Thomas Hallgren
Senior Principal Software Engineer at Polar Sky
Söderhamn, Gävleborg County, Sweden
Summary
🤩
Rockstar🎓
Top SchoolThomas Hallgren is a Senior Principal Software Engineer with over four decades in software and more than 22 years focused on cloud-native tools, notably building Go- and Java-based services and contributing to core Puppet language components in Ruby, Java, and Go. He blends deep systems-level experience—from C++ application frameworks and JVM tooling to modern Kubernetes-native API gateways—with hands-on leadership as a founder and long-tenured principal at firms like Tada AB, Ambassador Labs, and Puppet. His open-source work includes meaningful contributions to widely used projects such as Puppet Bolt and Emissary-ingress, improving orchestration workflows and gRPC-based CLI-daemon interactions. Known for practical architecture, mentorship, and clean pragmatic code, he often operates at the intersection of tooling, language design, and developer experience. Based in Söderhamn, Sweden, he brings a rare continuity of perspective across legacy systems and contemporary cloud ecosystems.
22 years of coding experience
38 years of employment as a software developer
Korsbackaskolan, KävlingeMicrocomputers and programming, Microcomputers and programming at Statens skola för vuxnaSoftware technician Computer Science, Software technician Computer Science at Skandinaviska Skolan
English
Github Skills (30)
apim10
puppeteer10
back-end-development10
datatypes10
puppet10
api-design10
configuration-management10
hiera10
interpolation10
bolt10
ruby10
go10
api10
orchestration10
orchestra10
Programming languages (13)
Github contributions (5)
puppetlabs/hiera
Jul 2013 - Jan 2017
Lightweight Pluggable Hierarchical Database
Role in this project:
Back-end Developer
Back-end DeveloperContributions:34 commits, 20 PRs, 10 pushes in 3 years 7 months
Contributions summary:Thomas primarily contributed to the core logic of the Hiera project. Their work involved implementing and modifying the backend lookup functionality, including support for dotted keys and array indexing. They also refactored configuration file handling to distinguish between missing keys and nil values. Additionally, they addressed issues related to interpolation and recursion within the Hiera configuration.
hierarchicalnested-objectsdatabasepluggabledistributed
puppetlabs/bolt
Sep 2017 - Jan 2018
Bolt is an open source orchestration tool that automates the manual work it takes to maintain your infrastructure on an as-needed basis or as part of a greater orchestration workflow. It can be installed on your local workstation and connects directly to remote nodes with SSH or WinRM, so you are not required to install any agent software.
Role in this project:Backend & DevOps Engineer
Backend & DevOps EngineerContributions:9 commits, 5 PRs, 2 pushes in 3 months
Contributions summary:Thomas primarily focused on enhancing the `Bolt` orchestration tool by implementing new data types (`ExecutionResult`, `Target`) and associated functionalities, which are crucial for handling results and managing targets. They also addressed Rubocop offenses, ensuring code quality and consistency. Further contributions involved fixing specification test failures and integrating the `ExecutionResult` and `Target` data types with the functions (`run_script`, `file_upload`, `run_task`, `run_command`), improving the data flow within the orchestration workflow.
workstationautomatessshbasistakes
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