Log request and response data to Syslog.


Terminology

  • plugin: a plugin executing actions inside Kong before or after a request has been proxied to the upstream API.
  • Service: the Kong entity representing an external upstream API or microservice.
  • Route: the Kong entity representing a way to map downstream requests to upstream services.
  • Consumer: the Kong entity representing a developer or machine using the API. When using Kong, a Consumer only communicates with Kong which proxies every call to the said upstream API.
  • Credential: a unique string associated with a Consumer, also referred to as an API key.
  • upstream service: this refers to your own API/service sitting behind Kong, to which client requests are forwarded.
  • API: a legacy entity used to represent your upstream services. Deprecated in favor of Services since 0.13.0.

Configuration

Enabling the plugin on a Service

Configure this plugin on a Service by making the following request:

$ curl -X POST http://kong:8001/services/{service}/plugins \
    --data "name=syslog" 
  • service: the id or name of the Service that this plugin configuration will target.

Enabling the plugin on a Route

Configure this plugin on a Route with:

$ curl -X POST http://kong:8001/routes/{route_id}/plugins \
    --data "name=syslog" 
  • route_id: the id of the Route that this plugin configuration will target.

Enabling the plugin on a Consumer

You can use the http://localhost:8001/plugins endpoint to enable this plugin on specific Consumers:

$ curl -X POST http://kong:8001/plugins \
    --data "name=syslog" \
    --data "consumer_id={consumer_id}" 

Where consumer_id is the id of the Consumer we want to associate with this plugin.

You can combine consumer_id and service_id

in the same request, to futhermore narrow the scope of the plugin.

Enabling the plugin on an API

If you are using an older version of Kong with the legacy API entity (deprecated since 0.13.0), you can configure this plugin on top of such an API by making the following request:

$ curl -X POST http://kong:8001/apis/{api}/plugins \
    --data "name=syslog" 
  • api: either id or name of the API that this plugin configuration will target.

Global plugins

All plugins can be configured using the http://kong:8001/plugins/ endpoint. A plugin which is not associated to any Service, Route or Consumer (or API, if you are using an older version of Kong) is considered "global", and will be run on every request. Read the Plugin Reference and the Plugin Precedence sections for more information.

Parameters

Here's a list of all the parameters which can be used in this plugin's configuration:

form parameterdefaultdescription
nameThe name of the plugin to use, in this case syslog
service_idThe id of the Service which this plugin will target.
route_idThe id of the Route which this plugin will target.
enabledtrueWhether this plugin will be applied.
consumer_idThe id of the Consumer which this plugin will target.
api_idThe id of the API which this plugin will target. Note: The API Entity is deprecated since Kong 0.13.0.
config.successful_severity
optional

info

An optional logging severity assigned to the all successful requests with response status code less then 400 .

config.client_errors_severity
optional

info

An optional logging severity assigned to the all failed requests with response status code 400 or higher but less than 500.

config.server_errors_severity
optional

info

An optional logging severity assigned to the all failed requests with response status code 500 or higher.

config.log_level
optional

info

An optional logging severity, any request with equal or higher severity will be logged to System log.

Log Format

Every request will be logged to System log in SYSLOG standard, with message component in the following format:

{
    "request": {
        "method": "GET",
        "uri": "/get",
        "url": "http://httpbin.org:8000/get",
        "size": "75",
        "querystring": {},
        "headers": {
            "accept": "*/*",
            "host": "httpbin.org",
            "user-agent": "curl/7.37.1"
        }
    },
    "upstream_uri": "/",
    "response": {
        "status": 200,
        "size": "434",
        "headers": {
            "Content-Length": "197",
            "via": "kong/0.3.0",
            "Connection": "close",
            "access-control-allow-credentials": "true",
            "Content-Type": "application/json",
            "server": "nginx",
            "access-control-allow-origin": "*"
        }
    },
    "tries": [
        {
            "state": "next",
            "code": 502,
            "ip": "127.0.0.1",
            "port": 8000
        },
        {
            "ip": "127.0.0.1",
            "port": 8000
        }
    ],
    "authenticated_entity": {
        "consumer_id": "80f74eef-31b8-45d5-c525-ae532297ea8e",
        "id": "eaa330c0-4cff-47f5-c79e-b2e4f355207e"
    },
    "route": {
        "created_at": 1521555129,
        "hosts": null,
        "id": "75818c5f-202d-4b82-a553-6a46e7c9a19e",
        "methods": null,
        "paths": [
            "/example-path"
        ],
        "preserve_host": false,
        "protocols": [
            "http",
            "https"
        ],
        "regex_priority": 0,
        "service": {
            "id": "0590139e-7481-466c-bcdf-929adcaaf804"
        },
        "strip_path": true,
        "updated_at": 1521555129
    },
    "service": {
        "connect_timeout": 60000,
        "created_at": 1521554518,
        "host": "example.com",
        "id": "0590139e-7481-466c-bcdf-929adcaaf804",
        "name": "myservice",
        "path": "/",
        "port": 80,
        "protocol": "http",
        "read_timeout": 60000,
        "retries": 5,
        "updated_at": 1521554518,
        "write_timeout": 60000
    },
    "consumer": {
        "username": "demo",
        "created_at": 1491847011000,
        "id": "35b03bfc-7a5b-4a23-a594-aa350c585fa8"
    },
    "latencies": {
        "proxy": 1430,
        "kong": 9,
        "request": 1921
    },
    "client_ip": "127.0.0.1",
    "started_at": 1433209822425
}

A few considerations on the above JSON object:

  • request contains properties about the request sent by the client
  • response contains properties about the response sent to the client
  • tries contains the list of (re)tries (successes and failures) made by the load balancer for this request
  • route contains Kong properties about the specific Route requested
  • service contains Kong properties about the Service associated with the requested Route
  • authenticated_entity contains Kong properties about the authenticated credential (if an authentication plugin has been enabled)
  • consumer contains the authenticated Consumer (if an authentication plugin has been enabled)
  • latencies contains some data about the latencies involved:
    • proxy is the time it took for the final service to process the request
    • kong is the internal Kong latency that it took to run all the plugins
    • request is the time elapsed between the first bytes were read from the client and after the last bytes were sent to the client. Useful for detecting slow clients.
  • client_ip contains the original client IP address
  • started_at contains the UTC timestamp of when the API transaction has started to be processed.

Notes

  • Make sure Syslog daemon is running on the instance and it's configured with logging level severity same as or lower than the set config.log_level.

Kong Process Errors

This logging plugin will only log HTTP request and response data. If you are looking for the Kong process error file (which is the nginx error file), then you can find it at the following path: {prefix}/logs/error.log

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