Pre-Function: Add a header to a request based on another header - Plugin

Add a header to a request based on another header

Use Lua code to check for the existence of a header in a request, and if that header exists, add a new header with the same value.

In this example, we want to check if requests contain a Request-Id header. If it’s present, we want to add a header named New-Request-Id with the same value.

Set up the plugin

Add this section to your declarative configuration file:

_format_version: "3.0"
plugins:
  - name: pre-function
    config:
      access:
      - |-
        local existing_request_id = kong.request.get_header("Request-Id")
           if(existing_request_id ~= nil) then
          kong.service.request.set_header("New-Request-Id", existing_request_id)
        end

Make the following request:

curl -i -X POST http://localhost:8001/plugins/ \
    --header "Accept: application/json" \
    --header "Content-Type: application/json" \
    --data '
    {
      "name": "pre-function",
      "config": {
        "access": [
          "local existing_request_id = kong.request.get_header(\"Request-Id\")\n\nif(existing_request_id ~= nil) then\n  kong.service.request.set_header(\"New-Request-Id\", existing_request_id)\nend"
        ]
      }
    }
    '

Make the following request:

curl -X POST https://{region}.api.konghq.com/v2/control-planes/{controlPlaneId}/core-entities/plugins/ \
    --header "accept: application/json" \
    --header "Content-Type: application/json" \
    --header "Authorization: Bearer $KONNECT_TOKEN" \
    --data '
    {
      "name": "pre-function",
      "config": {
        "access": [
          "local existing_request_id = kong.request.get_header(\"Request-Id\")\n\nif(existing_request_id ~= nil) then\n  kong.service.request.set_header(\"New-Request-Id\", existing_request_id)\nend"
        ]
      }
    }
    '

Make sure to replace the following placeholders with your own values:

region: Geographic region where your Kong Konnect is hosted and operates.
controlPlaneId: The id of the control plane.
KONNECT_TOKEN: Your Personal Access Token (PAT) associated with your Konnect account.

See the Konnect API reference to learn about region-specific URLs and personal access tokens.

echo "
apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: pre-function
  namespace: kong
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: 'true'
config:
  access:
  - |-
    local existing_request_id = kong.request.get_header('Request-Id')

    if(existing_request_id ~= nil) then
      kong.service.request.set_header('New-Request-Id', existing_request_id)
    end
plugin: pre-function
" | kubectl apply -f -

Prerequisite: Configure your Personal Access Token

terraform {
  required_providers {
    konnect = {
      source  = "kong/konnect"
    }
  }
}

provider "konnect" {
  personal_access_token = "$KONNECT_TOKEN"
  server_url            = "https://us.api.konghq.com/"
}

Add the following to your Terraform configuration to create a Konnect Gateway Plugin:

resource "konnect_gateway_plugin_pre_function" "my_pre_function" {
  enabled = true

  config = {
    access = [<<EOF
local existing_request_id = kong.request.get_header("Request-Id")

if(existing_request_id ~= nil) then
  kong.service.request.set_header("New-Request-Id", existing_request_id)
end
EOF]
  }

  control_plane_id = konnect_gateway_control_plane.my_konnect_cp.id
}

Add this section to your declarative configuration file:

_format_version: "3.0"
plugins:
  - name: pre-function
    service: serviceName|Id
    config:
      access:
      - |-
        local existing_request_id = kong.request.get_header("Request-Id")
           if(existing_request_id ~= nil) then
          kong.service.request.set_header("New-Request-Id", existing_request_id)
        end

Make sure to replace the following placeholders with your own values:

serviceName|Id: The id or name of the service the plugin configuration will target.

Make the following request:

curl -i -X POST http://localhost:8001/services/{serviceName|Id}/plugins/ \
    --header "Accept: application/json" \
    --header "Content-Type: application/json" \
    --data '
    {
      "name": "pre-function",
      "config": {
        "access": [
          "local existing_request_id = kong.request.get_header(\"Request-Id\")\n\nif(existing_request_id ~= nil) then\n  kong.service.request.set_header(\"New-Request-Id\", existing_request_id)\nend"
        ]
      }
    }
    '

Make sure to replace the following placeholders with your own values:

serviceName|Id: The id or name of the service the plugin configuration will target.

Make the following request:

curl -X POST https://{region}.api.konghq.com/v2/control-planes/{controlPlaneId}/core-entities/services/{serviceId}/plugins/ \
    --header "accept: application/json" \
    --header "Content-Type: application/json" \
    --header "Authorization: Bearer $KONNECT_TOKEN" \
    --data '
    {
      "name": "pre-function",
      "config": {
        "access": [
          "local existing_request_id = kong.request.get_header(\"Request-Id\")\n\nif(existing_request_id ~= nil) then\n  kong.service.request.set_header(\"New-Request-Id\", existing_request_id)\nend"
        ]
      }
    }
    '

Make sure to replace the following placeholders with your own values:

region: Geographic region where your Kong Konnect is hosted and operates.
controlPlaneId: The id of the control plane.
KONNECT_TOKEN: Your Personal Access Token (PAT) associated with your Konnect account.
serviceId: The id of the service the plugin configuration will target.

See the Konnect API reference to learn about region-specific URLs and personal access tokens.

echo "
apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: pre-function
  namespace: kong
  annotations:
    kubernetes.io/ingress.class: kong
config:
  access:
  - |-
    local existing_request_id = kong.request.get_header('Request-Id')

    if(existing_request_id ~= nil) then
      kong.service.request.set_header('New-Request-Id', existing_request_id)
    end
plugin: pre-function
" | kubectl apply -f -

Next, apply the KongPlugin resource by annotating the service resource:

kubectl annotate -n kong service SERVICE_NAME konghq.com/plugins=pre-function

Prerequisite: Configure your Personal Access Token

terraform {
  required_providers {
    konnect = {
      source  = "kong/konnect"
    }
  }
}

provider "konnect" {
  personal_access_token = "$KONNECT_TOKEN"
  server_url            = "https://us.api.konghq.com/"
}

Add the following to your Terraform configuration to create a Konnect Gateway Plugin:

resource "konnect_gateway_plugin_pre_function" "my_pre_function" {
  enabled = true

  config = {
    access = [<<EOF
local existing_request_id = kong.request.get_header("Request-Id")

if(existing_request_id ~= nil) then
  kong.service.request.set_header("New-Request-Id", existing_request_id)
end
EOF]
  }

  control_plane_id = konnect_gateway_control_plane.my_konnect_cp.id
  service = {
    id = konnect_gateway_service.my_service.id
  }
}

Add this section to your declarative configuration file:

_format_version: "3.0"
plugins:
  - name: pre-function
    route: routeName|Id
    config:
      access:
      - |-
        local existing_request_id = kong.request.get_header("Request-Id")
           if(existing_request_id ~= nil) then
          kong.service.request.set_header("New-Request-Id", existing_request_id)
        end

Make sure to replace the following placeholders with your own values:

routeName|Id: The id or name of the route the plugin configuration will target.

Make the following request:

curl -i -X POST http://localhost:8001/routes/{routeName|Id}/plugins/ \
    --header "Accept: application/json" \
    --header "Content-Type: application/json" \
    --data '
    {
      "name": "pre-function",
      "config": {
        "access": [
          "local existing_request_id = kong.request.get_header(\"Request-Id\")\n\nif(existing_request_id ~= nil) then\n  kong.service.request.set_header(\"New-Request-Id\", existing_request_id)\nend"
        ]
      }
    }
    '

Make sure to replace the following placeholders with your own values:

routeName|Id: The id or name of the route the plugin configuration will target.

Make the following request:

curl -X POST https://{region}.api.konghq.com/v2/control-planes/{controlPlaneId}/core-entities/routes/{routeId}/plugins/ \
    --header "accept: application/json" \
    --header "Content-Type: application/json" \
    --header "Authorization: Bearer $KONNECT_TOKEN" \
    --data '
    {
      "name": "pre-function",
      "config": {
        "access": [
          "local existing_request_id = kong.request.get_header(\"Request-Id\")\n\nif(existing_request_id ~= nil) then\n  kong.service.request.set_header(\"New-Request-Id\", existing_request_id)\nend"
        ]
      }
    }
    '

Make sure to replace the following placeholders with your own values:

region: Geographic region where your Kong Konnect is hosted and operates.
controlPlaneId: The id of the control plane.
KONNECT_TOKEN: Your Personal Access Token (PAT) associated with your Konnect account.
routeId: The id of the route the plugin configuration will target.

See the Konnect API reference to learn about region-specific URLs and personal access tokens.

echo "
apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: pre-function
  namespace: kong
  annotations:
    kubernetes.io/ingress.class: kong
config:
  access:
  - |-
    local existing_request_id = kong.request.get_header('Request-Id')

    if(existing_request_id ~= nil) then
      kong.service.request.set_header('New-Request-Id', existing_request_id)
    end
plugin: pre-function
" | kubectl apply -f -

Next, apply the KongPlugin resource by annotating the httproute or ingress resource:

kubectl annotate -n kong httproute  konghq.com/plugins=pre-function

kubectl annotate -n kong ingress  konghq.com/plugins=pre-function

Prerequisite: Configure your Personal Access Token

terraform {
  required_providers {
    konnect = {
      source  = "kong/konnect"
    }
  }
}

provider "konnect" {
  personal_access_token = "$KONNECT_TOKEN"
  server_url            = "https://us.api.konghq.com/"
}

Add the following to your Terraform configuration to create a Konnect Gateway Plugin:

resource "konnect_gateway_plugin_pre_function" "my_pre_function" {
  enabled = true

  config = {
    access = [<<EOF
local existing_request_id = kong.request.get_header("Request-Id")

if(existing_request_id ~= nil) then
  kong.service.request.set_header("New-Request-Id", existing_request_id)
end
EOF]
  }

  control_plane_id = konnect_gateway_control_plane.my_konnect_cp.id
  route = {
    id = konnect_gateway_route.my_route.id
  }
}

Kong Functions (Pre-Plugins)

Add a header to a request based on another header

Set up the plugin

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