Add Erlang clustering via libcluster and expose LiveDashboard

- libcluster with Kubernetes IP strategy for pod discovery
- RBAC for pod list/get, POD_IP from downward API, shared cookie
- LiveDashboard at /dashboard for all environments

config/runtime.exs

@@ -129,6 +129,20 @@ if config_env() == :prod do
        ]}
     ]
 
+  config :libcluster,
+    topologies: [
+      k8s: [
+        strategy: Cluster.Strategy.Kubernetes,
+        config: [
+          mode: :ip,
+          kubernetes_ip_lookup_mode: :pods,
+          kubernetes_node_basename: "microwaveprop",
+          kubernetes_selector: "app=prop",
+          kubernetes_namespace: "prop"
+        ]
+      ]
+    ]
+
   config :microwaveprop, :email_from, {"NTMS Propagation", "graham@w5isp.com"}
   config :microwaveprop, hrrr_base_url: System.get_env("HRRR_BASE_URL", "http://skippy.w5isp.com:8080")
   config :microwaveprop, srtm_tiles_dir: "/srtm"

k8s/deployment.yaml

@@ -30,6 +30,7 @@ spec:
                 matchLabels:
                   app: prop
               topologyKey: topology.kubernetes.io/physical-host
+      serviceAccountName: prop
       imagePullSecrets:
         - name: forgejo-registry
       securityContext:
@@ -43,6 +44,10 @@ spec:
           image: git.mcintire.me/graham/prop:main-1775486348-7654146 # {"$imagepolicy": "flux-system:prop"}
           imagePullPolicy: IfNotPresent
           env:
+            - name: POD_IP
+              valueFrom:
+                fieldRef:
+                  fieldPath: status.podIP
             - name: PHX_SERVER
               value: "true"
             - name: PHX_HOST

k8s/kustomization.yaml

@@ -3,5 +3,6 @@ kind: Kustomization
 resources:
   - namespace.yaml
   - secret.yaml
+  - rbac.yaml
   - deployment.yaml
   - service.yaml

k8s/rbac.yaml

@@ -0,0 +1,29 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: prop
+  namespace: prop
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: prop-pod-reader
+  namespace: prop
+rules:
+  - apiGroups: [""]
+    resources: ["pods"]
+    verbs: ["get", "list"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: prop-pod-reader
+  namespace: prop
+subjects:
+  - kind: ServiceAccount
+    name: prop
+    namespace: prop
+roleRef:
+  kind: Role
+  name: prop-pod-reader
+  apiGroup: rbac.authorization.k8s.io

lib/microwaveprop/application.ex

@@ -7,9 +7,12 @@ defmodule Microwaveprop.Application do
 
   @impl true
   def start(_type, _args) do
+    topologies = Application.get_env(:libcluster, :topologies, [])
+
     children = [
       MicrowavepropWeb.Telemetry,
       Microwaveprop.Repo,
+      {Cluster.Supervisor, [topologies, [name: Microwaveprop.ClusterSupervisor]]},
       {Phoenix.PubSub, name: Microwaveprop.PubSub},
       {Oban, Application.fetch_env!(:microwaveprop, Oban)},
       Microwaveprop.RepoListener,

lib/microwaveprop_web/router.ex

@@ -47,19 +47,19 @@ defmodule MicrowavepropWeb.Router do
   #   pipe_through :api
   # end
 
-  # Enable LiveDashboard and Swoosh mailbox preview in development
-  if Application.compile_env(:microwaveprop, :dev_routes) do
-    # If you want to use the LiveDashboard in production, you should put
-    # it behind authentication and allow only admins to access it.
-    # If your application does not have an admins-only section yet,
-    # you can use Plug.BasicAuth to set up some basic authentication
-    # as long as you are also using SSL (which you should anyway).
   import Phoenix.LiveDashboard.Router
 
-    scope "/dev" do
+  scope "/" do
     pipe_through :browser
 
     live_dashboard "/dashboard", metrics: MicrowavepropWeb.Telemetry
+  end
+
+  # Enable Swoosh mailbox preview in development
+  if Application.compile_env(:microwaveprop, :dev_routes) do
+    scope "/dev" do
+      pipe_through :browser
+
       forward "/mailbox", Plug.Swoosh.MailboxPreview
     end
   end

mix.exs

@@ -70,7 +70,8 @@ defmodule Microwaveprop.MixProject do
       {:axon, "~> 0.7", only: [:dev, :test]},
       {:exla, "~> 0.9", only: [:dev, :test]},
       {:polaris, "~> 0.1", only: [:dev, :test]},
-      {:tidewave, "~> 0.5", only: :dev}
+      {:tidewave, "~> 0.5", only: :dev},
+      {:libcluster, "~> 3.4"}
     ]
   end
 

mix.lock

@@ -23,6 +23,7 @@
   "idna": {:hex, :idna, "6.1.1", "8a63070e9f7d0c62eb9d9fcb360a7de382448200fbbd1b106cc96d3d8099df8d", [:rebar3], [{:unicode_util_compat, "~> 0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "92376eb7894412ed19ac475e4a86f7b413c1b9fbb5bd16dccd57934157944cea"},
   "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
   "lazy_html": {:hex, :lazy_html, "0.1.10", "ffe42a0b4e70859cf21a33e12a251e0c76c1dff76391609bd56702a0ef5bc429", [:make, :mix], [{:cc_precompiler, "~> 0.1", [hex: :cc_precompiler, repo: "hexpm", optional: false]}, {:elixir_make, "~> 0.9.0", [hex: :elixir_make, repo: "hexpm", optional: false]}, {:fine, "~> 0.1.0", [hex: :fine, repo: "hexpm", optional: false]}], "hexpm", "50f67e5faa09d45a99c1ddf3fac004f051997877dc8974c5797bb5ccd8e27058"},
+  "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"},
   "live_stash": {:hex, :live_stash, "0.1.1", "d6a715708d0d281608de62a15ee8aca63427046daaa6333a235aa9e55f2cccb2", [:mix], [{:phoenix_live_view, "~> 1.0", [hex: :phoenix_live_view, repo: "hexpm", optional: false]}, {:uniq, "~> 0.6", [hex: :uniq, repo: "hexpm", optional: false]}], "hexpm", "96341ebd35513f6e71b4e268ef4d413b1e21048a3d759cafe0cd8378ad8df908"},
   "mime": {:hex, :mime, "2.0.7", "b8d739037be7cd402aee1ba0306edfdef982687ee7e9859bee6198c1e7e2f128", [:mix], [], "hexpm", "6171188e399ee16023ffc5b76ce445eb6d9672e2e241d2df6050f3c771e80ccd"},
   "mint": {:hex, :mint, "1.7.1", "113fdb2b2f3b59e47c7955971854641c61f378549d73e829e1768de90fc1abf1", [:mix], [{:castore, "~> 0.1.0 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:hpax, "~> 0.1.1 or ~> 0.2.0 or ~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}], "hexpm", "fceba0a4d0f24301ddee3024ae116df1c3f4bb7a563a731f45fdfeb9d39a231b"},

rel/env.sh.eex

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+# Set the release node name from the pod IP for Erlang clustering
+if [ -n "$POD_IP" ]; then
+  export RELEASE_DISTRIBUTION=name
+  export RELEASE_NODE=microwaveprop@${POD_IP}
+  export RELEASE_COOKIE="${ERLANG_COOKIE:-microwaveprop_cookie}"
+fi