Let’s begin with a confession: Yes, open source still carries baggage. For some, it conjures images of cobbled-together projects and cryptic readme files that smell faintly of late nights and lukewarm coffee. For others, it suggests risk—code without warranty, support, or accountability, as if you’ve been handed a parachute with instructions in Esperanto.
And yet, open source doesn’t sit on the margins of cloud computing. It is the cloud. The majority of today’s foundational tools—Kubernetes
, Terraform, Prometheus—evolved and conquered as open-source projects despite commercial origins, shaped and strengthened by global communities spanning companies, industries, and time zones.
That’s not a coincidence. Open source thrives in cloud environments because it mirrors the cloud’s own principles: modularity, transparency, resilience through diversity. These tools succeed not despite being open, but because of it. Their public codebases allow for rapid scrutiny, faster iteration, and broad interoperability. They adapt to real-world needs rather than vendor lock-ins or internal roadmaps.
Still, that openness brings challenges—complexity, support concerns, and integration headaches among them. For consultancies and platform teams, the task is clear: to shape these raw materials into something stable, secure, and coherent.
What follows is a guide to the open-source tools that make modern cloud platforms possible. They’re not just tools; they’re the scaffolding behind the cloud.
1. The Foundation: Linux and Beyond
Before Kubernetes, before Terraform—before we even called it "the cloud"—there was Linux.
For decades, it has quietly run the web, the data centres, and the hyperscalers themselves. It’s the default OS for cloud virtual machines, containers, and embedded systems. Even Microsoft now ships a virtual Linux kernel inside Windows.
Linux’s dominance isn’t just a historical quirk. It reflects the strengths of open source: peer-reviewed code, transparent development, unparalleled adaptability and a focus on solutions rather profit. From edge devices to high-performance computing clusters, Linux scales in every direction precisely because no single entity defines its limits.
It set the precedent. Everything that follows builds on that idea: openness as an enabler of robustness.
2. Infrastructure and Orchestration
If Linux laid the groundwork, infrastructure and orchestration tools are what allow modern cloud systems to grow tall—and grow fast. These tools automate, standardise, and scale the core building blocks of your cloud environment. Whether you're running a single app or a suite of services across multiple regions, this is the layer that makes it all manageable.
- Kubernetes: Originally developed by Google, Kubernetes is now the de facto standard for container orchestration. It automates deployment, scaling, and management of containerised applications across clusters. For example, if your business runs a customer portal or internal app that needs to be reliable and available across time zones, Kubernetes keeps it running without manual intervention. On AWS, it's available as Amazon EKS; on Google Cloud as GKE; and on Azure as AKS—each offering a managed version of Kubernetes with varying levels of integration and control.
- Docker / containerd: Docker popularised containerisation—packaging software so it runs the same on every machine. containerd is its stripped-down runtime, now widely used in production systems. It also integrates well across AWS, Azure, and Google Cloud, and containerd underpins Kubernetes on all three.
- Terraform: The leading tool for Infrastructure as Code (IaC). It lets you define and provision infrastructure across cloud providers using a simple, declarative language. For an SME, that could mean spinning up identical staging and production environments without touching the console. Naturally, Terraform also works across all major cloud providers—offering an alternative to AWS CloudFormation, Azure Resource Manager templates, and Google Cloud Deployment Manager.
- Pulumi: A modern alternative to Terraform, allowing IaC using general-purpose languages like Python, Go, and TypeScript. It appeals to developer-led teams who want fewer context switches. Pulumi works across AWS, Azure, Google Cloud and Kubernetes.
- Ansible: A configuration management tool that automates software provisioning and application deployment that helps you ensure every machine in a cluster has the correct software installed and up to date. Freely available provider modules mean that all the major hyperscalers are supported.
- Helm: A package manager for Kubernetes that simplifies deploying and managing applications. Helm charts let you define, version, and share repeatable application configurations—making it easier to handle complexity in multi-environment deployments.
At the risk of oversimplifying it, what these tools do is solve the problem of scale. They bring reproducibility, automation, and auditability to infrastructure, but their open-source power lies in being cloud-agnostic. Used wisely, they can enable the holy grail of multi-cloud and hybrid deployments—if you can manage the kind of complexity that makes ‘just one more tweak’ sound like a reasonable way to spend your evening.
3. Observability and Monitoring
Once infrastructure is in place, the next challenge is knowing what's happening inside it. Observability and monitoring tools provide the visibility needed to detect problems, optimise performance, and understand how systems behave in the wild. Without this layer, you're flying blind.
- Prometheus: A metrics-based monitoring system with a powerful query language (PromQL). It collects and stores time-series data—things like CPU usage or error rates—and is often used with Amazon Managed Service for Prometheus on AWS.
- Grafana: A visualisation tool that integrates with Prometheus and many other data sources to produce flexible, powerful dashboards. For a business running e-commerce or SaaS, Grafana can surface real-time insights on performance and user experience.
- OpenTelemetry: A collaborative project to standardise the collection of telemetry data (metrics, logs, traces). If your app is spread across services and cloud functions, OpenTelemetry provides the plumbing to track what's happening.
These tools promote a shift in mindset: from passive monitoring to proactive observability. They allow teams to ask nuanced questions of their systems and get actionable answers.
We explore this shift in more depth in 4 Essential AI Use Cases for European SMEs, where observability feeds directly into smarter decision-making.
4. Security and Policy
Of course, building and observing systems is only part of the story. You also need to keep them secure—and prove that you're doing so. Open-source tools are increasingly central to this effort, not just by plugging gaps, but by embedding security and policy enforcement into every stage of the development and deployment lifecycle.
- Open Policy Agent (OPA): A general-purpose policy engine. It allows you to define fine-grained controls over everything from Kubernetes RBAC to API access. If you need to restrict who can deploy updates or access customer data, OPA can automate those rules.
- Falco: A runtime security tool for containers, developed by Sysdig and now part of the CNCF. It detects anomalous behaviour inside running containers—such as an unexpected network connection or shell access.
- Sigstore: A project focused on signing and verifying software supply chains. For regulated industries, this provides a cryptographic trail of trust.
Security has shifted left. Open-source tools make that shift practical, inspectable, and automatable. And while no single tool removes the need for process, together they help build a consistent and reliable security approach.
5. CI/CD and Developer Platforms
To innovate quickly, you need reliable ways of delivering software—and of enabling your teams to do their best work. Continuous integration and delivery (CI/CD), along with internal developer platforms, help turn code into customer-facing value. Open-source tools make this possible in a way that’s flexible, cost-effective, and tailored to your team’s needs.
- Backstage: Developed by Spotify, this tool provides a developer portal to centralise documentation, onboarding, service ownership, and more. It reduces cognitive load and helps teams move faster with confidence.
These tools are about developer experience. They shift teams from manual deploys and tribal knowledge to platforms that are observable, consistent, and self-service.
6. Data, Events, and Storage
Thanks to the cloud, modern businesses don’t just store data—they stream it, analyse it, and act on it in real time. Whether you’re building a recommendation engine, updating dashboards, or triggering automated workflows, you need tools that can move and transform data at speed. Open source provides a growing arsenal of technologies for precisely this task.
- Apache Kafka: The canonical event streaming platform, used for real-time data ingestion and processing. For example, it can power a live dashboard of customer behaviour or trigger fraud alerts in financial services.
- Apache Airflow: Workflow orchestration for complex data pipelines. Whether you're refreshing analytics reports or retraining a machine learning model, Airflow keeps the steps aligned and on schedule.
- Vitess / CockroachDB: Scalable, cloud-native databases with strong open-source pedigrees. These are designed to survive outages and grow with demand.
These tools solve one of the biggest cloud problems: not how to store data, but how to move it, process it, and query it efficiently across diverse environments. Without open source, we wouldn't have the flexible, interoperable foundation that allows cloud platforms to evolve quickly, integrate broadly, and scale efficiently across geographies and workloads.
Open Source in Practice
It’s tempting to imagine open source as a ready-made toolkit. Pick the right combination, wire them up, and your cloud platform builds itself. But the reality is more subtle—and more rewarding.
The real strength of open source isn’t just in what the tools do—it’s in how they let teams work: faster, more transparently, and with a greater sense of control. Even using just a few well-chosen tools can simplify collaboration, streamline updates, and help teams build more confidently.
One strong example from our own back-catalogue is TIER Mobility, who built a scalable, self-managed cloud environment using Kubernetes for orchestration, Terraform for infrastructure automation, Helm for application deployment, and Prometheus and Grafana for observability—all great open-source tools, each doing what it does best. The result was a robust and scalable platform that gave their teams autonomy and insight—without locking them into a proprietary stack.
TIER Mobility - A Success Story
Don't forget, it's more about confidence, flexibility and reliability than just saving money. When teams can see what's running, shape how it works, and change it when needed—they're not just using the cloud, they're building with it. And that changes the conversation—from buying solutions to building capabilities, from being tied to a roadmap to creating one that fits.
Ready to Build with Open Source?
If you're thinking about how open source could fit into your cloud strategy, you're not alone. Whether you're modernising infrastructure or looking to scale securely, we can help you connect the right tools with the right outcomes. Let’s talk!