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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.

Getting Started with Custom Launch Templates

Section titled “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.

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

.nx/workflows/agents.yaml
launch-templates:

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.

.nx/workflows/agents.yaml
launch-templates:
template-one:
template-two:
nx-cloud start-ci-run --distribute-on="3 template-one"

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

.nx/workflows/agents.yaml
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 in the credits pricing reference.

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

.nx/workflows/agents.yaml
launch-templates:
template-one:
image: 'ubuntu22.04-node20.11-v9'

Nx Cloud provides the following images:

Changes added in previous images are included in newer images unless otherwise denoted Images also have go 1.22 installed

  • ubuntu22.04-node20.11-v5

    • added elevated permission access via sudo
  • ubuntu22.04-node20.11-v6

  • ubuntu22.04-node20.11-v7

    • added java version 17
  • ubuntu22.04-node20.11-v9

  • windows-2022

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

Enterprise accounts can use custom images.

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.

.nx/workflows/agents.yaml
launch-templates:
template-one:
env:
MY_ENV_VAR: 'my-var-value'

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.

.nx/workflows/agents.yaml
launch-templates:
template-one:
init-steps:

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

.nx/workflows/agents.yaml
launch-templates:
template-one:
init-steps:
- name: 'My Helpful Step Name'

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.

.nx/workflows/agents.yaml
launch-templates:
template-one:
init-steps:
- uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/checkout/main.yaml'
- name: 'Install Node Modules'
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/install-node-modules/main.yaml'

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

.nx/workflows/agents.yaml
launch-templates:
template-one:
init-steps:
- name: 'Print Node Version and PATH'
script: |
node -v
echo $PATH

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.

.nx/workflows/agents.yaml
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"

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

.nx/workflows/agents.yaml
launch-templates:
template-one:
init-steps:
- name: Restore Node Modules Cache
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/cache/main.yaml'
inputs:
# Include patches directories to ensure cache is busted when patches change
key: 'package-lock.json|yarn.lock|pnpm-lock.yaml|patches/**|.yarn/patches/**|pnpm-patches/**'
paths: |
~/.npm
# or ~/.cache/yarn
# or .pnpm-store
base-branch: 'main'

You can define "step groups" that run in parallel. This can be useful for taking better advantage of the available CPUs of your chosen resource class. In the example below, we can run NPM Install and install the Rust dependencies in parallel, because they do not depend on each other and they write to different places on the filesystem. Running them in parallel can reduce agent startup time by up to 2 minutes, which can add up to a lot of compute time savings over the month.

⚠️ Tips for using parallel steps:

  • don't assume everything can be run in parallel
    • you'll notice below we had to run playwright install after the parallel group, as it was likely writing to the same locations and fighting for similar resources to npm install
    • experiment with different parallel groups and measure startup times until you land on the most optimal config for your use-case
  • write to PATH once
    • multiple parallel processes can overwrite each other's changes if they write to the same >> $NX_CLOUD_ENV location
    • below, we only update the PATH variable once at the end echo "PATH=$CARGO_PATH:$POETRY_PATH:$PATH" >> $NX_CLOUD_ENV
.nx/workflows/agents.yaml
launch-templates:
template-one:
init-steps:
- group-name: Install Dependencies
parallel: true
# all the below steps will start at the same time and run in parallel
steps:
- name: Install Rust
script: |
curl --proto '=https' --tlsv1.3 https://sh.rustup.rs -sSf | sh -s -- -y
source "~/workspace/.cargo/env"
# we write the CARGO_PATH now so that it can be set in the "Start Services" step below
echo "CARGO_PATH=~/workspace/.cargo/bin" >> $NX_CLOUD_ENV
rustc --version
rustup target add wasm32-wasip1-threads
cargo fetch
cargo check --locked
- name: NPM Install
uses: 'nrwl/nx-cloud-workflows/main/workflow-steps/install-node-modules/main.yaml'
- name: Install Poetry
script: |
curl -sSL https://install.python-poetry.org | python3 -
# we write the POETRY_PATH now so that it can be set in the "Start Services" step below
export POETRY_PATH="/home/workflows/.local/bin"
export PATH="$POETRY_PATH:$PATH"
echo "POETRY_PATH=$POETRY_PATH" >> $NX_CLOUD_ENV
poetry --version
poetry install
- name: Install Localstack
script: |
curl --output localstack-cli-3.7.0-linux-amd64-onefile.tar.gz --location https://github.com/localstack/localstack-cli/releases/download/v3.7.0/localstack-cli-3.7.0-linux-amd64-onefile.tar.gz
sudo tar xvzf localstack-cli-3.7.0-linux-*-onefile.tar.gz -C /usr/local/bin
# because both playwright and "npm install" use NPM and write to a lot of the same places on the filesystem, it would be slower to run them both in parallel
# so we run playwright after the parallel group above
- name: Install Playwright
script: npx playwright install --with-deps
- name: Start services
script: |
# we create the PATH here
echo "PATH=$CARGO_PATH:$POETRY_PATH:$PATH" >> $NX_CLOUD_ENV
npm run start-docker-services

We can also group steps and run them serially. This is actually the default behaviour when you don't set parallel: true for a group.

This can be useful if we have a set of quick enough steps, such as restoring from cache, where we don't need to optimise for speed, and instead we just want them grouped together logically. The below cache steps will also be collapsed together in the Agents UI, making the config look cleaner:

- group-name: Restore Cache
steps:
- name: Restore Node Modules Cache
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/cache/main.yaml'
inputs:
# Include patches directories to ensure cache is busted when patches change
key: 'package-lock.json|patches/**|.yarn/patches/**|pnpm-patches/**'
paths: |
~/.npm
base-branch: 'main'
- name: Restore Browser Binary Cache
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/cache/main.yaml'
inputs:
# Include patches directories to ensure cache is busted when patches change
key: 'package-lock.json|patches/**|.yarn/patches/**|pnpm-patches/**|"browsers"'
paths: |
'~/.cache/Cypress'
base-branch: 'main'

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

./nx/workflows/agents.yaml
# Define common setup steps that can be reused across templates
common-init-steps: &common-init-steps
# 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
- name: Checkout
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/checkout/main.yaml'
- name: Restore Node Modules Cache
uses: 'nrwl/nx-cloud-workflows/v5/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:
# Include patches directories to ensure cache is busted when patches change
# If you use a custom patches directory, add it to the key as well
key: 'package-lock.json|yarn.lock|pnpm-lock.yaml|patches/**|.yarn/patches/**'
paths: |
~/.npm
# or ~/.cache/yarn
# or .pnpm-store
base-branch: 'main'
- name: Restore Browser Binary Cache
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/cache/main.yaml'
inputs:
key: 'package-lock.json|yarn.lock|pnpm-lock.yaml|"browsers"'
paths: |
'~/.cache/Cypress'
base-branch: 'main'
- name: Install Node Modules
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/install-node-modules/main.yaml'
- name: Install Browsers (if needed)
uses: 'nrwl/nx-cloud-workflows/v5/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"
- name: Define Step Env Var
# this env var will be available to all future steps using these 'common-init-steps' reusable steps
# persist env vars between steps by writing to the $NX_CLOUD_ENV file
script: |
echo "MY_STEP_ENV=step-env-var" >> $NX_CLOUD_ENV
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:
resource-class: 'docker_linux_amd64/medium'
image: 'ubuntu22.04-node20.11-v9'
# Define environment variables shared among all steps in this launch template
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
# note we are using yaml anchors to reduce duplication with the below launch-template (they have the same init-steps)
init-steps: *common-init-steps
# 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-v9'
env:
MY_ENV_VAR: shared
# note we are using yaml anchors to reduce duplication with the above launch-template (they have the same init-steps)
init-steps:
# use YAML anchor to include common init setup
<<: *common-init-steps
- name: Print Env Var from reusable step
script: |
echo $MY_STEP_ENV # prints "step-env-var"
# template that installs rust (demonstrates extending base steps)
my-linux-rust-large:
resource-class: 'docker_linux_amd64/large'
image: 'ubuntu22.04-node20.11-v9'
init-steps:
# use YAML anchor to include common init setup
<<: *common-init-steps
# add Rust-specific steps
- name: Install Rust
script: |
curl --proto '=https' --tlsv1.3 https://sh.rustup.rs -sSf | sh -s -- -y
source "$HOME/.cargo/env"
rustup toolchain install stable
# 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"

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

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"

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.

./nx/workflows/agents.yaml
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

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.

.nx/workflows/agents.yaml
launch-templates:
my-linux-medium-js:
resource-class: 'docker_linux_amd64/medium'
image: 'ubuntu22.04-node20.11-v9'
init-steps:
- name: Checkout
uses: 'nrwl/nx-cloud-workflows/v5/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/v5/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"

Nx Agents come with node LTS installed. If you want to use a different version, you can add a step to install the desired node version.

Nx Cloud provides a pre-built step to install a custom node version within your workflow. This step is available as of v4 of the workflow steps and requires the minimum image version to be ubuntu22.04-node20.11-v9.

.nx/workflows/agents.yaml
launch-templates:
node-21:
resource-class: 'docker_linux_amd64/medium'
# note the image version of v9,
# earlier versions of the base image will not work
image: 'ubuntu22.04-node20.11-v9'
init-steps:
- name: Checkout
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/checkout/main.yaml'
- name: Install Node
# note the step is only released as of v4 of the workflow steps
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/install-node/main.yaml'
inputs:
# can omit value if a '.nvmrc' file is within the root of the repo
node_version: '21'

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

package.json
{
"packageManager": "yarn@4.1.1"
}

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.

./nx/workflows/agents.yaml
launch-templates:
my-linux-medium-js:
resource-class: 'docker_linux_amd64/medium'
image: 'ubuntu22.04-node20.11-v9'
init-steps:
- name: Install Extras
script: |
sudo apt install gh unzip zip -y

First, define the environment variables on your main agent, where you call nx-cloud start-ci-run. Pass the same environment variables to your agents via the --with-env-vars flag.

Minimally the AWS_REGION (or AWS_DEFAULT_REGION), AWS_ACCESS_KEY_ID, and AWS_SECRET_ACCESS_KEY environment variables are required.

Using the pre-built step simplifies and provides debugging checks to make sure the AWS CLI is properly authenticated to AWS before continuing. The step is recommended for most use cases.

./nx/workflows/agents.yaml
launch-templates:
my-linux-medium-js:
resource-class: 'docker_linux_amd64/medium'
image: 'ubuntu22.04-node20.11-v9'
init-steps:
- name: Install AWS CLI
uses: 'nrwl/nx-cloud-workflows/v5/workflow-steps/install-aws-cli/main.yaml'
# no additional inputs required, as all configuration is via environment variables via --with-env-vars

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:

.nx/workflows/dynamic-changesets.yaml
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"

You can add steps to your template which print information about your workspace, toolchains, or any other needs. Below are some common steps people use for debugging such as running nx commands, printing file contents and/or listing directory contents.

.nx/workflows/agents.yaml
launch-templates:
my-linux-medium-js:
resource-class: 'docker_linux_amd64/medium'
image: 'ubuntu22.04-node20.11-v9'
env:
# enable verbose logging for all steps
NX_VERBOSE_LOGGING: true
init-steps:
- name: 'Debug: Print Nx Report'
script: |
nx report
- name: 'Debug: List Directory Contents'
script: |
echo $HOME
ls -la $HOME
output_dir=$HOME/dist
# if output directory exists list it's contents
if [ -d output_dir ]; then
ls -la $output_dir
else
echo "$output_dir does not exist"
fi
- name: 'Debug: Show File Contents'
script: |
cat $HOME/.profile
- name: 'Debug: Check For Checkout Files'
script: |
git diff
- name: 'Debug: Print Versions'
script: |
# note if you use yarn and try to run pnpm, corepack might throw an error at you
# saying you're using the wrong package manager, in that case just remove the usage of pnpm
echo "Versions:"
echo "Node: $(node -v)"
echo "NPM: $(npm -v)"
echo "Yarn: $(yarn -v)"
echo "PNPM: $(pnpm -v)"
echo "Golang: $(go version)"
echo "Java: $(javac --version)"
# add any other toolchain you want
- name: 'Debug: Print env'
script: |
# !!! DO NOT RUN THIS IF YOU HAVE PASSWORD/ACCESS TOKENS IN YOUR ENV VARS !!!
# this will print your env as plain text values to the terminal
env
# This is a safer approach to prevent leaking tokens/passwords
echo "SOME_VALUE: $SOME_VALUE"