Define a Ruby service that runs via bundler

service "ruby" "ruby-service" {
  git {
    url = "github.com/niwasawa/ruby-sinatra-hello-world"
  }

  vars = { port = net::pickport() }
  log {
    format = "plain"
    filter = <<-EOT
      hasPrefix(line, "\tfrom ") or hasPrefix(line, "/Users/")
    EOT
  }

  runtime {
    cmd = ["bundle", "exec", "ruby", "myapp.rb", "-p", "${self.vars.port}"]
  }
}

Source

git or src, like Go (no crate). branch/tag/rev pin the revision; relative src resolves against the Alphasfile's directory.

Build & run

The default "build" is dependency install in the checkout:

bundle config set --local path vendor/bundle && bundle install

(--path was removed in Bundler 2.x, so the path is written to the per-checkout .bundle/config first — which also lets bundle exec find the gems at runtime.)

Ruby has no single binary, so the run command is not inferred — give an explicit runtime { cmd = [...] } (e.g. bundle exec ..., rails server, rackup). It runs with cwd = the per-invocation checkout, so Gemfile/app files resolve. Override the install step with build { cmd = [...] } if bundle install isn't what you want.

Logs

Ruby stack traces are noisy; a log { filter = "<expression>" } block drops matching lines (e.g. the from … backtrace frames) at the source, before they reach the streamed output or alpha's log. The filter is a small predicate DSL — hasPrefix/contains/matches on the raw line, plus json/logfmt/severity for structured fields — see the log filter reference.