Kotlin DSL

Project Settings Structure

After the commit to the repository, you will get the .teamcity settings directory with the following files:

• settings.kts — the main file containing all the project configuration

• pom.xml — required when opening the project in an IDE to get the auto-completion feature, and ability to compile code and write unit tests for it

Opening Project in IntelliJ IDEA

To open the Kotlin DSL project in IntelliJ IDEA, open the .teamcity/pom.xml file as a project. All necessary dependencies will be resolved automatically right away. If all dependencies have been resolved, no errors in red will be visible in settings.kts. If you already have an IntelliJ IDEA project and want to add a Kotlin DSL module to it, follow related instructions.

Editing Kotlin DSL

When creating an empty project, that's what you see in settings.kts in your IDE:

Here, project {} represents the current project whose settings you'll define in the DSL (in DSL code it is sometimes referenced as _Self). This is the same project where you enabled versioned settings on the previous step. This project ID and name can be accessed via a special DslContext object but cannot be changed via the DSL code.

You can create different entities in this project by calling vcsRoot(), buildType(), template(), or subProject() methods.

The following examples shows how to add a build configuration with a command line script:

Here, id will be used as the value of the Build configuration ID field in TeamCity. In the example above the id must be specified. If you omit it, there will be a validation error on an attempt to generate settings from this script.

There is also another way to define the same build configuration:

In this case the usage of the id() function call is optional because TeamCity will generate the id based on the class name (HelloWorld in our case).

After making the necessary changes in settings.kts file, you can submit them to the repository — TeamCity will detect and apply them. If there are no errors during the script execution, you should see a build configuration named "Hello world" in your project.

Generating XML Configuration Files Locally

The pom.xml file provided for a Kotlin project has the generate task which can be used to generate TeamCity XML configuration files locally from the DSL scripts. This task can be started from IDE (see Plugins | teamcity-configs | teamcity-configs:generate node in the Maven tool window), or from the command line:

The result of the task execution will be placed under the .teamcity/target/generated-configs directory.

Debugging Kotlin DSL Scripts

If you are using IntelliJ IDEA, you can easily start debugging of any Maven task:

1. Navigate to View | Tool Windows | Maven Projects. The Maven Projects tool window is displayed.

2. Locate the task node: Plugins | teamcity-configs | teamcity-configs:generate, the Debug option is available in the context menu for the task:

Editing Project Settings via Web UI

TeamCity allows editing a project settings via the web interface, even though the project settings are stored in Kotlin DSL. If DSL scripts were not changed manually, that is if they were generated by TeamCity and stay the same way in the repository, then changes via the web UI will be applied directly to these generated files.

But if generated files were changed, then TeamCity will have to produce a patch, since it no longer knows what part of .kt or .kts file should be changed.

In case of portable DSL the patches are placed under the .teamcity/patches directory, for example:

Restoring Build History After ID Change

To identify a build configuration in a project based on the portable DSL, TeamCity uses the ID assigned to this build configuration in the DSL. We recommend keeping this ID constant, so the changes made in the DSL code are consistently applied to the respective build configuration in TeamCity.

However, if you need to modify the build configuration ID in the DSL, note that for TeamCity this modification will look like if the configuration with the previous ID was deleted and a new configuration with the new ID was created. As a result of this change, the build configuration will not contain the builds' history anymore. Even so, TeamCity keeps the history of builds for 5 days until cleaning it up, and the history can still be restored during this period.

To restore the builds' history after changing the build configuration ID, go to the Build Configuration Settings of the build configuration whose ID was changed, open the Actions menu, and click Attach build history. You will be redirected to the Attach Build History tab. Select the detached build history and click Attach.

Viewing DSL in UI

When viewing your build configuration settings in the UI, you can click View as code in the sidebar: the DSL representation of the current configuration will be displayed and the setting being viewed (for example, a build step, a trigger, dependencies) will be highlighted. To go back, click Edit in UI.

This is especially useful if you need to add some build feature or trigger to your DSL scripts and you're not sure how DSL code should look like.

Sharing Kotlin DSL Scripts

One of the advantages of the portable DSL script is that the script can be used by more than one project on the same server or more than one server (hence the name: portable).

If you have a repository with .teamcity containing settings in portable format, you can easily create another project based on these settings. The Create Project From URL feature can be used for this.

Point TeamCity to your repository, and it will detect the .teamcity directory and offer to import settings from there:

Using Context Parameters in DSL

You can customize the DSL generation behavior using context parameters configured in the TeamCity UI. Context parameters are specified as a part of the project versioned settings in the UI.

With context parameters, it is possible to maintain a single Kotlin DSL code and use it in different projects on the same TeamCity server. Each of these projects can have own values of context parameters, and the same DSL code can produce different settings based on values of these parameters.

Visit our blog to watch a tutorial and learn how to use context parameters in your projects.

To use a context parameter in a TeamCity project, you need to (1) define it in the project versioned settings in the UI and (2) reference it in the project DSL.

1. Managing context parameters in UI
   You can manage project context parameters on the Versioned Settings | Context Parameters tab.

   

   
   After you add, edit, or delete the parameters and click Save, TeamCity will reload the DSL configuration and apply the changed values to the project settings.

2. Referencing context parameters in DSL
   To reference a context parameter in the DSL code, use the getParameter() method of the DslContext object. You can specify a default value of this parameter as an optional second argument: getParameter("<parameter-name>", "<default-value>").
   The following example shows how to use context parameters in DSL:

   object Build : BuildType({ /* a context parameter that defines a build configuration name; its default value is `Test Build` */ name = "${DslContext.getParameter("BuildName", "Test Build")}" script { scriptContent = "echo Build Successful" } /* disable the last build step depending on the value of the `environment` parameter */ script { scriptContent = "echo Deploy" enabled = DslContext.getParameter(name = "Environment") != "Staging" } })

Each context parameter is expected to have a value, either the default one, set in the DSL, or a project-specific one, set in the UI. When you create a project from DSL or update the project versioned settings, TeamCity detects all context parameters with missing values and prompts you to set them.

Build Chain DSL Extension

TeamCity Kotlin DSL provides an alternative way to configure a build chain in a pipeline style.

In the DSL code, a build chain is declared inside a project by the sequential method that lists chained builds one by one. To group builds that will run in parallel to each other inside a chain, use the parallel method: the first subsequent build after the parallel block will depend on all the preceding parallel builds.

The following example illustrates a typical pipeline for compiling and deploying an application:

If you define a build chain in a pipeline style, ensure there are no explicit snapshot dependencies defined within the referenced build configurations themselves.

In the example above, a build chain references already declared builds. Alternatively, you can register all listed builds after the chain declaration with a simplified syntax:

Explicit snapshot dependencies can be defined via a dependsOn() statement within both parallel and sequential blocks, with an optional lambda argument that allows setting dependency options. Non-default values of options for implicit snapshot dependencies can be set via the options lambda argument of any block.

Settings Validation

The settings using the DSL API version v2017_2+ are validated during DSL execution on the TeamCity server. You can also perform validation locally by generating XML configuration files with help of generate task.

Validation checks that the mandatory properties are specified, for example a build step like this:

will produce a validation error saying that the mandatory path property is not specified. This is similar to the checks performed by TeamCity when you create a new build step in the UI.

You can also extend the validation in a way relevant for your setup. To do that, you need to override the validate() method. For example, the following class adds a custom validation to Git VCS roots:

Ability to Use External Libraries

You can use external libraries in your Kotlin DSL code, which allows sharing code between different Kotlin DSL-based projects.

To use an external library in your Kotlin DSL code, add a dependency on this library to the .teamcity/pom.xml file in the settings repository and commit this change so that TeamCity detects it. Then, before starting the generation process, the TeamCity server will fetch the necessary dependencies from the Maven repository, compile code with them, and then start the settings' generator.

You can establish access to external libraries in private repositories. For this, specify all the required credentials in the Maven settings file (mavenSettingsDsl.xml) and upload it on the Maven Settings page of the Root project.

Non-Portable DSL

TeamCity versions before 2018.1 used a different format for Kotlin DSL settings. If you import a project in this obsolete non-portable format, TeamCity will allow working with it. In this case, the Generate portable DSL scripts option will become available.

When TeamCity generates a non-portable DSL, the project structure in the .teamcity directory looks as follows:

• pom.xml

• <project id>/settings.kts

• <project id>/Project.kt

• <project id>/buildTypes/<build conf id>.kt

• <project id>/vcsRoots/<vcs root id>.kt

where <project id> is the ID of the project where versioned settings are enabled. The Kotlin DSL files producing build configurations and VCS roots are placed under the corresponding subdirectories.

Working with secure values in DSL

In general, TeamCity processes a DSL parameter as a string. To mark a DSL value as secure, you can assign it to a parameter of the password type:

where <parameter_name> is a unique name which can be used as a key for accessing the secure value via DSL (for example, in the File Content Replacer build feature); <token> is the token corresponding to the target secure value.

Example:

Why portable DSL requires the same prefix for all IDs?

Templates, build configurations, and VCS roots have unique IDs throughout all the TeamCity projects on the server. These IDs usually look like: <parent project id>_<entity id>.

Since these IDs must be unique, there cannot be two different entities in the system with the same ID.

However, one of the reasons why portable DSL is called portable is because the same settings.kts script can be used to generate settings for two different projects even on the same server.
To achieve this while overcoming IDs uniqueness, TeamCity operates with relative IDs in portable DSL scripts. These relative IDs do not have parent project ID prefix in them. So when TeamCity generates portable Kotlin DSL scripts, it has to remove the parent project ID prefix from the IDs of all the generated entities.

But this will not work if not all the project entities have this prefix in their IDs. In this case the following error can be shown:

Build configuration id '<some id>' should have a prefix corresponding to its parent project id: '<parent project id>'

To fix this problem, change the ID of the affected entity. If there are many such IDs, use the Bulk edit IDs project action to change all of them at once.

How to Add .teamcity as a New Module to a Project?

Question: How to add the .teamcity settings directory as a new module to an existing project in IntelliJ IDEA?

Solution: In your existing project in IntelliJ IDEA:

• Go to File | Project Structure, or press Ctrl+Shift+Alt+S.

• Select Modules under the Project Settings section.

• Click the plus sign, select Import module and choose the directory containing your project settings. Click OK and follow the wizard.

• Click Apply. The new module is added to your project structure.

How to Access Auxiliary Scripts from DSL Settings

To keep your settings files neat, it is convenient to store lengthy code instructions in separate files. Such auxiliary scripts can be put in the .teamcity directory alongside the settings files. You can refer to them by their relative paths.

For example, this part of settings.kts creates an object with a function readScript which reads the contents of the file it receives on input:

In the build step, we call this function, so it reads the scripts\test.sh file located under the .teamcity directory:

As a result, your Command Line build step will run a custom script with the body specified in scripts\simple.sh.

New URL of Settings VCS Root (Non portable format)

Problem: I changed the URL of the VCS root where settings are stored in Kotlin, and now TeamCity cannot find any settings in the repository at the new location.

Solution:

• Fix the URL in the Kotlin DSL in the version control and push the fix.

• Disable versioned settings to enable the UI.

• Fix the URL in the VCS root in the UI.

• Enable versioned settings with the same VCS root and the Kotlin format again. TeamCity will detect that the repository contains the .teamcity directory and ask you if you want to import settings.

• Choose to import settings.

How to Read Files in Kotlin DSL

Problem: I want to generate a TeamCity build configuration based on the data in some file residing in the VCS inside the .teamcity directory.

Solution:
You can access the location of the .teamcity directory from DSL scripts with help of the DslContext.baseDir property, for example:

Since 2019.2, this is the preferable approach as TeamCity no longer guarantee that the current working directory for DSL scripts is the same as the .teamcity directory.

Before 2019.2, the following code could be used:

How to reorder projects and build configurations

To reorder subprojects or build configurations inside a project via DSL, similarly to the respective UI option, pass their lists to subProjectsOrder or buildTypesOrder respectively. For example,

With these settings, the build configurations will be displayed in the UI in the following order: C, A, B.