Category Archive: Docker

Sep 07

Getting the Docker Swarm Discovery Token

At the moment, docker swarm doesn’t have a self-discovery method. If you’ve mislaid or forgotten the discovery token you can’t add new elements. It just so happens that if you do a docker inspect $SWARM_AGENT_MASTER, the token will show up in the command line arguments.

Continue reading »

Apr 28

Heterogenous Docker Swarms Teaser

Note: This is all very experimental; Docker does not support any architecture other than X86_64. The last few evenings I’ve been working on Mulitifarious, a means of creating heterogenous Docker Swarms. I’d previously found that I can create a swarm with heterogenous members — a swarm which has, say, X86_64 and Raspberry Pi members. The …

Continue reading »

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 …

Continue reading »

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 …

Continue reading »

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 …

Continue reading »

Apr 14

Good Practices for Configuring Docker Private Registries

Private registries can be very helpful when using Docker — particularly if you’re wanting to be able to share code locally without either making it public or incurring the cost of a round trip. This post presents some practices which I think make life easier when using a Private Registry. Where to look Docker recognizes …

Continue reading »

Apr 12

Docker Workers Scale Nicely with Multiple Cores

Disclaimer: The title might be a bit misleading. For this workload, it’s scaling pretty much linearly. Other workloads might scale differently. I was running a quick-ish test on a Pi to see how long it would take to churn through 50GB compressed data. This processing consists of: Determining the files to be processed — this …

Continue reading »

Apr 12

Docker Commandline Arguments are Context Sensitive

TL;DR: Position of the commandline arguments matter. `-v` before `run` means something totally different than `-v` *after* `run`. More details below the link.

Apr 06

Why it’s Important to use TLS with Docker Swarm

There is nothing wrong with your docker host. Do not attempt to adjust the picture. We are controlling transmission. If we wish to make it louder, we will bring up the volume. If we wish to make it softer, we will tune it to a whisper. We will control the horizontal. We will control the …

Continue reading »

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 …

Continue reading »

Older posts «

» Newer posts