). Should not include any path separators.

Tag

Tag List

Optional

Tag to be applied to the renamed files

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

SetVersion

Updates the local version files (Engine/Source/Runtime/Launch/Resources/Version.h, Engine/Build/Build.version, and Engine/Source/Programs/DotNETCommon/Metadata.cs) with the given version information.

Change

Int32

Required

The changelist to set in the version files

CompatibleChange

Int32

Optional

The engine compatible changelist to set in the version files

Branch

String

Required

The branch string

Build

String

Optional

The build version string

Licensee

Boolean

Optional

Whether to set the IS_LICENSEE_VERSION flag to true

Promoted

Boolean

Optional

Whether to set the ENGINE_IS_PROMOTED_BUILD flag to true

SkipWrite

Boolean

Optional

If set, don't actually write to the files - just return the version files that would be updated. Useful for local builds.

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Sign

Signs a set of executable files with an installed certificate.

Files

File Spec

Required

List of file specifications separated by semicolons (eg. .cpp;Engine/.../.bat), or the name of a tag set

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Spawn

Spawns an external executable and waits for it to complete.

Exe

File Name

Required

Executable to spawn

Arguments

String

Optional

Arguments for the newly created process

ErrorLevel

Int32

Optional

The minimum exit code which is treated as an error.

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Stage

Stages files listed in a build receipt to an output directory.

Project

File Name

Optional

The project that this target belongs to

Target

String

Required

Name of the target to stage

Platform

UnrealTargetPlatform

Required

Platform to stage

Configuration

UnrealTargetConfiguration

Required

Configuration to be staged

Architecture

String

Optional

Architecture to be staged

ToDir

String

Required

Directory the receipt files should be staged to

Overwrite

Boolean

Optional

Whether to overwrite existing files

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Strip

Strips debugging information from a set of files.

Platform

UnrealTargetPlatform

Required

The platform toolchain to strip binaries

BaseDir

Directory Name

Optional

The directory to find files in

Files

File Spec

Required

List of file specifications separated by semicolons (eg. Engine/.../*.pdb), or the name of a tag set

OutputDir

Directory Name

Optional

Output directory for the stripped files. Defaults to the input path (overwriting the input files).

Tag

Tag List

Optional

Tag to be applied to build products of this task

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Submit

Creates a new changelist and submits a set of files to a Perforce stream.

Description

String

Required

The description for the submitted changelist

Files

File Spec

Required

The files to submit

FileType

String

Optional

The Perforce file type for the submitted files (eg. binary+FS32)

Workspace

String

Optional

The workspace name. If specified, a new workspace will be created using the given stream and root directory to submit the files. If not, the current workspace will be used.

Stream

String

Optional

The stream for the workspace; defaults to the current stream. Ignored unless If the Workspace attribute is also specified.

RootDir

Directory Name

Optional

Root directory for the stream. If not specified, defaults to the current root directory.

RevertUnchanged

Boolean

Optional

Whether to revert unchanged files before attempting to submit

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

SymStore

Task which strips symbols from a set of files

Platform

UnrealTargetPlatform

Required

The platform toolchain required to handle symbol files.

Files

String

Required

List of output files. PDBs will be extracted from this list.

StoreDir

String

Required

Output directory for the compressed symbols.

Product

String

Required

Name of the product for the symbol store records.

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Tag

Applies a tag to a given set of files. The list of files is found by enumerating the tags and file specifications given by the 'Files' parameter. From this list, any files not matched by the 'Filter' parameter are removed, followed by any files matched by the 'Except' parameter.

BaseDir

Directory Name

Optional

Set the base directory to resolve relative paths and patterns against. If set, any absolute patterns (eg. /Engine/Build/...) are taken to be relative to this path. If not, they are taken to be truly absolute.

Files

File Spec

Required

Set of files to work from, including wildcards and tag names, separated by semicolons. Resolved relative to BaseDir if set, otherwise to the branch root directory.

Filter

File Spec

Optional

Patterns to filter the list of files by, including tag names or wildcards. May include patterns that apply to the base directory if set. Defaults to all files if not specified.

Except

File Spec

Optional

Set of patterns to exclude from the matched list. May include tag names of patterns that apply to the base directory.

With

Tag List

Required

Name of the tag to apply

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

TagReceipt

Task which tags build products and/or runtime dependencies by reading from *.target files.

Files

File Spec

Required

Set of receipt files (*.target) to read, including wildcards and tag names, separated by semicolons.

EngineDir

Directory Name

Optional

Path to the Engine folder, used to expand $(EngineDir) properties in receipt files. Defaults to the Engine directory for the current workspace.

ProjectDir

Directory Name

Optional

Path to the project folder, used to expand $(ProjectDir) properties in receipt files. Defaults to the Engine directory for the current workspace.

BuildProducts

Boolean

Optional

Whether to tag the Build Products listed in receipts

BuildProductType

String

Optional

Which type of Build Products to tag (See TargetReceipt.cs - UnrealBuildTool.BuildProductType for valid values)

RuntimeDependencies

Boolean

Optional

Whether to tag the Runtime Dependencies listed in receipts

StagedFileType

String

Optional

Which type of Runtime Dependencies to tag (See TargetReceipt.cs - UnrealBuildTool.StagedFileType for valid values)

PrecompiledBuildDependencies

Boolean

Optional

Whether to tag the Precompiled Build Dependencies listed in receipts

PrecompiledRuntimeDependencies

Boolean

Optional

Whether to tag the Precompiled Runtime Dependencies listed in receipts

With

Tag List

Required

Name of the tag to apply

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Unzip

Extract files from a zip archive.

ZipFile

File Name

Required

Path to the zip file to extract

ToDir

Directory Name

Required

Output directory for the extracted files

Tag

Tag List

Optional

Tag to be applied to the extracted files

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.

Zip

Compresses files into a zip archive.

FromDir

Directory Name

Required

The directory to read compressed files from

Files

File Spec

Optional

List of file specifications separated by semicolons (eg. .cpp;Engine/.../.bat), or the name of a tag set. Relative paths are taken from FromDir.

ZipFile

File Name

Required

The zip file to create

Tag

Tag List

Optional

Tag to be applied to the created zip file

If

Condition

Optional

Whether to execute this task. It is ignored if this condition evaluates to false.