mikal – Page 10 – Made by Mikal

Turnover of Companies in OpenStack: Prevalence and Rationale

Post author:mikal
Post published:June 14, 2023
Post category:OpenStack

This paper examines the withdrawal behaviour of corporate contributors to OpenStack, which seems particularly relevant given most contributions in OpenStack are corporately supported, and corporate engagement is declining over time. Its also directly relevant to my own experiences contributing to the project, so seemed like a thing I should read. One interesting aspect of the study is how they define withdrawal from contributions. For each company, they calculate an individual frequency of contribution, and then use that to determine if the company is still making contributions. That is, of a company only ever contributed once a year, we must wait at least a year to know that they have indeed stopped contributing. The paper finds that in more recent OpenStack releases, more companies are leaving contributions than joining. The authors assert that in general engaged developers are now less experienced than previously, which presents risks in terms of developer effectiveness as well as code quality. However, the paper does note that companies with smaller contributions are more likely to disengage than "sustaining companies", however that's largely because there are a huge number of companies contributing only one developer who makes a small number of commits. Unsurprisingly, the paper notes that…

On-demand Container Loading in AWS Lambda

Post author:mikal
Post published:June 9, 2023
Post category:AWS

My team at work now has a daily personal learning time called “egg time” — its a slightly silly story involving a manager who was good at taking some time to learn things each day, and an egg shaped chair.

Today I decided that I should read this paper about container image loading in AWS lambda, as recommended by Robert Collins on LinkedIn. The paper details the work they had to do to transition from all Lambda functions being packaged as relatively small zip files (250mb), to relatively large Docker containers (10gb+) while maintaining their aggressive target cold-start time of 50ms.

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Holman CLXRGB60 RGB WiFi garden light controllers and tasmota

Post author:mikal
Post published:March 25, 2023
Post category:Electronics

Today I went forth to Bunnings in the rain to purchase a Holman CLXRGB60 RGB garden light controller so that I too could have fancy lighting in my garden and impress all those guests I never have over. I had been given hope by the Blakadder site that I would be able to flash tasmota onto the controller so it integrated with my Home Assistant home automation. Unfortunately, it was not to be. Despite the device being TYWE3L based, the warning on the blakaddr site was correct, and this is a next-gen Tuya device where the crypto hasn't been broken yet. Then again, I couldn't even get this device to pair in the Holman app, so it clearly hates me. This unfortunately means the excellent instructions from Jon Oxer were unforunately not helpful today. I think there is a theoretical option here to flash using the serial pins on the board, ala this guide. Also, it means my hair got wet for nothing. So as to take revenge for my wet hair I have decided to pivot. The Holman lights seem quite well made, but they're just 12 volt RGB PWM devices. So I can use their lights and build…

Minor questions in Linux file semantics

Post author:mikal
Post published:March 23, 2023
Post category:Linux

I’ve known for a long time that if you delete a file on Unix / Linux but that file is open somewhere, the blocks used by the file aren’t freed until that user closes the file (or is terminated), but I was left wondering about some other edge cases.

Shaken Fist has a distributed blob store. It also has a cache of images that virtual machines are using. If the blob store and the image cache are on the same filesystem, sometimes the image cache entry can be a hard link to an entry in the blob store (for example, if the entry in the blob store doesn’t need to be transcoded before use by the virtual machine). However, if they are on different file systems, I instead use a symbolic link.

This raises questions — what happens if you rename a file which is open for writing in a program? What happens if you change a symbolic link to point somewhere else while it is open? I suspect in both cases the right thing happens, but I decided I should test these theories out.

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Malware Analyst’s Cookbook and DVD

Post author:mikal
Post published:March 19, 2023
Post category:Book

Another technical book, this time because my employer lets me buy random technical books as long as I pinky swear to read them and this one sounded interesting and got good reviews. First off, the book is a bit dated given its from 2011 -- there are lots of references to Ubuntu 10.10 for example and they say to avoid Python 3, which has its historical charm. This is unfortunate given the first section of the book talks about setting up honeypots to collect malware to examine, but Dionaea for example had its last commit in 2021. I am left wondering if there are more modern honey pot systems that people use these days. Secondly the book is definitely a cookbook and that's on me for not noticing this about the book before buying it -- its a series of recipes / scripts that do interesting things with malware. That said, it isn't really teaching a cohesive set of skills, its more of a series of stepping stones along the path you might follow. I think that's an unintended piece of important learning -- books with "cookbook" or "recipes" in their title probably aren't very good as an overview of…

The BeyondCorp papers

Post author:mikal
Post published:March 15, 2023
Post category:Security Zero Trust

Google’s BeyondCorp effort would probably be what we would now call Zero Trust, although I am surprised by how little name recognition BeyondCorp has when I talk to security people about Zero Trust. Perhaps there are subtle differences between the two, but if there are they aren’t obvious to me. I find myself reading the relevant Usenix papers for BeyondCorp, so I figure I’ll post a summary of what I got from each paper here.

The earliest of these papers are quite old now (2014), especially for something the rest of the industry is only starting to talk a lot about at the moment. I wonder if there is a viable business model in watching what papers megacorps like Google publish, and the implementing them as commercialized products before the rest of the market catches on?

Either way, here’s a summary of the various papers from the perspective of an interested bystander…

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Cisco CyberOps Associate: Official Cert Guide

Post author:mikal
Post published:February 27, 2023
Post category:Book Security

I don't think I've really reviewed a technical book here before, but I read the thing so I guess I should. This book is the certification guide for a "Cisco CyberOps Associate" certification, which is what they now call the CCNA Security qualification. Its a relatively junior certification, qualifying you to be a level one operator in a Security Operations Centre (SOC). I read this book because I took a Cisco NetAcad course for the associated certification in the second half of 2022 (although it has continued to be a thing I plug away at in 2023). That was mainly motivated by a desire to more about a field that is clearly important, but hasn't been core to my personal career. This book is reasonably well written and readable -- I'd read a chapter in the evening after work and its wasn't a huge chore to churn though. I certainly learned things along the way, even if the certification seems to suffer from a desire to have everyone rote learn a lot of acronyms, which seems like a common ailment in the industry (AWS Certified Cloud Practitioner, I'm looking at you). My main critism is of the qualification itself, which…

Exploring more efficient remote large file storage

Post author:mikal
Post published:February 16, 2023
Post category:Shaken Fist

My primary personal project is a thing called Shaken Fist these days — it is an infrastructure as a service cloud akin to OpenStack Compute, but smaller and simpler. Shaken Fist doesn’t have an equivalent to the OpenStack Image service, instead letting your describe your instance images by a standard URL. One of the things Shaken Fist does to be easier to use is it maintains an official repository of common images, which allows users to refer to those images with a shorthand syntax instead of a complete URL. The images also contain small customizations (mainly including the Shaken Fist in-guest agent), which means I can’t just use the official upstream cloud images like OpenStack does.

The images were stored at DreamHost until this week, when a robot decided that they looked like offline backups, despite being served to the Internet via HTTP and being used regularly (although admittedly not frequently). DreamHost unilaterally decided to delete the web site, so now I am looking for new image hosting services, and thinking about better ways to build an image store.

(Oh, and recommending to anyone who asks that they consider using someone less capricious than DreamHost for their hosting needs).

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This is going to hurt

Post author:mikal
Post published:February 13, 2023
Post category:Book

This book is lots of things: honest, funny, and ultimately heart breaking. I don't remember how I came across it, but its a good read for when travelling as the diary format means you can put it down whenever you need to do something else. I'm left wondering how the Australian medical system compares to the NHS -- I know we have more patient choice and flexibility -- but I wonder what its like for those working within the system. Either way I definitely recommend this book.

Ansible 7.0 onwards requires blocking IO from stdin, stdout, and stderr

Post author:mikal
Post published:November 24, 2022
Post category:Ansible

Shaken Fist CI started failing this afternoon with this message logged: ERROR: Ansible requires blocking IO on stdin/stdout/stderr. Non-blocking file handles detected: <stdout> Specifically this was happening when using ansible-galaxy to install some requirements, but the check is a more generic check than that was implemented by this ansible pull request, which appears to have been released with ansible-core 2.14 on November 8. That sat around until today, when ansible 7.0.0 was released and broke CI for me. To be completely honest I'm not sure what's happening here -- somewhere in GitHub actions calling a shell script that calls ansible-galaxy the stdout file descriptor gets set to non-blocking and everything breaks. I'm unsure exactly where because its a pain to track down. That said, Jack came to the rescue with this gem: ansible-galaxy install andrewrothstein.etcd-cluster | cat - Which unblocks me. It will be interesting to see if other people encounter problems with this change.