Category Archive: gotchas

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 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 07

Cron the Eater of (CPU) Time

Note: This behaviour was observed on a Pi B+; it was not observed on a Pi 2. I happened to have top up while doing the bonded Nic test and noticed that the load was awfully high. Then the following popped up: Cron pretty much has the CPU pegged. Once I saw this, I wondered …

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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 …

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Jan 13

It’s a Trap: Losing Faith in Protex

Protex snippet match does not behave as expected.

Jan 12

Part of what makes Open Source analysis “interesting”

You unlock this door with the key of imagination. Beyond it is another dimension: a dimension of sound, a dimension of sight, a dimension of mind. You’re moving into a land of both shadow and substance, of things and ideas. You’ve just crossed over into… the Open Source Zone. — Not Rod Serling Consider a …

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Jan 02

How to make Ubuntu Snappy no longer snappy

In wishing to test my Snappy Swarm — scripts to run Docker Swarm under Ubuntu Snappy (work in progress, but almost ready for a release) — I decided to try running the scripts inside a Virtualbox instance spawned by Vagrant. kvm doesn’t work inside virtualbox, so qemu was the way to go. I’m modifying the …

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Sep 16

Docker Volumes Quirk

When specifying volume paths in a Docker run command, extra slashes can cause things not to work properly.

Jul 27

Using Openstack/Devstack Floating IPs from outside

I hope that this is of use to someone. After many hours of tearing down, building up, programming routers, etc., I’ve figured out why my devstack wasn’t allowing access from floating ips. I knew that the address was resolving (arp -a); I just couldn’t ssh to it (or do anything else with it) It was …

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Jun 22

cygwin and torquebox and rvm, oh my!

rvm, despite being wonderful, doesn’t play very well with torquebox under cygwin. In particular, the gem paths are not working. So, in order to fix this, simply do: rvm use system And then it will work right. Once you’re done with the torquebox work, you can go back to using rvm.

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