I have published a small update to cf-keycrypt, so that it’s now easier to compile the tool on Debian systems and it’s compatible with CFEngine 3.15. You can find it here.
For those who don’t know the tool, I’ll try to explain what it is in a few words. The communication between CFEngine agents on clients and the CFEngine server process on a policy hub is encrypted. The key pairs used to encrypt/decrypt the communication are created on each node, usually at installation time or manually with a specific command. cf-keycrypt is a tool that takes advantage of those keys to encrypt and decrypt files, so that they are readable only on the nodes that are supposed to use them. The fact that the keys are created on the nodes themselves eliminates the need to distribute the keys securely.
cf-keycrypt was created years ago by Jon Henrik Bjørnstad, one of the founders of CFEngine (the company). The code has finally landed the CFEngine core sources as cf-secret, but it’s not part of the current stable releases. I had an hard time trying to compile it, but I made it with good help from the CFEngine help mailing list. I decided to give the help back to the community, publishing my updates and opening a pull request to the original code. Until it’s merged, if it ever will, you can find my fork on my github.
After five years after the release of cf-deploy v3, I have just released cf-deploy v4. This version of cf-deploy fixes a number of shortcomings that made their way up to this point and that I wasn’t able to see until recently. It is now more flexible and easier to configure than it ever was. In particular, the documentation is way more comprehensive, covering installation, configuration and usage. The documentation also covers some of the internals, that will allow the hardcore user to fine tune the tool to better suit their needs.
You will find cf-deploy on github, as always. Enjoy!
Recently, while testing a configuration of Linux on a Lenovo laptop, I messed up. I had rebooted the laptop and there were some leftovers around from an attempted installation of the proprietary Nvidia driver. The system booted fine and was functional, but those leftovers where enough to make the screen go blank. The fix is easy, if you can enter the system in some other way: log in and remove anything related to the Nvidia driver. But unfortunately the only way to log in was from the console, so I was “de facto” locked out.
The first attempt to get out of the mud was to force a reboot of the system and in rescue mode. The system booted well, but after I typed the root password the boot process went a bit too far, loaded the infamous leftovers of the driver and here we go again, with a blank screen.
This article is about using configuration management to install software on your own computers (e.g. your laptops, or the computers used by your family and relatives) and how the complexity of this task is easy to overlook, no matter if you are a newbie or an expert.
If you already know about configuration management and how it makes sense to use it at a small scale like, again, your own computers or your family’s, you can just skip at the section “New job, new setup”.
If you already know about configuration management and you are asking yourself why it should make sense to use it at a small scale, I suggest that you start a section earlier, at Personal configuration management”.
If you are new to configuration management, or you wonder what could be difficult in installing software on a set of systems, I suggest that you read the whole article.
In any case, happy reading!
Having recently started to work for Riks TV, I got a new laptop to install with my favourite Linux distribution: Debian. The laptop is a Lenovo ThinkPad P1 Gen2. It’s a very nice laptop, quite powerful and fast, with a large screen and way lighter than the Lenovos I have owned before through my previous employers (Opera Software and Telenor Digital).
That’s all great, but on the other hand my previous story with Lenovo laptops has never been problem-free, and I was sure this one was no exception. Alas, I was right. So I decided to write a few notes about the installation, for myself and for anyone who wants to install Debian on this laptop. These won’t be detailed, walk-through installation instructions, but more of a high-level checklists.
Last month I wrote a new post, namely: Building a simple, resilient, cheap network service with AWS. Now that AWS’ billing cycle for November is complete we can ask ourselves how cheap was that “cheap” in the article, and give an answer. The cost is not exact to the cent, due to the presence of a a stopped instance I am keeping around, but will still be good enough.
To summarise, the article described how to set up a service on spot instances, thus saving on the EC2 cost. We want to understand if we really saved money, and if there are opportunities to save even more. If you haven’t read the previous post, it’s probably a good time to do it now. If you did, let’s go and check the bill.
In this post I’ll describe how I put together a number of pieces of information about AWS features to experiment with an idea. It’s nothing advanced, rather: it’s what happens when you are studying on something and you start seeing the possibilities. Don’t expect rocket science then, it’s more like a handful of notes I made in the hope they may be useful to more people than just myself.
Being an experiment where I was supposed to learn how to do things, it’s a manual set-up. Automation will follow, and in my case , it will be Terraform, but not in this post.
In the last few months I have been working, together with a colleague, on an API client for several well-known systems and cloud providers. When we started, I was a novice in the Go programming language, I had no experience in programming API clients, and I trusted the makers of the APIs enough to have great expectations at them.
Today, a few months later, several hours programming later and a bunch of lines of code later, I am a better novice Go programmer, I have some experience in interfacing with APIs, and my level of trust in the API makers is well beneath my feet.
This article will be a not-so-short summary of the reasons why we started this journey and all the unexpected bad surprises we got along the way. Unfortunately, I will be able to show only snippets of the code we have written because I didn’t get the authorisation to make it public. I will make the effort to ensure that the snippets are good enough to help you get a better understanding of the topics.
OK, enough preface. It’s time to tell the story.
Days ago I came across an article from the series “The long read” of The Guardian. The article, titled “Crash: how computers are setting us up for disaster” analyzes the downsides of overly reliance on computer-controlled systems and automation in general. It’s an incredibly well written essay and I wanted to contribute my own two cents to the topic.
This is not an article about how you can work with JSON in Go: you can easily learn that from the articles and web pages in the bibliography. Rather, this post is about the concepts that you must understand clearly before you set yourself for the task. Don’t sweat, it’s just two concepts two, and I’ve tried to explain them here.
In the last few weeks I have worked together with a colleague to write some automation with Golang and the Atlassian Crowd API. With several separate user databases (and, at the current state, no hope to unify them in a smart way) it would be very handy to take advantage of the APIs offered by, say, G Suite to fetch all the email addresses related to a user and use that information to automatically deactivate that user from all systems.
Coming from a Perl 5 background, I was hoping that decoding and encoding JSON in Go was as simple as it is in Perl. But it turns out that it wasn’t, and it’s obvious if you think about it: as Perl 5 is weakly typed, decoding any typed data into an “agnostic” data structure must be simple. Encoding a weakly typed data structure into a typed format may be a bit trickier, but as long as you don’t have too many fancy data (i.e., in this context: strings made of only digits or non-obvious boolean representations) this will also work well. But with strongly typed Go and struct field names having side effects depending on upper-/lowercase, that’s a different story.
As it often happens in cases like this, you will not find all the information you need in a single place. This is my attempt to collect it all and hand it to you, so that you won’t have to waste as much time as I did. You will still have to read through stuff though.