Service Monitoring¶

How to tell if each Mailyte service is healthy — quick checks you can run right now.

At a Glance¶

Bash

# One-liner: check all services
docker compose ps --format "table {{.Name}}\t{{.Status}}\t{{.Ports}}"

If everything says "Up" and "healthy," you're good. If not, read on.

Postfix (SMTP)¶

Postfix handles all email delivery. If it's down, no email goes in or out.

Quick check:

Bash

# Test SMTP connection
telnet localhost 25

# Or without telnet installed
echo "EHLO test" | nc -w 3 localhost 25

# Check the mail queue
docker compose exec postfix postqueue -p

# Count queued messages
docker compose exec postfix postqueue -p | tail -1

What healthy looks like:

Text Only

220 mail.yourdomain.com ESMTP Postfix

Key things to watch:

Metric	Healthy	Investigate
Queue size	< 100	> 500
Delivery delay	< 30s	> 5min
Bounce rate	< 3%	> 5%
Active connections	< 50	> 100

Common problems:

Queue growing: Check DNS resolution, recipient server availability
High bounces: Check sender reputation, SPF/DKIM records
Connection refused: Postfix service crashed, check logs

Bash

docker compose logs --tail=50 postfix

Dovecot (IMAP/POP3)¶

Dovecot handles mailbox access. If it's down, users can't read email.

Quick check:

Bash

# Test IMAP
echo "a1 LOGIN testuser testpass" | nc -w 3 localhost 143

# Check active connections
docker compose exec dovecot doveadm who

# Verify user mailbox
docker compose exec dovecot doveadm mailbox list -u user@domain.com

What healthy looks like:

Text Only

* OK [CAPABILITY IMAP4rev1 ...] Dovecot ready.

Key things to watch:

Metric	Healthy	Investigate
Active connections	Stable	Sudden drop or spike
Auth failures	< 10/min	> 50/min (possible brute force)
Mailbox size	Within quota	Near quota limit

Rspamd (Spam Filter)¶

Rspamd scans incoming email for spam. If it's down, you'll either reject all mail or let everything through (depending on your Postfix config).

Quick check:

Bash

# Ping Rspamd
curl http://localhost:11334/ping

# Get statistics
curl http://localhost:11334/stat

# Check Rspamd status
curl http://localhost:11334/stat | python3 -m json.tool

What healthy looks like:

Text Only

pong

Key things to watch:

Metric	Healthy	Investigate
Scan time	< 500ms	> 2s
Spam rate	10-40%	> 60% or < 5%
Memory usage	< 500MB	> 1GB

MySQL¶

MySQL stores user accounts, domains, aliases, and configuration. If it's down, the API can't function.

Quick check:

Bash

# Test connection
docker compose exec mysql mysqladmin -u root -p ping

# Check status
docker compose exec mysql mysqladmin -u root -p status

# Check process list
docker compose exec mysql mysql -u root -p -e "SHOW PROCESSLIST;"

# Check table sizes
docker compose exec mysql mysql -u root -p -e "
SELECT table_name,
       ROUND(data_length/1024/1024, 2) AS 'Size (MB)'
FROM information_schema.tables
WHERE table_schema = 'mailyte'
ORDER BY data_length DESC;"

What healthy looks like:

Text Only

mysqld is alive

Key things to watch:

Metric	Healthy	Investigate
Connections	< 80% of max	> 80% of max
Slow queries	0	Any
Replication lag	0s	> 5s
Buffer pool hit rate	> 99%	< 95%

Redis¶

Redis handles caching, session storage, and worker job queues. If it's down, the API slows down and workers stop processing.

Quick check:

Bash

# Ping Redis
docker compose exec redis redis-cli ping

# Check memory usage
docker compose exec redis redis-cli info memory | grep used_memory_human

# Check connected clients
docker compose exec redis redis-cli info clients | grep connected_clients

# Check queue lengths
docker compose exec redis redis-cli llen email_queue
docker compose exec redis redis-cli llen retry_queue

What healthy looks like:

Text Only

PONG

Key things to watch:

Metric	Healthy	Investigate
Memory usage	< 80% of max	> 85%
Connected clients	Stable	Climbing fast
Hit rate	> 90%	< 80%
Queue length	< 100	> 1000

FastAPI (API Server)¶

The API on port 5000 is how external systems interact with Mailyte.

Quick check:

Bash

# Health endpoint
curl http://localhost:5000/health

# Check response time
curl -w "Total time: %{time_total}s\n" -o /dev/null -s http://localhost:5000/health

# API docs (confirms the app is running)
curl -s http://localhost:5000/docs | head -5

What healthy looks like:

JSON

{"status": "ok", "version": "1.0.0"}

Key things to watch:

Metric	Healthy	Investigate
Response time (p95)	< 200ms	> 500ms
Error rate	< 1%	> 5%
Active requests	< 50	> 100

Workers¶

Workers process background jobs — sending emails, retrying deliveries, cleaning up.

Quick check:

Bash

# Check worker status
docker compose ps worker

# View recent worker logs
docker compose logs --tail=20 worker

# Check job queue depth
docker compose exec redis redis-cli llen email_queue

Key things to watch:

Metric	Healthy	Investigate
Queue depth	Stable or decreasing	Growing steadily
Job failure rate	< 1%	> 5%
Processing time	< 5s per job	> 30s per job
Last heartbeat	< 60s ago	> 120s ago

Health Check Script¶

Save this as check-all.sh for a quick full-system check:

Bash

#!/bin/bash

echo "=== Mailyte Service Status ==="
echo ""

services=("postfix:25" "dovecot:143" "rspamd:11334" "mysql:3306" "redis:6379" "api:5000" "health-monitor:8080")

for svc in "${services[@]}"; do
    name="${svc%%:*}"
    port="${svc##*:}"
    if nc -z -w 2 localhost "$port" 2>/dev/null; then
        echo "  [OK]   $name (:$port)"
    else
        echo "  [FAIL] $name (:$port)"
    fi
done

echo ""
echo "=== Docker Containers ==="
docker compose ps --format "table {{.Name}}\t{{.Status}}"

Bash

chmod +x check-all.sh
./check-all.sh