Which of the following is NOT a key component of Azure DevOps Services?

Azure Functions is not a key component of Azure DevOps Services, while the other options are integral parts of the Azure DevOps ecosystem.

Azure Boards is a service that helps in planning, tracking, and managing software projects. It provides comprehensive work item tracking, Agile project management tools like Kanban boards, and various reporting capabilities, which are essential for managing development workflows.

Azure Repos offers version control services, enabling teams to manage their code with Git repositories or Team Foundation Version Control (TFVC). It is crucial for collaboration in software development as it provides a central location for managing code, creating branches, and tracking changes.

Azure Pipelines facilitates continuous integration and continuous delivery (CI/CD), allowing teams to automate the building, testing, and deployment of applications. This service supports a variety of languages and platforms and is essential for streamlining the release process.

In contrast, Azure Functions is a serverless compute service that allows developers to run code without provisioning or managing servers. While it can be used in conjunction with Azure DevOps for specific tasks or deployments, it is not considered a core component of the Azure DevOps Services suite. Therefore, it does not belong to the primary tools that make up the Azure DevOps Services ecosystem.