RamalLive (RamalLive v0.2.0)

A LiveView inspector for Ramal branches.

It shows the open and proposed branches of one Ash domain as columns. Each column has the branch's name, status, age and overlay size, and its Ramal.diff/1 as before and after rows. Buttons fork, merge and discard an open branch and approve or reject a proposal; merge, discard, approve and reject ask for a second click first. While the page is open, Ramal's telemetry keeps the columns current: only the branch that changed is read again.

ramal_live is a separate package that depends on ramal. Ramal itself never depends on it, and it has no JavaScript, no Tailwind and no asset pipeline: the page is a LiveView with inline CSS, mounted by the host's router inside the host's own live_session, so it uses the host's socket and the host's JavaScript.

Setup

1. Depend on it. It is not on Hex yet, so use a checkout of the Ramal repository, which holds both packages (ramal_live finds Ramal one directory up):

   {:ramal, path: "../ramal"},
   {:ramal_live, path: "../ramal/ramal_live"}

2. Start RamalLive.Broadcaster after the PubSub and Ramal.Supervisor, in every node that runs branches:

   {RamalLive.Broadcaster, pubsub: MyApp.PubSub}

3. Mount the page in the router, behind the host's authorization (see RamalLive.Router):

   import RamalLive.Router
   
   scope "/admin" do
     pipe_through [:browser, :require_admin]
   
     live_session :admin, on_mount: [{MyAppWeb.UserAuth, :ensure_admin}] do
       ramal_inspector "/ramal", domain: MyApp.Farm, pubsub: MyApp.PubSub, actor: {MyAppWeb.Inspector, :actor}
     end
   end

Things to know

• Authorization is the host's. Whoever can open the page can merge and discard any branch of the domain. Ramal records who decided but never checks; RamalLive.Router requires an :actor option to pass the current user along.
• Fonts. Headings ask for Barlow Condensed and data for IBM Plex Mono. The page does not load them, so a host that wants them adds the link tag to its root layout; otherwise the system's condensed and monospace fonts are used.
• Content security policy. The CSS is an inline <style> element. A policy without style-src 'unsafe-inline' blocks it.
• Reading loads. The page reads each branch it shows with Ramal.get/1, which starts the branch's process if it was unloaded. Processes unload again after Ramal.Supervisor's idle_timeout.
• Telemetry. Every read of a branch emits [:ramal_live, :column, :read], with %{branch_id, domain} metadata and a duration measurement in native time units.
• Themes. The page follows prefers-color-scheme; the buttons in its header pick a theme for the open page only.