six demon bag

Wind, fire, all that kind of thing!


Generate a Solr Password Hash With a Shell Script

In 2017 I published a small Java utility for generating Solr password hashes, because I didn't like launching Solr with well-known credentials. I would've preferred doing it with just a shell script, but found myself unable to replicate the hash creation process with sha256sum.

A couple days ago user rmalchow contacted me on Github with a solution for that, which I want to share here.

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Posted 15:28 [permalink]


Generate a Solr Password Hash

Recent versions of Solr allow restricting access via authentication and authorization plugins, for instance the basic authentication plugin. The documentation shows an example security.json that you can upload into Zookeeper (assuming that you're running SolrCloud).

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Posted 22:15 [permalink]


Forwarding JVM Garbage Collector Logs

Recently I was tasked with forwarding logs to a central log server - in this case JVM garbage collector logs from Solr instances. Normally not a big deal. Configure log rotation (to avoid filling the disk), then have rsyslog read the active log file via an imfile input.

Sounds simple, right? Until you realize that JVM log rotation marks the active log with the extension .current and rotates that extension instead of actually rotating the logs.

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Posted 23:23 [permalink]


Spark Workers Not Starting

If you're using Apache Spark and run into an issue where your workers fail to start, make sure that the workers use the same SPARK_MASTER_IP value that was used when starting the master. You can see it in the top left corner of the master's web interface:

URL field in Spark web interface

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Posted 21:37 [permalink]


VBSdoc - A VBScript API Documentation Generator

API documentation is nice, and being able to generate it from the code is even nicer. However, unlike Perl, Python, Java, or several other languages, VBScript doesn't have a feature or tool that supports this. Which kinda sucks.

I tried VBDOX, but didn't find usability or results too convincing. I also tried doxygen by adapting Basti Grembowietz' Visual Basic doxygen filter. However, doxygen does a lot of things I don't actually need, and I didn't manage to make it do some of the things I do need. Thus I ended up writing my own VBScript documentation generator.

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Posted 16:31 [permalink]


3D Simulation

Back in college, one of my software engineering classes was a project to develop a simple 3D engine without resorting to existing 3D routines. The implementation of my group was done in Java, because that way it was rather easy to implement the GUI, and the requirements were simple enough to be met by contemporary hardware. It's probably not really helpful to anyone, but it was fun to do, so I'm posting it anyway.

Run simulation
Project report (PDF, 307 kB, in German language)
Source code (Zip archive, 293 kB)

Posted 18:47 [permalink]