letsencrypt support in propellor

I've integrated letsencrypt into propellor today.

I'm using the reference letsencrypt client. While I've seen complaints that it has a lot of dependencies and is too complicated, it seemed to only need to pull in a few packages, and use only a few megabytes of disk space, and it has fewer options than ls does. So seems fine. (Although it would be nice to have some alternatives packaged in Debian.)

I ended up implementing this:

letsEncrypt :: AgreeTOS -> Domain -> WebRoot -> Property NoInfo

This property just makes the certificate available, it does not configure the web server to use it. This avoids relying on the letsencrypt client's apache config munging, which is probably useful for many people, but not those of us using configuration management systems. And so avoids most of the complicated magic that the letsencrypt client has a reputation for.

Instead, any property that wants to use the certificate can just use leteencrypt to get it and set up the server when it makes a change to the certificate:

letsEncrypt (LetsEncrypt.AgreeTOS (Just "me@my.domain")) "example.com" "/var/www"
    `onChange` setupthewebserver

(Took me a while to notice I could use onChange like that, and so divorce the cert generation/renewal from the server setup. onChange is awesome! This blog post has been updated accordingly.)

In practice, the http site has to be brought up first, and then letsencrypt run, and then the cert installed and the https site brought up using it. That dance is automated by this property:

Apache.httpsVirtualHost "example.com" "/var/www"
    (LetsEncrypt.AgreeTOS (Just "me@my.domain"))

That's about as simple a configuration as I can imagine for such a website!


The two parts of letsencrypt that are complicated are not the fault of the client really. Those are renewal and rate limiting.

I'm currently rate limited for the next week because I asked letsencrypt for several certificates for a domain, as I was learning how to use it and integrating it into propellor. So I've not quite managed to fully test everything. That's annoying. I also worry that rate limiting could hit at an inopportune time once I'm relying on letsencrypt. It's especially problimatic that it only allows 5 certs for subdomains of a given domain per week. What if I use a lot of subdomains?

Renewal is complicated mostly because there's no good way to test it. You set up your cron job, or whatever, and wait three months, and hopefully it worked. Just as likely, you got something wrong, and your website breaks. Maybe letsencrypt could offer certificates that will only last an hour, or a day, for use when testing renewal.

Also, what if something goes wrong with renewal? Perhaps letsencrypt.org is not available when your certificate needs to be renewed.

What I've done in propellor to handle renewal is, it runs letsencrypt every time, with the --keep-until-expiring option. If this fails, propellor will report a failure. As long as propellor is run periodically by a cron job, this should result in multiple failure reports being sent (for 30 days I think) before a cert expires without getting renewed. But, I have not been able to test this.

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Ubuntu trademark nonsense

Canonical appear to require that you remove all trademarks entirely even if using them wouldn't be a violation of trademark law.

-- Matthew Garrett

Each time Matthew brings this up, and as evidence continues to mount that Canonical either actually intends their IP policy to be read that way, or is intentionally keeping the situation unclear to FUD derivatives, I start wondering about references to Ubuntu in my software.

Should such references be removed, or obscured, like "U*NIX" in software of old, to prevent exposing users to this trademark nonsense?

joey@darkstar:~/src/git-annex>git grep -i ubuntu |wc -l
457
joey@darkstar:~/src/ikiwiki>git grep -i ubuntu |wc -l
80
joey@darkstar:~/src/etckeeper>git grep -i ubuntu |wc -l
14

Most of the code in git-annex, ikiwiki, and etckeeper is licensed under the GPL or AGPL, and so Canonical's IP policy probably does not require that anyone basing a distribution on Ubuntu strip all references to "Ubuntu" from them. But then, there's Propellor:

joey@darkstar:~/src/propellor>git grep -i ubuntu |wc -l
10

Propellor is BSD licensed. It's in Ubuntu universe. It not only references Ubuntu in documentation, but contains code that uses that trademark:

data Distribution
        = Debian DebianSuite
        | Ubuntu Release

So, if an Ubuntu-derived distribution has to remove "Ubuntu" from Propellor, they'd end up with a Propellor that either differs from upstream, or that can't be used to manage Ubuntu systems. Neither choice is good for users. Probably most small derived distributions would not have expertise to patch data types in a Haskell program and would have to skip including Propellor. That's not good for Propellor getting wide distribution either.

I think I've convinced myself it would be for the best to remove all references to "Ubuntu" from Propellor.
done

Similarly, Debconf is BSD licensed. I originally wrote it, but it's now maintained by Colin Watson, who works for Canonical. If I were still maintaining Debconf, I'd be looking at removing all instances of "Ubuntu" from it and preventing that and other Canonical trademarks from slipping back in later. Alternatively, I'd be happy to re-license all Debconf code that I wrote under the AGPL-3+.

Update: Another package that comes to mind is Debootstrap, which is also BSD licensed. Of course it contains "Ubuntu" in lots of places, since it is how Ubuntu systems are built. I'm no longer an active developer of Debootstrap, but I hope its current developers carefully consider how this trademark nonsense affects it.

PS: Shall we use "*buntu" as the, erm, canonical trademark-free spelling of "Ubuntu"? Seems most reasonable, unless Canonical has trademarked that too.

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documentation first

I write documentation first and code second. I've mentioned this from time to time (previously, previously) but a reader pointed out that I've never really explained why I work that way.

It's a way to make my thinking more concrete without diving all the way into the complexities of the code right away. So sometimes, what I write down is design documentation, and sometimes it's notes on a bug report[1], but if what I'm working on is user-visible, I start by writing down the end user documentation.

Writing things down lets me interact with them as words on a page, which are more concrete than muddled thoughts in the head, and much easier to edit and reason about. Code constrains to existing structures; a blank page frees you to explore and build up new ideas. It's the essay writing process, applied to software development, with a side effect of making sure everything is documented.

Also, end-user documentation is best when it doesn't assume that the user has any prior knowledge. The point in time when I'm closest to perfect lack of knowledge about something is before I've built it[2]. So, that's the best time to document it.

I understand what I'm trying to tell you better now that I've written it down than I did when I started. Hopefully you do too.


[1] I'll often write a bug report down even if I have found the bug myself and am going to fix it myself on the same day. (example) This is one place where it's nice to have bug reports as files in the same repository as the code, so that the bug report can be included in the commit fixing it. Often the bug report has lots of details that don't need to go into the commit message, but explain more about my evolving thinking about a problem.

[2] Technically I'm even more clueless ten years later when I've totally forgotten whatever, but it's not practical to wait. ;-)

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