Category Archives: IT

A story of a web server installation

A recent interaction with AWS support reminded me of something that happened to me and a co-worker some years ago in a previous job. The people and companies in the story have been anonymized, but I’m “Eric”. I (“Eric”) worked … Continue reading

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AccessDeniedException: Access to KMS is not allowed

So that happened. And I spent much longer than should’ve been necessary to figure it out. What I was trying to do was this: Create a symmetric AWS KMS CMK Use that to generate a couple of asymmetric key pairs … Continue reading

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Explicit workspaces for Terraform

NOTE 2019-06-26: The original way this check worked with Terraform 11 no longer works with Terraform 12, as v12 checks that attribute names are valid. The code has been updated accordingly. Instead of a null resource, we now use a … Continue reading

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Elastic Beanstalk applications using two ports and Websockets

This blog post describes how to set up and deploy an AWS Elastic Beanstalk application written in Node.js that listens to both regular HTTP requests and Websocket connections. TL;DR: Download the sample application, and deploy it into an EB environment … Continue reading

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Useful paths for debugging Elastic Beanstalk deployments

Sometimes it can be painful to try and get an Elastic Beanstalk application to deploy cleanly. In order to effectively debug the issues, it’s necessary to SSH into the instance. This requires that you’ve added a Key Pair in the … Continue reading

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Setting up a Raspberry Pi from scratch

Getting started with a Raspberry Pi is basically really easy: All you need to do is get a disk image and burn it to an SD card. But of course, that’s just the very basic starting point. Theres’s plenty of … Continue reading

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Forwarding SSH keys to a Vagrant box

Scenario: A new Linux box has been installed with Vagrant, and now I must git clone a non-open repository to the server, so I need to forward my SSH keys to the root user on the virtual server. 1) Add … Continue reading

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Filtering out outliers in Arduino ultrasonic distance sensor data

A friend of mine asked me how he could remove invalid data points from the measurements made by the ultrasonic range finder in his Arduino project. A quick search got me to this page, but some of the links were … Continue reading

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Nginx as origin for S3 with authentication, with CDN on top

We recently had a small problem with our content delivery system. The setup is as follows: – AWS S3 bucket that requires authentication – EC2 instance, running Nginx with ngx_aws_auth – ELB load balancer in front of the EC2 instance … Continue reading

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Nginx: Reject request if header is not present

It was surprisingly difficult to find a full working example of this, so here’s my take on “How to make Nginx require that a certain header is present with a certain value in the incoming request”: nginx.conf: http { map … Continue reading

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