Build

Defined insandbox.hcl

The build resource builds a container image from a Dockerfile during provisioning and, optionally, pushes it to one or more registries. Other resources can then reference the built image, letting a lab ship custom images without a separate CI pipeline.

HCL Syntax

Basic Syntax

resource "build" "app" {
  container {
    context    = "./src"
    dockerfile = "./Dockerfile"
  }
}

Full Syntax

resource "build" "app" {
  container {
    context    = "./src"
    dockerfile = "./Dockerfile"
    args = {
      VERSION = "1.0.0"
    }
    ignore = ["node_modules", ".git"]
  }

  registry {
    name = "registry.example.com/app:latest"
  }
}

Fields

Field	Type	Required	Description
container	block	✓	Container build configuration
output	block	—	Files or directories to copy from the containerrepeatable
registry	block	—	Registry to push the built image torepeatable

Container

build→Container

Container build configuration

Field	Type	Required	Description
dockerfile	string	—	Location of Dockerfile inside build context, defaults to ./Dockerfile
context	string	✓	Path to build context
ignore	list(string)	—	Files to ignore in the build context, same as .dockerignore
args	map(string)	—	Build args to pass to the container

Output

build→Output

Files or directories to copy from the container

Field	Type	Required	Description
source	string	✓	Source file or directory in the container
destination	string	✓	Destination for copied file or directory

Registry

build→Registry

Registry to push the built image to

Field	Type	Required	Description
name	string	✓	Full image name including registry and tag
username	string	—	Registry username for authentication
password	string	—	Registry password for authentication

Computed Attributes

These attributes are set by the system and are read-only.

Attribute	Type	Description
image	string	Full local reference of the built image
build_checksum	string	Checksum calculated from the build context files

Examples

Build and reference an image

resource "build" "app" {
  container {
    context = "./app"
  }
}

resource "container" "app" {
  image {
    name = resource.build.app.image
  }
}

Best Practices

1. Small contexts: Keep the build context minimal and use ignore to exclude files that don’t belong in the image.
2. Explicit tags: Give pushed images explicit tags in registry.name rather than relying on latest.