A container is a packaged unit of software that encapsulates an application with all necessary dependencies (5). The containers themselves are ephemeral and isolated from both the host environment and other containers. Those qualities ensure that changes occurring within a container are not shared across other containers and that they are not affected by any changes that might occur outside of the container. In that way, using containers increases reliability and reproducibility, even when multiple containers of the same software are running concurrently on the same system.

Software containerization approaches rely on a container engine, such as Docker (https://www.docker.com) or Apptainer (formerly Singularity) (https://apptainer.org), which oversees the tasks associated with creating and using these discrete software environments (6). Container images are created using a build file that provides a base image (an initial state for the environment) and stepwise instructions for bundling software code and dependencies. Once the image has been built, it can be used locally or hosted on a public resource where the container can be released and made publicly accessible. Those hosted container images can be downloaded and run on a variety of computing infrastructures, from laptops to high-performance computing (HPC) clusters, greatly simplifying the process of development to deployment (7).

Figure 1

Figure 1. Monthly container image downloads across all State Public Health Bioinformatics containers hosted in Docker Hub (https://hub.docker.com/u/staphb) in study of advantages of software containerization in public health infectious disease...

Recognizing the value of containers, the State Public Health Bioinformatics (StaPH-B) community developed and actively maintains a repository of containerized software (https://github.com/StaPH-B/docker-builds). The StaPH-B docker-builds repository is a collection of dockerfiles used to build containers of bioinformatics software that are commonly used in public health genomic workflows. Those containers are publicly available and hosted at both Docker Hub (https://hub.docker.com/u/staphb) and Quay.io (https://quay.io/organization/staphb); total monthly downloads from Docker Hub range from 100,000 to >700,000 (Figure 1). The emphasis on quality assurance and quality control in the StaPH-B container repository separates the project from other container repositories. Anyone can submit a new or updated container to the StaPH-B repository following the contributing instructions on the GitHub repository (https://staphb.org/docker-builds/contribute). Each submission includes a test that confirms the functionality of the container image, and all pull requests are reviewed carefully by the repository maintainers to ensure that the software meets the needs and expectations of public health laboratories.

The reliable and reproducible nature of containers is advantageous for public health and clinical laboratories. Deploying bioinformatic analytical workflows and software in a clinical and public health setting is challenging and requires managing computer systems with capacity for scientific computing workloads under regulatory oversight (8). Software containerization approaches provide key advantages to genomic workflows.

Figure 2

Figure 2. Top container image downloads across State Public Health Bioinformatics containers hosted in Docker Hub (https://hub.docker.com/u/staphb) in study of advantages of software containerization in public health infectious disease genomic...

During the beginning of the COVID-19 pandemic, initiatives were created to enhance genomic surveillance (11), which led to many clinical and public health laboratories rapidly developing NGS-based surveillance testing to support variant detection. During that time, the StaPH-B docker project played a critical role in supporting the advancement of bioinformatic workflows by providing a reliable resource for SARS-CoV-2 sequence analysis containers. The StaPH-B container of Pangolin, a critical SARS-CoV-2 lineage tool, saw an addition of >500,000 downloads, from 2,360,607 downloads in 2022 to 2,944,235 downloads in 2023 (Figure 2) (12). Similarly, the StaPH-B container of iVar, a tool for amplicon-based viral sequencing, has been downloaded >1,836,046 times since it was added in 2020 (Figure 2) (13). The scale of downloads from this repository highlights the use of these programs in bioinformatic workflows and the effect of the project during the pandemic.

One of the largest effects on laboratories was a time savings in software installation and management, which grows substantially when scaling workflows to run in an HPC or Cloud environment. Installing Pangolin and its dependencies using Conda takes approximately 3 minutes on a new system, whereas downloading and running the StaPH-B container of Pangolin takes only 1 minute. Similarly, installing iVar takes 4.5 minutes, whereas downloading and running the StaPH-B container of iVar takes only 4 seconds. When using a distributed computing environment such as an HPC or Cloud environment, those time savings become a critical efficiency and cost savings. Those times also assume no installation issues or conflicts with other software and dependencies, a common occurrence with bioinformatics software that can stretch software deployment into days or weeks.

In summary, software containerization has rapidly changed the landscape of bioinformatics over the past 10 years and will continue to be a critical component of public health genomic workflows for the future. The StaPH-B docker project represents a community-based effort providing a valuable resource of standardized bioinformatic tools, supporting reproducibility and regulatory compliance.