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Monitoring Nginx on Instances

Overview#

Nginx monitoring involves monitoring of the following elements:

  • Nginx Access Logs

  • Nginx Error Logs

  • Nginx Server Health

Pre-requisites#

  1. Ensure Nginx access logs are in format expected by sfAgent parser. Edit nginx conf file /etc/nginx/nginx.conf and set log format as follows: 

    '$remote_addr $remote_user [$time_local] '  '"$request" $status $body_bytes_sent ' '"$http_referer" "$http_user_agent" ua="$upstream_addr" ' 'rt=$request_time uct=$upstream_connect_time  uht=$upstream_header_time urt=$upstream_response_time';

    Sample: 

    log_format snappyflow   '$remote_addr $remote_user [$time_local] '  '"$request" $status $body_bytes_sent '  '"$http_referer" "$http_user_agent" ua="$upstream_addr" ' 'rt=$request_time uct=$upstream_connect_time uht=$upstream_header_time urt=$upstream_response_time'; access_log  /var/log/nginx/access.log snappyflow buffer=16k flush=5s;

    After configuring log format, the expected log entry would be: 

    172.31.72.81 - [01/Jul/2020:03:36:04 +0000] "POST /owners/6/edit HTTP/1.1" 504 167 "-" "Apache-HttpClient/4.5.7 (Java/1.8.0_252)" ua="-" rt=60.004 uct=- uht=- urt=60.004

    Description of log fields is as follows: 

    log_format snappyflow  '$remote_addr:$remote_port  $remote_user .... 
              'rt=$request_time uct=$upstream_connect_time uht=$upstream_header_time urt=$upstream_response_time rs=$request_length';

  2. Enable Nginx status module: This is required to monitor Nginx server health

    Open source Nginx exposes several basic metrics about server activity on a simple status page, provided that you have HTTP Stub Status Module enabled. To check if the module is already enabled, run: 

    nginx -V 2>&1 | grep -o with-http_stub_status_module

    The status module is enabled if you see with-http_stub_status_module as output in the terminal.

    In order to enable mod_status , you will need to enable the status module. You can use the --with-http_stub_status_module configuration parameter when building Nginx from source: 

      ./configure \    … \    --with-http_stub_status_module    make    sudo make install

    After verifying the module is enabled, you will also need to modify your Nginx configuration to set up a locally accessible URL (e.g., /stats) for the status page: 

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

 The server blocks of Nginx config are usually found not in the master configuration file (e.g., /etc/nginx/nginx.conf) but in supplemental configuration files that are referenced by the master config. To find the relevant configuration files, first locate the master config by running:

nginx -t

Open the master configuration file listed, and look for lines that begin with “include” near the end of the http block, e.g.:

include /etc/nginx/conf.d/*.conf;

In one of the referenced config files you should find the main server block, which you can modify as above to configure Nginx metrics reporting. After changing any configurations, reload the configs by executing:

nginx -s reload

Now you can view the status page to see your metrics: http://127.0.0.1/stats

Configuration#

sfAgent section provides steps to install and automatically generate plugin configurations. User can also manually add the configuration shown below to config.yaml under /opt/sfagent/ directory 

key: <profile key> generate_name: true tags:   Name: <unique instance name or will be generated from IP>   appName: <add application name>   projectName: <add project name> metrics:   plugins:     - name: nginx       enabled: true       interval: 300       config:   port: 80         secure: false         location: ‘stats’ logging:   plugins:     - name: nginx-access       enabled: true       config:         geo_info: true          log_path: /var/log/nginx/access.log, /var/log/nginx/access_log         ua_parser: true     - name: nginx-error       enabled: true       config:         log_level:           - emerg           - alert           - error         log_path: /var/log/nginx/error.log, /var/log/nginx/error_log

Viewing data and dashboards#

  • Data generated by plugin can be viewed in “browse data” page inside the respective application under plugin=jvm and documentType=jvm
  • Dashboard for this data can be instantiated by Importing dashboard template JVM to the application dashboard.