Writing a system

Require Mobilis and declare services inside Mobilis::DSL.generate. The outer block exposes DSL methods; service configuration uses an explicit block argument.

require "mobilis"

Mobilis::DSL.generate("my-system") do
  database = postgres("app-db")
  rails("app", primary_database: database) do |service|
    service.use_rspec!
    service.add_rails_model("user") do |model|
      model.string "name"
      model.integer "score"
    end
  end
end

This is a materializing entrypoint: running the definition writes generate/ and performs image builds and scaffolding commands.

Service declarations

Area	DSL methods
Ruby applications	rails, rack
HTTP applications and proxy	flask, fastapi, go_http, envoy, grafbase
Databases and cache	postgres, mysql, redis, pgadmin
Object storage	s3 (also s3_storage)
Messaging	google_pubsub, goaws, legacy localstack
Observability	otel_collector, jaeger, prometheus, grafana, loki, alloy

Declarations return service nodes. Pass those nodes to options such as primary_database: or to connect:

Mobilis::DSL.generate("rack-example") do
  cache = redis("cache")
  app = rack("app")
  connect(from: app, to: cache)
end

connect records a directed dependency and supplies URL environment wiring. Plugins and service writers also generate type-specific code, including filtered ActiveResource clients and OpenTelemetry setup. See Connection affordances for exactly what each connection produces.

Names and references

Node names normalize underscores to hyphens. named and string-based connect look up the original name passed to the DSL; node references avoid that distinction.

Ruby dependencies and source

Rails and Rack nodes support add_gem for dependencies and local_gem / use_local_gem for generated shared libraries. See Shared local gems for paths, source files, and image builds.

Service nodes accept write_file(path, content) for generated source. The example scripts show service-specific configuration, observability connections, models, and HTTP migration routes.

Kubernetes intent

Add deploy_kubernetes alongside service declarations to emit resources for the same realized environments. See Kubernetes and Istio.