A Little Background⌗
(aka: Why Ren cares so much despite all the trouble)
In 2008, I got my first laptop that was mine enough to be able to begin my experimentation with other operating systems. I had previous experience with Solaris, due to my father and his job, so my first steps into the world of UNIX started there. I’d downloaded OpenSolaris and got to work. Years later when I wanted to install something a little more familiar than Linux or FreeBSD, I go to look for an OpenSolaris iso. Much to my dismay, OpenSolaris is dead, after the goons at Oracle closed all the sources.
Most people would quit their search at this point, but my brain doesn’t work quite like that. I kept pushing at the problem. I tried out Oracle Solaris 11 for a few weeks. I played around with Solaris 10, but neither of them offered me a good look into the OS/NET stack like I wanted. Eventually, I discovered that a fork of OpenSolaris was still alive and kicking: Illumos.
So I ran OpenIndiana on everything I could. It was beautiful. Familiar. Wonderful. A little bit later, I discover SmartOS, right in time, while I was going to school for cyber security. Containerization was a big talking point. Everyone was on about Docker and how cool it was. I will admit, it is very cool, but the security around it at the time was a little bit sketchy at best. I mean, I’d just read a few stories about how people were able to break out of Docker containers!
So I built my home lab around SmartOS, a core component to my digital life and sense of security. When I wanted to start expanding, I figured I aught to look into a decent way to orchestrate multiple SmartOS compute nodes. Thus enters the Triton DataCenter.
Triton is an open source stack of software designed specifically to orchestrate an entire public cloud. Everything from an api for external control, down to the operating system itself. All wrapped up in a nice little installer package and very minimal networking setup required to get it all go. So I started using it, but it came with a few problems.
Tips and Tricks⌗
First, I’d discovered that the headnode should not be treated as a general purpose compute node with extra stuff on it. They warn about this, but I figured that maybe it was just under true datacenter-scale load that it was true. Not a chance. Don’t provision zones on the headnode. Use other members of the cluster for provisioning.
Second, I’d accidentally included the headnode in my planning for the VXLan setup. The headnode will slowdown exponentially if you do this. I have no idea why, either, but maybe one day I’ll ask the devs what particular set of things happen to make this a bad idea (or maybe I’ll debug it myself).
Third, provision high availability if you have the space for it in your deployment. No really. High availability will help distribute the load and actually improves the reliability of your cluster, even in a 5 node setup. I’ve accidentally broken and destroyed a core zone irrepairably just by poking around (admittedly doing so while mildly impaired).
Fourth, read the manual. Joyent’s manuals are all very nice and have a decent depth to them. The only caveat is that they are all over on github, and not included with the software (maybe they are, but if so, I haven’t been able to find them). You can start with the Triton Architecture Document. Yes, it is that good.
Fifth, nearly everything about the cluster itself can be controlled using
sdcadm, a fancy tool that manages updates, maintenances, and deployments.
Make sure you know how to use it, though, because accidentally doing things in
the wrong order can and will break the headnode and prevent all compute
nodes from booting. I have done this on a live deployment. It sucks to have
everything ripped out from under you, and not have enough time or resources to
properly debug what happened. I’m still recovering from that mistake.
Sixth, most hardware is supported, even if its not on the HCL. With that in mind, its still sometimes hard to work around specific issues with older hardware. My cluster runs some Dell servers and some HP servers. For some reason, occasionally the HP servers will take extra long to provision a zone (I will debug this at some point, when I get the time). Other times, the Dell servers simply stop responding due to awkward network hangs or the IPMI interface throwing a fault (I can’t fix this, as network latency is due to hardware itself and IPMI throwing fault and causing the system to halt is a good thing).
Problems with HA deployments⌗
There are some issues with using ZooKeeper to manage clustering of high availability services. For example, if you have total loss of power in the datacenter, or otherwise have every node go down at the same time, the way binder is configured, it has to have the majority alive in order to come up. This can cause issues during internal communications, since all of the internal APIs communicate to eachother using binder provided DNS names. In my experience, this also prevents other nodes from booting, though that may have been an issue specific to my setup (I cannot replicate it, though I desperately want to know why it happened).
Additional issues I’ve found is that host instability can cause wild things to happen with manatee. Specifically, I accidentally dropped a manatee node on to a server that can receive large load from other database servers sharing the same compute resources. Under these intense loads, network connections will remain to be alive and happy. Even ZooKeeper continues to report that it is in fact the primary manatee node. However, it will refuse to let the topology change, and all replication to other nodes will cease entirely.
In order to resolve that, I had to tell the server to refresh all of its configuration (by booting into a smartos live usb and clearing the configuration file). After that, I let manatee sync back up, then deposed it as primary and went through the rather quick process of rebuilding it. However, none of this would have been an issue if I’d had been paying attention to my…
Monitoring (and Dashboards)⌗
Monitoring is really important for these things in order to keep them well tuned and to quickly recover from faults. Triton includes monitoring, but requires a few things to be setup. You’ll need to setup CMON, CNS, and Prometheus before you can even setup Grafana.
According to the documentation, this should all just work once its setup. I had to go in and create some new authentication certificates for prometheus in order for it to pull data correctly.
Why Triton is Worth It⌗
Despite all of the above problems I’ve been through with Triton, its still a very stable bit of software. Once its up and kicking, it won’t have issues outside of total power loss or host instability. It will even outlast other systems (such as Linux and K8S) for stability in the face of hardware faults. That’s amazing to me. It may have a learning curve, but ultimately, the easy command line interface, the truly amazing resilience, and the ability to have the best of Illumos and Linux is a pure joy.