Create a new application accelerator

This topic guides you through creating an accelerator and registering it in a Tanzu Application Platform (commonly known as TAP) instance.

Tanzu Application Platform offers a selection of built-in accelerators to streamline your development process. However, if these accelerators don’t meet your needs, you can create a new accelerator. By creating an accelerator, you can ensure that your technology stacks and organizational best practices are adhered to.

Note
This guide follows a quick start format. See the Application Accelerator documentation for advanced features.

What you will do

Create a new accelerator project that contains an accelerator.yaml file and README.md file.
Configure the accelerator.yaml file to alter the project’s README.md.
Test your accelerator locally using the Tanzu CLI generate-from-local command.
Create a new Git repository for the project and push the project to it.
Register the accelerator in a Tanzu Application Platform instance.
Verify project generation with the new accelerator by using Tanzu Developer Portal.

Set up Visual Studio Code

To simplify accelerator authoring, code assist capabilities are available. To install the extension, navigate to the Marketplace page for the YAML plug-in and click Install.

Note
Code assist for authoring accelerators is also available in the IntelliJ IDE. You can enable this by selecting Application Accelerator in the schema mapping drop-down menu. For more information about how to enable this, see the IntelliJ Using schemas from JSON Schema Store documentation.
After you install the plug-in, editing files entitled accelerator.yaml automatically uses the code assist capabilities.

Create a simple project

To create your project, follow these instructions to set up the project directory, prepare the README.md and accelerator.yaml, and test your accelerator.

Set up the project directory

Create a new directory for the project named myProject and change to the newly created directory.
```
mkdir myProject
cd myProject
```
Create two new files in the myProject directory named README.md and accelerator.yaml.
```
touch README.MD accelerator.yaml
```

Prepare the README.md and accelerator.yaml

The following instructions require using Visual Studio Code to edit the files.

Using Visual Studio Code, open the README.md, copy and paste the following code block into it, and save the file. CONFIGURABLE_PARAMETER_# is targeted to be transformed during project generation in the upcoming accelerator.yaml definition.


## Tanzu Application Accelerator Sample Project

This is some very important placeholder text that should describe what this project can do and how to use it.

Here are some configurable parameters:

* CONFIGURABLE_PARAMETER_1
* CONFIGURABLE_PARAMETER_2

Open accelerator.yaml and begin populating the file section using the snippet below. This section contains important information, such as the accelerator’s display name, description, tags, and more.

For all possible parameters available in this section, see Creating accelerator.yaml.
```
accelerator:
  displayName: Simple Accelerator
  description: Contains just a README
  iconUrl: https://blogs.vmware.com/wp-content/uploads/2022/02/tap.png
  tags:
    - simple
    - getting-started
```

Add the configuration parameters using the following code snippet. This configures what parameters are displayed in the accelerator form during project creation.

In this example snippet, the field firstConfigurableParameter takes in text the user provides. The secondConfigurableParameter does the same, except it is only displayed if the user checks secondConfigurableParameterCheckbox because of the dependsOn parameter.

For more information about possible options, see Creating accelerator.yaml.

# Place this after the 'tags' section from the previous step
  options:
    - name: firstConfigurableParameter
      inputType: text
      label: The text used to replace the first placeholder text in the README.md. Converted to lowercase.
      defaultValue: Configurable Parameter 1
      required: true
    - name: secondConfigurableParameterCheckbox
      inputType: checkbox
      dataType: boolean
      label: Enable to configure the second configurable parameter, otherwise use the default value.
    - name: secondConfigurableParameter
      inputType: text
      label: The text used to replace the second placeholder text in the README.md. Converted to lowercase.
      defaultValue: Configurable Parameter 2
      dependsOn:
        name: secondConfigurableParameterCheckbox

Add the engine configuration by using the following code snippet and save the file.

The engine configuration tells the accelerator engine behind the scenes what must be done to the project files during project creation. In this example, this instructs the engine to replace CONFIGURABLE_PARAMETER_1 and, if the check box is checked, CONFIGURABLE_PARAMETER_2 with the parameters that the user passes in during project creation.

This also leverages Spring Expression Language (SpEL) syntax to convert the text input to all lowercase.

For more information about the possible parameters for use within the engine section, see Creating accelerator.yaml.
```
# Place this after the `options` section from the previous step
engine:
  merge:
    - include: [ "README.md" ]
      chain:
        - type: ReplaceText
          substitutions:
            - text: "CONFIGURABLE_PARAMETER_1"
              with: "#firstConfigurableParameter.toLowerCase()"
        - condition: "#secondConfigurableParameterCheckbox"
          chain:
          - type: ReplaceText
            substitutions:
              - text: "CONFIGURABLE_PARAMETER_2"
                with: "#secondConfigurableParameter.toLowerCase()"
```

Test the accelerator

It is important to quickly test and iterate on accelerators as they are being developed to ensure that the resulting project is generated as expected.

Using the terminal of your choice with access to the tanzu command, run the following command to test the accelerator created earlier.

This step takes the local accelerator.yaml and project files, configures the project using the parameters passed in through the --options field, and outputs the project to a specified directory.

Important
This step requires that the TANZU-APPLICATION-ACCELERATOR-URL endpoint is exposed and accessible. For more information, see Server API connections for operators and developers.
```
tanzu accelerator generate-from-local \
    --accelerator-path simple-accelerator="$(pwd)" `# The path to new accelerator` \
    --server-url TANZU-APPLICATION-ACCELERATOR-URL `# Example: https://accelerator.mytapcluster.myorg.com` \
    --options '{"firstConfigurableParameter": "Parameter 1", "secondConfigurableParameterCheckbox": true, "secondConfigurableParameter":"Parameter 2"}' \
    -o "${HOME}/simple-accelerator/" `# Change this path to change where the project folder gets generated`
```
After the project is generated, a status message is displayed.
```
generated project simple-accelerator
```

Navigate to the output directory and verify that the README.md is updated based on the --options specified in the preceding generate-from-local command.

## Tanzu Application Accelerator Sample Project

This is some very important placeholder text that should describe what this project can do and how to use it.

Here are some configurable parameters:

- parameter 1
- parameter 2

Upload the project to a Git repository

The Application Accelerator system and Tanzu Developer Portal depend on an accelerator project residing inside a Git repository. For this example, GitHub is used.

Create a new repository in GitHub and ensure that Visibility is set to Public. Click Create Repository.
To push your accelerator project (not the generated project from generate-from-local) to GitHub, follow the instructions that GitHub provides for the …or create a new repository on the command line that is shown after clicking Create Repository. Instructions can also be found in the GitHub documentation.
Verify that the project is pushed to the target repository.

Register the accelerator to the Tanzu Application Platform and verify project generation output

Now that the accelerator is committed to its own repository, you can register the accelerator to Tanzu Developer Portal for developers to generate projects from the newly created accelerator.

To do so, use the URL of the Git repository and branch name created earlier and run the following command using the Tanzu CLI to register the accelerator to Tanzu Developer Portal.

Note
tanzu accelerator create works with monorepos as well. Add the --git-sub-path parameter with the desired subpath to fetch the accelerator project in that directory. For more information, see the [Tanzu CLI Command Reference](https://docs.vmware.> com/en/VMware-Tanzu-CLI/1.4/tanzu-cli/command-ref.html) documentation.

tanzu accelerator create simple-accelerator --git-repository https://github.com/myusername/myprojectrepository --git-branch main

The accelerator can take time to reconcile. After it has reconciled, it is available for use in Tanzu Developer Portal and the Application Accelerator extension for Visual Studio Code.

Verify project generation output by using Tanzu Developer Portal

Navigate to your organization’s instance of Tanzu Developer Portal.
On the left navigation pane, click Create.
Using the search bar near the left side of the page, search for simple accelerator. After you’ve found it, click Choose on the accelerator card.
Configure the project by filling in the parameters in the form.

The options you defined in accelerator.yaml are now displayed for you to configure. The secondConfigurableParameter dependsOn secondConfigurableParameterCheckbox might be hidden depending on whether the check box is selected.
After configuration is complete, click Next.

Note
Depending on your organization’s Tanzu Application Platform configuration, you might be presented with an option to create a Git repository. In this guide, this is skipped and is covered in Deploy an app on Tanzu Application Platform.
On the Review and generate step, review the parameters and click Generate Accelerator.
Explore the ZIP file of the configured project and verify that the project is generated with the parameters you provided during configuration.

Learn more about Application Accelerator

For advanced functionality when creating accelerators, such as accelerator best practices, accelerator fragments, engine transforms, and more, see the Application Accelerator documentation.
For more information about Application Accelerator configurations, see the Configure Application Accelerator documentation.
For information about installing the Application Accelerator extension for Visual Studio Code, see the Application Accelerator Visual Studio Code extension documentation.
For general accelerator troubleshooting, see Troubleshooting Application Accelerator for VMware Tanzu.