[ClusterLabs] Proposal for machine-friendly output from Pacemaker tools

[Kristoffer Grönlund]

On Tue, 2019-01-08 at 10:07 -0600, Ken Gaillot wrote:
> On Tue, 2019-01-08 at 10:30 +0100, Kristoffer Grönlund wrote:
> > On Mon, 2019-01-07 at 17:52 -0600, Ken Gaillot wrote:
> > > 
> > Having all the tools able to produce XML output like cibadmin and
> > crm_mon would be good in general, I think. So that seems like a
> > good
> > proposal to me.
> > 
> > In the case of an error, at least in my experience just getting a
> > return code and stderr output is enough to make sense of it -
> > getting
> > XML on stderr in the case of an error wouldn't seem like something
> > that
> > would add much value to me.
> 
> There are two benefits: it can give extended information (such as the
> text string that corresponds to a numeric exit status), and because
> it
> would also be used by any future REST API (which won't have stderr),
> API/CLI output could be parsed identically.
> 

Hm, am I understanding you correctly:

My sort-of vision for implementing a REST API has been to move all of
the core functionality out of the command line tools and into the C
libraries (I think we discussed something like a libpacemakerclient
before) - the idea is that the XML output would be generated on that
level?

If so, that is something that I am all for :)

Right now, we are experimenting with a REST API based on taking what we
use in Hawk and moving that into an API server written in Go, and just
calling crm_mon --as-xml to get status information that can be exposed
via the API. Having that available in C directly and not having to call
out to command line tools would be great and a lot cleaner:

https://github.com/krig/hawk-apiserver
https://github.com/hawk-ui/hawk-web-client

Cheers,
Kristoffer