decK

1.17.x

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Object Defaults

Kong Gateway sets some default values for most objects, including Kong plugins. You can see what the defaults are for each object in the Admin API reference, or use the /schemas endpoint to check the latest object schemas for your instance of the Kong Gateway.

decK recognizes value defaults and doesn’t interpret them as changes to configuration. If you push a config for an object to Kong Gateway with deck sync, Kong Gateway applies its default values to the object, but a further diff or sync does not show any changes.

If you upgrade Kong Gateway to a version that introduces a new property with a default value, a deck diff will catch the difference.

You can also configure your own custom defaults to enforce a set of standard values and avoid repetition in your configuration.

Value order of precedence

decK assigns values in the following order of precedence, from highest to lowest:

Values set for a specific instance of an object in the state file (for example, for a service named example_service defined in kong.yml).
Values set in the {_info: defaults:} object in the state file.
Self-managed Kong Gateway only: Values are checked against the Kong Admin API schemas.
Konnect Cloud only: Values are checked against the Kong Admin API for plugins, and against hardcoded defaults for Service, Route, Upstream, and Target objects.

Test default value handling

Create a sample kong.yaml file with a service, route, and plugin, push it to Kong Gateway, and then pull Kong Gateway’s configuration down again to see how decK interprets default values.

Create a kong.yaml configuration file.

Add the following sample service, route, and plugin to the file:

_format_version: "3.0"
services:
  - host: mockbin.org
    name: example_service
    routes:
      - name: mockpath
        paths:
        - /mock
plugins:
- name: basic-auth
  config:
    hide_credentials: true

Compare this file with the object configuration in Kong Gateway:
Command

Response
deck diff
creating service example_service creating route mockpath creating plugin basic-auth (global) Summary: Created: 3 Updated: 0 Deleted: 0
If you’re using a completely empty instance, you should only see the service, route, and basic-auth plugin creation messages with no extra JSON data.
Sync your changes with Kong Gateway:
```
deck sync
```
Now, run another diff and note the response:
Command

Response
deck diff
Summary: Created: 0 Updated: 0 Deleted: 0
Notice that the diff doesn’t show any changes. This is because decK checked the values against the service and route schemas and didn’t find any differences.

You can check that any missing default values were set by exporting Kong Gateway’s object configuration into a file. If you want to avoid overwriting your current state file, specify a different filename:

deck dump -o kong-test.yaml

Even though deck diff didn’t show any changes, the result now has default values populated for the service, route, and Basic Auth plugin:

_format_version: "3.0"
plugins:
- config:
    anonymous: null
    hide_credentials: true
  enabled: true
  name: basic-auth
  protocols:
  - grpc
  - grpcs
  - http
  - https
services:
- connect_timeout: 60000
  host: mockbin.org
  name: example_service
  port: 80
  protocol: http
  read_timeout: 60000
  retries: 5
  routes:
  - https_redirect_status_code: 426
    name: mockpath
    path_handling: v0
    paths:
    - /mock
    preserve_host: false
    protocols:
    - http
    - https
    regex_priority: 0
    request_buffering: true
    response_buffering: true
    strip_path: true
  write_timeout: 60000

Set custom defaults

You can set custom configuration defaults for the following core Kong Gateway objects:

Service
Route
Upstream
Target

Default values get applied to both new and existing objects. See the order of precedence for more detail on how they get applied.

You can choose to define custom default values for any subset of entity fields, or define all of them. decK still finds the default values using a combination of your defined fields and the object’s schema, based on the order of precedence.

decK supports setting custom object defaults both in self-managed Kong Gateway and with Kong Konnect.

Important: This feature has the following limitations:

Custom plugin object defaults are not supported.

If an existing property’s default value changes in a future Kong Gateway release, decK has no way of knowing that this change has occurred, as its defaults configuration would overwrite the value in your environment.

In your kong.yaml configuration file, add an _info section with defaults:
```
_format_version: "3.0"
_info:
  defaults:
services:
  - host: mockbin.org
    name: example_service
    routes:
      - name: mockpath
        paths:
          - /mock
```
For production use in larger systems, we recommend that you break out your defaults into a separate defaults.yaml file or use tags to apply the defaults wherever they are needed.

Define the properties you want to set for Kong Gateway objects.

You can define custom defaults for service, route, upstream, and target objects.

For example, you could define default values for a few fields of the Service object:

_format_version: "3.0"
_info:
  defaults:
    service:
      port: 8080
      protocol: https
      retries: 10
services:
  - host: mockbin.org
    name: example_service
    routes:
      - name: mockpath
        paths:
          - /mock

Or you could define custom default values for all available fields:

_format_version: "3.0"
_info:
  defaults:
    route:
      https_redirect_status_code: 426
      path_handling: v1
      preserve_host: false
      protocols:
      - http
      - https
      regex_priority: 0
      request_buffering: true
      response_buffering: true
      strip_path: true
    service:
      port: 8080
      protocol: https
      connect_timeout: 60000
      write_timeout: 60000
      read_timeout: 60000
      retries: 10
services:
  - host: mockbin.org
    name: example_service
    routes:
      - name: mockpath
        paths:
          - /mock

Sync your changes with Kong Gateway:
```
deck sync
```
Run a diff and note the response:

         Command
       

         Response
       
deck diff
Summary:
     Created: 0
     Updated: 0
     Deleted: 0

Whether you choose to define a subset of custom defaults or all available
options, the result is the same: the diff doesn't show any changes.

Find defaults for an object

Kong Gateway defines all the defaults it applies in object schema files. Check the schemas to find the most up-to-date default values for an object.

If you want to completely avoid differences between the configuration file and the Kong Gateway, set all possible default values for an object in your kong.yaml file.

Route

Service

Upstream

Target

Plugins