Phase 4a: deployment-provisioning choreography saga

Wire a full tenant deployment as one orchestrated, compensating saga:
mark → create droplet → wait active → register in inventory → link to
deployment → point DNS → activate. A failure anywhere rolls the whole
thing back — droplet destroyed, DNS reverted, deployment moved to
cancelled.

- New lifecycle state `provisioning`; deployments created via the
  provision path enter here and only reach `active` once the saga's
  ActivateDeployment step runs.
- Four new steps: MarkDeploymentProvisioning (owns the deployment's
  failure state), LinkDeploymentResource, PointDeploymentDns,
  ActivateDeployment.
- Provisioning.provision_deployment/2 assembles + starts the saga.
- DeploymentController: POST /deployments with provision:true creates
  in `provisioning` and kicks the saga (202); GET /deployments/:id now
  returns the provisioning saga + per-step progress.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/arcadia_cloud/deployments.ex

@@ -24,6 +24,7 @@ defmodule ArcadiaCloud.Deployments do
 
   # from_state => [allowed to_states]
   @transitions %{
+    "provisioning" => ~w(active cancelled),
     "trial" => ~w(active cancelled),
     "active" => ~w(paused past_due cancelled),
     "paused" => ~w(active cancelled),

lib/arcadia_cloud/deployments/cloud_deployment.ex

@@ -5,7 +5,7 @@ defmodule ArcadiaCloud.Deployments.CloudDeployment do
   @primary_key {:id, :binary_id, autogenerate: true}
   @foreign_key_type :binary_id
 
-  @states ~w(trial active past_due paused suspended cancelled archived)
+  @states ~w(provisioning trial active past_due paused suspended cancelled archived)
   @llm_modes ~w(managed byo none)
 
   def states, do: @states

lib/arcadia_cloud/provisioning.ex

@@ -148,6 +148,54 @@ defmodule ArcadiaCloud.Provisioning do
     })
   end
 
+  alias ArcadiaCloud.Provisioning.Steps
+
+  @doc """
+  Assembles + starts the full deployment-provisioning choreography saga
+  for a deployment that was created in the `provisioning` state.
+
+  Steps: mark → create droplet → wait active → register in inventory →
+  link to deployment → point DNS → activate. A failure anywhere rolls
+  the whole thing back (droplet destroyed, DNS reverted, deployment
+  moved to `cancelled`).
+
+  Required opts: :size, :image. Optional: :region (falls back to the
+  deployment's region), :dns_domain, :dns_record_name (falls back to the
+  deployment slug), :triggered_by.
+  """
+  def provision_deployment(deployment, opts \\ []) do
+    region = opts[:region] || deployment.region
+
+    inputs = %{
+      droplet_name: opts[:droplet_name] || "dep-#{deployment.slug}",
+      droplet_region: region,
+      droplet_size: opts[:size],
+      droplet_image: opts[:image],
+      droplet_tags: [
+        "deployment:#{deployment.id}",
+        "tenant:#{deployment.tenant_id}"
+      ],
+      dns_domain: opts[:dns_domain],
+      dns_record_name: opts[:dns_record_name] || deployment.slug
+    }
+
+    start_saga(%{
+      kind: "provision",
+      deployment_id: deployment.id,
+      triggered_by: opts[:triggered_by] || "manual",
+      step_modules: [
+        Steps.MarkDeploymentProvisioning,
+        Steps.CreateDroplet,
+        Steps.WaitDropletActive,
+        Steps.RegisterDroplet,
+        Steps.LinkDeploymentResource,
+        Steps.PointDeploymentDns,
+        Steps.ActivateDeployment
+      ],
+      inputs: inputs
+    })
+  end
+
   def get_saga(id), do: Repo.get(SagaRun, id)
   def get_saga!(id), do: Repo.get!(SagaRun, id)
 

lib/arcadia_cloud/provisioning/steps/activate_deployment.ex

@@ -0,0 +1,48 @@
+defmodule ArcadiaCloud.Provisioning.Steps.ActivateDeployment do
+  @moduledoc """
+  Final step of the deployment-provisioning choreography: moves the
+  deployment from `provisioning` to `active` now that its infra is up,
+  registered, linked, and reachable by DNS.
+
+  Idempotent: `transition_state/3` returns `{:ok, deployment}` when the
+  deployment is already `active`.
+
+  No compensation: this is the last step, so the saga only ever rolls
+  back from a step BEFORE this one — meaning this step never ran and the
+  deployment is still `provisioning` (cancelled by
+  MarkDeploymentProvisioning's compensate).
+  """
+
+  @behaviour ArcadiaCloud.Provisioning.Step
+
+  alias ArcadiaCloud.Deployments
+
+  @impl true
+  def name, do: "activate_deployment"
+
+  @impl true
+  def execute(state) do
+    with {:ok, deployment} <- fetch_deployment(state) do
+      case Deployments.transition_state(deployment, "active",
+             reason: "provisioning_complete",
+             actor: "saga:#{state.saga_id}"
+           ) do
+        {:ok, _} -> {:ok, state}
+        {:error, reason} -> {:error, {:activate_failed, reason}}
+      end
+    end
+  end
+
+  defp fetch_deployment(state) do
+    case state.saga && state.saga.deployment_id do
+      nil ->
+        {:error, :saga_has_no_deployment}
+
+      id ->
+        case Deployments.get_deployment(id) do
+          nil -> {:error, :deployment_not_found}
+          deployment -> {:ok, deployment}
+        end
+    end
+  end
+end

lib/arcadia_cloud/provisioning/steps/link_deployment_resource.ex

@@ -0,0 +1,80 @@
+defmodule ArcadiaCloud.Provisioning.Steps.LinkDeploymentResource do
+  @moduledoc """
+  Attaches the freshly-registered cloud resource (set by RegisterDroplet
+  as `cloud_resource_id` in context) to the saga's deployment: stamps
+  `deployment_id` and `tenant_id` onto the `cloud_resources` row.
+
+  This is what makes the resource show up under the deployment in
+  inventory and bill against the right tenant.
+
+  Idempotent: re-running just re-writes the same two columns.
+
+  Compensation: clears `deployment_id` and `tenant_id` back to nil. The
+  resource row itself (and the droplet) are undone by RegisterDroplet /
+  CreateDroplet compensation.
+  """
+
+  @behaviour ArcadiaCloud.Provisioning.Step
+
+  import Ecto.Query
+
+  alias ArcadiaCloud.Deployments
+  alias ArcadiaCloud.Cloud.CloudResource
+  alias ArcadiaCloud.Provisioning.SagaState
+  alias ArcadiaCloud.Repo
+
+  @impl true
+  def name, do: "link_deployment_resource"
+
+  @impl true
+  def execute(state) do
+    with {:ok, resource_id} <- fetch(state, :cloud_resource_id),
+         {:ok, deployment} <- fetch_deployment(state) do
+      {_, _} =
+        from(r in CloudResource, where: r.id == ^resource_id)
+        |> Repo.update_all(
+          set: [
+            deployment_id: deployment.id,
+            tenant_id: deployment.tenant_id,
+            updated_at: DateTime.utc_now() |> DateTime.truncate(:second)
+          ]
+        )
+
+      {:ok, state}
+    end
+  end
+
+  @impl true
+  def compensate(state) do
+    case SagaState.get_output(state, :cloud_resource_id) do
+      nil ->
+        :ok
+
+      resource_id ->
+        from(r in CloudResource, where: r.id == ^resource_id)
+        |> Repo.update_all(set: [deployment_id: nil, tenant_id: nil])
+
+        :ok
+    end
+  end
+
+  defp fetch(state, key) do
+    case SagaState.get_output(state, key) do
+      nil -> {:error, {:missing_context, key}}
+      value -> {:ok, value}
+    end
+  end
+
+  defp fetch_deployment(state) do
+    case state.saga && state.saga.deployment_id do
+      nil ->
+        {:error, :saga_has_no_deployment}
+
+      id ->
+        case Deployments.get_deployment(id) do
+          nil -> {:error, :deployment_not_found}
+          deployment -> {:ok, deployment}
+        end
+    end
+  end
+end

lib/arcadia_cloud/provisioning/steps/mark_deployment_provisioning.ex

@@ -0,0 +1,57 @@
+defmodule ArcadiaCloud.Provisioning.Steps.MarkDeploymentProvisioning do
+  @moduledoc """
+  First step of the deployment-provisioning choreography.
+
+  Forward: a no-op — `Provisioning.provision_deployment/2` already
+  created the deployment row in the `provisioning` state. Having this
+  step at index 0 gives the saga a compensation hook that owns the
+  deployment's failure state: if ANY later step fails, the runner walks
+  compensation back to here and we move the deployment to `cancelled`.
+
+  Without this step a mid-saga failure would leave the deployment stuck
+  in `provisioning` forever.
+  """
+
+  @behaviour ArcadiaCloud.Provisioning.Step
+
+  require Logger
+
+  alias ArcadiaCloud.Deployments
+
+  @impl true
+  def name, do: "mark_deployment_provisioning"
+
+  @impl true
+  def execute(state), do: {:ok, state}
+
+  @impl true
+  def compensate(state) do
+    case deployment(state) do
+      nil ->
+        :ok
+
+      deployment ->
+        case Deployments.transition_state(deployment, "cancelled",
+               reason: "provision_failed",
+               actor: "saga:#{state.saga_id}"
+             ) do
+          {:ok, _} ->
+            :ok
+
+          {:error, reason} ->
+            Logger.warning(
+              "[saga #{state.saga_id}] could not cancel deployment on rollback: #{inspect(reason)}"
+            )
+
+            :ok
+        end
+    end
+  end
+
+  defp deployment(state) do
+    case state.saga && state.saga.deployment_id do
+      nil -> nil
+      id -> Deployments.get_deployment(id)
+    end
+  end
+end

lib/arcadia_cloud/provisioning/steps/point_deployment_dns.ex

@@ -0,0 +1,161 @@
+defmodule ArcadiaCloud.Provisioning.Steps.PointDeploymentDns do
+  @moduledoc """
+  Points a deployment's hostname at its droplet by upserting an A record.
+
+  Reads the droplet's public IPv4 from context (`droplet_public_ip`, set
+  by WaitDropletActive) — the IP isn't known at saga-start, so this can't
+  be a generic UpsertDnsRecord with the data baked into inputs.
+
+  Saga inputs:
+    dns_domain       — the zone (e.g. "sky-ai.com"); when absent the
+                       step is a no-op (deployment opted out of DNS)
+    dns_record_name  — subdomain; defaults handled by the assembler
+    dns_record_ttl   — optional, defaults 1800
+
+  Behaviour mirrors UpsertDnsRecord: create / no-op / update, with the
+  prior record stashed for compensation.
+  """
+
+  @behaviour ArcadiaCloud.Provisioning.Step
+
+  alias ArcadiaCloud.DigitalOcean.Client
+  alias ArcadiaCloud.Provisioning.SagaState
+
+  @default_ttl 1800
+  @type_a "A"
+
+  @impl true
+  def name, do: "point_deployment_dns"
+
+  @impl true
+  def execute(state) do
+    domain = SagaState.get_input(state, :dns_domain)
+    rname = SagaState.get_input(state, :dns_record_name)
+    ip = SagaState.get_output(state, :droplet_public_ip)
+    ttl = SagaState.get_input(state, :dns_record_ttl) || @default_ttl
+
+    cond do
+      is_nil(domain) or domain == "" ->
+        {:ok, SagaState.put_output(state, :dns_outcome, "skipped")}
+
+      is_nil(rname) or rname == "" ->
+        {:error, :missing_dns_record_name}
+
+      is_nil(ip) ->
+        {:error, :no_droplet_public_ip_in_context}
+
+      true ->
+        upsert(state, domain, rname, ip, ttl)
+    end
+  end
+
+  @impl true
+  def compensate(state) do
+    domain = SagaState.get_input(state, :dns_domain)
+    outcome = SagaState.get_output(state, :dns_outcome)
+    record_id = SagaState.get_output(state, :dns_record_id)
+
+    case outcome do
+      "created" -> delete_record(domain, record_id)
+      "updated" -> restore_record(state, domain, record_id)
+      _ -> :ok
+    end
+  end
+
+  # ---- execute helpers ------------------------------------------------------
+
+  defp upsert(state, domain, rname, ip, ttl) do
+    case find_record(domain, rname) do
+      {:ok, nil} ->
+        create(state, domain, rname, ip, ttl)
+
+      {:ok, existing} ->
+        if normalize(existing["data"]) == normalize(ip) and existing["ttl"] == ttl do
+          {:ok, record_outcome(state, existing["id"], "noop", nil)}
+        else
+          update(state, domain, existing, rname, ip, ttl)
+        end
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
+  defp create(state, domain, rname, ip, ttl) do
+    case Client.create_domain_record(domain, %{type: @type_a, name: rname, data: ip, ttl: ttl}) do
+      {:ok, %{"id" => id}} -> {:ok, record_outcome(state, id, "created", nil)}
+      {:error, reason} -> {:error, reason}
+    end
+  end
+
+  defp update(state, domain, existing, rname, ip, ttl) do
+    prior = %{
+      "type" => existing["type"],
+      "name" => existing["name"],
+      "data" => existing["data"],
+      "ttl" => existing["ttl"]
+    }
+
+    case Client.update_domain_record(domain, existing["id"], %{
+           type: @type_a,
+           name: rname,
+           data: ip,
+           ttl: ttl
+         }) do
+      {:ok, %{"id" => id}} -> {:ok, record_outcome(state, id, "updated", prior)}
+      {:error, reason} -> {:error, reason}
+    end
+  end
+
+  defp record_outcome(state, record_id, outcome, prior) do
+    state
+    |> SagaState.put_output(:dns_record_id, record_id)
+    |> SagaState.put_output(:dns_outcome, outcome)
+    |> SagaState.put_output(:dns_prior, prior)
+  end
+
+  # ---- compensate helpers ---------------------------------------------------
+
+  defp delete_record(domain, record_id) do
+    case Client.delete_domain_record(domain, record_id) do
+      {:ok, _} -> :ok
+      {:error, {:http, 404, _}} -> :ok
+      {:error, reason} -> {:error, reason}
+    end
+  end
+
+  defp restore_record(state, domain, record_id) do
+    case SagaState.get_output(state, :dns_prior) do
+      nil ->
+        :ok
+
+      prior ->
+        case Client.update_domain_record(domain, record_id, %{
+               type: prior["type"],
+               name: prior["name"],
+               data: prior["data"],
+               ttl: prior["ttl"]
+             }) do
+          {:ok, _} -> :ok
+          {:error, {:http, 404, _}} -> :ok
+          {:error, reason} -> {:error, reason}
+        end
+    end
+  end
+
+  # ---- shared ---------------------------------------------------------------
+
+  defp find_record(domain, rname) do
+    case Client.list_domain_records(domain) do
+      {:ok, records} ->
+        {:ok, Enum.find(records, &(&1["type"] == @type_a and &1["name"] == rname))}
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
+  defp normalize(nil), do: ""
+  defp normalize(v) when is_binary(v), do: v |> String.trim() |> String.trim_trailing(".")
+  defp normalize(v), do: to_string(v)
+end