Sap system restoration

lib/trento/application/projectors/database_projector.ex

@@ -22,7 +22,8 @@ defmodule Trento.DatabaseProjector do
     DatabaseInstanceHealthChanged,
     DatabaseInstanceRegistered,
     DatabaseInstanceSystemReplicationChanged,
-    DatabaseRegistered
+    DatabaseRegistered,
+    DatabaseRestored
   }
 
   alias Trento.Repo
@@ -160,6 +161,24 @@ defmodule Trento.DatabaseProjector do
     end
   )
 
+  project(
+    %DatabaseRestored{
+      sap_system_id: sap_system_id,
+      health: health
+    },
+    fn multi ->
+      db = Repo.get!(DatabaseReadModel, sap_system_id)
+
+      changeset =
+        DatabaseReadModel.changeset(
+          db,
+          %{deregistered_at: nil, health: health}
+        )
+
+      Ecto.Multi.update(multi, :database, changeset)
+    end
+  )
+
   project(
     %DatabaseInstanceDeregistered{
       instance_number: instance_number,
@@ -279,6 +298,21 @@ defmodule Trento.DatabaseProjector do
     )
   end
 
+  @impl true
+  def after_update(
+        %DatabaseRestored{sap_system_id: sap_system_id},
+        _,
+        _
+      ) do
+    database = Repo.get!(DatabaseReadModel, sap_system_id)
+
+    TrentoWeb.Endpoint.broadcast(
+      @databases_topic,
+      "database_registered",
+      SapSystemView.render("database_registered.json", database: database)
+    )
+  end
+
   @impl true
   def after_update(
         %DatabaseDeregistered{

lib/trento/application/projectors/sap_system_projector.ex

@@ -15,6 +15,7 @@ defmodule Trento.SapSystemProjector do
     SapSystemDeregistered,
     SapSystemHealthChanged,
     SapSystemRegistered,
+    SapSystemRestored,
     SapSystemUpdated
   }
 
@@ -134,6 +135,28 @@ defmodule Trento.SapSystemProjector do
     end
   )
 
+  project(
+    %SapSystemRestored{
+      sap_system_id: sap_system_id,
+      tenant: tenant,
+      db_host: db_host,
+      health: health
+    },
+    fn multi ->
+      sap_system = Repo.get!(SapSystemReadModel, sap_system_id)
+
+      changeset =
+        SapSystemReadModel.changeset(sap_system, %{
+          tenant: tenant,
+          db_host: db_host,
+          health: health,
+          deregistered_at: nil
+        })
+
+      Ecto.Multi.update(multi, :sap_system, changeset)
+    end
+  )
+
   project(
     %ApplicationInstanceDeregistered{
       instance_number: instance_number,
@@ -170,6 +193,7 @@ defmodule Trento.SapSystemProjector do
   @sap_systems_topic "monitoring:sap_systems"
 
   @impl true
+  @spec after_update(any, any, any) :: :ok | {:error, any}
   def after_update(
         %SapSystemRegistered{},
         _,
@@ -258,6 +282,21 @@ defmodule Trento.SapSystemProjector do
     )
   end
 
+  @impl true
+  def after_update(
+        %SapSystemRestored{sap_system_id: sap_system_id},
+        _,
+        _
+      ) do
+    sap_system = Repo.get!(SapSystemReadModel, sap_system_id)
+
+    TrentoWeb.Endpoint.broadcast(
+      @sap_systems_topic,
+      "sap_system_registered",
+      SapSystemView.render("sap_system_registered.json", sap_system: sap_system)
+    )
+  end
+
   @impl true
   def after_update(
         %ApplicationInstanceDeregistered{

lib/trento/domain/sap_system/events/database_restored.ex

@@ -0,0 +1,14 @@
+defmodule Trento.Domain.Events.DatabaseRestored do
+  @moduledoc """
+  This event is emitted when a database is restored.
+  """
+
+  use Trento.Event
+
+  require Trento.Domain.Enums.Health, as: Health
+
+  defevent do
+    field :sap_system_id, Ecto.UUID
+    field :health, Ecto.Enum, values: Health.values()
+  end
+end

lib/trento/domain/sap_system/events/sap_system_restored.ex

@@ -0,0 +1,16 @@
+defmodule Trento.Domain.Events.SapSystemRestored do
+  @moduledoc """
+  This event is emitted when a sap system is restored.
+  """
+
+  use Trento.Event
+
+  require Trento.Domain.Enums.Health, as: Health
+
+  defevent do
+    field :sap_system_id, Ecto.UUID
+    field :tenant, :string
+    field :db_host, :string
+    field :health, Ecto.Enum, values: Health.values()
+  end
+end

lib/trento/domain/sap_system/sap_system.ex

@@ -77,9 +77,11 @@ defmodule Trento.Domain.SapSystem do
     DatabaseInstanceRegistered,
     DatabaseInstanceSystemReplicationChanged,
     DatabaseRegistered,
+    DatabaseRestored,
     SapSystemDeregistered,
     SapSystemHealthChanged,
     SapSystemRegistered,
+    SapSystemRestored,
     SapSystemRolledUp,
     SapSystemRollUpRequested,
     SapSystemTombstoned,
@@ -161,6 +163,60 @@ defmodule Trento.Domain.SapSystem do
     ]
   end
 
+  # Database restore
+  def execute(
+        %SapSystem{database: %Database{deregistered_at: deregistered_at}},
+        %RegisterDatabaseInstance{
+          system_replication: "Secondary"
+        }
+      )
+      when not is_nil(deregistered_at),
+      do: {:error, :sap_system_not_registered}
+
+  # When a deregistered database is present, we add the new database instance
+  # and restore the database, the conditions are the same as registration
+  def execute(
+        %SapSystem{database: %Database{deregistered_at: deregistered_at}},
+        %RegisterDatabaseInstance{
+          sap_system_id: sap_system_id,
+          sid: sid,
+          tenant: tenant,
+          host_id: host_id,
+          instance_number: instance_number,
+          instance_hostname: instance_hostname,
+          features: features,
+          http_port: http_port,
+          https_port: https_port,
+          start_priority: start_priority,
+          system_replication: system_replication,
+          system_replication_status: system_replication_status,
+          health: health
+        }
+      )
+      when not is_nil(deregistered_at) do
+    [
+      %DatabaseRestored{
+        sap_system_id: sap_system_id,
+        health: health
+      },
+      %DatabaseInstanceRegistered{
+        sap_system_id: sap_system_id,
+        sid: sid,
+        tenant: tenant,
+        instance_number: instance_number,
+        instance_hostname: instance_hostname,
+        features: features,
+        http_port: http_port,
+        https_port: https_port,
+        start_priority: start_priority,
+        host_id: host_id,
+        system_replication: system_replication,
+        system_replication_status: system_replication_status,
+        health: health
+      }
+    ]
+  end
+
   # When a RegisterDatabaseInstance command is received by an existing SAP System aggregate,
   # the SAP System aggregate registers the Database instance if it is not already registered
   # and updates the health when needed.
@@ -185,6 +241,26 @@ defmodule Trento.Domain.SapSystem do
     |> Multi.execute(&maybe_emit_sap_system_health_changed_event/1)
   end
 
+  # Restore sap system
+  # Same registration rules
+  def execute(
+        %SapSystem{deregistered_at: deregistered_at} = sap_system,
+        %RegisterApplicationInstance{} = instance
+      )
+      when not is_nil(deregistered_at) do
+    sap_system
+    |> Multi.new()
+    |> Multi.execute(fn sap_system ->
+      maybe_emit_application_instance_registered_or_moved_event(
+        sap_system,
+        instance
+      )
+    end)
+    |> Multi.execute(fn sap_system ->
+      maybe_emit_sap_system_restored_event(sap_system, instance)
+    end)
+  end
+
   # SAP system not registered, application already present
   # If the instance is not one of MESSAGESERVER or ABAP we discard.
   # Otherwise if the instance we want register together with already present instances
@@ -615,6 +691,22 @@ defmodule Trento.Domain.SapSystem do
     }
   end
 
+  def apply(
+        %SapSystem{database: database} = sap_system,
+        %DatabaseRestored{
+          health: health
+        }
+      ) do
+    %SapSystem{
+      sap_system
+      | database: %Database{
+          database
+          | health: health,
+            deregistered_at: nil
+        }
+    }
+  end
+
   def apply(
         %SapSystem{} = sap_system,
         %SapSystemDeregistered{
@@ -627,6 +719,16 @@ defmodule Trento.Domain.SapSystem do
     }
   end
 
+  def apply(%SapSystem{} = sap_system, %SapSystemRestored{
+        health: health
+      }) do
+    %SapSystem{
+      sap_system
+      | health: health,
+        deregistered_at: nil
+    }
+  end
+
   def apply(%SapSystem{} = sap_system, %SapSystemTombstoned{}), do: sap_system
 
   defp maybe_emit_database_instance_registered_event(
@@ -829,6 +931,25 @@ defmodule Trento.Domain.SapSystem do
     end
   end
 
+  defp maybe_emit_sap_system_restored_event(
+         %SapSystem{application: %Application{instances: instances}},
+         %RegisterApplicationInstance{
+           sap_system_id: sap_system_id,
+           tenant: tenant,
+           db_host: db_host,
+           health: health
+         }
+       ) do
+    if instances_have_abap?(instances) and instances_have_messageserver?(instances) do
+      %SapSystemRestored{
+        db_host: db_host,
+        health: health,
+        sap_system_id: sap_system_id,
+        tenant: tenant
+      }
+    end
+  end
+
   defp maybe_emit_sap_system_registered_or_updated_event(
          %SapSystem{sid: nil, application: %Application{instances: instances}},
          %RegisterApplicationInstance{

test/support/factory.ex

@@ -21,6 +21,7 @@ defmodule Trento.Factory do
   }
 
   alias Trento.Domain.Events.{
+    ApplicationInstanceDeregistered,
     ApplicationInstanceRegistered,
     ClusterDeregistered,
     ClusterRegistered,
@@ -29,6 +30,7 @@ defmodule Trento.Factory do
     DatabaseInstanceDeregistered,
     DatabaseInstanceRegistered,
     DatabaseRegistered,
+    DatabaseRestored,
     HostAddedToCluster,
     HostDetailsUpdated,
     HostRegistered,
@@ -267,6 +269,13 @@ defmodule Trento.Factory do
     })
   end
 
+  def database_restored_event_factory do
+    DatabaseRestored.new!(%{
+      sap_system_id: Faker.UUID.v4(),
+      health: Health.passing()
+    })
+  end
+
   def deregister_database_instance_command_factory do
     DeregisterDatabaseInstance.new!(%{
       sap_system_id: Faker.UUID.v4(),
@@ -298,6 +307,15 @@ defmodule Trento.Factory do
     }
   end
 
+  def application_instance_deregistered_event_factory do
+    ApplicationInstanceDeregistered.new!(%{
+      sap_system_id: Faker.UUID.v4(),
+      deregistered_at: DateTime.utc_now(),
+      instance_number: "00",
+      host_id: Faker.UUID.v4()
+    })
+  end
+
   def deregister_application_instance_command_factory do
     DeregisterApplicationInstance.new!(%{
       sap_system_id: Faker.UUID.v4(),