Learning to love Ansible

Jul 24, 2017 / 0 comments

This post attempts to chart my journey towards getting usefully started with Ansible to manage my system configurations. It’s a high level discussion of how I went about doing so and what I got out of it, rather than including any actual config snippets - there are plenty of great resources out there that handle the actual practicalities of getting started much better than I could.

I’ve been convinced about the merits of configuration management for machines for a while now; I remember conversations about producing an appropriate set of recipes to reproduce our haphazard development environment reliably over 4 years ago. That never really got dealt with before I left, and as managing systems hasn’t been part of my day job since then I never got around to doing more than working my way through the Puppet Learning VM. I do, however, continue to run a number of different Linux machines - a few VMs, a hosted dedicated server and a few physical machines at home and my parents’. In particular I have a VM which handles my parents’ email, and I thought that was a good candidate for trying to properly manage. It’s backed up, but it would be nice to be able to redeploy that setup easily if I wanted to move provider, or do hosting for other domains in their own VMs.

I picked Ansible, largely because I wanted something lightweight and the agentless design appealed to me. All I really need to do is ensure Python is on the host I want to manage and everything else I can bootstrap using Ansible itself. Plus it meant I could use the version from Debian testing on my laptop and not require backports on the stable machines I wanted to manage.

My first attempt was to write a single Ansible YAML file which did all the appropriate things for the email VM; installed Exim/Apache/Roundcube, created users, made sure the appropriate SSH keys were in place, installed configuration files, etc, etc. This did the job, but I found myself thinking it was no better than writing a shell script to do the same things.

Things got a lot better when instead of concentrating on a single host I looked at what commonality was shared between hosts. I started with simple things; Debian is my default distro so I created an Ansible role debian-system which configured up APT and ensured package updates were installed. Then I added a task to setup my own account and install my SSH keys. I was then able to deploy those 2 basic steps across a dozen different machine instances. At one point I got an ARM64 VM from Scaleway to play with, and it was great to be able to just add it to my Ansible hosts file and run the playbook against it to get my basic system setup.

Adding email configuration got trickier. In addition to my parents’ email VM I have my own email hosted elsewhere (along with a whole bunch of other users) and the needs of both systems are different. Sitting down and trying to manage both configurations sensibly forced me to do some rationalisation of the systems, pulling out the commonality and then templating the differences. Additionally I ended up using the lineinfile module to edit the Debian supplied configurations, rather than rolling out my own config files. This helped ensure more common components between systems. There were also a bunch of differences that had grown out of the fact each system was maintained by hand - I had about 4 copies of each Let’s Encrypt certificate rather than just putting one copy in /etc/ssl and pointing everything at that. They weren’t even in the same places on different systems. I unified these sorts of things as I came across them.

Throughout the process of this rationalisation I was able to easily test using containers. I wrote an Ansible role to create systemd-nspawn based containers, doing all of the LVM + debootstrap work required to produce a system which could then be managed by Ansible. I then pointed the same configuration as I was using for the email VM at this container, and could verify at each step along the way that the results were what I expected. It was still a little nerve-racking when I switched over the live email config to be managed by Ansible, but it went without a hitch as hoped.

I still have a lot more configuration to switch to being managed by Ansible, especially on the machines which handle a greater number of services, but it’s already proved extremely useful. To prepare for a jessie to stretch upgrade I fired up a stretch container and pointed the Ansible config at it. Most things just worked and the minor issues I was able to fix up in that instance leaving me confident that the live system could be upgraded smoothly. Or when I want to roll out a new SSH key I can just add it to the Ansible setup, and then kick off an update. No need to worry about whether I’ve updated it everywhere, or correctly removed the old one.

So I’m a convert; things were a bit more difficult by starting with existing machines that I didn’t want too much disruption on, but going forward I’ll be using Ansible to roll out any new machines or services I need, and expect that I’ll find that new deployment to be much easier now I have a firm grasp on the tools available.

Just because you can, doesn't mean you should

Jul 17, 2017 / 0 comments

There was a recent Cryptoparty Belfast event that was aimed at a wider audience than usual; rather than concentrating on how to protect ones self on the internet the 3 speakers concentrated more on why you might want to. As seems to be the way these days I was asked to say a few words about the intersection of technology and the law. I think people were most interested in all the gadgets on show at the end, but I hope they got something out of my talk. It was a very high level overview of some of the issues around the Investigatory Powers Act - if you’re familiar with it then I’m not adding anything new here, just trying to provide some sort of details about why it’s a bad thing from both a technological and a legal perspective.


Going to DebConf 17

Jul 10, 2017 / 0 comments

Going to DebConf17

Completely forgot to mention this earlier in the year, but delighted to say that in just under 4 weeks I’ll be attending DebConf 17 in Montréal. Looking forward to seeing a bunch of fine folk there!


2017-08-04 11:40 DUB -> 13:40 KEF WW853
2017-08-04 15:25 KEF -> 17:00 YUL WW251


2017-08-12 19:50 YUL -> 05:00 KEF WW252
2017-08-13 06:20 KEF -> 09:50 DUB WW852

(Image created using GIMP, fonts-dkg-handwriting and the DebConf17 Artwork.)

Rational thoughts on the GitHub ToS change

Mar 2, 2017 / 0 comments

I woke this morning to Thorsten claiming the new GitHub Terms of Service could require the removal of Free software projects from it. This was followed by joeyh removing everything from github. I hadn’t actually been paying attention, so I went looking for some sort of summary of whether I should be worried and ended up reading the actual ToS instead. TL;DR version: No, I’m not worried and I don’t think you should be either.

First, a disclaimer. I’m not a lawyer. I have some legal training, but none of what I’m about to say is legal advice. If you’re really worried about the changes then you should engage the services of a professional.

The gist of the concerns around GitHub’s changes are that they potentially circumvent any license you have applied to your code, either converting GPL licensed software to BSD style (and thus permitting redistribution of binary forms without source) or making it illegal to host software under certain Free software licenses on GitHub due to being unable to meet the requirements of those licenses as a result of GitHub’s ToS.

My reading of the GitHub changes is that they are driven by a desire to ensure that GitHub are legally covered for the things they need to do with your code in order to run their service. There are sadly too many people who upload code there without a license, meaning that technically no one can do anything with it. Don’t do this people; make sure that any project you put on GitHub has some sort of license attached to it (don’t write your own - it’s highly likely one of Apache/BSD/GPL will suit your needs) so people know whether they can make use of it or not. “I don’t care” is not a valid reason not to do this.

Section D, relating to user generated content, is the one causing the problems. It’s possibly easiest to walk through each subsection in order.

D1 says GitHub don’t take any responsibility for your content; you make it, you’re responsible for it, they’re not accepting any blame for harm your content does nor for anything any member of the public might do with content you’ve put on GitHub. This seems uncontentious.

D2 reaffirms your ownership of any content you create, and requires you to only post 3rd party content to GitHub that you have appropriate rights to. So I can’t, for example, upload a copy of ‘Friday’ by Rebecca Black.

Thorsten has some problems with D3, where GitHub reserve the right to remove content that violates their terms or policies. He argues this could cause issues with licenses that require unmodified source code. This seems to be alarmist, and also applies to any random software mirror. The intent of such licenses is in general to ensure that the pristine source code is clearly separate from 3rd party modifications. Removal of content that infringes GitHub’s T&Cs is not going to cause an issue.

D4 is a license grant to GitHub, and I think forms part of joeyh’s problems with the changes. It affirms the content belongs to the user, but grants rights to GitHub to store and display the content, as well as make copies such as necessary to provide the GitHub service. They explicitly state that no right is granted to sell the content at all or to distribute the content outside of providing the GitHub service.

This term would seem to be the minimum necessary for GitHub to ensure they are allowed to provide code uploaded to them for download, and provide their web interface. If you’ve actually put a Free license on your code then this isn’t necessary, but from GitHub’s point of view I can understand wanting to make it explicit that they need these rights to be granted. I don’t believe it provides a method of subverting the licensing intent of Free software authors.

D5 provides more concern to Thorsten. It seems he believes that the ability to fork code on GitHub provides a mechanism to circumvent copyleft licenses. I don’t agree. The second paragraph of this subsection limits the license granted to the user to be the ability to reproduce the content on GitHub - it does not grant them additional rights to reproduce outside of GitHub. These rights, to my eye, enable the forking and viewing of content within GitHub but say nothing about my rights to check code out and ignore the author’s upstream license.

D6 clarifies that if you submit content to a GitHub repo that features a license you are licensing your contribution under these terms, assuming you have no other agreement in place. This looks to be something that benefits projects on GitHub receiving contributions from users there; it’s an explicit statement that such contributions are under the project license.

D7 confirms the retention of moral rights by the content owner, but states they are waived purely for the purposes of enabling GitHub to provide service, as stated under D4. In particular this right is revocable so in the event they do something you don’t like you can instantly remove all of their rights. Thorsten is more worried about the ability to remove attribution and thus breach CC-BY or some BSD licenses, but GitHub’s whole model is providing attribution for changesets and tracking such changes over time, so it’s hard to understand exactly where the service falls down on ensuring the provenance of content is clear.

There are reasons to be wary of GitHub (they’ve taken a decentralised revision control system and made a business model around being a centralised implementation of it, and they store additional metadata such as PRs that aren’t as easily extracted), but I don’t see any indication that the most recent changes to their Terms of Service are something to worry about. The intent is clearly to provide GitHub with the legal basis they need to provide their service, rather than to provide a means for them to subvert the license intent of any Free software uploaded.

GnuK on the Maple Mini

Feb 7, 2017 / 0 comments

Last weekend, as a result of my addiction to buying random microcontrollers to play with, I received some Maple Minis. I bought the Baite clone direct from AliExpress - so just under £3 each including delivery. Not bad for something that’s USB capable, is based on an ARM and has plenty of IO pins.

I’m not entirely sure what my plan is for the devices, but as a first step I thought I’d look at getting GnuK up and running on it. Only to discover that chopstx already has support for the Maple Mini and it was just a matter of doing a ./configure --vidpid=234b:0000 --target=MAPLE_MINI --enable-factory-reset ; make. I’d hoped to install via the DFU bootloader already on the Mini but ended up making it unhappy so used SWD by following the same steps with OpenOCD as for the FST-01/BusPirate. (SWCLK is D21 and SWDIO is D22 on the Mini). Reset after flashing and the device is detected just fine:

usb 1-1.1: new full-speed USB device number 73 using xhci_hcd
usb 1-1.1: New USB device found, idVendor=234b, idProduct=0000
usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.1: Product: Gnuk Token
usb 1-1.1: Manufacturer: Free Software Initiative of Japan
usb 1-1.1: SerialNumber: FSIJ-1.2.3-87155426

And GPG is happy:

$ gpg --card-status
Reader ...........: 234B:0000:FSIJ-1.2.3-87155426:0
Application ID ...: D276000124010200FFFE871554260000
Version ..........: 2.0
Manufacturer .....: unmanaged S/N range
Serial number ....: 87155426
Name of cardholder: [not set]
Language prefs ...: [not set]
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [not set]
Signature PIN ....: forced
Key attributes ...: rsa2048 rsa2048 rsa2048
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: [none]
Encryption key....: [none]
Authentication key: [none]
General key info..: [none]

While GnuK isn’t the fastest OpenPGP smart card implementation this certainly seems to be one of the cheapest ways to get it up and running. (Plus the fact that chopstx already runs on the Mini provides me with a useful basis for other experimentation.)

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