Our Blog

Deploying and Troubleshooting Self-Hosted MicroBin

By Muhammad Najmi bin Ahmad Zabidi
September 13, 2024

Note: This write-up was based on the installation done on Rocky Linux 9. You may need to adjust this example for other distros with their package manager commands.

In the world of collaboration between our team members and the public, secure and efficient ways to share text and files are essential. While there are many cloud-based options available, some might prefer to keep their data in their own hands. If you’re one of those individuals, MicroBin might be just the solution you’re looking for.

What is MicroBin?

MicroBin is a Rust-based software that acts as a self-hosted pastebin alternative. It allows users to share publicly accessible text or encrypted text files, putting you in control of your data sharing needs. Users can choose whether to share the data/text publicly or privately. MicroBin also has syntax highlighting capabilities.

Installation

There are several ways to install MicroBin. In this case, we will install it directly on a Rocky Linux server. You might need to install git, Rust packages, and cargo before starting.

Cargo

For those comfortable with Rust and its package manager, Cargo, installing MicroBin is a breeze. Simply use the following command as …

Automating DNS Management with GitLab CI/CD

By Kannan Ponnusamy
September 6, 2024

Photo by Simon Kadula

At End Point, managing DNS records across multiple domains has historically been a manual task. This blog post details our journey from manual processes to an automated workflow using GitLab CI/CD.

Our Initial Approach

With multiple domains and frequent updates necessary to manage the servers, manual handling of DNS changes became a bottleneck. Initially, our process looked like this:

• Make changes to the OpenTofu configuration files
• Create a merge request (MR) in GitLab
• They would run tofu plan manually and paste the plan output into the MR for review
• A coworker would review the MR and approve the changes
• Once merged, the engineer would manually run tofu apply to implement the changes

While this process worked, automating it could enhance our productivity and minimize errors, integrating our DNS management directly into our CI/CD pipeline.

The Solution: Automating with GitLab CI/CD

• Change Submission: Engineers make changes to the OpenTofu files and submit a merge request
• Plan Creation: A GitLab CI/CD job automatically generates an OpenTofu plan when changes are proposed
• Review Process: A coworker reviews the automatically generated plan in the MR
• Applying …

Streamlining SELinux Policies: From Policy Modules to Modules and Silent SELinux Denials

By Bharathi Ponnusamy
August 26, 2024

Introduction

SELinux (Security-Enhanced Linux) provides a robust security layer that enforces security policies to control system access. When dealing with SELinux, you often encounter the terms “policy_module” and “module”. Understanding the difference between these and knowing how to convert between them is crucial for efficient system administration.

What is a policy_module?

A policy_module in SELinux is a type of module used to define additional policies. These modules encapsulate specific security rules that can be loaded into the SELinux policy to grant or restrict permissions. Policy modules are particularly useful for adding or modifying policies without changing the base SELinux policy.

policy_module(my_policy, 1.0)

require {
    type my_app_t;
}

#============= my_app_t ==============
allow my_app_t my_log_t:file read;

What is a module?

A module in SELinux is a compiled version of a policy module. The compilation process translates the high-level policy rules into a binary format that SELinux can enforce. Modules are loaded into the SELinux policy store to extend or modify the active policy.

module my_module 1.0;

require {
    type my_app_t; …

Exploring Geodatabase Files

By Constante “Tino” Gonzalez
August 14, 2024

One of our clients recently provided us with a dataset of real estate properties that they manage, and asked us to generate content based off of the points and polygons in the dataset.

We will walk through the process of extracting polygons, placemarks, and other info from a geodatabase file and converting them into separate KML files using the ogr2ogr command-line tool, adding some logic to the data selection to limit the subset of features. We will also explore the GDB file using the GDAL Python library to export the data as JSON for use in other scripts.

Prerequisites

• Basic understanding of geospatial data
• Installed versions of the GDAL/OGR library
• A geodatabase file (.gdb, .gdb.zip, or .shp)

A first look into the contents of the GDB file

ogrinfo example.gdb.zip

This command will list all layers that are available in the dataset. Add a specific layer as a parameter to the same command, and it will output all the fields, their types, and values for every feature in the layer.

ogrinfo example.gdb.zip a_layer_name

The parameter -so can be used to omit the values from the output and get only the layer field names and types:

#$> ogrinfo example.gdb.zip Land_Points -so
INFO: …

Measuring Metamorphopsia

By Darius Clynes
August 7, 2024

Photo in public domain.

Metamorphopsia is an abnormal condition of vision that can cause deformation of the visual field. This condition, aside from having a wonderful name, has a real effect on my vision: Even after a successful operation to correct the macular hole which causes this, I still see circles as ellipses. Faces are elongated vertically like in a funhouse mirror, so I have an “ugly face” eye and a “normal face” eye.

My ophthalmologist assured me that with time — 6 weeks to 6 months — my vision should become normal and this distortion and visual alignment problem should disappear, or at least improve drastically. It occurred to me it would be nice to have an application to measure any progress in the restoration of my vision.

What Causes Metamorphopsia?

The most common cause of metamorphopsia is an irregularity in the retinal surface of the eye. A typical irregularity of the retinal surface that can produce a noticeable distortion in the center of the visual field is referred to as a “macular” anomaly. Macular anomalies come in different varieties. One such anomaly, a macular hole, arises when the retina in the area of the fovea in the center of the eye is …

The Perl and Raku Conference 2024

By Andrew Baerg
August 2, 2024

Next Generation of Perl

I attended The Perl and Raku Conference in Las Vegas, NV, which took place June 25–28, 2024. It was HOT outside (over 40 °C/110 °F) but we stayed cool inside at the Alexis Park Resort.

Curtis Poe (Ovid) got things started with the keynote encouraging us to Party Like It’s 19100+e^iπ, and reminded us that Vegas is lexically scoped (what happens in Vegas stays in Vegas)! More importantly he reminded us that Perl is about people, not just the technology. The Perl community has been meeting all over the world since 1999, with this being the 25th anniversary of the first The Perl Conference (aka YAPC::NA).

Ovid Keynote

Meeting in person with people who you interact with primarily through digital channels, code commits, and MetaCPAN documentation really highlighted the importance of the community. On the first day, I messed up timezones, showed up an hour before registration opened, and witnessed the conference organizers and core members arrive and greet each other with hugs. I also enjoyed visiting with one of the very welcoming board members of The Perl and Raku Foundation (TPRF).

Many of the speakers and attendees put a “Hallway++” …

Writing a WebSocket-Controlled State Machine

By Will Plaut
July 20, 2024

This article was co-authored by Jacob Minshall

We recently developed a state machine to control a piece of software for a client. The client wanted to have an API to interact with the state machine, triggering state changes while it was running. Depending on the current state’s requirements, the state machine could either wait for a WebSocket message to proceed to another state or transition to the next state without outside input. WebSockets allow for two way communication so the clients can also have visibility into the state machine’s current state.

To start, we looked for a simple way to implement a state machine within our TypeScript/Node.js based project. The typescript-fsm library on GitHub was a good solution for us. What made us consider this package was the simplicity of the library: the entire source file is around 100 lines of code.

We did end up making some custom changes to the library that won’t be shown here; for example, we wanted to broadcast state change messages via WebSockets to any connected clients. With such a simple library, it was a breeze adding that code. The code in this post will still run with the vanilla library, it just won’t notify you when …

Using Docker Compose to Deploy a Multi-Application .NET System

By Kevin Campusano
July 13, 2024

This post was co-authored by Juan Pablo Ventoso

We recently developed a system that involved several runtime components. It was an ecommerce site that included a database, a web API, an admin control panel web app, and a frontend SPA.

There are many ways to deploy such a system. For us, we wanted the infrastructure to be easily replicable for multiple environments with slightly different configurations. We wanted to be able to have, for example, a production and a staging version that could be deployed easily, with minimal configuration changes. We also wanted the infrastructure to be captured in files and version controlled, to further help replicability and maintainability.

With all that in mind, Docker Compose seemed like an ideal option. We could author a series of configuration files, parameterize environment-specific changes and, with a single command, we could spin up a whole environment to run the various applications within the system.

In this blog post, I’ll explain how we did that using a demo .NET code base that has a similar set of components. Let’s get started.

Getting familiar with the demo project

In .NET terms, our demo code base is organized as a …