Category Archive: Computers

Feb 11

Docker: Could not find container for entity id

I had an instance where the docker filesystem ran out of space. After cleaning up with docker rm and docker rmi, I got:

I followed iwidanalage‘s suggestion from “Creating fail with Could not find container for entity id after upgrading to 1.9.0 · Issue #17691 · docker/docker”

After this, it worked.

Jan 28

Cloudera Manager, Embedded DB and Docker

If you ever see a message like:

on startup and the Cloudera manager won’t start, it’s because you did not start the container in privileged mode:

Oct 09

Mounting Partitions from Image Files on Linux

I’ve been working with disk images from the excellent crew from Hypriot and there are times when I wish to mount the filesystems within to inspect and or make alterations to them. Since there are multiple filesystems, it’s not like mounting an ISO image — there’s more work which needs to be done. Being a …

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Oct 08

Solving File Filtering Problems with this One Weird Trick

One Weird Trick

I was asked an interesting question — how to create a regular expression which would allow a user to specify an arbitrary case insensitive series of strings, all of which must be on a line, as well as a series of strings which must not be on a line in order to filter logs. In …

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Oct 06

Ruby Enumerables ‘with_index’

Ruby’s Enumerable module provides a couple of methods for stepping through an enumerable with the index of the element as well. However, a couple are missing — there is no inject_with_index or map_with_index. There are a couple of ways of remedying this.

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Oct 06

Just because I Koan

"Rubin, biotyt, Ihosy, Madagaskar". Licensed under CC BY-SA 3.0 via Wikimedia Commons.

If you have some ice cream, I will give it to you. If you have no ice cream, I will take it away from you. It is an ice cream koan. Ruby Metakoans In software, koans are a form of kata, or practice. There are a number of these; one of the first I’d encountered …

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Sep 30

From the vaults…. on Parentheses

To paren, or not to paren: that is the question: Whether ’tis nobler in the mind to suffer The bugs and errors of maintenance programs, Or to take arms against a host of typos, And by debugging end them? To hack: to slash; No more; and by a slash to say we end The heart-ache …

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Sep 21

F5 LTM Monitoring and Wildfly

TL;DR The F5 BigPipe LTM uses HTTP/0.9 to send its HTTP monitoring requests by default. Wildfly 9.0 does not like this; moving to a monitor request of HTTP/1.1 fixed the problem. Caution: LTM 10.2.x and 11.x do not append a CR/LF to the end unless you are using Basic Authentication. This is contrary to previous …

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Sep 18

OBS for Videos

I recently discovered a really interesting tool for producing videos of screen captures, optionally with webcam inserts. It’s called Open Broadcaster Software and it works on Linux, Windows, and there is a beta version for Apple OSX. It seems that it was originally intended for streaming to websites, but it has a lot more features …

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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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