API differences, in general

Kea DHCP migration
1

OMAPI (dhcpd):

  1. omshell:
  • omshell is a command-line tool provided with dhcpd for interactive management of the DHCP server through OMAPI.
  • It allows you to connect to the DHCP server and execute commands to make configuration changes, retrieve lease information, and manage other aspects of the server.
  1. OMAPI Commands:
  • With OMAPI, you primarily use a set of C API functions to interact with the DHCP server programmatically.
  • These functions include operations such as opening and closing connections, creating and modifying DHCP objects (e.g., leases, subnets, hosts), and sending configuration changes to the server.

Kea REST API:

  1. HTTP Methods:
  • The Kea REST API utilizes standard HTTP methods such as GET, POST, PUT, and DELETE to interact with the server.
  • Each method corresponds to a specific action or operation that can be performed on the Kea server.
  1. REST API Endpoints:
  • Kea exposes a set of RESTful endpoints that correspond to different resources and functionalities within the DHCP server.
  • For example, you may have endpoints for managing DHCP subnets, lease reservations, configuration options, or server statistics.
  1. JSON or XML Payloads:
  • When interacting with the Kea REST API, you typically use JSON or XML payloads to send data to the server or receive responses.
  • These payloads contain the necessary information to perform operations such as configuring subnets, retrieving lease details, or modifying server settings.

Here’s an example to illustrate the command differences:

OMAPI (dhcpd):

$ omshell
> server localhost
> key omapi_key
> connect
> new lease
> set lease.ip-address = 192.168.1.100
> set lease.hw-address = 00:11:22:33:44:55
> update
> quit

Kea REST API:

$ curl -X POST -H "Content-Type: application/json" -d '
{
  "subnet_id": 1,
  "ip_address": "192.168.1.100",
  "hw_address": "00:11:22:33:44:55"
}' http://localhost:8000/leases

In the example above, with OMAPI, you interact directly with the DHCP server using the omshell tool and a series of commands to create a new lease. On the other hand, with the Kea REST API, you use the curl command (e.g.), to send a POST request with a JSON payload to the /leases endpoint on the Kea server to achieve the same result.

These examples highlight the differences in command syntax and the mechanisms used to interact with the DHCP server. The Kea REST API provides a more standardized and web-based approach, while OMAPI relies on the OMAPI-specific commands and the C API for configuration and management. Not sure whether this affects the users or not – it depends on whether the switch to Kea means certain OMAPI calls don’t have a Kea REST API analog, which means some other things might quit working, or work differently.

Really need to do a command coverage chart to see how this might play out.

My best stab at that chart

These are a lot of the things that map, I think. Not exhaustive, but at first blush, it looks as though if you can do it with OMAPI, you can also do it with Kea. It also looks like Kea provides new functionality that OMAPI didn’t provide. Maybe this isn’t as big a deal as I was worried about.

I only looked at the top 20%, skipping endpoints like Enable DHCP, etc. Feel free to critique, or better yet, add the ones that bother you to the table below. Just remember that there are about 140 endpoints in Kea alone. I tried to pick and choose the ones that might not be similar.

Operation Kea REST API Command dhcpd OMAPI Command
Create a subnet subnetn-add new subnet
Update a subnet subnetn-update modify subnet
Delete a subnet subnetn-del remove subnet
Get subnet details subnetn-get open subnet
Reserve a lease leasen-add new lease
Update a lease leasen-update modify lease
Release a lease leasen-del remove lease
Get lease details leasen-get open lease
Configure options config-set new option-def
Update option details config-set modify option-def
Delete an option config-set remove option-def
Get option details config-get open option-def
Get server statistics statistic-get(-all) server-statistics
Get server configuration config-get server-config
Update server configuration config-set set-config
Create host reservation reservation-add new host
Update host details reservation-del/reservation-add modify host
Delete a host reservation-del remove host
Get host details reservation-get-by-hostname open host
Set failover configuration config-set N/A
Set shared network configuration networkn-add N/A
Get shared network details networkn-get N/A
Add lease to host leasen-add N/A
Remove lease from host leasen-del N/A
Create reservation scope reservation-add N/A
Update reservation scope reservation-del/reservation-add N/A
Delete reservation scope reservation-del N/A
Get reservation scope details reservation-get-all/reservation-get-hostname N/A
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