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.
  • API: (deprecated) the Kong entity representing your upstream service placed behind Kong, for which Kong proxies requests to.
  • 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.

Configuration

Enabling the plugin for a Service

Configure on top of a Service by executing the following request on your Kong server:

$ 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 for a Route

Configure on top of 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 for an API

If you are using the deprecated API entity, you can configure on top of an API by executing the following request on your Kong server:

$ 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.

Enabling the plugin for a Consumer

You can use the http://localhost:8001/plugins endpoint to target Consumers:

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

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

You can combine adding consumer_id and service_id in the same request.

Once applied, any user with a valid credential can access the Service/API. To restrict usage to only some of the authenticated users, also add the ACL plugin (not covered here) and create whitelist or blacklist groups of users.

Global plugins

All plugins can be configured using the http:/kong:8001/plugins/ endpoint. A plugin which is not associated to any API, Service, Route or Consumer 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
api_idThe id of the API which this plugin will target.
service_idThe id of the Service which this plugin will target.
route_idThe id of the Route which this plugin will target.
consumer_idThe id of the Consumer which this plugin will target.
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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