NGINXの基礎から応用まで

第4部：アプリケーションスタック＆監視

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1. Access Logs và Error Logs

1.1. Default Log Configuration

http {
    # Default log format
    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
                    '$status $body_bytes_sent "$http_referer" '
                    '"$http_user_agent" "$http_x_forwarded_for"';
# Access log
access_log /var/log/nginx/access.log main;

# Error log with level
error_log /var/log/nginx/error.log warn;

server {
    listen 80;
    server_name example.com;
    
    # Server-specific logs
    access_log /var/log/nginx/example.com.access.log main;
    error_log /var/log/nginx/example.com.error.log;
    
    location / {
        root /var/www/html;
    }
    
    # Disable logging for specific location
    location /health {
        access_log off;
        return 200 "OK\n";
    }
    
    # Location-specific log
    location /api/ {
        access_log /var/log/nginx/api.access.log main;
        proxy_pass http://backend;
    }
}

}

1.2. Error Log Levels

# Error log levels (highest to lowest severity)
error_log /var/log/nginx/error.log emerg;   # System is unusable
error_log /var/log/nginx/error.log alert;   # Action must be taken immediately
error_log /var/log/nginx/error.log crit;    # Critical conditions
error_log /var/log/nginx/error.log error;   # Error conditions (default)
error_log /var/log/nginx/error.log warn;    # Warning conditions
error_log /var/log/nginx/error.log notice;  # Normal but significant
error_log /var/log/nginx/error.log info;    # Informational messages
error_log /var/log/nginx/error.log debug;   # Debug messages

Recommended for production
error_log /var/log/nginx/error.log warn;
For debugging
error_log /var/log/nginx/error.log debug;

1.3. Custom Log Formats

Detailed log format:

http {
log_format detailed '$remote_addr - $remote_user [$time_local] '
'"$request" $status $body_bytes_sent '
'"$http_referer" "$http_user_agent" '
'rt=$request_time uct="$upstream_connect_time" '
'uht="$upstream_header_time" urt="$upstream_response_time"';

access_log /var/log/nginx/access.log detailed;

}

JSON log format:

http {
log_format json_combined escape=json
'{'
'"time_local":"$time_local",'
'"remote_addr":"$remote_addr",'
'"remote_user":"$remote_user",'
'"request":"$request",'
'"status": "$status",'
'"body_bytes_sent":"$body_bytes_sent",'
'"request_time":"$request_time",'
'"http_referrer":"$http_referer",'
'"http_user_agent":"$http_user_agent",'
'"http_x_forwarded_for":"$http_x_forwarded_for",'
'"upstream_addr":"$upstream_addr",'
'"upstream_status":"$upstream_status",'
'"upstream_response_time":"$upstream_response_time",'
'"upstream_connect_time":"$upstream_connect_time",'
'"upstream_header_time":"$upstream_header_time"'
'}';

access_log /var/log/nginx/access.log json_combined;

}

Cache status log:

http {
log_format cache_status '$remote_addr - [$time_local] "$request" '
'$status $body_bytes_sent '
'"$http_referer" "$http_user_agent" '
'cache_status=$upstream_cache_status '
'response_time=$request_time';

access_log /var/log/nginx/cache.log cache_status;

}

Performance tracking log:

http {
log_format performance '$time_iso8601 $remote_addr '
'"$request" $status $body_bytes_sent '
'rt=$request_time '
'ua="$upstream_addr" '
'us=$upstream_status '
'ut=$upstream_response_time '
'ul="$upstream_response_length" '
'cs=$upstream_cache_status';

access_log /var/log/nginx/performance.log performance;

}

Security log:

http {
log_format security '$remote_addr [$time_local] '
'"$request" $status '
'user_agent="$http_user_agent" '
'referer="$http_referer" '
'forwarded_for="$http_x_forwarded_for" '
'host="$host"';

# Log only suspicious requests
map $status $loggable {
    ~^[23] 0;
    default 1;
}

access_log /var/log/nginx/security.log security if=$loggable;

}

1.4. Conditional Logging

http {
# Don't log successful health checks
map $request_uri $loggable_request {
~^/health$ 0;
~^/ping$ 0;
default 1;
}

# Don't log static files
map $request_uri $loggable_static {
    ~*\.(jpg|jpeg|png|gif|ico|css|js)$ 0;
    default 1;
}

# Combine conditions
map "$loggable_request:$loggable_static" $final_loggable {
    "0:0" 0;
    "0:1" 0;
    "1:0" 0;
    default 1;
}

server {
    listen 80;
    
    access_log /var/log/nginx/access.log combined if=$final_loggable;
    
    # Or per-location
    location /api/ {
        access_log /var/log/nginx/api.log combined;
        proxy_pass http://backend;
    }
    
    location /static/ {
        access_log off;
        root /var/www;
    }
}

}

1.5. Log Variables

Available variables:

# Client information
$remote_addr          # Client IP address
$remote_user          # Client username (HTTP auth)
$remote_port          # Client port

Request information
$request              # Full request line
$request_method       # GET, POST, etc.
$request_uri          # Full URI with arguments
$uri                  # URI without arguments
$args                 # Query string
$scheme               # http or https
$server_protocol      # HTTP version (HTTP/1.1, HTTP/2.0)
Response information
$status               # Response status code
$body_bytes_sent      # Bytes sent to client
$bytes_sent           # Total bytes sent (including headers)
Timing information
$request_time         # Total request processing time
$upstream_response_time    # Backend response time
$upstream_connect_time     # Time to connect to backend
$upstream_header_time      # Time to receive headers from backend
Upstream information
$upstream_addr        # Backend server address
$upstream_status      # Backend response status
$upstream_cache_status     # Cache status (HIT, MISS, etc.)
Headers
$http_referer         # Referer header
$http_user_agent      # User-Agent header
$http_x_forwarded_for # X-Forwarded-For header
Time
$time_local           # Local time
$time_iso8601         # ISO 8601 format
$msec                 # Unix timestamp with milliseconds

---

2. Log Rotation

2.1. Logrotate Configuration

# /etc/logrotate.d/nginx
/var/log/nginx/.log {
daily                    # Rotate daily
missingok               # Don't error if log is missing
rotate 14               # Keep 14 days of logs
compress                # Compress rotated logs
delaycompress          # Compress after one rotation
notifempty             # Don't rotate if empty
create 0640 nginx adm  # Create new file with permissions
sharedscripts          # Run postrotate once for all logs
postrotate
if [ -f /var/run/nginx.pid ]; then
kill -USR1 cat /var/run/nginx.pid
fi
endscript
}

Weekly rotation:

# /etc/logrotate.d/nginx-weekly
/var/log/nginx/access.log
/var/log/nginx/error.log {
weekly
rotate 52
compress
delaycompress
notifempty
create 0640 nginx adm
sharedscripts
postrotate
[ -f /var/run/nginx.pid ] && kill -USR1 cat /var/run/nginx.pid
endscript
}

Size-based rotation:

# /etc/logrotate.d/nginx-size
/var/log/nginx/.log {
size 100M           # Rotate when file reaches 100MB
rotate 10           # Keep 10 rotated files
compress
delaycompress
notifempty
create 0640 nginx adm
sharedscripts
postrotate
[ -f /var/run/nginx.pid ] && kill -USR1 cat /var/run/nginx.pid
endscript
}

Test logrotate:

# Test configuration
sudo logrotate -d /etc/logrotate.d/nginx

Force rotation
sudo logrotate -f /etc/logrotate.d/nginx
Check status
cat /var/lib/logrotate/status

2.2. Manual Log Rotation Script

#!/bin/bash

rotate_nginx_logs.sh
LOG_DIR="/var/log/nginx"
BACKUP_DIR="/var/log/nginx/archive"
DAYS_TO_KEEP=30
Create backup directory
mkdir -p $BACKUP_DIR
Get current date
DATE=$(date +%Y%m%d-%H%M%S)
Rotate logs
for log in access.log error.log; do
if [ -f "$LOG_DIR/$log" ]; then
# Move log file
mv "$LOG_DIR/$log" "$BACKUP_DIR/${log%.*}-$DATE.log"
    # Compress
    gzip "$BACKUP_DIR/${log%.*}-$DATE.log"
    
    # Create new empty log
    touch "$LOG_DIR/$log"
    chmod 640 "$LOG_DIR/$log"
    chown nginx:adm "$LOG_DIR/$log"
fi

done
Reload Nginx
nginx -s reopen
Delete old logs
find $BACKUP_DIR -name "*.gz" -mtime +$DAYS_TO_KEEP -delete
echo "Log rotation complete: $DATE"

Cron job:

# /etc/cron.d/nginx-logrotate
0 0 * * * root /usr/local/bin/rotate_nginx_logs.sh >> /var/log/nginx-rotation.log 2>&1

---

3. Log Analysis Tools

3.1. GoAccess (Real-time Web Log Analyzer)

Install GoAccess:

# Ubuntu/Debian
sudo apt install goaccess

CentOS/RHEL
sudo yum install goaccess
macOS
brew install goaccess

Analyze logs:

# Real-time terminal dashboard
sudo goaccess /var/log/nginx/access.log -c

Generate HTML report
sudo goaccess /var/log/nginx/access.log -o /var/www/html/report.html --log-format=COMBINED
Real-time HTML dashboard
sudo goaccess /var/log/nginx/access.log -o /var/www/html/report.html --log-format=COMBINED --real-time-html
With custom log format
sudo goaccess /var/log/nginx/access.log --log-format='%h %^[%d:%t %^] "%r" %s %b "%R" "%u"' --date-format=%d/%b/%Y --time-format=%H:%M:%S

GoAccess configuration:

# /etc/goaccess/goaccess.conf

Log format
log-format %h %^[%d:%t %^] "%r" %s %b "%R" "%u"
date-format %d/%b/%Y
time-format %H:%M:%S
UI options
color-scheme 1
hl-header true
Output options
html-prefs {"theme":"bright","perPage":10}
html-report-title "Nginx Statistics"
Enable/disable panels
enable-panel VISITORS
enable-panel REQUESTS
enable-panel REQUESTS_STATIC
enable-panel NOT_FOUND
enable-panel HOSTS
enable-panel OS
enable-panel BROWSERS
enable-panel STATUS_CODES
enable-panel REFERRING_SITES
enable-panel KEYPHRASES
enable-panel GEO_LOCATION

3.2. AWK Scripts for Log Analysis

Requests per second:

#!/bin/bash

requests_per_second.sh
awk '{print $4}' /var/log/nginx/access.log | 

cut -d: -f1-3 | 

uniq -c | 

awk '{print $2, $1}' | 

sort

Top 10 IP addresses:

#!/bin/bash

top_ips.sh
awk '{print $1}' /var/log/nginx/access.log | 

sort | 

uniq -c | 

sort -rn | 

head -10

Top 10 URLs:

#!/bin/bash

top_urls.sh
awk '{print $7}' /var/log/nginx/access.log | 

sort | 

uniq -c | 

sort -rn | 

head -10

Status code distribution:

#!/bin/bash

status_codes.sh
awk '{print $9}' /var/log/nginx/access.log | 

sort | 

uniq -c | 

sort -rn

Average response time:

#!/bin/bash

avg_response_time.sh
Assuming response time is logged
awk '{sum+=$NF; count++} END {print "Average:", sum/count "s"}' /var/log/nginx/access.log

Requests by hour:

#!/bin/bash

requests_by_hour.sh
awk '{print $4}' /var/log/nginx/access.log | 

cut -d: -f2 | 

sort -n | 

uniq -c

404 errors:

#!/bin/bash

404_errors.sh
awk '$9 == "404" {print $7}' /var/log/nginx/access.log | 

sort | 

uniq -c | 

sort -rn | 

head -20

Bandwidth by IP:

#!/bin/bash

bandwidth_by_ip.sh
awk '{ip[$1]+=$10} END {for (i in ip) print i, ip[i]/1024/1024 "MB"}' /var/log/nginx/access.log | 

sort -k2 -rn | 

head -10

3.3. Complete Log Analysis Script

#!/bin/bash

analyze_nginx_logs.sh
LOG_FILE="/var/log/nginx/access.log"
OUTPUT_DIR="/var/www/reports"
DATE=$(date +%Y-%m-%d)
mkdir -p $OUTPUT_DIR
echo "Nginx Log Analysis - $DATE" > $OUTPUT_DIR/report-$DATE.txt
echo "=====================================" >> $OUTPUT_DIR/report-$DATE.txt
echo "" >> $OUTPUT_DIR/report-$DATE.txt
Total requests
echo "Total Requests:" >> $OUTPUT_DIR/report-$DATE.txt
wc -l < $LOG_FILE >> $OUTPUT_DIR/report-$DATE.txt
echo "" >> $OUTPUT_DIR/report-$DATE.txt
Top 10 IPs
echo "Top 10 IP Addresses:" >> $OUTPUT_DIR/report-$DATE.txt
awk '{print $1}' $LOG_FILE | sort | uniq -c | sort -rn | head -10 >> $OUTPUT_DIR/report-$DATE.txt
echo "" >> $OUTPUT_DIR/report-$DATE.txt
Top 10 URLs
echo "Top 10 URLs:" >> $OUTPUT_DIR/report-$DATE.txt
awk '{print $7}' $LOG_FILE | sort | uniq -c | sort -rn | head -10 >> $OUTPUT_DIR/report-$DATE.txt
echo "" >> $OUTPUT_DIR/report-$DATE.txt
Status codes
echo "Status Code Distribution:" >> $OUTPUT_DIR/report-$DATE.txt
awk '{print $9}' $LOG_FILE | sort | uniq -c | sort -rn >> $OUTPUT_DIR/report-$DATE.txt
echo "" >> $OUTPUT_DIR/report-$DATE.txt
Top user agents
echo "Top 10 User Agents:" >> $OUTPUT_DIR/report-$DATE.txt
awk -F'"' '{print $6}' $LOG_FILE | sort | uniq -c | sort -rn | head -10 >> $OUTPUT_DIR/report-$DATE.txt
echo "" >> $OUTPUT_DIR/report-$DATE.txt
Requests by hour
echo "Requests by Hour:" >> $OUTPUT_DIR/report-$DATE.txt
awk '{print $4}' $LOG_FILE | cut -d: -f2 | sort -n | uniq -c >> $OUTPUT_DIR/report-$DATE.txt
echo "" >> $OUTPUT_DIR/report-$DATE.txt
Top 404 errors
echo "Top 404 Errors:" >> $OUTPUT_DIR/report-$DATE.txt
awk '$9 == "404" {print $7}' $LOG_FILE | sort | uniq -c | sort -rn | head -10 >> $OUTPUT_DIR/report-$DATE.txt
echo "Report generated: $OUTPUT_DIR/report-$DATE.txt"

---

4. Prometheus + Grafana Integration

4.1. Nginx Prometheus Exporter

Install nginx-prometheus-exporter:

# Download latest release
wget https://github.com/nginxinc/nginx-prometheus-exporter/releases/download/v0.11.0/nginx-prometheus-exporter_0.11.0_linux_amd64.tar.gz

Extract
tar -xzf nginx-prometheus-exporter_0.11.0_linux_amd64.tar.gz
Move to bin
sudo mv nginx-prometheus-exporter /usr/local/bin/
Create systemd service
sudo nano /etc/systemd/system/nginx-exporter.service

Systemd service:

[Unit]
Description=Nginx Prometheus Exporter
After=network.target

[Service]
Type=simple
User=nginx-exporter
Group=nginx-exporter
ExecStart=/usr/local/bin/nginx-prometheus-exporter 

-nginx.scrape-uri=http://localhost:8080/stub_status 

-web.listen-address=:9113
Restart=always
RestartSec=10
[Install]
WantedBy=multi-user.target

Enable stub_status in Nginx:

server {
listen 8080;
server_name localhost;

location /stub_status {
    stub_status;
    access_log off;
    allow 127.0.0.1;
    deny all;
}

}

Start exporter:

sudo systemctl daemon-reload
sudo systemctl start nginx-exporter
sudo systemctl enable nginx-exporter

Check status
sudo systemctl status nginx-exporter
Test metrics endpoint
curl http://localhost:9113/metrics

4.2. Prometheus Configuration

# /etc/prometheus/prometheus.yml
global:
scrape_interval: 15s
evaluation_interval: 15s

scrape_configs:


job_name: 'nginx'
static_configs:

targets: ['localhost:9113']
labels:
instance: 'nginx-server-1'
environment: 'production'



job_name: 'node'
static_configs:

targets: ['localhost:9100']
labels:
instance: 'nginx-server-1'

4.3. VTS Module (Advanced Metrics)

Install Nginx with VTS module:

# Clone VTS module
git clone https://github.com/vozlt/nginx-module-vts.git



Download Nginx source
wget http://nginx.org/download/nginx-1.24.0.tar.gz
tar -xzf nginx-1.24.0.tar.gz
cd nginx-1.24.0
Configure with VTS module
./configure --add-module=../nginx-module-vts 

--prefix=/etc/nginx 

--sbin-path=/usr/sbin/nginx 

--conf-path=/etc/nginx/nginx.conf
Compile and install
make
sudo make install

Configure VTS:

http {
vhost_traffic_status_zone;

server {
    listen 80;
    
    location /status {
        vhost_traffic_status_display;
        vhost_traffic_status_display_format html;
        access_log off;
        allow 127.0.0.1;
        deny all;
    }
}

}

4.4. Grafana Dashboard

Install Grafana:

# Ubuntu/Debian
sudo apt install -y software-properties-common
sudo add-apt-repository "deb https://packages.grafana.com/oss/deb stable main"
wget -q -O - https://packages.grafana.com/gpg.key | sudo apt-key add -
sudo apt update
sudo apt install grafana

Start Grafana
sudo systemctl start grafana-server
sudo systemctl enable grafana-server

Access Grafana:

• URL: http://localhost:3000
• Default login: admin/admin

Import Nginx dashboard:

1. Go to Dashboards → Import
2. Enter dashboard ID: 12708 (Nginx Prometheus Exporter)
3. Select Prometheus datasource
4. Import

Custom Grafana dashboard queries:

# Request rate
rate(nginx_http_requests_total[5m])

Error rate
rate(nginx_http_requests_total{status=~"5.."}[5m])
Average response time
rate(nginx_http_request_duration_seconds_sum[5m]) /
rate(nginx_http_request_duration_seconds_count[5m])
Active connections
nginx_connections_active
Request rate by status code
sum(rate(nginx_http_requests_total[5m])) by (status)
Bandwidth
rate(nginx_http_request_bytes_total[5m])

---

5. ELK Stack Integration

5.1. Elasticsearch Installation

# Import Elasticsearch GPG key
wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -

Add repository
echo "deb https://artifacts.elastic.co/packages/8.x/apt stable main" | sudo tee /etc/apt/sources.list.d/elastic-8.x.list
Install Elasticsearch
sudo apt update
sudo apt install elasticsearch
Configure
sudo nano /etc/elasticsearch/elasticsearch.yml

Elasticsearch configuration:

# /etc/elasticsearch/elasticsearch.yml
cluster.name: nginx-logs
node.name: node-1
path.data: /var/lib/elasticsearch
path.logs: /var/log/elasticsearch
network.host: localhost
http.port: 9200
discovery.type: single-node

Security
xpack.security.enabled: false

Start Elasticsearch:

sudo systemctl start elasticsearch
sudo systemctl enable elasticsearch

Test
curl http://localhost:9200

5.2. Logstash Configuration

Install Logstash:

sudo apt install logstash

Logstash pipeline:

# /etc/logstash/conf.d/nginx.conf
input {
file {
path => "/var/log/nginx/access.log"
start_position => "beginning"
type => "nginx-access"
}

file {
path => "/var/log/nginx/error.log"
start_position => "beginning"
type => "nginx-error"
}
}
filter {
if [type] == "nginx-access" {
grok {
match => {
"message" => '%{IPORHOST:remote_addr} - %{DATA:remote_user} [%{HTTPDATE:time_local}] "%{WORD:request_method} %{DATA:request_path} HTTP/%{NUMBER:http_version}" %{NUMBER:status} %{NUMBER:body_bytes_sent} "%{DATA:http_referer}" "%{DATA:http_user_agent}"'
}
}
date {
  match => [ "time_local", "dd/MMM/yyyy:HH:mm:ss Z" ]
  target => "@timestamp"
}

geoip {
  source => "remote_addr"
}

mutate {
  convert => {
    "status" => "integer"
    "body_bytes_sent" => "integer"
  }
}

}
if [type] == "nginx-error" {
grok {
match => {
"message" => "(?<timestamp>%{YEAR}[./-]%{MONTHNUM}[./-]%{MONTHDAY}[- ]%{TIME}) [%{LOGLEVEL:severity}] %{POSINT:pid}#%{NUMBER:threadid}: *%{NUMBER:connectionid} %{GREEDYDATA:errormessage}"
}
}
}
}
output {
elasticsearch {
hosts => ["localhost:9200"]
index => "nginx-logs-%{+YYYY.MM.dd}"
}
Debug output
stdout { codec => rubydebug }
}

Start Logstash:

sudo systemctl start logstash
sudo systemctl enable logstash

Test configuration
sudo -u logstash /usr/share/logstash/bin/logstash --path.settings /etc/logstash -t

5.3. Kibana Installation

# Install Kibana
sudo apt install kibana

Configure
sudo nano /etc/kibana/kibana.yml

Kibana configuration:

# /etc/kibana/kibana.yml
server.port: 5601
server.host: "localhost"
elasticsearch.hosts: ["http://localhost:9200"]

Start Kibana:

sudo systemctl start kibana
sudo systemctl enable kibana

Access at: http://localhost:5601

Configure Nginx reverse proxy for Kibana:

server {
listen 80;
server_name kibana.example.com;

location / {
    proxy_pass http://localhost:5601;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
    proxy_set_header Host $host;
    proxy_cache_bypass $http_upgrade;
}

}

5.4. Kibana Visualizations

Create index pattern:

1. Management → Index Patterns
2. Create index pattern: nginx-logs-*
3. Select time field: @timestamp

Sample visualizations:

1. Request Rate Over Time
   • Type: Line chart
   • Y-axis: Count
   • X-axis: Date Histogram (@timestamp)
2. Status Code Distribution
   • Type: Pie chart
   • Slice by: status.keyword
3. Top 10 URLs
   • Type: Data table
   • Metrics: Count
   • Buckets: request_path.keyword
4. Geographic Distribution
   • Type: Coordinate map
   • Geohash: geoip.location
5. Error Rate
   • Type: Metric
   • Aggregation: Count
   • Filter: status >= 400

5.5. Filebeat Alternative

# Install Filebeat
sudo apt install filebeat

Configure
sudo nano /etc/filebeat/filebeat.yml

Filebeat configuration:

# /etc/filebeat/filebeat.yml
filebeat.inputs:



type: log
enabled: true
paths:

/var/log/nginx/access.log
fields:
log_type: nginx-access



type: log
enabled: true
paths:

/var/log/nginx/error.log
fields:
log_type: nginx-error



filebeat.config.modules:
path: ${path.config}/modules.d/*.yml
reload.enabled: false
setup.template.settings:
index.number_of_shards: 1
output.elasticsearch:
hosts: ["localhost:9200"]
index: "filebeat-nginx-%{+yyyy.MM.dd}"
setup.kibana:
host: "localhost:5601"
processors:

add_host_metadata: ~
add_cloud_metadata: ~

Enable Nginx module:

sudo filebeat modules enable nginx

Configure module
sudo nano /etc/filebeat/modules.d/nginx.yml

# /etc/filebeat/modules.d/nginx.yml



module: nginx
access:
enabled: true
var.paths: ["/var/log/nginx/access.log"]
error:
enabled: true
var.paths: ["/var/log/nginx/error.log"]

Start Filebeat:

# Setup
sudo filebeat setup -e



Start
sudo systemctl start filebeat
sudo systemctl enable filebeat

---

6. Alerting Systems

6.1. Prometheus Alertmanager

Install Alertmanager:

wget https://github.com/prometheus/alertmanager/releases/download/v0.26.0/alertmanager-0.26.0.linux-amd64.tar.gz
tar -xzf alertmanager-0.26.0.linux-amd64.tar.gz
sudo mv alertmanager-0.26.0.linux-amd64/alertmanager /usr/local/bin/
sudo mv alertmanager-0.26.0.linux-amd64/amtool /usr/local/bin/

Alertmanager configuration:

# /etc/alertmanager/alertmanager.yml
global:
resolve_timeout: 5m
smtp_smarthost: 'smtp.gmail.com:587'
smtp_from: '[email protected]'
smtp_auth_username: '[email protected]'
smtp_auth_password: 'your-password'

route:
group_by: ['alertname', 'cluster']
group_wait: 10s
group_interval: 10s
repeat_interval: 12h
receiver: 'email-notifications'
receivers:


name: 'email-notifications'
email_configs:

to: '[email protected]'
headers:
Subject: 'Nginx Alert: {{ .GroupLabels.alertname }}'



name: 'slack-notifications'
slack_configs:

api_url: 'https://hooks.slack.com/services/YOUR/WEBHOOK/URL'
channel: '#alerts'
title: 'Nginx Alert'
text: '{{ range .Alerts }}{{ .Annotations.description }}{{ end }}'



inhibit_rules:


source_match:
severity: 'critical'
target_match:
severity: 'warning'
equal: ['alertname', 'instance']

Prometheus alert rules:

# /etc/prometheus/rules/nginx_alerts.yml
groups:



name: nginx
interval: 30s
rules:
High error rate

alert: NginxHighErrorRate
expr: rate(nginx_http_requests_total{status=~"5.."}[5m]) > 10
for: 5m
labels:
severity: critical
annotations:
summary: "High error rate on {{ $labels.instance }}"
description: "Error rate is {{ $value }} errors/sec"

High response time

alert: NginxHighResponseTime
expr: nginx_http_request_duration_seconds{quantile="0.99"} > 5
for: 5m
labels:
severity: warning
annotations:
summary: "High response time on {{ $labels.instance }}"
description: "99th percentile response time is {{ $value }}s"

Nginx down

alert: NginxDown
expr: up{job="nginx"} == 0
for: 1m
labels:
severity: critical
annotations:
summary: "Nginx is down on {{ $labels.instance }}"
description: "Nginx exporter is not responding"

High connection count

alert: NginxHighConnections
expr: nginx_connections_active > 1000
for: 5m
labels:
severity: warning
annotations:
summary: "High connection count on {{ $labels.instance }}"
description: "Active connections: {{ $value }}"

Low request rate (possible issue)

alert: NginxLowRequestRate
expr: rate(nginx_http_requests_total[5m]) < 1
for: 10m
labels:
severity: warning
annotations:
summary: "Low request rate on {{ $labels.instance }}"
description: "Request rate is {{ $value }} req/sec"

6.2. Email Alerts Script

#!/bin/bash



nginx_alert.sh
THRESHOLD_ERROR_RATE=100
THRESHOLD_RESPONSE_TIME=5
EMAIL="[email protected]"
LOG_FILE="/var/log/nginx/access.log"
Check error rate
ERROR_COUNT=$(grep -c " 5[0-9][0-9] " $LOG_FILE)
if [ $ERROR_COUNT -gt $THRESHOLD_ERROR_RATE ]; then
echo "ALERT: High error rate detected: $ERROR_COUNT errors" | 

mail -s "Nginx Alert: High Error Rate" $EMAIL
fi
Check response time (if logged)
AVG_RESPONSE_TIME=$(awk '{sum+=$NF; count++} END {print sum/count}' $LOG_FILE)
if (( $(echo "$AVG_RESPONSE_TIME > $THRESHOLD_RESPONSE_TIME" | bc -l) )); then
echo "ALERT: High response time: ${AVG_RESPONSE_TIME}s" | 

mail -s "Nginx Alert: High Response Time" $EMAIL
fi

6.3. Slack Webhook Integration

#!/bin/bash

slack_alert.sh
WEBHOOK_URL="https://hooks.slack.com/services/YOUR/WEBHOOK/URL"
LOG_FILE="/var/log/nginx/error.log"
Check for errors
ERROR_COUNT=$(wc -l < $LOG_FILE)
if [ $ERROR_COUNT -gt 100 ]; then
MESSAGE="⚠️ Nginx Alert: $ERROR_COUNT errors detected!"
curl -X POST $WEBHOOK_URL \
    -H 'Content-Type: application/json' \
    -d "{\"text\":\"$MESSAGE\"}"

fi

6.4. Automated Response Script

#!/bin/bash

auto_response.sh
LOG_FILE="/var/log/nginx/error.log"
THRESHOLD=100
Count recent errors (last 5 minutes)
ERROR_COUNT=$(find /var/log/nginx -name "error.log" -mmin -5 -exec wc -l {} ; | awk '{sum+=$1} END {print sum}')
if [ $ERROR_COUNT -gt $THRESHOLD ]; then
echo "High error rate detected: $ERROR_COUNT errors"
# Reload Nginx
echo "Reloading Nginx..."
systemctl reload nginx

# Send alert
echo "High error rate triggered Nginx reload: $ERROR_COUNT errors" | \
    mail -s "Nginx Auto-Response" [email protected]

# Log action
echo "$(date): Auto-reload triggered due to $ERROR_COUNT errors" >> /var/log/nginx-auto-response.log

fi

---

7. Real-time Monitoring Dashboard

7.1. Custom HTML Dashboard

<!DOCTYPE html>
<html>
<head>
<title>Nginx Real-time Monitor</title>
<meta http-equiv="refresh" content="5">
<style>
body {
font-family: Arial, sans-serif;
margin: 20px;
background: #f5f5f5;
}
.container {
max-width: 1200px;
margin: 0 auto;
}
.metric {
background: white;
padding: 20px;
margin: 10px 0;
border-radius: 5px;
box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
.metric h2 {
margin: 0 0 10px 0;
color: #333;
}
.value {
font-size: 32px;
font-weight: bold;
color: #007bff;
}
.alert {
background: #ff4444;
color: white;
}
.warning {
background: #ffaa00;
color: white;
}
.ok {
background: #00c851;
color: white;
}
</style>
</head>
<body>
<div class="container">
<h1>Nginx Real-time Monitor</h1>

    &lt;?php
    // Read Nginx stats
    $stats = file_get_contents('http://localhost:8080/stub_status');
    
    preg_match('/Active connections: (\d+)/', $stats, $active);
    preg_match('/(\d+)\s+(\d+)\s+(\d+)/', $stats, $totals);
    preg_match('/Reading: (\d+) Writing: (\d+) Waiting: (\d+)/', $stats, $current);
    
    $activeConnections = $active[1];
    $accepts = $totals[1];
    $handled = $totals[2];
    $requests = $totals[3];
    $reading = $current[1];
    $writing = $current[2];
    $waiting = $current[3];
    
    // Determine status
    $status = 'ok';
    if ($activeConnections &gt; 1000) $status = 'alert';
    elseif ($activeConnections &gt; 500) $status = 'warning';
    ?&gt;
    
    &lt;div class="metric &lt;?php echo $status; ?&gt;"&gt;
        &lt;h2&gt;Active Connections&lt;/h2&gt;
        &lt;div class="value"&gt;&lt;?php echo $activeConnections; ?&gt;&lt;/div&gt;
    &lt;/div&gt;
    
    &lt;div class="metric"&gt;
        &lt;h2&gt;Total Requests&lt;/h2&gt;
        &lt;div class="value"&gt;&lt;?php echo number_format($requests); ?&gt;&lt;/div&gt;
    &lt;/div&gt;
    
    &lt;div class="metric"&gt;
        &lt;h2&gt;Connection Details&lt;/h2&gt;
        &lt;p&gt;Reading: &lt;?php echo $reading; ?&gt;&lt;/p&gt;
        &lt;p&gt;Writing: &lt;?php echo $writing; ?&gt;&lt;/p&gt;
        &lt;p&gt;Waiting: &lt;?php echo $waiting; ?&gt;&lt;/p&gt;
    &lt;/div&gt;
    
    &lt;div class="metric"&gt;
        &lt;h2&gt;Server Stats&lt;/h2&gt;
        &lt;p&gt;Accepts: &lt;?php echo number_format($accepts); ?&gt;&lt;/p&gt;
        &lt;p&gt;Handled: &lt;?php echo number_format($handled); ?&gt;&lt;/p&gt;
        &lt;p&gt;Requests per connection: &lt;?php echo round($requests/$handled, 2); ?&gt;&lt;/p&gt;
    &lt;/div&gt;
    
    &lt;p&gt;&lt;small&gt;Last updated: &lt;?php echo date('Y-m-d H:i:s'); ?&gt;&lt;/small&gt;&lt;/p&gt;
&lt;/div&gt;

</body>
</html>

7.2. Python Real-time Monitor

#!/usr/bin/env python3

nginx_monitor.py
import requests
import time
import re
from datetime import datetime
def get_nginx_stats():
"""Fetch Nginx stub_status"""
try:
response = requests.get('http://localhost:8080/stub_status')
return response.text
except Exception as e:
print(f"Error fetching stats: {e}")
return None
def parse_stats(stats):
"""Parse stub_status output"""
if not stats:
return None
active = re.search(r'Active connections: (\d+)', stats)
totals = re.search(r'(\d+)\s+(\d+)\s+(\d+)', stats)
current = re.search(r'Reading: (\d+) Writing: (\d+) Waiting: (\d+)', stats)

return {
    'active_connections': int(active.group(1)),
    'accepts': int(totals.group(1)),
    'handled': int(totals.group(2)),
    'requests': int(totals.group(3)),
    'reading': int(current.group(1)),
    'writing': int(current.group(2)),
    'waiting': int(current.group(3)),
    'timestamp': datetime.now()
}

def display_stats(stats):
"""Display stats in terminal"""
print("\033[2J\033[H")  # Clear screen
print("=" * 50)
print("Nginx Real-time Monitor")
print("=" * 50)
print(f"Time: {stats['timestamp'].strftime('%Y-%m-%d %H:%M:%S')}")
print()
print(f"Active Connections: {stats['active_connections']}")
print(f"Total Requests: {stats['requests']:,}")
print()
print(f"Reading: {stats['reading']}")
print(f"Writing: {stats['writing']}")
print(f"Waiting: {stats['waiting']}")
print()
print(f"Accepts: {stats['accepts']:,}")
print(f"Handled: {stats['handled']:,}")
print(f"Requests/Connection: {stats['requests']/stats['handled']:.2f}")
print()
# Alerts
if stats['active_connections'] > 1000:
    print("⚠️  ALERT: High connection count!")
elif stats['active_connections'] > 500:
    print("⚠️  WARNING: Elevated connection count")
else:
    print("✓ Status: OK")

def main():
print("Starting Nginx monitor...")
print("Press Ctrl+C to exit")
time.sleep(2)
try:
    while True:
        stats_text = get_nginx_stats()
        stats = parse_stats(stats_text)
        
        if stats:
            display_stats(stats)
        
        time.sleep(5)
except KeyboardInterrupt:
    print("\nMonitor stopped")

if name == 'main':
main()

---

まとめ

このレッスンで学んだこと：

• ✅ Access logs và error logs configuration
• ✅ Custom log formats (JSON, detailed, performance)
• ✅ Log rotation với logrotate
• ✅ Log analysis tools (GoAccess, AWK scripts)
• ✅ Prometheus + Grafana monitoring
• ✅ ELK Stack integration (Elasticsearch, Logstash, Kibana)
• ✅ Alerting systems (Alertmanager, email, Slack)
• ✅ Real-time dashboards
• ✅ Performance metrics và troubleshooting

重要なポイント：

• Use structured logging (JSON) for better analysis
• Implement log rotation to manage disk space
• Set up real-time monitoring for quick issue detection
• Create dashboards for visualization
• Configure alerts for critical issues
• Automate log analysis with scripts
• Integrate with centralized logging systems

Monitoring checklist:

• ✅ Access and error logs configured
• ✅ Log rotation enabled
• ✅ Prometheus exporter running
• ✅ Grafana dashboards created
• ✅ Alerting rules configured
• ✅ ELK stack (optional) integrated
• ✅ Regular log analysis scheduled
• ✅ Backup and retention policies defined

次のレッスン： 高可用性と高度なロードバランシング - Nginx Plus features, health checks, session persistence, active-active setups, failover strategies, và disaster recovery để đảm bảo uptime tối đa trong production environments.