GitHub Actions Dynamic Matrix

In configuring GitHub Actions to run a matrix of jobs with dynamic values, specific challenges such as handling secret authentication tokens and reading configuration files arise, which are not well-documented in GitHub's official resources. A streamlined approach is to define "matrix-prep" jobs that prepare necessary values for the matrix dimensions by executing bash one-liners and aggregating results into a JSON array. This method allows for conditional execution, such as checking for available secrets or reading values from files within the repository. By using outputs from these preparatory jobs, the matrix can dynamically adapt to varying conditions, facilitating more flexible and secure CI/CD workflows. This approach circumvents the need for separate JSON files and adapts to GitHub's evolving syntax, ensuring that workflows remain efficient and up-to-date.