Our Blog

Google Chrome Yum/​RPM package update fails on RHEL/​CentOS 7

By Jon Jensen
June 8, 2023

Painting by Willgard Krause, Pixabay license

One of our clients uses the Chrome web browser running on their continuous integration server with Jenkins for automated e2e (end-to-end) testing of their website. That server runs Red Hat Enterprise Linux (RHEL) 7—actually the rebuild CentOS 7.

Last month, in May 2023, Google started signing Chrome RPMs with a GnuPG subkey, where they before had signed with the main key. Now yum upgrade fails when trying to update Chrome, giving this error:

warning: /var/cache/yum/x86_64/7/google-chrome/packages/google-chrome-stable-114.0.5735.106-1.x86_64.rpm: Header V4 RSA/SHA512 Signature, key ID a3b88b8b: NOKEY
Retrieving key from https://dl.google.com/linux/linux_signing_key.pub


The GPG keys listed for the "google-chrome" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.


 Failing package is: google-chrome-stable-114.0.5735.106-1.x86_64
 GPG Keys are configured as: https://dl.google.com/linux/linux_signing_key.pub

To double-check, we tried to manually verify the signature on the downloaded RPM package with:

# rpm -K …

Migrating from Universal Analytics to GA4

By Juan Pablo Ventoso
June 1, 2023

Image: Migration by Aivar Ruukel, 2014. Attribution 2.0 Generic (CC BY 2.0), obtained from Flickr

Most public-facing websites rely on Google Analytics to track their traffic, analyze the user’s characteristics and behavior, and run reports based on that information to improve marketing strategies, engage their public, and ultimately, increase the user’s loyalty.

Universal Analytics vs. Google Analytics 4

Until 2020, Google relied on Universal Analytics, a system that offered a set of reports that were mainly based on page visits and content visualization. But in October 2020, Google announced that the new Google Analytics 4 (GA4) was launched, using an event-centered approach for metrics. That allows several improvements in the way the data is collected and analyzed, like taking into account several platforms and devices as a source for the data (for example, combining website traffic with mobile app usage and activity on social networks).

Another improvement is privacy: Among the new features, anonymous IP addresses are now the default setting for GA4. The user’s IP address will be still registered and used to group data when doing the initial collection, but it won’t …

I wrote the same app twice, with Hotwire and Blazor Server — here’s what I learned

By Kevin Campusano
May 27, 2023

There’s been a very interesting movement that has emerged recently in the world of frontend web development: a rise of little-to-no-JavaScript frontend frameworks.

The promise here is that we would be able to develop web applications with rich interactive capabilities without the need to write a whole lot of JavaScript. As such, these new approaches present themselves as alternatives to the likes of Vue, React, Angular, etc.

Two recent technologies that try to fulfill this promise come from two of the most prolific web application development frameworks of today: Blazor, built on .NET, and Hotwire, built on Ruby on Rails.

Now, I love my JS frameworks as much as the next guy, but these new technologies are intriguing. So I decided to build the same application twice, with Hotwire and with Blazor. I learned a few things along the way that I would like to share in this blog post.

Note that there is a table of contents at the end of this post.

What this article is

I want to present some of my findings when working with these two technologies. I also want to discuss how they work and how they feel. How they are similar and how they are different. How they take different routes …

Mount a remote filesystem over SSH using SSHFS

By Trevor Slocum
May 25, 2023

While creating and debugging software, it is important to reduce the amount of friction between each iteration of making a change to the software and then testing that change. Over time, even small amounts of friction can lead to fatigue and decreased performance of a developer. Because of this, we should take every opportunity to make our workflow as smooth and comfortable as possible.

A common source of friction when developing software running on remote systems is the separation between your personal computer and the server. Your personal computer likely has an IDE configured just the way you like. The server, on the other hand, is likely configured to be easily available to everyone on your team.

You could copy files back and forth between systems using SFTP or some other file transfer protocol. This works for quick one-off changes, but for development requiring multiple iterations you likely want a more streamlined workflow.

If only there was a way to use the software installed on your personal system to edit files on a remote system, without copying the files back and forth…

There is! SSHFS is a tool for mounting and interacting with remote directories over SSH. …

Cesium Labels

By Dmitry Kiselev
May 24, 2023

Improving place labels in CesiumJS, the open source JavaScript library for 3D globes and maps, has been a longstanding request from some of our VisionPort clients. The display of labels embedded in imagery has not been up to their expectations. The names look upside down as the globe is rotated and there’s no option to change the language:

Cesium has vector labels which allow you to anchor some text to a point on a map which will always be aligned with the camera. However, there is no ready-to-use solution to display city names in particular and no way to load them according to a specific zoom level.

To improve performance when displaying labels in Cesium it would make sense to load labels as a tile tree and only show some of the top of the tree at different zoom levels in a manner similar to how KML Regions with NetworkLinks work. Unfortunately, although Cesium supports KML, it doesn’t support KML Regions and NetworkLinks updates on Region change.

Another off-the-shelf solution that might conceivably work would be to use Cesium 3D tiles, but unfortunately, tiles do not support 2D Billboards.

Calculating regions and their level of detail is complicated, but Cesium already …

eCR Coordinator job opening

By Shannon Sandall
May 23, 2023

This position has been filled. See our active job listings here.

We are seeking a full-time Electronic Case Reporting (eCR) Coordinator to provide high-level expertise in the validation and automation of eCR messages.

This position is responsible for establishing complete, up-to-date, timely, and automated reporting of individual-level data, and automation of incoming EHR data. Position is remote, in the United States only.

The person in this role will be responsible for coordinating and overseeing the eCR onboarding process for our clients. Additionally, the person will become our subject matter expert for the NNDSS Modernization Initiative (NMI) and how systems in place within EpiTrax can be configured to report through the NMI module.

Job responsibilities

1. eCR onboarding—40%

   • Assist the on-boarding team with eCR reporters.
   • Develop Structure, Dictionary, LOINC and SNOMED codes in EMSA.
   • Assist in eCR message structure approval.
   • Assist with EMSA management.

2. Troubleshooting—30%

   • Issues found by the program epis and the LHDs.
   • Issues found by the surveillance team.
   • Create trouble tickets for issues.

3. Testing—15%

   • Test the structure for incoming messages.
   • Test new enhancement functionality.
   • Test bug fixes.

4. Grant document development—5% …

How to use the Caps Lock key as an Escape key on Windows, macOS, and Linux

By Trevor Slocum
April 17, 2023

On most keyboards, the Escape key is distant from the most common keys. In order to reach it, you likely need to lift your hand from the keyboard. This interrupts the flow of typing and, over time, may cause repetitive strain injuries.

When using modal applications which require frequent use of the Escape key, such as the text editor Vim, shortening the distance your fingers travel to and from the Escape key helps prevent injury and saves time.

After following the instructions below, you may need to restart your system in order to finish applying the changes.

Windows instructions

Download and install PowerToys, a set of utilities created by Microsoft.

Open PowerToys and browse to the Keyboard Manager. Enable the Keyboard Manager and click Remap a key. Choose Caps Lock -> Escape.

Note that this fix requires PowerToys to be running.

macOS instructions

Go to Apple menu -> System preferences -> Keyboard. If you have multiple keyboards, make sure your active keyboard is selected.

Click on the Modifier keys button to open a popup dialog. Open the dropdown next to Caps Lock and select Escape.

Linux instructions

There are separate instructions for Linux depending on whether you …

SSH host key verification: a few useful tips

By Selvakumar Arumugam
April 13, 2023

The SSH connections between a client and a remote server begin with a host key verification as an initial handshake. If the default key algorithm is not supported between the client and server, the SSH connection attempt is closed with no matching host key type response.

$ sftp username@domain
Unable to negotiate with xx.xx.xx.xx port 22: no matching host key type found. Their offer: ssh-rsa
Connection closed.
Connection closed

In this article, we will explore the host key verification process and discuss ways to handle the non-matching host key issue to establish the connection.

Host keys

By default, OpenSSH automatically generates a public-private key pair on the server and stores it in /etc/ssh. These keys, known as host keys, are created using several encryption algorithms including RSA, DSA, ECDSA, and ed25519.

The pair of private and public keys is available on the host server at the path /etc/ssh.

$ ls /etc/ssh | grep key
ssh_host_dsa_key
ssh_host_dsa_key.pub
ssh_host_ecdsa_key
ssh_host_ecdsa_key.pub
ssh_host_ed25519_key
ssh_host_ed25519_key.pub
ssh_host_rsa_key
ssh_host_rsa_key.pub

How does OpenSSH decide which host key to use?

During SSH connection establishment, the …