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Like PHP-FPM, Docker, and Apache, Nginx has a built-in status page that helps view and monitor Nginx status. This article introduces how to collect Nginx status information by using Log Service Logtail, query and count the collected status information, build dashboards, and create custom alarms, providing all-round monitoring for your Nginx cluster.

Prepare the environment

Follow these steps to enable the Nginx status plug-in.

Verify if Nginx has the status function.

Run the following command to check whether or not Nginx has the status function:
```
nginx -V 2>&1 | grep -o with-http_stub_status_module
with-http_stub_status_module
```
Nginx has the status function if the output is with-http_stub_status_module.
Configure Nginx status.

Enable the status function in the Nginx configuration file (the default path is /etc/nginx/nginx.conf). A sample configuration is as follows:
```
     location /private/nginx_status {
       stub_status on;
       access_log   off;
       allow 11.132.232.238;
       deny all;
     }
```
Note: This configuration only allows hosts with the IP address 11.132.232.238 to access the nginx status function.

Verify if the hosts with Logtail installed have access to nginx status.

Run the following command for verification:

$curl http://11.132.232.59/private/nginx_status
Active connections: 1
server accepts handled requests
2507455 2507455 2512972
Reading: 0 Writing: 1 Waiting: 0

Collect data

Install Logtail

Install Logtail by following the instructions in Install Logtail. Make sure that the version is 0.16.0 or later. If not, upgrade Logtail to the latest version by following Install Logtail.

Configure collection information

Method

Create a Logstore in the Log Service console. In the data wizard, select Nginx Monitor under Self-built software.

Follow the prompts to configure the URL and corresponding parameters of Nginx monitor. The collection configuration is based on HTTP collection function.

Note:

Modify the Addresses field value in the sample configuration to the URL list that you want to monitor.
If the returned information of Nginx status differs from the default one, modify processors to support HTTP body parsing. For more information, see Data processing configuration.

Sample configuration:

{
"inputs": [
  {
      "type": "metric_http",
      "detail": {
          "IntervalMs": 60000,
          "Addresses": [
              "http://11.132.232.59/private/nginx_status",
              "http://11.132.232.60/private/nginx_status",
              "http://11.132.232.62/private/nginx_status"
          ],
          "IncludeBody": true
      }
  }
],
"processors": [
  {
      "type": "processor_regex",
      "detail": {
          "SourceKey": "content",
          "Regex": "Active connections: (\\d+)\\s+server accepts handled requests\\s+(\\d+)\\s+(\\d+)\\s+(\\d+)\\s+Reading: (\\d+) Writing: (\\d+) Waiting: (\\d+)[\\s\\S]*",
          "Keys": [
              "connection",
              "accepts",
              "handled",
              "requests",
              "reading",
              "writing",
              "waiting"
          ],
          "FullMatch": true,
          "NoKeyError": true,
          "NoMatchError": true,
          "KeepSource": false
      }
  }
]
}

Preview data

After you apply the configuration, wait one minute and then click Preview. You can see that the status data has been collected successfully. The HTTP collection of Logtail uploads the body parsing data, URL, status code, method name, response time, and request result (successful or not).

Note: If no data is collected, check whether the configuration is a valid json. If yes, see Query Logtail collection errors for troubleshooting.

_address_:http://11.132.232.59/private/nginx_status  
_http_response_code_:200  
_method_:GET  
_response_time_ms_:1.83716261897  
_result_:success  
accepts:33591200  
connection:450  
handled:33599550  
reading:626  
requests:39149290  
waiting:68  
writing:145

Query and analysis

Custom query

See Log Service query.

To query the status of a specific IP address: _address_ : 10.168.0.0.
To query the requests that have a response time over 100 ms: _response_time_ms_ > 100.
To query requests whose status code is not 200: not _http_response_code_ : 200.

Analysis and statistics

For more information about statistics and analysis syntax, see Log Service statistics syntax.

Count the average waiting time, reading time, writing time, and connection time every five minutes:

*| select  avg(waiting) as waiting, avg(reading)  as reading,  avg(writing)  as writing,  avg(connection)  as connection,  from_unixtime( __time__ - __time__ % 300) as time group by __time__ - __time__ % 300 order by time limit 1440

Count the top 10 entries with longest waiting time:

*| select  max(waiting) as max_waiting, address, from_unixtime(max(__time__)) as time group by address order by max_waiting desc limit 10

Count the current total number of Nginx and the number of invalid:

* | select  count(distinct(address)) as total

not _result_ : success | select  count(distinct(address))

Count the 10 latest failed requests:

not _result_ : success | select _address_ as address, from_unixtime(__time__) as time  order by __time__ desc limit 10

Count the total number of request processing every five minutes:

*| select  avg(handled) * count(distinct(address)) as total_handled, avg(requests) * count(distinct(address)) as total_requests,  from_unixtime( __time__ - __time__ % 300) as time group by __time__ - __time__ % 300 order by time limit 1440

Count the average request latency every five minutes:

*| select  avg(_response_time_ms_) as avg_delay,  from_unixtime( __time__ - __time__ % 300) as time group by __time__ - __time__ % 300 order by time limit 1440

Count the number of valid/invalid requests:

not _http_response_code_ : 200  | select  count(1)

_http_response_code_ : 200  | select  count(1)

Dashboard

By default, Log Service provides dashboards for Nginx monitoring data. For how to build a dashboard, see Log Service dashboard settings.

Dashboard

Set alarms

Save the query not _http_response_code_ : 200 | select count(1) as invalid_count as a quick query, and name it as invalid_nginx_status.

Create alarm rules based on this quick query. Samples are as follows:

Option	Value
Alarm rule name	`invalid_nginx_alarm`
Quick query name	`invalid_nginx_status`
Data query time (mins)	`15`
Check interval (mins)	`5`
Number of triggers	`1`
Field name	`invalid_count`
Comparison operator	`greater than`
Check threshold	`0`
Notification type	`Notification center`
Notification content	`An exception occurred while obtaining the Nginx status. Go to Log Service for detailed exception message. Project: xxxxxxxx, logstore : nginx_status`