Observer

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Continuum Observer is an optional Phoenix LiveView UI for inspecting workflow runs. It is not started by Continuum.Application; mount it in your Phoenix router when your app directly depends on :phoenix_live_view and :phoenix_html. Continuum declares Phoenix as optional; host applications that mount the Observer must include the Phoenix dependencies they use.

defmodule MyAppWeb.Router do
  use MyAppWeb, :router

  import Continuum.Observer.Router

  scope "/admin" do
    pipe_through [:browser, :authenticate_admin]

    continuum_observer "/continuum", instance: :myapp_continuum
  end
end

Do not mount the Observer publicly. Continuum does not ship authentication or authorization callbacks in v0.2; the host application owns access control.

The Observer provides:

  • a runs index at /continuum with state, workflow, run id search, and stable cursor pagination
  • a run detail page at /continuum/runs/:id with run metadata and decoded journal events
  • operator actions for cancelling a run and sending a JSON signal payload
  • an operational health panel at /continuum/health backed by Continuum.Health, including partition/version drift, run wait reasons, durable wake and timer lag, lease heartbeats, activity queues, dead-letter candidates, and signal backlog

Health repairs in the panel always perform a dry-run preview first. The confirmation step executes the same fenced, idempotent repair API exposed by mix continuum.health; stale lease epochs, owners, and attempts are rejected.

The index subscribes to the per-instance "continuum:runs" PubSub topic. That topic intentionally receives only coarse state changes and terminal transitions. Detail pages subscribe to the existing per-run topic, "continuum:run:<run_id>".

Event payloads are decoded with :erlang.binary_to_term/1 because Continuum stores its own journal data as bytea. Treat database write access as trusted; the Observer is not a sandbox for malicious journal rows.

Run and event payloads are bounded before decoding. Configure a unary redactor globally with config :continuum, observer_redactor: MyApp.Redactor, where the module exports redact/1, or pass redactor: and max_payload_bytes: to the Observer query helpers. Oversized payloads are represented by an omission map that includes their encoded byte size. Event pages use sequence cursors and the display renderer also applies a hard byte cap.

The underlying Continuum.Query API supports nested, type-preserving attribute filters without abandoning the generated JSONB GIN index:

Continuum.query(
  where: [{:eq, [:attributes, :customer, :profile, :tier], 4}],
  cursor: previous_page.next_cursor
)

Continuum includes priv/static/observer.css as a small baseline stylesheet. Copy or serve it from your host app if you want the default styling. One simple option is to serve it directly from the Continuum dependency:

plug Plug.Static,
  at: "/",
  from: :continuum,
  only: ~w(observer.css)

You can also copy it into your app's priv/static directory and allow it from your existing Plug.Static:

plug Plug.Static,
  at: "/",
  from: :my_app,
  gzip: false,
  only: ~w(assets fonts images favicon.ico robots.txt observer.css)