Refreshing SSH known hosts after reinstall
Clearing outdated SSH host keys after rebuilding a server so you can reconnect cleanly.
Johbo's Notes - Working on the Web
Latest posts
Using Emacs batch mode in Spacemacs
Generating presentations from Org files is very useful, this note lists how to use Emacs' batch mode to render the presentation from the command line.
A simple DNS server for development and testing in Kubernetes
Using CoreDNS as a easy to deploy DNS server to host custom domains for development and testing purposes.
Running a local nameserver for the .test domain on MacOS
Running a local dns server is useful to assign domain names for testing purposes. This note is about running dnsmasq on MacOS.
Using a local nameserver for the .test domain on MacOS
How to redirect DNS queries for the domain ".test" to a local DNS server like dnsmasq.
Customized image in Kubernetes
Using a locally built image in Kubernetes during development
Flashing an image to USB drive on MacOS
Flashing an ISO image to an external drive like a USB stick or an SDCard is a common way to get up and running with a new system. The "classic" way of burning this to a CD-ROM is not really in use anymore. Still, many projects do provide images as …
Virtual Conferences - Thoughts after Lead Dev Live Summer 2020
A wrap up of my thoughts around the concept of virtual conferences including first conclusions from comparing to on-site conferences.
Using Nix in Docker to build Sphinx documents
Building PDF documents via Sphinx depends of LaTeX being available, this resulted in quite heavy container images which took also very long to build. Out of curiosity I tested to build a minimal Texlive environment based on Nix and got surprisingly nice results, both the image size and the build time dropped significantly.
Run a command with extra packages available
Small snippet how to run a command with a few extra dependencies inside of the environment in an ad-hoc fashion.
Building a NixOS image for VirtualBox
NixOS allows to easily build images of a machine configuration. This post shows in an example how to build a more recent version of the base image which NixOPS uses to spin off Virtualbox based machines. The idea should be applicable to all kinds of machine configurations.
Minikube setup on macOS
Installation of minikube on OSX via Nix.
NixOPS Defaults
Quick note about the attribute "defaults" in a NixOPS network description.
NixCon 2017 - Wrap Up
My personal review of NixCon 2017 in Munich. It's about topics I discussed, people I did meet, experiences I made and a few thoughts which I took with me.
Building a NixOS container from macOS
When experimenting with NixOS containers, it is sometimes quite nice to just build the container derivation and inspect the result. Being able to use the remote building features makes this even more convenient.
NixCon 2017 - Hackathon Day 2
Wrap up of the second hackathon day after NixCon 2017.
Nixpkgs library discovery: remove
A quick example about how to use the library function remove to adjust a package's dependencies based on a given condition.
Remote building
Quick note about the needed bits to get remote building for Nix into a working state on OSX.
NixCon 2017 - Hackathon Day 1
Wrap up of the first hackathon day after NixCon 2017.
Loading a text dump into PostgreSQL
Just got a plain SQL dump of a database and in this case pg_restore does not work. This post shows how to use psql to load such a dump into a database in the context of a local development environment.
Reproducible Development Environments with Nix
Export of the slides from my talk at PyConWEB 2017 about using Nix the purely functional package manager to get reproducible development environments.
NixOPS Container
Slide content plus my notes from the talk "Deep Dive into NixOPS' Container Backend" which a gave at a NixOS Meetup in Munich.
Presentations with Org-mode
Notes from first experiments using org-reveal to create presentations from Org files. The rendered presentations are based on reveal.js.
First steps using GPGSuite
Notes about starting out with GPGSuite on OSX to get a working GnuPG integration with Apple's Mail application. Had to tweak things slightly to use the GnuPG installation from Nix.
On demand Redis service for your development environment
Howto start a Redis service ad-hoc thanks to nix-shell.
On demand PostgreSQL for your development environment
A quick way how to run PostgreSQL in your development environment without any upfront setup work.
Archive multiple headlines in Org Mode
Org's agenda view allows to perform bulk actions on a set of nodes from the outline. This post shows how to use it based on the example of bulk archiving a few tasks.
How to revert a merge commit in Git
Undoing a merge in Git can be a bit tricky and cause unintended side-effects. This is a small wrap up of the most important bits to keep in mind.
NixOS Klinik - Hacking in November
Notes from the NixOS-Meetup in November 2016 in Berlin, focusing on pip2nix and pypi2nix.
#Nix geht mehr!
My personal collection of Nix related jokes in German. Can't help myself, I still like those ;)
Spacemacs layer: elfeed
elfeed is an integrated RSS reader for Emacs which also comes as a ready made configuration layer for Spacemacs. The list of feeds can be managed in Org files.
Dump HTTP headers via cURL
Useful command line examples to inspect the headers in HTTP responses, using the command line utility cURL.
Update your node-env.nix for recent nixpkgs
Quick hints on getting your node2nix based environment updated for recent versions of nixpkgs.
Python development with Nix - an update
Review on using Nix to manage development environments for Python projects.
Spacemacs layer: imenu-list
Every now and then I am presenting one layer of Spacemacs which I find useful. This time I am writing about imenu-list which allows to have a nice outline of your current buffer.
Creating a partial unique index with SQLAlchemy in PostgreSQL
A partial unique index allows to constrain only a subset of the records in a table. This post shows an example how to implement a partial unique constraint with SQLAlchemy.
Upgrading old NixOS machines
Upgrading old NixOS machines can lead to a situation where the rebuild fails due to an unknown hash algorithm. This post shows a workaround to get started again.
Custom meta tags with Pelican, canonical URL as example
Setting custom meta data with Pelican can be implemented easily. This post shows a small example how I solved it.
Printing the generated query including parameters
Small example how to print out a SQLAlchemy query with parameters being expanded.
Sort certain result items on top in PostgreSQL
When displaying items based on a database search, one sometimes wants to display a specific set of items at the top or bottom of the result set. Applying the custom order inside of the database query allows to still use LIMIT and OFFSET in a natural way.
Storing the Heroku Connect configuration in a repository
A hint on how to store the Heroku Connect mapping configuration in a repository, so that diffs are readable and a useful information of the system changes over time.
Comparing tables in PostgreSQL
Two approaches to quickly compare two similar tables and get an idea of how many records differ based on an example with geo data.
Thoughts on a command line toolkit for Pyramid
Thoughts on how an integration of a CLI (command line interface) toolkit for the Pyramid web framework might look like and could be integrated into the configuration mechanisms of Pyramid itself.
Heroku Connect - Trigger sync of failed records
Working with Heroku Connect means that at some point some records will end up in a failed state. This post shows a few options how to trigger the sync manually again.
Build a Nix derivation against a specific channel
Channels can play a tricky role when using the Nix package manager to manage development environments. Especially when one want to make sure that a derivation builds against multiple channels. This post shows how to quickly build a derivation against a different channel based on setting a URL into the include path for Nix.
List of all packages for Nix
Having a list of all packages available in a simple text file is enough to get a good overview of available packages.
Environment for the Salesforce migration tool
An example Nix snippet which provides the Salesforce migration tool inside of a shell environment based on the Nix package manager.
Thoughts on the CLI of Pyramid applications
Thoughts on providing a nice CLI (command line interface) for Pyramid applications based on Click and the API of the Pyramid web framework.
Roughly counting rows in PostgreSQL
Small SQL snippet to quickly get an overview of the row count in a PostgreSQL database.
Spin up a local web server with Python
A common need is to bring up a web server ad-hoc to serve out some files via HTTP. Most of the time I am using this trick when I want to serve a local directly quickly via HTTP without setting up anything for it. Python has a module http.server …