Re: [PATCH 2/2] daemon: Introduce the possibility for users to register custom XML validator

On a Monday in 2022, Daniel P. Berrangé wrote: > On Fri, Sep 23, 2022 at 05:42:13PM +0200, Peter Krempa wrote: > > Introduce a new config option 'xml_validator' into the daemon config > > file which will allow users to make libvirt daemons use a custom XML > > validator. > > > > The rationale is that validators such as 'jing'[1] provide drastically > > better error specification when compared to the native libxml2 validator > > we use. A drawback though is that jing is written in Java and thus > > unusable by libvirt directly and also not a popular package present in > > distros. > > > > For power users and developers it still is worth having this feature to > > provide better errors in a native way. > > I kinda wonder if those users need it integrated in libvirt > though, as opposed to just calling jing themselves when > needed. It feels like a fairly narrow set of users benefitting > here from this change, made even smaller by the fact that those > users have to remember to reconfigure libvirt to enable this. > > I would be more convinced if jing was still packaged for Fedora. > > > An example showing the quality of the errors: > > > > XML used: > > > > <vcpu placement='static' current='1'>asdf8</vcpu> > > > > native validator: > > error: XML document failed to validate against schema: Unable to validate doc against /home/pipo/libvirt/src/conf/schemas/domain.rng > > Extra element vcpu in interleave > > Invalid sequence in interleave > > Element domain failed to validate content > > > > jing: > > error: XML document failed to validate against schema: Unable to validate doc against /home/pipo/libvirt/src/conf/schemas/domain.rng > > /dev/stdin:6:52: error: character content of element "vcpu" invalid; must be an integer > > No doubt the errors are way better, but a power user > can just invoke this script below themselves if they > ever want to understand a XML problem better. > > > > > Example script to make this feature work with jing: > > > > #!/bin/bash > > java -jar /home/pipo/git/jing-trang/build/jing.jar $1 /dev/stdin 2>&1 || exit 1 > > > > [1] https://github.com/relaxng/jing-trang > > To me this is only compelling if there's an option we can reasonably > wire up out of the box. Would switching to a different schema format make finding a validator with frendlier messages easier?