So a while ago we started talking about this userops thing. Basically, the idea is "deployment for the people", focusing on user computing / networking freedom (in contrast to "devops", benefits to large institutions are sure to come as a side effect, but are not the primary focus. There's kind of a loose community surrounding the term now, and a number of us are working towards solutions. But I think something that has been missing for me at least is something to test against. Everyone in the group wants to make deployment easiser. But what does that mean?
This is an attempt to sketch out requirements. Keep in mind that I'm writing out this draft on my own, so it might be that I'm missing some things. And of course, some of this can be interpreted in multiple ways. But it seems to me that if we want to make running servers something for mere mortals to do for themselves, their friends, and their families, these are some of the things that are needed:
Free as in Freedom:
I think this one's a given. If your solution isn't free and open source software, there's no way it can deliver proper network freedoms. I feel like this goes without saying, but it's not considered a requirement in the "devops" world... but the focus is different there. We're aiming to liberate users, so your software solution should of course itself start with a foundation of freedom.
It's important to users that they be able to have the same system produced over and over again. This is important for experimenting with a setup before deployment, for ensuring that issues are reproducible and friends and communities helping each other debug problems when they run into them. It's also important for security; you should be able to be sure that the system you have described is the system you are really running, and that if someone has compromised your system, that you are able to rebuild it. And you shouldn't be relying on someone to build a binary version of your system for you, unless there's a way to rebuild that binary version yourself and you have a way to be sure that this binary version corresponds to the system's description and source. (Use the source, Luke!)
Nonetheless, I've noticed that when people talk about reproducibility, they sometimes are talking about two distinct but highly related things.
The ability to compile from source any given package in a distribution, and to have clear methods and procedures to do so. While has been a given in the free software world for a long time, there's been a trend in the devops-type world towards a determination that packaging and deployment in modern languages has gotten too complex, so simply rely on some binary deployment. For reasons described above and more, you should be able to rebuild your packages... *and* all of your packages' dependencies... and their dependencies too. If you can't do this, it's not really reproducible.
An even better goal is to guarantee not only that packages can be built, but that they are byte-for-byte identical to each other when built upon all their previous dependencies on the same architecture. The Debian Reproducibility Project is a clear example of this principle in action.
Take the package reproducibility description above, and apply it to a whole system. It should be possible to, one way or another, either describe or keep record of (or even better, both) the system that is to be built, and rebuild it again. Given selected packages, configuration files, and anything else that is not "user data" (which is addressed in the next section), it should be possible to have the very same system that existed previously.
As with many things on this list, this is somewhat of a gradient. But one extrapoliation, if taken far enough, I believe is a useful one (and ties in with the "recoverable sytem" part): systems should not be necessarily dependent upon the date and time they are deployed. That is to say, if I deployed a system yesterday, I should be able to redeploy that same system today on an entirely new system using all the packages that were installed yesterday, even if my distribution now has newer, updated packages. It should be possible for a system to be reproducible towards any state, no matter what fixed point in time we were originally referring to.
- Reproducible packages:
Few things are more stressful than having a computer that works, is doing something important for you, and then something happens... and suddenly it doesn't, and you can't get back to the point where your computer was working anymore. Maybe you even lost important data!
If something goes wrong, it should be possible to set things right again. A good userops system should do this. There are two domains to which this applies:
In other words, backups. Anything that's special, mutable data that the user wants to keep fits in this territory. As much as possible, a userops system should seek to make running backups easy. Identifying based on system configuration which files to copy and helping to provide this information to a backup system, or simply only leaving all mutable user data in an easy-to-back-up location would help users from having to determine what to back up on their own, which can be easily overwhelming and error-prone for an individual.
Some data (such as data in many SQL databases) is a bit more complex than just copying over files. For something like this, it would be best if a system could help with setting up this data to be moved to a more appropriate backup serialization.
Linking somewhat to the "reproducible system" concept, a user should be able to upgrade without fear of becoming stuck. Upgrade paralysis is something I know I and many others have experienced. Sometimes it even appears that an upgrade will go totally fine, and you may have tested carefully to make sure it will, but you do an upgrade, and suddenly things are broken. The state of the system has moved to a point where you can't get back! This is a problem.
If a user experiences a problem in upgrading their system software and configuration, they should have a good means of rolling back. I believe this will remove much of the anxiety out of server administration especially for smaller scale deployments... I know it would for me.
- Recoverable data:
It should be possible to install the system via a friendly GUI. This probably should be optional; there may be lower level interfaces to the deployment system that some users would prefer to use. But many things probably can be done from a GUI, and thus should be able to be.
Many aspects of configuring a system require filling in shared data between components; a system should generally follow a Don't Repeat Yourself type philosophy. A web application may require the configuration details of a mail transfer agent, and the web application may also need to provide its own details to a web server such as Nginx or Apache. Users should have to fill in these details in one place each, and they should propagate configuration to the other components of the system.
Not everyone should have to work with this layer directly, but everyone benefits from scriptability. Having your system be scriptable means that users can properly build interfaces on top of your system and additional components that extend it beyond directions you may be able to do directly. For example, you might not have to build a web interface yourself; if your system exposes its internals in a language capable enough of building web applications, someone else can do that for you. Similarly with provisioning, etc.
Working with the previous section, bonus points if the GUI can "guide users" into learning how to work with more lower level components; the Blender UI is a good example of this, with most users being artists who are not programmers, but hovering over user interface elements exposes their Python equivalents, and so many artists do not start out as developers, but become so in working to extend the program for their needs bit by bit. (Emacs has similar behavior, but is already built for developers, so is not as good of an example.) "Self Extensibility" is another way to look at this.
Though many individuals will be deploying on their own, many server deployments are set up to serve a community. It should be possible for users to help each other collaborate on deployment. This may mean a variety of things, from being able to collaborate on configuration, to having an easy means to reproduce a system locally.
Additionally, many deployments share steps. Users should be able to help each other out and share "recipes" of deployment steps. The most minimalist (and least useful) version of this is something akin to snippet sharing on a wiki. Most likely, wikis already exist, so more interestingly, it should be possible to share deployment strategies via code that is proceduralized in some form. As such, in an ideal form, deployment recipes should be made available similar to how packages are in present distributions, with the appropriate slots left open for customization for a particular deployment.
Many users have not one but many computers to take care of these days. Keeping so many systems up to date can be very hard; being able to do so for many systems at once (especially if your system allows them to share configuration components) can help a user actually keep on track of things and lead to less neglected systems.
There may be different sets, or "fleets", of computers to take care of... you may find that a user discovers that she needs to both take care of a set of computers for her (and maybe her loved ones') personal use, but she also has servers to take care of for a hobby project, and another set of servers for work.
Not all users require this, and perhaps this can be provided on another layer via some other scripting. But enough users are in "maintainance overload" of keeping track of too many computers that this should probably be provided.
One of the most important and yet open ended requirements, proper security is critical. Security decisions usually involve tradeoffs, so what security decisions are made is left somewhat open ended, but there should be a focus of security within your system. Most importantly, good security hygeine should be made easy for your users, ideally as easy or easier than not following good hygeiene.
Particular areas of interest include: encrypted communication, preferring or enforcing key based authentication over passwords, isolating and sandboxing applications.
To my knowledge, at this time no system provides all the features above in a way that is usable for many everyday users. (I've also left some ambiguity in how to achieve these properties above, so in a sense, this is not a pass/fail type test, but rather a set of properties to measure a system against.) In an ideal future, more Userops type systems will provide the above properties, and ideally not all users will have to think too much about their benefits. (Though it's always great to give the opportunity to users who are interested in thinking about these things!) In the meanwhile, I hope this document will provide a useful basis for implementing and thinking about mapping one's implementation against!