[Kea-users] Host-cmds and pgsql in Docker

[Andrei Pavel]

Hi!

1. You might be looking for the "operation-target": "memory" parameter 
for the reservation commands. 
https://kea.readthedocs.io/en/latest/arm/hooks.html#the-operation-target-parameter

2. ISC is aware of MySQL and PostgreSQLhook libraries missing from 2.7.7 
Docker images and up. Kea 3.0.0 will have this fixed. Reverting to 2.7.6 
or setting up the Cloudsmith repo inside the container and installing 
packages with `apk add isc-kea-mysql isc-kea-pgsql` can help.

Thanks!
Andrei

On 22/05/2025 17:58, Matt Crum via Kea-users wrote:
>
> Hi all,
>
> We’re rewriting some code to use the newly available subnet/host 
> hooks, testing with the ISC Kea 2.7.8 Docker image with a simple JSON 
> backend, aiming to reduce the amount of whole-file operations that we 
> need to do.
>
> The host-cmds hooks are proving difficult to use - couple of questions 
> if anyone can help (please):
>
> 1: JSON Configuration
>
> I cannot get the write (add/del/update) host-cmds hooks to work with a 
> basic JSON configuration; despite this snippet in the latest 
> documentation “These commands can also modify hosts from the JSON 
> configuration independently from the hosts database. The changes 
> provided in the JSON configuration are volatile and can be made 
> permanent by sending the *config-write* 
> <https://kea.readthedocs.io/en/latest/arm/ctrl-channel.html#std-isccmd-config-write> command.” 
> (https://kea.readthedocs.io/en/latest/arm/hooks.html#libdhcp-host-cmds-so-host-commands). 
>
>
> I always get “host database not available, cannot update host” or 
> similar when trying to use it. Do we know of a way to manage 
> reservations in a JSON backend, without having to resort to whole 
> configuration file operations? Do I have to specifically set 
> hosts-database to empty or something (it’s not mentioned in the 
> configuration file at all at the moment)?
>
> Note that the subnet-cmds hooks do support updating the JSON 
> configuration; I’d ideally fall back to using these to manage 
> reservations in each subnet, but it isn’t supported.
>
> 2: Docker and PGSQL
>
> I tried to enable a hosts backend running on Postgres, but the kea4 
> Docker container does not come with the PGSQL hook - same with MySQL. 
> Is this going to be available in the v3 Docker release / is there a 
> way to install it in the container using apk commands, so I can test 
> in the meantime?
>
> As things stand, I’m unable to test the writeable host-cmds using the 
> Kea Docker image. The get commands work OK with a JSON backend.
>
> Any questions, let me know.
>
> Thanks
>
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