Correlation ID plugin

Correlate requests and responses using a unique ID transmitted over an HTTP header.

Configuration Reference

This plugin is compatible with DB-less mode.

In DB-less mode, you configure Kong Gateway declaratively. Therefore, the Admin API is mostly read-only. The only tasks it can perform are all related to handling the declarative config, including:

Setting a target's health status in the load balancer
Validating configurations against schemas
Uploading the declarative configuration using the /config endpoint

Example plugin configuration

Enable on a service

Enable on a route

Enable on a consumer

Enable globally

The following examples provide some typical configurations for enabling the correlation-id plugin on a service.

Admin API

Kubernetes

Declarative (YAML)

Konnect Cloud

Kong Manager

Make the following request:

curl -X POST http://localhost:8001/services/SERVICE_NAME|SERVICE_ID/plugins \
    --data "name=correlation-id"  \
    --data "config.header_name=Kong-Request-ID" \
    --data "config.generator=uuid#counter" \
    --data "config.echo_downstream=false"

Replace SERVICE_NAME|SERVICE_ID with the id or name of the service that this plugin configuration will target.

First, create a KongPlugin resource:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: correlation-id-example
config: 
  header_name: Kong-Request-ID
  generator: uuid#counter
  echo_downstream: false
plugin: correlation-id

Next, apply the KongPlugin resource to a service by annotating the service as follows:

apiVersion: v1
kind: Service
metadata:
  name: SERVICE_NAME|SERVICE_ID
  labels:
    app: SERVICE_NAME|SERVICE_ID
  annotations:
    konghq.com/plugins: correlation-id-example
spec:
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
    name: SERVICE_NAME|SERVICE_ID
  selector:
    app: SERVICE_NAME|SERVICE_ID

Replace SERVICE_NAME|SERVICE_ID with the id or name of the service that this plugin configuration will target.

Note: The KongPlugin resource only needs to be defined once and can be applied to any service, consumer, or route in the namespace. If you want the plugin to be available cluster-wide, create the resource as a KongClusterPlugin instead of KongPlugin.

Add this section to your declarative configuration file:

plugins:
- name: correlation-id
  service: SERVICE_NAME|SERVICE_ID
  config: 
    header_name: Kong-Request-ID
    generator: uuid#counter
    echo_downstream: false

Replace SERVICE_NAME|SERVICE_ID with the id or name of the service that this plugin configuration will target.

You can configure this plugin through the Konnect UI.

From the Service Hub, select a service version, then set up the plugin:

In the Plugins section, click Add Plugin.
Find and select the Correlation ID plugin.
Click Create.

You can configure this plugin through the Kong Manager UI.

In Kong Manager, select the workspace.
From the Services section, click View for the service row.
From the plugin section, click Add Plugin.
Find and select the Correlation ID plugin.
If the option is available, select Scoped.
Add the service name and ID to the Service field if it is not already pre-filled.
Click Create.

The following examples provide some typical configurations for enabling the correlation-id plugin on a route.

Admin API

Kubernetes

Declarative (YAML)

Konnect Cloud

Kong Manager

Make the following request:

curl -X POST http://localhost:8001/routes/ROUTE_NAME|ROUTE_ID/plugins \
  --data "name=correlation-id"  \
    --data "config.header_name=Kong-Request-ID" \
    --data "config.generator=uuid#counter" \
    --data "config.echo_downstream=false"

Replace ROUTE_NAME|ROUTE_ID with the id or name of the route that this plugin configuration will target.

First, create a KongPlugin resource:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: correlation-id-example
config: 
  header_name: Kong-Request-ID
  generator: uuid#counter
  echo_downstream: false
plugin: correlation-id

Then, apply it to an ingress (route or routes) by annotating the ingress as follows:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ROUTE_NAME|ROUTE_ID
  annotations:
    kubernetes.io/ingress.class: kong
    konghq.com/plugins: correlation-id-example
spec:
  rules:
  - host: examplehostname.com
    http:
      paths:
      - path: /bar
        backend:
          service:
            name: echo
            port:
              number: 80

Replace ROUTE_NAME|ROUTE_ID with the id or name of the route that this plugin configuration will target.

Note: The KongPlugin resource only needs to be defined once and can be applied to any service, consumer, or route in the namespace. If you want the plugin to be available cluster-wide, create the resource as a KongClusterPlugin instead of KongPlugin.

Add this section to your declarative configuration file:

plugins:
- name: correlation-id
  route: ROUTE_NAME
  config: 
    header_name: Kong-Request-ID
    generator: uuid#counter
    echo_downstream: false

Replace ROUTE_NAME|ROUTE_ID with the id or name of the route that this plugin configuration will target.

You can configure this plugin through the Konnect UI.

From the Service Hub, select a service version, then set up the plugin:

Select a route.
In the Plugins section, click Add Plugin.
Find and select the Correlation ID plugin.
Click Create.

You can configure this plugin through the Kong Manager UI.

In Kong Manager, select the workspace.
Open Routes from the menu, then click View for the route row.
From the plugin section, click Add Plugin.
Find and select the Correlation ID plugin.
If the option is available, select Scoped.
Add the route ID if it is not already prefilled.
Click Create.

The following examples provide some typical configurations for enabling the correlation-id plugin on a consumer.

Admin API

Kubernetes

Declarative (YAML)

Kong Manager

Make the following request:

curl -X POST http://localhost:8001/consumers/CONSUMER_NAME|CONSUMER_ID/plugins \
  --data "name=correlation-id"  \
    --data "config.header_name=Kong-Request-ID" \
    --data "config.generator=uuid#counter" \
    --data "config.echo_downstream=false"

Replace CONSUMER_NAME|CONSUMER_ID with the id or name of the consumer that this plugin configuration will target.

You can combine consumer.id, service.id, or route.id in the same request, to further narrow the scope of the plugin.

First, create a KongPlugin resource:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: correlation-id-example
config: 
  header_name: Kong-Request-ID
  generator: uuid#counter
  echo_downstream: false
plugin: correlation-id

Then, apply it to a consumer by annotating the KongConsumer resource as follows:

apiVersion: configuration.konghq.com/v1
kind: KongConsumer
metadata:
  name: CONSUMER_NAME|CONSUMER_ID
  annotations:
    konghq.com/plugins: correlation-id-example
    kubernetes.io/ingress.class: kong

Replace CONSUMER_NAME|CONSUMER_ID with the id or name of the consumer that this plugin configuration will target.

Note: The KongPlugin resource only needs to be defined once and can be applied to any service, consumer, or route in the namespace. If you want the plugin to be available cluster-wide, create the resource as a KongClusterPlugin instead of KongPlugin.

Add this section to your declarative configuration file:

plugins:
- name: correlation-id
  consumer: CONSUMER_NAME|CONSUMER_ID
  config: 
    header_name: Kong-Request-ID
    generator: uuid#counter
    echo_downstream: false

Replace CONSUMER_NAME|CONSUMER_ID with the id or name of the consumer that this plugin configuration will target.

You can configure this plugin through the Kong Manager UI.

In Kong Manager, select the workspace.
From the Consumers section, click View for the consumer row.
Select the Plugins tab, then click Add Plugin.
Find and select the Correlation ID plugin.
If the option is available, select Scoped.
Add the consumer ID if it is not already prefilled.
Click Create.

A plugin which is not associated to any 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.

The following examples provide some typical configurations for enabling the correlation-id plugin globally.

Admin API

Kubernetes

Declarative (YAML)

Kong Manager

Make the following request:

curl -X POST http://localhost:8001/plugins/ \
  --data "name=correlation-id"  \
    --data "config.header_name=Kong-Request-ID" \
    --data "config.generator=uuid#counter" \
    --data "config.echo_downstream=false"

Create a KongClusterPlugin resource and label it as global:

apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: <global-correlation-id>
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: \"true\"
config: 
  header_name: Kong-Request-ID
  generator: uuid#counter
  echo_downstream: false
plugin: correlation-id

Add a plugins entry in the declarative configuration file:

plugins:
- name: correlation-id
  config: 
    header_name: Kong-Request-ID
    generator: uuid#counter
    echo_downstream: false

You can configure this plugin through the Kong Manager UI.

In Kong Manager, select the workspace.
Open Plugins from the menu, then click New Plugin.
Find and select the Correlation ID plugin.
If the option is available, set the plugin scope to Global.
Click Create.

Parameters

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

Form Parameter	Description
`name` required Type: string	The name of the plugin, in this case `correlation-id`.
`service.name` or `service.id` Type: string	The name or ID of the service the plugin targets. Set one of these parameters if adding the plugin to a service through the top-level `/plugins` endpoint. Not required if using `/services/SERVICE_NAME\|SERVICE_ID/plugins`.
`route.name` or `route.id` Type: string	The name or ID of the route the plugin targets. Set one of these parameters if adding the plugin to a route through the top-level `/plugins` endpoint. Not required if using `/routes/ROUTE_NAME\|ROUTE_ID/plugins`.
`consumer.name` or `consumer.id` Type: string	The name or ID of the consumer the plugin targets. Set one of these parameters if adding the plugin to a consumer through the top-level `/plugins` endpoint. Not required if using `/consumers/CONSUMER_NAME\|CONSUMER_ID/plugins`.
`enabled` Type: boolean Default value: `true`	Whether this plugin will be applied.
`config.header_name` optional Type: string Default value: `Kong-Request-ID`	The HTTP header name to use for the correlation ID.
`config.generator` optional Type: string Default value: `uuid#counter`	The generator to use for the correlation ID. Accepted values are `uuid`, `uuid#counter`, and `tracker`. See Generators.
`config.echo_downstream` optional Type: boolean Default value: `false`	Whether to echo the header back to downstream (the client).

How it works

When you enable this plugin, it adds a new header to all of the requests processed by Kong. This header bears the name configured in config.header_name, and a unique value is generated according to config.generator.

This header is always added in calls to your upstream services, and optionally echoed back to your clients according to the config.echo_downstream setting.

If a header with the same name is already present in the client request, the plugin honors it and does not tamper with it.

Generators

uuid

Format:

xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

This format generates a heaxadecimal UUID for each request.

uuid#counter

Format:

xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx#counter

This format generates a single UUID on a per-worker basis, and further the requests simply append a counter to the UUID after a # character. The counter value starts at 0 for each worker, and gets incremented independently of the others.

This format provides better performance, but might be harder to store or process for analyzing (due to its format and low cardinality).

tracker

Format:

ip-port-pid-connection-connection_requests-timestamp

This correlation id contains more practical implications for each request.

The following is a detailed description of the field

form parameter	description
`ip`	an address of the server that accepts a request
`port`	port of the server that accepts a request
`pid`	pid of the nginx worker process
`connection`	connection serial number
`connection_requests`	current number of requests made through a connection
`timestamp`	a floating-point number for the elapsed time in seconds (including milliseconds as the decimal part) from the epoch for the current timestamp from the nginx cached time

FAQ

Can I see my correlation IDs in my Kong logs?

You can see your correlation ID in the Nginx access log if you edit your Nginx logging parameters.

To edit your Nginx parameters, do the following:

Locate Kong Gateway’s template files and make a copy of nginx_kong.lua.
Add a log_format section on the root level of the config file which includes the $sent_http_Kong_Request_ID variable.

In the following example, we create a new log format named customformat. It’s a copy of the default combined log format, but the last line adds $sent_http_Kong_Request_ID, preceded by the string Kong-Request-ID=. Marking the variable this way is optional, and will make testing the feature easier. Further customize the log_format by adding or removing variables:
```
log_format customformat '$remote_addr - $remote_user [$time_local] '
              '"$request" $status $body_bytes_sent  '
              '"$http_referer" "$http_user_agent" '
              'Kong-Request-ID="$sent_http_Kong_Request_ID"';
```
Use your custom log format for the proxy access log phase. Locate the following line:
```
access_log ${PROXY_ACCESS_LOG};
```
Modify it by adding the customformat format that we just created:
```
access_log ${{PROXY_ACCESS_LOG}} customformat;
```
Note that the file contains several access_log entries. Only modify the line that uses ${PROXY_ACCESS_LOG}.
Reload Kong:
```
kong reload
```
Tail the access log:
```
tail /usr/local/kong/logs/access.log
```
You should now see Correlation ID entries in the access log.

Learn more in Custom Nginx templates & embedding Kong.

You can also use this plugin along with one of the logging plugins, or store the ID on your backend.

Changelog

Kong Gateway 2.2.x

The plugin now generates a correlation-id value by default if the correlation ID header arrives empty.

About this Plugin
Plugin Version	3.0.x
Made by	Kong Inc.
Categories	Transformations
DB-less compatible?	Yes
Konnect Cloud compatible?	Yes
Compatible protocols	`http` `https`