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.
Category Archive: Docker
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 …
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 …
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 …
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 …
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 …
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 …
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 …
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 …
