nginx

nginx is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server. For more information visit nginx.org.

The nginx receivers can collect and ingest logs and metrics from your nginx instance.

Prerequisites

To collect and ingest nginx logs and metrics, you must install Ops Agent version 2.1.0 or higher.

Configure your nginx instance

You must enable the stub_status module in the nginx configuration file to set up a locally reachable URL, for example, http://www.example.com/status for the status page. To enable the stub_status module, complete the following steps:

  1. Edit the status.conf file, or create the file if it doesn't exist. You can find this file in the nginx configuration directory, typically found at /etc/nginx/conf.d.

  2. Add the following lines to the server section:

    location /status {
    stub_status on;
}

    Your configuration file might look like the following example:

    server {
   listen 80;
   server_name mynginx.domain.com;
   location /status {
       stub_status on;
   }
   location / {
       root /dev/null;
   }
}

  3. Reload the nginx configuration.

    sudo service nginx reload

You can run the following command to automate the previous steps. It creates a status.conf file if it doesn't exist or overwrites the existing one if it does exist. The command turns on stub_status, reloads nginx, and verifies that the expected information is exposed through the endpoint.

sudo tee /etc/nginx/conf.d/status.conf > /dev/null << EOF
server {
    listen 80;
    server_name 127.0.0.1;
    location /status {
        stub_status on;
        access_log off;
        allow 127.0.0.1;
        deny all;
    }
    location / {
       root /dev/null;
    }
}
EOF
sudo service nginx reload
curl http://127.0.0.1:80/status

The sample output is:

Active connections: 1
server accepts handled requests
 23 23 74
Reading: 0 Writing: 1 Waiting: 0

Alternately, instead of using a separate status.conf file, you can also directly embed the lines to the main nginx.conf file, which is typically located in one of the following directories: /etc/nginx, /usr/local/nginx/conf, or /usr/local/etc/nginx.

Configure the Ops Agent for nginx

Following the guide for Configuring the Ops Agent, add the required elements to collect logs and metrics from your nginx instances, and restart the agent.

Logs collection

To ingest logs from nginx, you must create receivers for the logs nginx produces and then create a pipeline for the new receivers. To configure a receiver for your nginx_access logs, specify the following fields:

Field Default Description
type The value must be nginx_access.
include_paths [/var/log/nginx/access.log] The log files to read.
exclude_paths The log files to exclude, if include_paths contains a glob or directory.


To configure a receiver for your nginx_error logs, specify the following fields:

Field Default Description
type The value must be nginx_error.
include_paths [/var/log/nginx/error.log] The log files to read.
exclude_paths The log files to exclude, if include_paths contains a glob or directory.

What is logged

The logName of the nginx_access and nginx_error logs are derived from the receiver IDs specified in the configuration. Detailed fields inside the LogEntry are as follows.

nginx_access logs contain the httpRequest field:

Field Type Description
httpRequest.protocol string Protocol used for the request
httpRequest.referer string Contents of the Referer header
httpRequest.remoteIp string Client IP address
httpRequest.requestMethod string HTTP method
httpRequest.requestUrl string Request URL (typically just the path part of the URL)
httpRequest.responseSize string (int64) Response size
httpRequest.status number HTTP status code
httpRequest.userAgent string Contents of the User-Agent header
jsonPayload.host string Contents of the Host header (usually not reported by nginx)
jsonPayload.user string Authenticated username for the request
timestamp string (Timestamp) Time the request was received

Log entries don't contain any fields that are blank or missing.


nginx_error logs contain the following fields in the LogEntry:

Field Type Description
jsonPayload.level string Log entry level
jsonPayload.pid number Process ID
jsonPayload.tid number Thread ID
jsonPayload.connection number Connection ID
jsonPayload.message string Log message
jsonPayload.client string Client IP address (optional)
jsonPayload.server string Nginx server name (optional)
jsonPayload.request string Original HTTP request (optional)
jsonPayload.subrequest string Nginx subrequest (optional)
jsonPayload.upstream string Upstream request URI (optional)
jsonPayload.host string Host header (optional)
jsonPayload.referer string Referer header (optional)
severity string (LogSeverity) Log entry level (translated)
timestamp string (Timestamp) Time the entry was logged

To verify the logs are ingested, go to the Logs Explorer and run the following query to view the nginx logs:

resource.type="gce_instance"
logName=("projects/PROJECT_ID/logs/nginx_default_error" OR "projects/PROJECT_ID/logs/nginx_default_access")

It might take one or two minutes for logs to appear in Logs Explorer.

Metrics collection

To collect metrics from nginx, you must create a receiver for nginx metrics and then create a pipeline for the new receiver. To configure a receiver for your nginx metrics, specify the following fields:

Field Default Description
type The value must be nginx.
stub_status_url http://localhost/status The URL exposed by the nginx stub status module.
collection_interval 60s A time.Duration value, such as 30s or 5m.

What is monitored

The following table provides the list of metrics that the Ops Agent collects from the nginx instance.

Metric type 
Kind, Type
Monitored resources		 Labels
workload.googleapis.com/nginx.requests
CUMULATIVE, INT64
gce_instance 		 
workload.googleapis.com/nginx.connections_accepted
CUMULATIVE, INT64
gce_instance 		 
workload.googleapis.com/nginx.connections_handled
CUMULATIVE, INT64
gce_instance 		 
workload.googleapis.com/nginx.connections_current
GAUGE, INT64
gce_instance 		state

To verify the metrics are ingested, go to Metrics Explorer and run the following query in the MQL tab.

fetch gce_instance
| metric 'workload.googleapis.com/nginx.requests'
| align rate(1m)
| every 1m

It might take one or two minutes for metrics to appear in Metrics Explorer.

Example configuration and command

The example command creates the configuration to collect and ingest logs and metrics for nginx and restart the Ops Agent on Linux.

sudo tee /etc/google-cloud-ops-agent/config.yaml > /dev/null << EOF
logging:
  receivers:
    nginx_default_access:
      type: nginx_access
    nginx_default_error:
      type: nginx_error
  service:
    pipelines:
      nginx:
        receivers:
          - nginx_default_access
          - nginx_default_error
metrics:
  receivers:
    nginx_metrics:
      type: nginx
      stub_status_url: http://127.0.0.1:80/status
      collection_interval: 60s
  service:
    pipelines:
      nginx_pipeline:
        receivers:
          - nginx_metrics
EOF
sudo service google-cloud-ops-agent restart

Troubleshooting

On most distributions, nginx comes with ngx_http_stub_status_module enabled. You can check if the module is enabled by running the following command:

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

The expected output is with-http_stub_status_module, which means the module is enabled. In rare cases, if the command returns no output, you must compile nginx from source with the -with-http_stub_status_module following the nginx public documentation.