A public inbox S3 bucket

A few weeks ago I found myself in need of a a place where I could share public encryption keys with others for a side project of mine. As the adjective public implies, there is nothing secret about public keys: they can be shared in the open safely, so that was not a concern. The problem was to find a convenient way to do that. More precisely, I needed a place where I could share certain public keys with everyone, and where anyone could put their public keys to share them with me, and with me only.

In the end, I turned to AWS S3 as it is a natural place to look at when it comes to file storage and sharing. But it took a lot of trial and error before I was actually able to find an appropriate configuration for the bucket. I also put some automation with terraform into the mix, both because I prefer to automate things that I may have to do several times, and because it turned out that I’ll have to bring this inbox of mine up and down at need. The outcome is a terraform module that I have just published on github.

Sounds interesting? Read on!

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Name/address resolution from the perspective of the OS

TL;DR: I put together a Perl script that does name/address resolution from the perspective of the OS instead of relying solely on the DNS like the dig or host commands. If this makes sense and sounds useful, just go check out my resolve-pl repository on github. If it doesn’t fully make sense, then read on.

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Automating installation/updates of the AWS CLI on Linux

Are you annoyed that there are no native Linux packages for the AWS CLI (deb, rpm…)? And, thus, no repositories? I am, a bit.

But it’s also true that the installation is not difficult at all, right? Well, yes, if you want to install it in locations different than the defaults (e.g. your user’s home directory) and on more than one machine you still have to do some work, but it’s not terrible, is it?

Then, one day, you find that one of the AWS CLI commands you need to use was added in a newer version than the one you are running, so you have to update the AWS CLI on all machines, and possibly rediscover the parameters you used during the initial installation. Are you happy with that?

I am not, and I decided to do something to automate the process: a Makefile, the simplest form of automation you can have on UNIX systems. Here you go: aws-cli-manager on github.

If you find it useful, I am happy. And if you want to support more Linux distributions or more operating systems (MacOS should be fairly easy, I expect), just go ahead and throw me a pull request. Enjoy!

An update to cf-keycrypt

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.

cf-deploy v4 released

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!

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A multi-platform API client in Go

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.

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cf-deploy v2 released

Update: this article refers to the third version of cf-deploy. For the latest release, check the github repository.


Errata corrige: it’s actually v3! This is what happens when you don’t publish updates for your software for too long…


github-logo I took some time this weekend to release an update for cf-deploy. You have now the option to override the configuration hardcoded in the script by means of environment variables. Check the README for the details.

If you don’t know what cf-deploy is, that’s fair 😉 In two words, it’s a Makefile and a Perl front-end to it that makes it easier to pack together a set of files for a configuration management tools and send them to a distribution server. Designed with git and CFEngine in mind, it’s general enough that you can easily adapt it to any version control system and any configuration management tool by simply modifying the Makefile. If it sounds interesting, you are welcome to read Git repository and deployment procedures for CFEngine policies on this same blog. Enjoy!

 

cfengine-tap now on GitHub

github-logo Back from the holiday season, I have finally found the time to publish a small library on GitHub. It’s called cfengine-tap and can help you writing TAP-compatible tests for your CFEngine policies.

TAP is the test anything protocol. It is a simple text format that test scripts can use to print out the results and test suites can consume. Originally born in the Perl world, it is now supported in many other languages.

Using this library it’s easier to write test suites for your CFEngine policies. Since it’s publicly available on GitHub and published under a GPL license, you are free to use it and welcome to contribute and make it better (please do).

Enjoy!

An init system in a Docker container

DockerHere’s another quick post about docker, sorry again if it will come out a bit raw.

In my previous post I talked about my first experiments with docker. There was a number of unanswered questions at first, which got an answer through updates to the blog post during the following days. All but one. When talking about a containerized process that needs to log through syslog to an external server, the post concluded:

if the dockerized process itself needs to communicate with a syslog service “on board”, this may not be enough…

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systemd unit files for CFEngine

systemd logoLearning more of systemd has been on my agenda since the release of Debian 8 “Jessie”. With the new year I decided that I had procrastinated enough, I made a plan and started to study according to the plan. Today it was time for action: to verify my understanding of the documentation I read up to now, I decided to put together unit files for CFEngine. It was an almost complete success and the result is now on GitHub for everyone to enjoy. I would appreciate if you’d give them a shot and report back.

Main goals achieved:

  1. I successfully created three service unit files, one for each of CFEngine’s daemons: cf-serverd, cf-execd and cf-monitord; the units are designed so that if any of the daemon is killed for any reason, systemd will bring it back immediately.
  2. I successfully created a target unit file that puts together the three service units. When the cfengine3 target is started, the three daemons are requested to start; when the cfengine3 target is stopped, the three daemons are stopped. The cfengine3 target completely replaces the init script functionality.

Goal not achieved: I’ve given a shot at socket activation, so that the activation of cf-serverd was delayed until a connection was initiated to port 5308/TCP. That didn’t work properly: systemd tried to start cf-serverd but it died immediately, and systemd tried and tried again until it was too much. I’ll have to investigate if cf-serverd needs to support socket activation explicitly or if I was doing something wrong. The socket unit is not part of the distribution on GitHub but its content are reported here below. In case you spot any problem please let me know.

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