Fugue Composer

What is Composer?

Fugue Composer (currently in Preview) is a tool that allows users to explore visualizations of compositions (Ludwig files). By selecting a Fugue Project Directory containing your compositions, you can use the File Browser to open an individual Ludwig file that will launch a detailed interactive diagram of the declared AWS infrastructure. Fugue Composer can also scan your AWS account to generate a composition and visualization of any infrastructure that is already running.

Since Fugue Composer is still in Preview, you may experience minor issues with performance and service coverage. We appreciate your patience during this time, and if you do run into any issues we want to know! Send us your questions and feedback at support@fugue.co.

One item to note – the “Generate Composition” feature (Preview) currently works best with accounts that have less than 40 resources. If you have trouble generating a composition with a larger amount of resources, contact support@fugue.co.

Note: If you don’t have a Fugue account, you can sign up for free here. Don’t have Composer yet - download it here.

Fugue Composer visualization.

Fugue Composer visualization.

How does it work?

When you open Fugue Composer, you’ll see a “Welcome to Composer” screen that provides a quick overview and helpful links to get started. You have the option to disable the initial screen so that subsequent sessions open with the launch screen.

Fugue Composer Welcome screen.

Fugue Composer Welcome screen.

After the Welcome screen you’ll see the launch screen where you can choose the “Open Fugue Project Directory” button or the “Generate Composition” button. The next time you launch Composer, you’ll also see a “Recently Accessed Directories” list.

Fugue Composer Launch page.

Fugue Composer Launch page.

Once you’ve selected a directory or generated a composition, Fugue Composer displays the selected composition, or Ludwig file, side-by-side with a detailed architecture visualization. Composer allows you to view all of the components of your infrastructure architecture and to modify the visualization in real time by modifying the composition in the Editor. When you make changes and save your composition, Composer compiles the Ludwig and updates the visualization. Any changes that you make to the composition are instantly reflected in the visualization, including errors and policy violations. In addition, Composer includes a switch to toggle for the compilation of GovCloud specific compositions. If you toggle this switch while the composition is visible (selected) it will recompile.


You can also use your favorite text editor or IDE to modify Ludwig files, and Composer will watch the selected directory for changes, updating the visualization automatically.

If a composition fails to compile, Composer shows an error message indicating the type of error, the line number where the error occurs, and other relevant error information. When the error is fixed, the visualization returns. You can view or hide the error message by selecting the triangular Error icon in the utility bar on the right border of the screen.

Fugue Composer error.

Fugue Composer error.

Selecting an individual element in the visualization provides configuration details through an element Inspector. In the Inspector Panel, click on underlined bindings to view information about that resource. The > character indicates that a field can be expanded or collapsed to view or hide further configuration information.

Fugue Composer Inspector Panel.

Fugue Composer Inspector Panel.

In the Editor, top-level bindings are indicated by bold text in a purple rectangle. Comments are gray and italicized.

Generate Composition Feature

The Generate Composition feature (Preview) provides functionality powered by Fugue Transcriber. It just needs read-only IAM permissions. You can access the feature by selecting the “Generate Composition” button when you open Fugue Composer. Or, if you’ve already opened a directory, you can select the “Generate Composition” button in the bottom-left corner of Composer.

Note: Learn more about Transcriber here.

You’ll be taken to a screen prompting you to enter your AWS account details and optionally customize how resources in your AWS accounts are included in the generated composition. For instance, you can generate a composition that excludes specific resources in the account by AWS service.

The Generate Composition feature describes AWS resources in one of two ways - first, by generating the Ludwig code necessary to create the resource, or second by emitting an External binding that references an existing resource.

  • The first approach is used when generating bindings for included services; and is useful for creating compositions to replicate existing resources in one or more AWS accounts.
  • The second approach is used when generating bindings for excluded services; and is useful for creating compositions without bindings for specific resources. Externals are generated instead of the appropriate type declarations in order for the composition to compile successfully.

In both cases, the generated composition can be edited as needed. Fugue provides capabilities to declare AWS resources, as well as manage them after provisioning. These phases are roughly analogous to “compile time” and “run time” in the traditional computing model. Since this feature generates a composition that is used at “compile time”, the Ludwig bindings in those compositions do not contain information generated during “run time”, such as resource IDs.


Composer only supports generating compositions that can provision the services prepopulated in the “Included AWS Services” picklist under “Service Options.” Compositions can contain excluded services (via externals) but only if an excluded resource is needed by an included resource.

Fugue Composer Generate Composition.

Fugue Composer Generate Composition.

AWS Account Details

Enter the AWS access key and AWS secret key associated with the account you want to scan. Select the region you want to scan from the drop-down menu.

Every time you open the “Generate Composition” screen, you’ll need to reenter your keys.


Keys are only used for scanning your AWS account. Your credentials are not sent to Fugue, nor are they stored in Composer.

Service Options

If you want Composer to include a certain AWS service in the scan, select it from the “Excluded AWS Services” list and click the < button to move it to the “Included AWS Services” list. To move that service back to the “Excluded AWS Services” list, click the > button.

Resource Options

Optionally, if you only want Composer to include resources tagged with a specific key or key-value pair, enter the key my-key or the key-value pair my-key:my-value.

To include Fugue-managed resources in Composer’s scan, check the “Include Resources Created By a Fugue Process (Tagged with a Fugue ID)” box.

The Fugue Conductor has its own set of resources. To include Fugue runtime resources in Composer’s scan, check the “Include Fugue Conductor Runtime Resources” box.

Composer uses these options to filter the results of the services scan.

When you are ready, select the “Generate Composition” button. You’ll be prompted to save the resulting composition in a directory of your choosing. The default name is composition.lw and the default location is your Home directory.

The Generated Composition

Once you’ve given the composition a name and directory, Composer will scan your AWS account and create a composition incorporating all of your existing AWS infrastructure in the specified region (excluding any services in the “Excluded AWS Services” list).

When Composer is done scanning, you’ll see the generated composition in the Editor alongside a visualization of the infrastructure. Each resource declaration in the composition is preceded by a comment that indicates the type and ID of the resource that it represents.

For example:

#   Generated from AWS resource: vpc-ba7cd2dc
ec2-vpc-2: EC2.Vpc.new {
  cidrBlock: "",
  dhcpOptions: ec2-dhcpoptions-1,
  instanceTenancy: EC2.DefaultTenancy,
  region: region,


As part of Composer, Fugue is tracking some metrics related to application usage. The purpose of these metrics is exclusively to help us understand how Composer is being used, and what we can do to improve this tool. Users can opt out of sending metrics at any time by unchecking the “Help Us Improve Composer” checkbox on the Composer welcome screen. All users are anonymous and any data we collect will never be shared externally. You can read the complete details and see an example here.


How do I install Fugue Composer?

Fugue Composer is part of the Fugue Client Tools. To install the Fugue Client Tools, log into the Fugue Download Portal and download the appropriate Client Tools package for your platform. Install the Client Tools by following the instructions here. Once the Client Tools have been successfully installed, you can launch Fugue Composer from your Applications directory on OS X, from the desktop shortcut on Windows (or alternatively from c:\Program Files\Fugue\bin), and via the desktop entry for both Ubuntu and RHEL 7.

How do I update Fugue Composer?

While some auto-updates may be deployed for small fixes, the full version of Composer must be updated manually. Existing users will receive a notification announcing any new releases, otherwise to get the latest version visit the Download Portal here.

How do I uninstall Fugue Composer?

You can remove Fugue Composer by uninstalling Fugue Client Tools. Follow the instructions here.

What IAM permissions are necessary for using Fugue Composer?

The Generate Composition feature simply requires read-only permissions for each AWS service to be scanned. For more information, including how to generate an IAM user with read-only permissions, see IAM Policies for Transcriber. No other permissions are required for Fugue Composer.

Where can I find sample compositions to use with Fugue Composer?

If you don’t have any compositions you can test out the Composer with a sample composition from our Composer sample public repo. In addition, the Fugue Fake Book is a great place to start for simple service-specific compositions, as well as more complex full-stack compositions. You can also find more sample compositions in our walkthroughs.

Where can I learn more about how to write Ludwig?

How do I change the parent file directory?

To change the parent file directory, select “Change Project Directory” in the top-left corner of Composer.

How do I zoom in or out?

In the bottom of the visualization pane, select the + to zoom in and the - to zoom out. You can also drag the zoom slider to a particular value, or scroll up or down with your mouse wheel or trackpad.

How can I reset the visualization size?

Select the crosshairs icon in the bottom-right corner of the screen. Composer will fit the diagram to the width of the visualization panel.

How do I update the visualization? (How do I save the composition?)

When you save your composition after making changes in the Editor, Composer will redraw the visualization. Save your composition by pressing CMD+S (in OSX), CTRL+S (in Windows), or by clicking the purple save button at the top-right of the screen (this button is only visible when a file is modified and has not been saved). If you’d prefer to use your own text editor or IDE, you can edit and save your composition there and Composer will automatically update the visualization when it detects a file change.

How can I hide or show the File Browser or Editor?

Click the panel icon near the top-right corner of the screen to select the panels you want to show or hide.

How can I send my Composer feedback to Fugue?

We’d love to hear your comments and suggestions! Just click the “Send Feedback” button in the top-right corner of the screen.

What if I have a question that isn’t answered here?

You can reach out to us at support@fugue.co.