Hello everyone, I just wanted to send out an email about the hawk-apiserver project which was moved into the ClusterLabs organization on Github today. This project is used by us at SUSE for Hawk in our latest releases already, and is also available in openSUSE for use with Hawk. However, I am hoping that it can prove to be useful more generally, not just for Hawk but for other projects that may want to integrate with Pacemaker using the C API, and also to show what is possible when using the API.
To describe the hawk-apiserver briefly, I'll start by describing the use case it was designed to cover: Previously, we were using lighttpd as the web server for Hawk (a Ruby on Rails application), but a while ago the maintainers of lighttpd decided that since Hawk was the only user of this project in SLE, they would like to remove it from the next release. This left Apache as the web server available to us, which has some interesting issues for Hawk: Mainly, we expect people to run apache as a resource in the cluster which might result in a confusing mix of processes on the systems. At the same time, I had started looking at Go and discovered how easy it was to write a basic proxying web server in Go. So, as an experiment I decided to see if I could replace the use of lighttpd with a custom web server written in Go. Turns out the answer was yes! Once we had our own web server, I discovered new things we could do with it. So here are some of the other unique features in hawk-apiserver now: * SSL certificate termination, and automatic detection and redirection from HTTP to HTTPS *on the same port*: Hawk runs on port 7630, and if someone accesses that port via HTTP, they will get a redirect to the same port but on HTTPS. It's magic. * Persistent connection to Pacemaker via the C API, enabling instant change notification to the web frontend. From the point of view of the web frontend, this is a long-lived connection which completes when something changes in the CIB. On the backend side, it uses goroutines to enable thousands of such long-lived connections with minimal overhead. * Optional exposure of the CIB as a REST API. Right now this is somewhat primitive, but we are working on making this a more fully featured API. * Configurable static file serving routes (serve images on /img from /srv/http/images for example). * Configurable proxying of subroutes to other web applications. The URL to the project is https://github.com/ClusterLabs/hawk-apiserver, I hope you will find it useful. Comments, issues and contributions are of course more than welcome. One final note: hawk-apiserver uses a project called go-pacemaker located at https://github.com/krig/go-pacemaker. I indend to transfer this to ClusterLabs as well. go-pacemaker is still somewhat rough around the edges, and our plan is to work on the C API of pacemaker to make using and exposing it via Go easier, as well as moving functionality from crm_mon into the C API so that status information can be made available in a more convenient format via the API as well. -- // Kristoffer Grönlund // kgronl...@suse.com _______________________________________________ Users mailing list: Users@clusterlabs.org https://lists.clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org
