Development Archive - Page 6 of 8

Packaging Python projects for Debian / Raspbian with dh-virtualenv

By Maximilian Batz | 2019-04-19

This article aims to explain some things to developers which don’t use Python a lot, and might struggle with some of the concepts otherwise. I highly recommend the lecture of the following article as an introduction to the concepts discussed here: https://www.dabapps.com/blog/introduction-to-pip-and-virtualenv-python/ pypi.org pypi.org is an official repository of software for the Python programming language.…

mongo_orm custom name for collection

By Maximilian Batz | 2019-04-17

mongo_orm will automatically determine the name for your collection by using the Module and Class name, and appending an “s”. In cases where you want to name your collection, you can simply do this: class PapiTest < Mongo::ORM::Document collection_name “Buster” field test : String end get “/” do pt = PapiTest.new pt.test = “I want…

Instructions for adding a user to a mongo database for mongo_orm

By Maximilian Batz | 2019-02-09

You don’t want your web application to access the database using your database admin user. Additionally you want it to access only one specific database – maybe you have additional databases running in your mongo instance. Prerequisites: mongo_orm expects the database configuration as environment variables or as a file config/database.yml in your project. The config/database.yml…

Building a persistent in-line editing experience with Crystal, MongoDB (datanoise / sam0x17)

By Maximilian Batz | 2019-02-05

As documentation is still sparse, I would like to add some. This is what I am building currently: The individual fields are going to be editable with an inline editor, which will automatically save to the backend – no need for reloading the whole page. The point of the whole is a backend for my…

Using nuitka compiler for python3 on Alpine Linux ARMHF (musl)

By Maximilian Batz | 2019-01-31

Motivation pidoctor is written in Python (as there was no easy way to get Crystal to work on ARMHF / musl). This means a dependency on Python – which adds overhead. I suspect that this overhead is the reason that pidoctor will not run on 256 MB Raspberry Pi’s – because the RAM is exhausted…

kemal-session does not persist data

By Maximilian Batz | 2019-01-22

https://github.com/kemalcr/kemal-session Analyse what is happening with your session cookie. In my case, the session cookie was reset everytime I went to login. I realized, that my idea of cleaning up the old session as a first statement after successful login, before setting up the new session is not a good idea. I suspect, that the…

Using modules in crystal

By Maximilian Batz | 2019-01-22

As your application grows, you would like to move from one big .cr file to separating your code into smaller files. You can use require from your main .cr file to add code from other files: require “./tools/*” This statement will add code from the tools directory, relative to your main .cr file. This will…

The scope of ecr within crystal: or how do I pass in variables and Objects into ECR templates?

By Maximilian Batz | 2019-01-21

As a beginner in the Crystal language I still struggle to get my head around some of the concepts in it, and develop a feel for coding in Crystal. When I come across difficult problems, which I solve or start to understand, I blog about them, so others can benefit – as lack of documentation…

Route & Redirect with envoy

By Maximilian Batz | 2019-01-17

An example envoy.yaml showing how to route & redirect. There are different options, see here https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route.proto#route-redirectaction This envoy.yaml routes /taxgod and /taxgod/ (the second could probably be omitted because the first one should also match it, I think) to a new port and a different protocol. /picockpit is simply redirected to / and then finally…

Envoy routing and rewriting snippet

By Maximilian Batz | 2019-01-17

It is possible to rewrite URLs with Envoy for the backend. Please note that the HTML output needs to have the proper routes! (That is why I am not going to investigate further in this direction). REF: https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/route/route.proto#route-route Also note that the string is going to be rendered literally for direct_response –> body –> inline_string,…