nx/docs/nx-cloud/reference/launch-templates.md

Launch Templates

A launch template defines the setup steps Nx Agents will run before running tasks. A custom launch template isn't required to use Nx Agents. Nx Cloud provides several pre-built launch templates for common use-cases. You can view available templates in the nx-cloud-workflows repository.

{% github-repository url="https://github.com/nrwl/nx-cloud-workflows/tree/main/launch-templates" title="Pre-Built Launch Templates" /%}

Getting Started with Custom Launch Templates

The easiest way to create a new custom launch template is to modify one of the pre-built ones. To do that, create a file in the .nx/workflows folder and copy one of the pre-built templates. You can name the file any way you want (e.g., agents.yaml) and customize the steps as needed.

Launch Template Structure

launch-templates

A map of launch template configurations. This value is required.

launch-templates:

launch-templates.<template-name>

The name of your custom launch template. This name is used via --distribute-on="<# of agents> <template-name>" when starting the ci run. Supports one to many uniquely named launch templates. Multiple launch templates can be useful for setting up different toolchains (rust, java, node versions) or resources classes for your workspace needs.

launch-templates:
  template-one:
  template-two:

nx-cloud start-ci-run --distribute-on="3 template-one"

launch-templates.<template-name>.resource-class

A launch template's resource-class defines the memory and vCPUs available to each agent machine.

launch-templates:
  template-one:
    resource-class: 'docker_linux_amd64/medium'

The following resource classes are available:

• docker_linux_amd64/small
• docker_linux_amd64/medium
• docker_linux_amd64/medium+
• docker_linux_amd64/large
• docker_linux_amd64/large+
• docker_linux_amd64/extra_large
• docker_linux_amd64/extra_large+
• docker_linux_arm64/medium
• docker_linux_arm64/large
• docker_linux_arm64/extra_large
• windows/medium

See their detailed description and pricing at nx.app/pricing.

launch-templates.<template-name>.image

A launch template's image defines the available base software for the agent machine.

launch-templates:
  template-one:
    image: 'ubuntu22.04-node20.11-v7'

Nx Cloud provides the following images:

Changes added in previous images are included in newer images unless otherwise denoted

• ubuntu22.04-node20.11-v5
  • added elevated permission access via sudo
• ubuntu22.04-node20.11-v6
  • corepack is enabled by default
• ubuntu22.04-node20.11-v7
  • added java version 17
• windows-2022

Note: Windows-based images can only run on Windows-based resource classes.

Enterprise accounts can use custom images.

launch-templates.<template-name>.env

A launch template's env defines a map of environment variable names and values to be available within all steps of the specific launch template.

launch-templates:
  template-one:
    env:
      MY_ENV_VAR: 'my-var-value'

launch-templates.<template-name>.init-steps

A launch template's init-steps defines the series of steps to perform before an Nx Agent runs. Without a defined init-steps the Nx Agent is unable to process any tasks.

Typical init-steps perform actions such as checking out your workspace source code and installing any necessary dependencies. Any extra setup your workspace needs to run should be defined as an init-step. Once all steps run successfully, the agent machine will inform Nx Cloud that it is ready to accept tasks.

launch-templates:
  template-one:
    init-steps:

launch-templates.<template-name>.init-steps[*].name

An init-step's name is the label that will be reflected in the Nx Cloud UI. name can be used in conjunction with uses and script

launch-templates:
  template-one:
    init-steps:
      - name: 'My Helpful Step Name'

launch-templates.<template-name>.init-steps[*].uses

When defined, specifies an existing step file to be used. Cannot be used when script is also defined

You can find the list of Nx Cloud reusable steps here. If you cannot find a reusable step that suits your needs, you can create your own custom steps.

launch-templates:
  template-one:
    init-steps:
      - uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/checkout/main.yaml'
      - name: 'Install Node Modules'
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/install-node-modules/main.yaml'

launch-templates.<template-name>.init-steps[*].script

When defined, allows an inline script to be run. Cannot be used when uses is also defined

launch-templates:
  template-one:
    init-steps:
      - name: 'Print Node Version and PATH'
        script: |
          node -v
          echo $PATH

launch-templates.<template-name>.init-steps[*].env

An init-step's env is similar to the launch-template.<template-name>.env, except the environment variable map is scoped for the current step only.

launch-templates:
  template-one:
    init-steps:
      - name: 'Print Env'
        env:
          MY_STEP_ENV: 'step-env-var'
        script: |
          echo $MY_STEP_ENV # prints "step-env-var"

launch-templates.<template-name>.init-steps[*].inputs

An init-step's inputs is defined by the step file in the launch-template.<template-name>.init-steps[*].uses property. Refer to the step file's documentation for specific inputs.

Validation can also be done to validate the step against the step file's defined inputs

launch-templates:
  template-one:
    init-steps:
      - name: Restore Node Modules Cache
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/cache/main.yaml'
        inputs:
          env: 'package-lock.json|yarn.lock|pnpm-lock.yaml'
          paths: 'node_modules'
          base-branch: 'main'

Full Example

This is an example of a launch template using all pre-built features:

launch-templates:
  # Custom template name, the name is referenced via --distribute-on="3 my-linux-medium-js"
  # You can define as many templates as you need, commonly used to make different sizes or toolchains depending on your workspace needs
  my-linux-medium-js:
    # see the available resource list below
    resource-class: 'docker_linux_amd64/medium'
    # see the available image list below
    image: 'ubuntu22.04-node20.11-v7'
    # Define environment variables shared among all steps
    env:
      MY_ENV_VAR: shared
      # list out steps to run on the agent before accepting tasks
      # the agent will need a copy of the source code and dependencies installed
    init-steps:
      - name: Checkout
        # using a reusable step in an external GitHub repo,
        # this step is provided by Nx Cloud: https://github.com/nrwl/nx-cloud-workflows/tree/main/workflow-steps
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/checkout/main.yaml'
      - name: Restore Node Modules Cache
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/cache/main.yaml'
        # the cache step requires configuration via env vars
        # https://github.com/nrwl/nx-cloud-workflows/tree/main/workflow-steps/cache#options
        inputs:
          env: 'package-lock.json|yarn.lock|pnpm-lock.yaml'
          paths: 'node_modules'
          base-branch: 'main'
      - name: Restore Browser Binary Cache
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/cache/main.yaml'
        inputs:
          env: 'package-lock.json|yarn.lock|pnpm-lock.yaml|"browsers"'
          paths: |
            '~/.cache/Cypress'
            '~/.cache/ms-playwright'
          base-branch: 'main'
      - name: Install Node Modules
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/install-node-modules/main.yaml'
      - name: Install Browsers (if needed)
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/install-browsers/main.yaml'
        # You can also run a custom script to configure various things on the agent machine
      - name: Run a custom script
        script: |
          git config --global user.email test@test.com
          git config --global user.name "Test Test"
      # You can also set any other env vars to be passed to the following steps
      # by setting their value in the `$NX_CLOUD_ENV` file.
      # Most commonly for redefining PATH for further steps
      - name: Setting env
        script: |
          # Update PATH with custom value
          echo "PATH=$HOME/my-folder:$PATH" >> $NX_CLOUD_ENV
      - name: Print path from previous step
        # will include my-folder
        script: echo $PATH
      - name: Define env var for a step
        env:
          MY_ENV_VAR: 'env-var-for-step'
        # will print env-var-for-step
        script: echo $MY_ENV_VAR
      # after you're last step Nx Agents will start accepting tasks to process
      # no need to manually start up the agent yourself

  # another template which does the same as above, but with a large resource class
  # You're not required to define a template for every resource class, only define what you need!
  my-linux-large-js:
    resource-class: 'docker_linux_amd64/large'
    image: 'ubuntu22.04-node20.11-v7'
    env:
      MY_ENV_VAR: shared
    init-steps:
      - name: Checkout
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/checkout/main.yaml'
      - name: Restore Node Modules Cache
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/cache/main.yaml'
        inputs:
          env: 'package-lock.json|yarn.lock|pnpm-lock.yaml'
          paths: 'node_modules'
          base-branch: 'main'
      - name: Restore Browser Binary Cache
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/cache/main.yaml'
        inputs:
          env: 'package-lock.json|yarn.lock|pnpm-lock.yaml|"browsers"'
          paths: |
            '~/.cache/Cypress'
            '~/.cache/ms-playwright'
          base-branch: 'main'
      - name: Install Node Modules
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/install-node-modules/main.yaml'
      - name: Install Browsers (if needed)
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/install-browsers/main.yaml'
      - name: Run a custom script
        script: |
          git config --global user.email test@test.com
          git config --global user.name "Test Test"
      - name: Setting env
        script: |
          echo "PATH=$HOME/my-folder:$PATH" >> $NX_CLOUD_ENV
      - name: Print path from previous step
        script: echo $PATH
      - name: Define env var for a step
        env:
          MY_ENV_VAR: 'env-var-for-step'
        script: echo $MY_ENV_VAR
  # template that installs rust
  my-linux-rust-large:
    resource-class: 'docker_linux_amd64/large'
    image: 'ubuntu22.04-node20.11-v7'
    init-steps:
      - name: Checkout
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/checkout/main.yaml'
      - name: Restore Node Modules Cache
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/cache/main.yaml'
        inputs:
          env: 'package-lock.json|yarn.lock|pnpm-lock.yaml'
          paths: 'node_modules'
          base-branch: 'main'
      - name: Install Node Modules
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/install-node-modules/main.yaml'
      - name: Install Rust
        script: |
          curl --proto '=https' --tlsv1.3 https://sh.rustup.rs -sSf | sh -s -- -y
          source "$HOME/.cargo/env"
          rustup toolchain install 1.70.0
          # persist cargo bin into PATH
          echo "PATH=$HOME/.cargo/bin:$PATH" >> $NX_CLOUD_ENV

These templates can be used by passing the number of agents desired, and the template name via --distribute-on when starting your CI run.

nx-cloud start-ci-run --distribute-on="4 my-linux-medium-js"

nx-cloud start-ci-run --distribute-on="4 my-linux-large-js"

nx-cloud start-ci-run --distribute-on="4 my-linux-large-rust"

Validating Launch Templates

{% callout type="note" title="Commit before Validation" %} Before Nx Cloud can validate your custom templates, you must first commit any changes to these templates to your source control repository. Running the validation command from a CI is the recommended approach. {% /callout %} After creating your custom launch template, it's recommended to validate it. This ensures that all necessary fields within the launch template and all respective inputs within each step are appropriately defined.

To do this, run the nx-cloud validate command, with the path to the launch template:

nx-cloud validate --workflow-file=./.nx/workflows/agents.yaml

Pass Environment Variables to Agents

If you need to send environment variables to agents, you can use the --with-env-vars flag on the nx-cloud start-ci-run command. You can pass a specific list of environment variables like this:

nx-cloud start-ci-run --distribute-on="8 linux-medium-js" --with-env-vars="VAR1,VAR2"

Or pass all the environment variables except OS-specific ones with this --with-env-vars="auto":

nx-cloud start-ci-run --distribute-on="8 linux-medium-js" --with-env-vars="auto"

Pass Values Between Steps

If you need to pass a value from one step to another step, such as assigning the value to an existing or new environment variable. You can write to the NX_CLOUD_ENV environment file.

Commonly used for redefining the PATH or setting options for tooling.

launch-templates:
  my-template-name:
    init-steps:
      - name: Set PATH
        script: echo "PATH=$HOME/.cargo/bin:$PATH" >> $NX_CLOUD_ENV
      - name: Check PATH
        script: |
          # now contains $HOME/.cargo/bin
          echo $PATH 
          # can invoke cargo directly because it's in the PATH now. 
          cargo --version

Private NPM Registry

If your project consumes packages from a private registry, you'll have to set up an authentication step in a custom launch template and authenticate like you normally would, usually this is via a .npmrc or .yarnrc file. You can pass the auth token from your main agent, so it's available to the agent machines.

launch-templates:
  my-linux-medium-js:
    resource-class: 'docker_linux_amd64/medium'
    image: 'ubuntu22.04-node20.11-v7'
    init-steps:
      - name: Checkout
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/checkout/main.yaml'
      - name: Auth to Registry
        script: |
          # create .npmrc with @myorg scoped packages pointing to GH npm registry
          echo "@myorg:registry=https://npm.pkg.github.com" >> .npmrc
          echo "//npm.pkg.github.com/:_authToken=${SOME_AUTH_TOKEN}" >> .npmrc
      - name: Install Node Modules
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/install-node-modules/main.yaml'

Pass SOME_AUTH_TOKEN via --with-env-vars

# this assumes SOME_AUTH_TOKEN is already defined on the main agent
nx-cloud start-ci-run --distribute-on="5 my-linux-medium-js" --with-env-vars="SOME_AUTH_TOKEN"

Custom Node Version

Nx Agents come with node LTS installed. If you want to use a different version, you can create a custom step to install the desired node version. Here is a simplified launch template using nvm to install a different node version.

launch-templates:
  node-21:
    resource-class: 'docker_linux_amd64/medium'
    image: 'ubuntu22.04-node20.11-v7'
    init-steps:
      - name: Checkout
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/checkout/main.yaml'
      - name: Install nvm
        script: |
          # run nvm install script
          curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash
          # source the updated profile to get the nvm command available
          source ~/.profile
          # install the needed version of node via nvm
          nvm install 21.7.3
          # echo the current path (which now includes the nvm-provided version of node) to NX_CLOUD_ENV
          echo "PATH=$PATH" >> $NX_CLOUD_ENV
      - name: Print node version
        # confirm that the node version has changed
        script: node -v
      - name: Install Node Modules
        uses: 'nrwl/nx-cloud-workflows/v4/workflow-steps/install-node-modules/main.yaml'
      # Continue setup steps as needed

Specific Package Manager Version

Nx Agents have corepack enabled by default, allowing you to define the yarn or pnpm version via the package.json.

{
  "packageManager": "yarn@4.1.1"
}

{% callout type="note" title="Supported Package Managers" %} Currently, corepack only supports yarn or pnpm as package managers. If you need to use a specific npm version, you will need to create a custom launch template and install the specific npm version. {%/callout %}

Installing Packages on Nx Agents

You can use apt to install popular linux packages. This is helpful in streamlining setting up various toolchains needed for your workspace.

For example, you can install the GitHub CLI on the agents if needed.

launch-templates:
  my-linux-medium-js:
    resource-class: 'docker_linux_amd64/medium'
    image: 'ubuntu22.04-node20.11-v7'
    init-steps:
      - name: Install GH CLI
        script: |
          sudo apt install gh -y

{% callout type="note" title="Installing without apt" %} If you're trying to install a package that isn't available on apt, check that packages install steps for Debian base linux. Usually there are a handful of installation scripts that can be used similar to nvm {% /callout %}

Dynamic Changesets

NxCloud can calculate how big your pull request is based on how many projects in your workspace it affects. You can then configure Nx Agents to dynamically use a different number of agents based on your changeset size.

Here we define a small, medium and large distribution strategy:

distribute-on:
  small-changeset: 3 linux-medium-js
  medium-changeset: 8 linux-medium-js
  large-changeset: 12 linux-medium-js

Then you can pass the path to the file to the --distribute-on parameter.

nx-cloud start-ci-run --distribute-on=".nx/workflows/dynamic-changesets.yaml"