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Customizing router behavior

Document updated on Jan 12, 2023

The optional router configuration allows you to set global flags that change how KrakenD processes the requests globally at the router layer.

Generally speaking you don’t need this. But in every case, there is an exception, and you might need to change some values.

Configuration for the router

The router controls the behavior of KrakenD toward users. Its settings affect all activity in the gateway. For instance, you can obfuscate the X-KrakenD-version header, set a custom body for 404 errors, or remove the requests from the logs, to name a few examples.

To change the router behavior, you must add the namespace router inside the extra_config at the root of the configuration file. For instance:

{
  "version": 3,
  "extra_config": {
    "router": {
       "hide_version_header": true
    }
  }
}

All the options you can set under router are:

app_engine

boolean
The app_engine boolean trusts headers starting with X-AppEngine… for better integration with that PaaS.
auto_options

boolean
When true, enables the autogenerated OPTIONS endpoint for all the registered paths
disable_access_log

boolean
Stops registering access requests to KrakenD and leaving any logs out from the output.
Defaults to false
disable_gzip

boolean
Enterprise only. All the output to the end user on the Enterprise Edition uses gzip when accepted by the client. Use this flag to remove gzip compression.
Defaults to false
disable_handle_method_not_allowed

boolean
Whether to checks if another method is allowed for the current route, if the current request can not be routed. If this is the case, the request is answered with Method Not Allowed and HTTP status code 405. If no other Method is allowed, the request is a 404.
disable_health

boolean
When true you don’t have any exposed health endpoint. You can still use a TCP checker or build an endpoint yourself.
Defaults to false
disable_path_decoding

boolean
Disables automatic validation of the url params looking for url encoded ones.
disable_redirect_fixed_path

boolean
If true, the router tries to fix the current request path, if no handle is registered for it
disable_redirect_trailing_slash

boolean
Disables automatic redirection if the current route can’t be matched but a handler for the path with (without) the trailing slash exists.
error_body

object
Sets custom error bodies for 404 and 405 errors.
404

object
Write any JSON object structure you would like to return to users when they request an endpoint not known by KrakenD. 404 Not Found errors.
405

object
Write any JSON object structure you would like to return to users
forwarded_by_client_ip

boolean
When set to true, client IP will be parsed from the request’s headers. If no IP can be fetched, it falls back to the IP obtained from the request’s remote address.
Defaults to false
health_path

string
The path where you’d like to expose the health endpoint.
Defaults to "/__health"
hide_version_header

boolean
Removes the version of KrakenD used in the X-KrakenD-version headers.
Defaults to false
logger_skip_paths

array
Defines the set of paths that are removed from the logging.
max_multipart_memory

integer
Sets the maxMemory param that is given to http.Request’s Multipart Form method call.
remote_ip_headers

array
List of headers used to obtain the client IP when forwarded_by_client_ip is set to true and the remote address is matched by at least one of the network origins of trusted_proxies.
remove_extra_slash

boolean
A parameter can be parsed from the URL even with extra slashes.
Defaults to false
return_error_msg

boolean
When there is an error in the gateway (such as a timeout, a non-200 status code, etc.) it returns to the client the reason for the failure. The error is written in the body as is.
Defaults to false
trusted_proxies

array
List of network origins (IPv4 addresses, IPv4 CIDRs, IPv6 addresses or IPv6 CIDRs) from which to trust request’s headers that contain alternative client IP when forwarded_by_client_ip is true.

Schema: https://www.krakend.io/schema/v2.2/router.json
* indicates a required field.

Caution with disable_redirect_fixed_path
This flag can lead to the malfunctioning of your router. If your API configuration has paths that could collide, leave its value with the safe choice disable_redirect_fixed_path=true to avoid possible panics.

Example: Hide the version in the X-KrakenD-version header

{
  "version": 3,
  "extra_config": {
    "router": {
       "hide_version_header": true
    }
  }
}

When the flag is set to true, the banner header will show an undefined version. To remove the header entirely, you must remove it in the CDN or layer in front of KrakenD.

Example: Custom JSON body for 404 and 405 errors

{
  "version": 3,
  "extra_config": {
    "router": {
      "error_body": {
        "404": {
          "msg": "Unknown endpoint",
          "status": 404
        },
        "405": {
          "oh-my-god": "What on earth are you requesting?"
        }
      }
    }
  }
}

Example: Returning the gateway error message

The secure choice of KrakenD is that all errors generated at the gateway are not returned to the client in the body. By setting return_error_msg (boolean) to true, when there is an error in the gateway (such as a timeout, a non-200 status code, etc.), it returns the client the reason for the failure. The error is written in the body as is.

Gateway errors != backend errors
This option does not relate to the body of your backend errors. If you are looking for this option, see return detailed errors instead.
{
  "version": 3,
  "extra_config": {
      "router":{
          "return_error_msg":true
      }
}

Example: Obtaining the real IP

The flags - forwarded_by_client_ip, remote_ip_headers, and trusted_proxies determine how to get the client IP address (read its documentation above)

The following example shows a configuration that takes the user IP from the X-Custom-Ip header only when the network origin is 172.20.0.1/16:

{
  "version": 3,
  "extra_config": {
      "router":{
          "forwarded_by_client_ip": true,
          "remote_ip_headers": [
            "X-Custom-Ip"
          ],
          "trusted_proxies": [
            "172.20.0.1/16"
          ]
      }
}

Example: Remove requests from logs

There are two options to remove content from logs, the logger_skip_paths (list of paths you don’t want to see in the logs), and disable_access_log, which stops registering access requests.

{
  "version": 3,
  "extra_config": {
      "router":{
          "logger_skip_paths":[
            "/__health"
          ],
          "disable_access_log": true
      }
}

Unresolved issues?

The documentation is only a piece of the help you can get! Whether you are looking for Open Source or Enterprise support, see more support channels that can help you.

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