Adding Steps

You can easily customize the install and build commands with environment variables. However, sometimes you can also add additional steps to your build. This is useful if you want to optimize cache hits or don’t want to affect the automatically generated provider commands.

Adding a Step

To add a step, you can use the steps field in your configuration file.

{
  "$schema": "https://schema.railpack.com",
  "steps": {
    "new-step": {
      "commands": ["echo 'Hello, world!'"]
    },
  }
}

The default inputs for a new step is:

"inputs": [
  { "step": "packages:mise" }
]

This means that the commands will run in the build image with access to Mise and build apt packages.

If you want to run after a specific provider-generated step, you can specify the inputs. For example, this will run the new-step after the build step.

{
  "$schema": "https://schema.railpack.com",
  "steps": {
    "new-step": {
      "inputs": [
        { "step": "build" }
      ],
      "commands": ["echo 'Hello, world!'"]
    },
  }
}

Including the step output in the final image

By default, the entire /app directory is included in the final image. You can customize this by specifying a deployOutputs field. For example, this will include the dist directory in the final image.

{
  "$schema": "https://schema.railpack.com",
  "steps": {
    "new-step": {
      "commands": ["echo 'Hello, world!'"],
      "deployOutputs": [
        "dist"
      ]
    },
  }
}

Note: deployOutputs is syntactic sugar for adding this layer to the deploy.inputs field. The above example is equivalent to.

{
  "$schema": "https://schema.railpack.com",
  "steps": {
    "new-step": {
      "commands": ["echo 'Hello, world!'"],
      "deployOutputs": []
    },
  },
  "deploy": {
    "inputs": [
      { "step": "new-step", "include": ["dist"] }
    ]
  }
}

Setting the deployOutputs to an empty array will mean that no files from the step are included in the final image and therefore no commands will be executed.

Running commands that affect the runtime image

This is possible, but not recommended at the moment. Is is instead recommended to use

• deploy.aptPackages to install packages that are needed at runtime
• Copy specific files from a step into the runtime image with deployOutputs

Does this not work? Let us know on Discord or GitHub.