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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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!

From AWS instance IDs to private DNS names

github-logoJust a small bash snippet for those cases where, for example, a command returns AWS instance IDs but not the matching DNS names or an IP addresses. The function id2dns, that you can add to your .bashrc file, will do the translation for you. In order to use the function you will:

  • ensure you have the aws CLI installed and functional;
  • ensure you have jq command available;
  • ensure you have valid AWS credentials set, so that your aws CLI will work.


Update 2020-08-14: jq not needed any more


Creating and terminating test instances in AWS quickly

This is mostly a note to self. When I need an EC2 instance to run a quick test, it may be overly annoying to provision one through the web console, or it may feel a bit overkill to do that using large frameworks like terraform. Using the AWS command line is just fine, if you know what command to run with which parameters, and it pays off quickly if, to run your tests, you use the settings often (AMI, subnet, security groups…) or if during the same test session¬† you need to scrap and rebuild test instances a few times. Here is an example on how to do so with the AWS command line client.

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How cheap is cheap?

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.

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Building a simple, resilient, cheap network service with AWS

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.

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