TerraMetrics: An Open Source Tool for Infrastructure-as-Code (IaC) Quality Metrics in Terraform

Infrastructure-as-Code (IaC) constitutes a pivotal DevOps methodology, leading edge of software deployment onto cloud platforms. IaC relies on source code files rather than manual configuration to manage the infrastructure of a software system. Terraform, an IaC tool and its declarative configuration language named HCL, has recently garnered considerable attention among IaC practitioners. Like other software artefacts, Terraform files could be affected by misconfigurations, faults, and smells. Therefore, DevOps practitioners might benefit from a quality assurance tool to help them perform quality assurance activities on Terrafrom artefacts. This paper introduces TerraMetrics, an open-source tool designed to characterize the quality of Terraform artefacts by providing a catalogue of 40 quality metrics. TerraMetrics leverages the Terraform Abstract Syntax Tree (AST) to extract the metric list, offering a potentially enduring solution compared to conventional regular expressions. This tool comprises three main components: (i) a parser transforming HCL code into an AST, (ii) visitors that traverse the AST nodes to extract the metrics, and (iii) collectors for storing the collected metrics in JSON format. The TerraMetrics tool is publicly available as an Open Source tool, with a demo video, at: https://github.com/stilab-ets/terametrics.