Category Archive: cloud

Sep 07

Bulk Adding Hosts to a Pi Swarm

I’ve refreshed my stack and am rebuilding the cluster. I’m using Hypriot for the linux distribution, but I’m a smart sysadmin (read lazy) and don’t want to manually add them each time. Also, I want to make a script so that I can quickly rebuild. This is inspired by Let Docker Swarm all over your …

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Apr 21

‘Piping’ Hot Docker Containers

One of the possibly lesser used flags for docker run is -a which allows you to attach the container’s STDIN, STDOUT or STDERR and pipe it back to the shell which invoked the container. This allows you to construct pipelines of commands, just as you can with UNIX processes. For instance, using UNIX commands to …

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Apr 19

Docker Containers: Smaller is not always better

Generally smaller Docker containers are preferred to larger ones. However, a smaller container is not always as performant as a larger one. By using a (slightly) larger container, performance improved over 30x. TL;DR The grep included in busybox is painfully slow. When doing using grep to process lots of data, add a (real) grep to …

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Apr 15

Swarming Raspberry Pi: Private Registry for Swarm Images


Some more backstory on the Pi Swarm I was really excited when Amazon announced their Lambda offering. I thought that it was an awesome idea, but for the lack of an open solution and that it locked you into javascript. I believe that using Docker, we can have a relatively simple Amazon Lambda work-alike which …

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Apr 07

Swarming Raspberry Pi: Of Network Bondage

Apologies to W. Somerset Maugham for the title. For my Cloud in a Box, I want the Data hosts, at the least to have “more” network I/O capability, whether it be for a Docker Registry or other data. (As an aside, I am playing with doing substructure matching of chemical compounds and/or other Cheminformatics with …

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Apr 05

SSD on a Raspberry Pi

As a part of building out the Cloud in a Box, I wanted some storage for Docker images, as well as data. Based upon my previous experience, I believed that a SSD would be faster than a Micro SD, but I hadn’t tested it as yet. The challenge from Dieter Reuter (@Quintus23M), asking how I’d …

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Apr 03

Swarming Raspberry Pi: Docker Swarm Discovery Options

Docker Swarm supports a variety of methods for discovering swarm members. Each has arguments in its favor. In this post I shall discuss the various methods and thoughts regarding each. Background I originally started with the idea of having a portable cluster, a “cloud in a box” if you will, so that I could go …

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Mar 29

Swarming Raspberry Pi, Part 2: Registry & Mirror

This episode will consist of a quick aside to build a Docker Registry Mirror. Previous: Part 1 Why Do We Need a Mirror?? The Docker Registry is, to my mind, one of the greatest contributors to the rapid growth of Docker. Having a central location for images encourages sharing and re-use. Obviously some images are …

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Mar 23

Shrinking Docker Images

Size does matter. Docker images can become quite large as each RUN generates a new layer which becomes part of the image, even if it’s not in the final container. This wastes disk space and network bandwidth. The following are some steps for shrinking the size of a docker container in which builds have been …

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Mar 22

Registrator for Pi: /gliderlabs/registrator ported to Pi

I’ve made a port of gliderlabs/registrator to the raspberry pi. The repository for the Pi port is at: nimblestratus/registrator. At first glance, the part I find most interesting is the size of the resulting image — ~12M. I firmly believe it’s a direct result of starting from Alpine Linux. This will definitely warrant further investigation. …

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