Expand keepalived healthcheck to cover all critical components

Create healthcheck.sh that checks mysqlrouter process, mysqladmin ping,
Docker daemon, Superset swarm service, and Redis. Update keepalived to
use the new script with interval=5, weight=-20, fall=3, rise=2. Copy the
script to the named volume during init container setup.

Closes #66

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: szachovy

CHANGELOG.md

@@ -16,6 +16,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * CI workflow to build and push service images to GitHub Container Registry on master merge. (#97)
 * Pull-first with local build fallback for container images during deployment. (#97)
 
+### Fixed
+
+* Expand keepalived healthcheck to cover MySQL Router, Docker daemon, Superset service, and Redis. (#66)
+
 ### Changed
 
 * Completed [ARCHITECTURE.md](./docs/ARCHITECTURE.md) (#93)

services/mysql-mgmt/docker_compose.yml

@@ -76,6 +76,8 @@ services:
           --execute="DROP USER 'superset'@'$(mysqlsh --python --execute "exec(open('/opt/interfaces.py').read())")';"
         ifmetric ${VIRTUAL_NETWORK_INTERFACE} 2
         /opt/envsubst-Linux-x86_64 < "/opt/keepalived.conf.tpl" > "/opt/default/keepalived.conf";
+        cp "/opt/healthcheck.sh" "/opt/default/healthcheck.sh";
+        chmod 755 "/opt/default/healthcheck.sh";
         chown --recursive superset:superset "/opt/default"
     cap_add:
       - "NET_ADMIN"

services/mysql-mgmt/healthcheck.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -euo pipefail
+
+killall -0 mysqlrouter 2>/dev/null || exit 1
+mysqladmin --login-path=superset --port=6446 ping 2>/dev/null || exit 1
+docker info > /dev/null 2>&1 || exit 1
+docker service inspect superset --format '{{.Spec.Name}}' 2>/dev/null | grep -q superset || exit 1
+docker exec redis redis-cli ping 2>/dev/null | grep -q PONG || exit 1
+
+exit 0

services/mysql-mgmt/keepalived.conf.tpl

@@ -6,9 +6,11 @@ global_defs {
 }
 
 vrrp_script status {
-    script "/bin/killall -0 mysqlrouter"
-    interval 1
-    weight 2
+    script "/opt/default/healthcheck.sh"
+    interval 5
+    weight -20
+    fall 3
+    rise 2
 }
 
 vrrp_instance virtual_instance {