Extension Block

The extension block defines extension configuration at workspace scope. These settings apply globally and can be overridden in PROJECT files.

Example

extension @dotnet {
  container = "mcr.microsoft.com/dotnet/sdk:8.0"
  platform = "linux/arm64"
  cpus = 2
  variables = [ "NUGET_KEY" ]
  defaults = {
    configuration = var.configuration
  }
}

extension npm_ci {
  script = "tools/extensions/npm-ci.fss"
}

Arguments

• identifier (required): extension identifier.
• container (optional): container image used to run extension actions.
• platform (optional): target container platform (linux/amd64, linux/arm64, …).
• cpus (optional): max CPUs for container execution (strictly positive).
• variables (optional): host env variable names forwarded to container.
• defaults (optional): default action arguments for this extension.
• script (optional): scripted implementation source.

Identifier conventions

• Built-in extensions use @... identifiers (for example @dotnet, @npm, @terraform).
• Custom extensions should use non-@ identifiers.

Script sources

script supports:

• local .fss path inside the workspace
• HTTPS URL to a .fss script

See Script Extensibility.