feat(backend): init horizontal clustering

REUSE.toml

@@ -86,3 +86,9 @@ path = ".github/CODEOWNERS"
 precedence = "aggregate"
 SPDX-FileCopyrightText = "2026 Seco Mind Srl"
 SPDX-License-Identifier = "Apache-2.0"
+
+[[annotations]]
+path = "backend/rel/env.sh.eex"
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2026 Seco Mind Srl"
+SPDX-License-Identifier = "Apache-2.0"

backend/lib/edgehog/application.ex

@@ -45,11 +45,15 @@ defmodule Edgehog.Application do
       Router.Helpers.astarte_trigger_url(Endpoint, :process_event, slug)
     end
 
+    clustering_opts = [Config.clustering_topologies!(), [name: Edgehog.Cluster.Supervisor]]
+
     children = [
       # Prometheus metrics
       Edgehog.PromEx,
       # Start the Ecto repository
       Edgehog.Repo,
+      # Clustering supervisor
+      {Cluster.Supervisor, clustering_opts},
       # Start the Telemetry supervisor
       EdgehogWeb.Telemetry,
       # Start the PubSub system
@@ -63,7 +67,8 @@ defmodule Edgehog.Application do
       # Start the Tenant Reconciler Supervisor
       {Edgehog.Tenants.Reconciler.Supervisor, tenant_to_trigger_url_fun: tenant_to_trigger_url_fun},
       # Start Containers reconciler
-      {Registry, keys: :unique, name: Edgehog.Containers.Reconciler.Registry},
+      {Horde.Registry, keys: :unique, name: Edgehog.Containers.Reconciler.Registry},
+      {Horde.Registry, keys: :unique, name: Edgehog.Devices.Reconciler.Registry},
       # Start the Endpoint (http/https)
       Endpoint,
       # Fetch Astarte devices

backend/lib/edgehog/config.ex

@@ -24,6 +24,7 @@ defmodule Edgehog.Config do
   """
   use Skogsra
 
+  alias Edgehog.Config.ClusteringStrategy
   alias Edgehog.Config.GeocodingProviders
   alias Edgehog.Config.GeolocationProviders
   alias Edgehog.Config.JWTPublicKeyPEMType
@@ -96,6 +97,26 @@ defmodule Edgehog.Config do
     type: GeocodingProviders,
     default: [GoogleGeocoding]
 
+  @envdoc "The Erlang cluster strategy to use. One of `none`, `kubernetes`, `docker-compose`. Defaults to `none`."
+  app_env :clustering_strategy, :edgehog, :clustering_strategy,
+    os_env: "EDGEHOG_CLUSTERING_STRATEGY",
+    type: ClusteringStrategy,
+    default: :none
+
+  @envdoc "The endpoint label to query to get other edgehog instances. Defaults to `app=edgehog-backend`."
+  app_env :edgehog_clustering_kubernetes_selector,
+          :edgehog,
+          :edgehog_clustering_kubernetes_selector,
+          os_env: "EDGEHOG_CLUSTERING_KUBERNETES_SELECTOR",
+          type: :binary,
+          default: "app=edgehog-backend"
+
+  @envdoc "The Kubernetes namespace to use when `kubernetes` Erlang clustering strategy is used. Defaults to `edgehog`."
+  app_env :clustering_kubernetes_namespace, :edgehog, :clustering_kubernetes_namespace,
+    os_env: "EDGEHOG_CLUSTERING_KUBERNETES_NAMESPACE",
+    type: :binary,
+    default: "edgehog"
+
   @doc """
   Returns true if edgehog should use an ssl connection with the database.
   """
@@ -190,4 +211,40 @@ defmodule Edgehog.Config do
     admin_jwk!()
     :ok
   end
+
+  @doc """
+  The clustering topology to use. The topology sets up node discovery.
+  """
+  def clustering_topologies! do
+    case clustering_strategy!() do
+      :none ->
+        []
+
+      :kubernetes ->
+        [
+          edgehog_k8s: [
+            strategy: Cluster.Strategy.Kubernetes,
+            config: [
+              mode: :ip,
+              kubernetes_node_basename: "edgehog",
+              kubernetes_selector: edgehog_clustering_kubernetes_selector!(),
+              kubernetes_namespace: clustering_kubernetes_namespace!(),
+              polling_interval: 10_000
+            ]
+          ]
+        ]
+
+      :docker_compose ->
+        [
+          edgehog: [
+            strategy: Cluster.Strategy.DNSPoll,
+            config: [
+              polling_interval: 5_000,
+              query: "edgehog-backend",
+              node_basename: "edgehog"
+            ]
+          ]
+        ]
+    end
+  end
 end

backend/lib/edgehog/config/clustering_strategy.ex

@@ -0,0 +1,46 @@
+#
+# This file is part of Edgehog.
+#
+# Copyright 2026 SECO Mind Srl
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+defmodule Edgehog.Config.ClusteringStrategy do
+  @moduledoc """
+  The clustering strategy that the node should use to discover other nodes.
+  """
+
+  use Skogsra.Type
+
+  @strategies [:none, :kubernetes, :docker_compose]
+  @allowed_strategies ~w(none kubernetes docker-compose)
+  @strategy_map @allowed_strategies |> Enum.zip(@strategies) |> Map.new()
+
+  @impl Skogsra.Type
+  def cast(value) when is_binary(value) do
+    Map.fetch(@strategy_map, value)
+  end
+
+  @impl Skogsra.Type
+  def cast(value) when value in @strategies do
+    {:ok, value}
+  end
+
+  @impl Skogsra.Type
+  def cast(_) do
+    :error
+  end
+end

backend/lib/edgehog/containers/reconciler/reconciler.ex

@@ -144,7 +144,7 @@ defmodule Edgehog.Containers.Reconciler do
   end
 
   defp name(tenant) do
-    {:via, Registry, {Edgehog.Containers.Reconciler.Registry, tenant.tenant_id}}
+    {:via, Horde.Registry, {Edgehog.Containers.Reconciler.Registry, tenant.tenant_id}}
   end
 
   defp do_register_device(device, state) do

backend/lib/edgehog/devices/reconciler/reconciler.ex

@@ -28,7 +28,7 @@ defmodule Edgehog.Devices.Reconciler do
   require Logger
 
   def start_link(opts \\ []) do
-    GenServer.start_link(__MODULE__, opts, name: __MODULE__)
+    GenServer.start_link(__MODULE__, opts, name: name())
   end
 
   @impl GenServer
@@ -79,10 +79,36 @@ defmodule Edgehog.Devices.Reconciler do
     {:noreply, state}
   end
 
+  @impl GenServer
+  def handle_info({:EXIT, _pid, {:name_conflict, {_name, _value}, _registry, _winning_pid}}, state) do
+    _ =
+      Logger.warning(
+        "Received a :name_conflict signal from the outer space, maybe a netsplit occurred? Gracefully shutting down.",
+        tag: "RPC exit"
+      )
+
+    {:stop, :shutdown, state}
+  end
+
+  @impl GenServer
+  def handle_info({:EXIT, _pid, :shutdown}, state) do
+    _ =
+      Logger.warning(
+        "Received a :shutdown signal from the outer space, maybe the supervisor is mad? Gracefully shutting down.",
+        tag: "RPC exit"
+      )
+
+    {:stop, :shutdown, state}
+  end
+
   defp spawn_reconciliation_task(tenant) do
     Task.Supervisor.async(Reconciler.Supervisor, fn ->
       Logger.info("Reconciling tenant #{tenant.slug}")
       Reconciler.Core.reconcile(tenant)
     end)
   end
+
+  defp name do
+    {:via, Horde.Registry, {Edgehog.Devices.Reconciler.Registry, :auto}}
+  end
 end

backend/mix.exs

@@ -136,7 +136,9 @@ defmodule Edgehog.MixProject do
       {:absinthe_phoenix, "~> 2.0"},
       {:mix_audit, "~> 2.1", only: [:dev, :test], runtime: false},
       {:sobelow, "~> 0.13", only: [:dev, :test], runtime: false},
-      {:ex_doc, "~> 0.24", only: :dev}
+      {:ex_doc, "~> 0.24", only: :dev},
+      {:libcluster, "~> 3.5"},
+      {:horde, "~> 0.10"}
     ]
   end
 

backend/mix.lock

@@ -23,6 +23,7 @@
   "dataloader": {:hex, :dataloader, "1.0.11", "49bbfc7dd8a1990423c51000b869b1fecaab9e3ccd6b29eab51616ae8ad0a2f5", [:mix], [{:ecto, ">= 3.4.3 and < 4.0.0", [hex: :ecto, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "ba0b0ec532ec68e9d033d03553561d693129bd7cbd5c649dc7903f07ffba08fe"},
   "db_connection": {:hex, :db_connection, "2.9.0", "a6a97c5c958a2d7091a58a9be40caf41ab496b0701d21e1d1abff3fa27a7f371", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "17d502eacaf61829db98facf6f20808ed33da6ccf495354a41e64fe42f9c509c"},
   "decimal": {:hex, :decimal, "2.3.0", "3ad6255aa77b4a3c4f818171b12d237500e63525c2fd056699967a3e7ea20f62", [:mix], [], "hexpm", "a4d66355cb29cb47c3cf30e71329e58361cfcb37c34235ef3bf1d7bf3773aeac"},
+  "delta_crdt": {:hex, :delta_crdt, "0.6.5", "c7bb8c2c7e60f59e46557ab4e0224f67ba22f04c02826e273738f3dcc4767adc", [:mix], [{:merkle_map, "~> 0.2.0", [hex: :merkle_map, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "c6ae23a525d30f96494186dd11bf19ed9ae21d9fe2c1f1b217d492a7cc7294ae"},
   "dialyxir": {:hex, :dialyxir, "1.4.7", "dda948fcee52962e4b6c5b4b16b2d8fa7d50d8645bbae8b8685c3f9ecb7f5f4d", [:mix], [{:erlex, ">= 0.2.8", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "b34527202e6eb8cee198efec110996c25c5898f43a4094df157f8d28f27d9efe"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.44", "f20830dd6b5c77afe2b063777ddbbff09f9759396500cdbe7523efd58d7a339c", [:mix], [], "hexpm", "4778ac752b4701a5599215f7030989c989ffdc4f6df457c5f36938cc2d2a2750"},
   "ecto": {:hex, :ecto, "3.13.5", "9d4a69700183f33bf97208294768e561f5c7f1ecf417e0fa1006e4a91713a834", [:mix], [{:decimal, "~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "df9efebf70cf94142739ba357499661ef5dbb559ef902b68ea1f3c1fabce36de"},
@@ -46,6 +47,7 @@
   "goth": {:hex, :goth, "1.4.5", "ee37f96e3519bdecd603f20e7f10c758287088b6d77c0147cd5ee68cf224aade", [:mix], [{:finch, "~> 0.17", [hex: :finch, repo: "hexpm", optional: false]}, {:jason, "~> 1.1", [hex: :jason, repo: "hexpm", optional: false]}, {:jose, "~> 1.11", [hex: :jose, repo: "hexpm", optional: false]}], "hexpm", "0fc2dce5bd710651ed179053d0300ce3a5d36afbdde11e500d57f05f398d5ed5"},
   "guardian": {:hex, :guardian, "2.4.0", "efbbb397ecca881bb548560169922fc4433a05bc98c2eb96a7ed88ede9e17d64", [:mix], [{:jose, "~> 1.11.9", [hex: :jose, repo: "hexpm", optional: false]}, {:plug, "~> 1.3.3 or ~> 1.4", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm", "5c80103a9c538fbc2505bf08421a82e8f815deba9eaedb6e734c66443154c518"},
   "hackney": {:hex, :hackney, "1.25.0", "390e9b83f31e5b325b9f43b76e1a785cbdb69b5b6cd4e079aa67835ded046867", [:rebar3], [{:certifi, "~> 2.15.0", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "~> 6.1.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "~> 1.0.0", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~> 1.4", [hex: :mimerl, repo: "hexpm", optional: false]}, {:parse_trans, "3.4.1", [hex: :parse_trans, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "~> 1.1.0", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}, {:unicode_util_compat, "~> 0.7.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "7209bfd75fd1f42467211ff8f59ea74d6f2a9e81cbcee95a56711ee79fd6b1d4"},
+  "horde": {:hex, :horde, "0.10.0", "31c6a633057c3ec4e73064d7b11ba409c9f3c518aa185377d76bee441b76ceb0", [:mix], [{:delta_crdt, "~> 0.6.2", [hex: :delta_crdt, repo: "hexpm", optional: false]}, {:libring, "~> 1.7", [hex: :libring, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.0 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:telemetry_poller, "~> 0.5.0 or ~> 1.0", [hex: :telemetry_poller, repo: "hexpm", optional: false]}], "hexpm", "0b51c435cb698cac9bf9c17391dce3ebb1376ae6154c81f077fc61db771b9432"},
   "hpax": {:hex, :hpax, "1.0.3", "ed67ef51ad4df91e75cc6a1494f851850c0bd98ebc0be6e81b026e765ee535aa", [:mix], [], "hexpm", "8eab6e1cfa8d5918c2ce4ba43588e894af35dbd8e91e6e55c817bca5847df34a"},
   "httpoison": {:hex, :httpoison, "1.8.2", "9eb9c63ae289296a544842ef816a85d881d4a31f518a0fec089aaa744beae290", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "2bb350d26972e30c96e2ca74a1aaf8293d61d0742ff17f01e0279fef11599921"},
   "idna": {:hex, :idna, "6.1.1", "8a63070e9f7d0c62eb9d9fcb360a7de382448200fbbd1b106cc96d3d8099df8d", [:rebar3], [{:unicode_util_compat, "~> 0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "92376eb7894412ed19ac475e4a86f7b413c1b9fbb5bd16dccd57934157944cea"},
@@ -55,11 +57,14 @@
   "joken": {:hex, :joken, "2.6.2", "5daaf82259ca603af4f0b065475099ada1b2b849ff140ccd37f4b6828ca6892a", [:mix], [{:jose, "~> 1.11.10", [hex: :jose, repo: "hexpm", optional: false]}], "hexpm", "5134b5b0a6e37494e46dbf9e4dad53808e5e787904b7c73972651b51cce3d72b"},
   "jose": {:hex, :jose, "1.11.12", "06e62b467b61d3726cbc19e9b5489f7549c37993de846dfb3ee8259f9ed208b3", [:mix, :rebar3], [], "hexpm", "31e92b653e9210b696765cdd885437457de1add2a9011d92f8cf63e4641bab7b"},
   "json_xema": {:hex, :json_xema, "0.6.5", "060459c9c9152650edb4427b1acbc61fa43a23bcea0301d200cafa76e0880f37", [:mix], [{:conv_case, "~> 0.2", [hex: :conv_case, repo: "hexpm", optional: false]}, {:xema, "~> 0.16", [hex: :xema, repo: "hexpm", optional: false]}], "hexpm", "b8ffdbc2f67aa8b91b44e1ba0ab77eb5c0b0142116f8fbb804977fb939d470ef"},
+  "libcluster": {:hex, :libcluster, "3.5.0", "5ee4cfde4bdf32b2fef271e33ce3241e89509f4344f6c6a8d4069937484866ba", [:mix], [{:jason, "~> 1.1", [hex: :jason, repo: "hexpm", optional: false]}, {:telemetry, "~> 1.3", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "ebf6561fcedd765a4cd43b4b8c04b1c87f4177b5fb3cbdfe40a780499d72f743"},
   "libgraph": {:hex, :libgraph, "0.16.0", "3936f3eca6ef826e08880230f806bfea13193e49bf153f93edcf0239d4fd1d07", [:mix], [], "hexpm", "41ca92240e8a4138c30a7e06466acc709b0cbb795c643e9e17174a178982d6bf"},
+  "libring": {:hex, :libring, "1.7.0", "4f245d2f1476cd7ed8f03740f6431acba815401e40299208c7f5c640e1883bda", [:mix], [], "hexpm", "070e3593cb572e04f2c8470dd0c119bc1817a7a0a7f88229f43cf0345268ec42"},
   "logfmt": {:hex, :logfmt, "3.3.3", "6521ee4a5c532088e15d487fab9f736c07bdd161d643560c73cd4b10685deb65", [:mix], [], "hexpm", "dbd51cd3fe37c3429b9bd687bad1f531a533505f4a641592129e7a47e24104d1"},
   "makeup": {:hex, :makeup, "1.2.1", "e90ac1c65589ef354378def3ba19d401e739ee7ee06fb47f94c687016e3713d1", [:mix], [{:nimble_parsec, "~> 1.4", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "d36484867b0bae0fea568d10131197a4c2e47056a6fbe84922bf6ba71c8d17ce"},
   "makeup_elixir": {:hex, :makeup_elixir, "1.0.1", "e928a4f984e795e41e3abd27bfc09f51db16ab8ba1aebdba2b3a575437efafc2", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "7284900d412a3e5cfd97fdaed4f5ed389b8f2b4cb49efc0eb3bd10e2febf9507"},
   "makeup_erlang": {:hex, :makeup_erlang, "1.0.3", "4252d5d4098da7415c390e847c814bad3764c94a814a0b4245176215615e1035", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "953297c02582a33411ac6208f2c6e55f0e870df7f80da724ed613f10e6706afd"},
+  "merkle_map": {:hex, :merkle_map, "0.2.2", "f36ff730cca1f2658e317a3c73406f50bbf5ac8aff54cf837d7ca2069a6e251c", [:mix], [], "hexpm", "383107f0503f230ac9175e0631647c424efd027e89ea65ab5ea12eeb54257aaf"},
   "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm", "69b09adddc4f74a40716ae54d140f93beb0fb8978d8636eaded0c31b6f099f16"},
   "mime": {:hex, :mime, "2.0.7", "b8d739037be7cd402aee1ba0306edfdef982687ee7e9859bee6198c1e7e2f128", [:mix], [], "hexpm", "6171188e399ee16023ffc5b76ce445eb6d9672e2e241d2df6050f3c771e80ccd"},
   "mimerl": {:hex, :mimerl, "1.4.0", "3882a5ca67fbbe7117ba8947f27643557adec38fa2307490c4c4207624cb213b", [:rebar3], [], "hexpm", "13af15f9f68c65884ecca3a3891d50a7b57d82152792f3e19d88650aa126b144"},

backend/rel/env.sh.eex

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+export RELEASE_DISTRIBUTION=name
+
+if [ -z "$MY_POD_IP" ]
+then
+    HOSTNAME=`hostname -i`
+    export RELEASE_NODE="<%= @release.name %>@$HOSTNAME"
+else
+    export RELEASE_NODE="<%= @release.name %>@$MY_POD_IP"
+fi

backend/test/edgehog_web/controllers/astarte_trigger_controller_test.exs

@@ -313,7 +313,7 @@ defmodule EdgehogWeb.Controllers.AstarteTriggerControllerTest do
       timestamp = utc_now_second()
       event = disconnection_trigger(device.device_id, timestamp)
 
-      Registry.register(Edgehog.Containers.Reconciler.Registry, tenant.tenant_id, self())
+      Horde.Registry.register(Edgehog.Containers.Reconciler.Registry, tenant.tenant_id, self())
 
       stub(DeviceStatusMock, :get, fn _client, _device_id -> flunk() end)
       assert conn |> post(path, event) |> response(200)