fix: update Phoenix.PubSub.Redis configuration for 3.1.0 compatibility (#197)

The recent dependency update to phoenix_pubsub_redis 3.1.0 introduced
breaking changes in the configuration API. The new version no longer
accepts connection options at the top level - they must be nested in
:redis_opts.

Changes:
- Move Redix connection options into :redis_opts keyword list
- Keep only :node_name at top level per v3.1.0 requirements
- Maintains all resilience settings (timeouts, backoff, keepalive)

Before (invalid for v3.1.0):
  [node_name: node(), host: "...", port: 6379, timeout: 5000, ...]

After (valid for v3.1.0):
  [node_name: node(), redis_opts: [host: "...", port: 6379, timeout: 5000, ...]]

This fixes the production crash with error:
  NimbleOptions.ValidationError: unknown options [:timeout, :backoff_initial,
  :backoff_max, :exit_on_disconnection, :sync_connect]

Related: commit 0399b30d (Update Elixir dependencies)

Reviewed-on: graham/towerops-web#197

CHANGELOG.txt

@@ -1,3 +1,14 @@
+2026-03-27
+fix: update Phoenix.PubSub.Redis configuration for 3.1.0 compatibility
+  - Fixed NimbleOptions.ValidationError crash on production pod startup
+  - Updated redis_pubsub_config/0 to use new phoenix_pubsub_redis 3.1.0 API structure
+  - Moved connection options (timeout, backoff_*, exit_on_disconnection, sync_connect, socket_opts) into :redis_opts keyword
+  - Top-level options now only :node_name and :redis_opts per v3.1.0 requirements
+  - Caused by recent dependency update to phoenix_pubsub_redis 3.1.0 (commit 0399b30d)
+  - Breaking change: v3.1.0 changed valid options from [:timeout, :backoff_initial, :backoff_max, :exit_on_disconnection, :sync_connect]
+    to [:node_name, :redis_pool_size, :compression_level, :redis_opts]
+  Files: lib/towerops/application.ex (redis_pubsub_config/0)
+
 2026-03-27
 fix: handle alert_changed message in DashboardLive
   - Fixed FunctionClauseError when DashboardLive receives {:alert_changed, org_id} message

lib/towerops/application.ex

@@ -245,28 +245,12 @@ defmodule Towerops.Application do
   defp redis_pubsub_config do
     redis_config = Application.get_env(:towerops, :redis, [])
 
-    # Base configuration for Phoenix.PubSub.Redis
-    base_opts = [
+    # Build Redix connection options (phoenix_pubsub_redis 3.1.0+ requires :redis_opts key)
+    redis_opts = [
       host: Keyword.get(redis_config, :host, "localhost"),
       port: Keyword.get(redis_config, :port, 6379),
-      node_name: node()
-    ]
-
-    # Add password if configured (read from application config set by runtime.exs)
-    base_opts =
-      case Keyword.get(redis_config, :password) do
-        nil -> base_opts
-        "" -> base_opts
-        password -> Keyword.put(base_opts, :password, password)
-      end
-
-    # Add resilience options for better reconnection handling
-    resilience_opts = [
-      # Redix connection options for better resilience
-      socket_opts: [
-        # TCP keepalive to detect dead connections
-        keepalive: true
-      ],
+      # TCP keepalive to detect dead connections
+      socket_opts: [keepalive: true],
       # Connection timeout (5 seconds)
       timeout: 5_000,
       # Backoff settings for reconnection
@@ -278,7 +262,19 @@ defmodule Towerops.Application do
       sync_connect: false
     ]
 
-    Keyword.merge(base_opts, resilience_opts)
+    # Add password if configured (read from application config set by runtime.exs)
+    redis_opts =
+      case Keyword.get(redis_config, :password) do
+        nil -> redis_opts
+        "" -> redis_opts
+        password -> Keyword.put(redis_opts, :password, password)
+      end
+
+    # Phoenix.PubSub.Redis 3.1.0+ configuration structure
+    [
+      node_name: node(),
+      redis_opts: redis_opts
+    ]
   end
 
   # Register file logger backend for development (only available in :dev environment)

priv/static/changelog.txt

@@ -1,4 +1,5 @@
 2026-03-27 — Stability Improvements
+* Fixed production deployment crash related to real-time messaging infrastructure
 * Fixed dashboard crashes when alerts change
 * Improved real-time alert updates reliability