Development Process Summary

This section provides a high-level overview of key Axom software development topics and includes links to more detailed discussion.

Software Development Cycles

The Axom team uses a sprint-based development process. We collect and track issues (bugs, feature requests, tasks, etc.) using Github and define a set of development tasks (i.e., issues) to complete for each sprint. While the team meets to discuss issues and plan which ones will be worked in each sprint, developers of individual Axom components may plan and schedule work in any way that works for them as long as this is coordinated with other team efforts. Work performed in each sprint work period is tracked as a single unified sprint encompassing activities for the entire project.

Software Releases and Version Numbers

Typically, Axom releases are done when it makes sense to make new features or other changes available to users. A release may coincide with the completion of a sprint cycle or it may not.

See Release Process for a description of the Axom release process.

The Axom team follows the semantic versioning scheme for assigning release numbers. Semantic versioning conveys specific meaning about the code and modifications from version to version by the way version numbers are constructed.

See Semantic Versioning for a description of semantic versioning.

Branch Development

The Axom project has a Github project space and the team follows the Gitflow branching model for software development and reviews. Gitflow is a common workflow centered around software releases. It makes clear which branches correspond to which phases of development and those phases are represented explicitly in the structure of the source code repository. As in other branching models, developers develop code locally and push their work to a central repository.

See Gitflow Branching Model for a detailed description of how we use Gitflow.

Code Reviews and Acceptance

Before any code is merged into one of our main Gitflow branches (i.e., develop or main), it must be adequately tested, documented, and reviewed for acceptance by other team members. The review process is initiated via a pull request on the Axom Github project.

See Pull Requests and Code Reviews for a description of our review process and how we use pull requests.

Contributors and Project Access

Axom maintains three levels of project access on it GitHub project:

  • Core team members. Individuals on the core Axom team are frequent Axom contributors and participate regularly in project meetings, discussions, and other project activities. They are members of the LLNL GitHub organization and the axom GitHub team. Their project privileges include the ability to create branches in the repository, push code changes to the Axom repo, make PRs, and merge them when they are approved and all checks have passed.

  • Regular contributors. Individuals, who are not on the core Axom team, but are members of the LLNL GitHub organization and are involved in some aspects of Axom development are considered regular contributors. They are members of the axom-contrib GitHub team. Their project privileges include the ability to create branches in the repository, push code changes to the Axom repo, and make PRs. However, they may not merge PRs and must coordinate with the core team to have their work included in the develop branch. This is mainly due to the way GitHub structures its project access levels.

  • Everyone else. Anyone with a GitHub account is welcome to contribute to Axom. Individuals outside of the two groups described above, and specifically not a member of LLNL GitHub organization, can make PRs in the Axom project, but must do so from a branch on a fork of the Axom repo. Thus, the process of reviewing and merging contributions involves additional steps which we describe here.

Forking the repository

The requirement for individuals outside of the LLNL GitHub organization to contribute on a fork of the repo is due to policies enforced by the LLNL organization on GitHub (in which the Axom project resides) and the Livermore Computing (LC) organization (in which we run our GitLab CI testing). Fortunately, you may still contribute to Axom by forking the Axom repo. Forking creates a copy of the Axom repository that you own. You can make changes on your local copy and push them to your fork on GitHub. When you are ready to have your Axom contribution reviewed and added to the Axom project, you may create a pull request in the Axom project.

Accepting a pull request from a forked repository

Due to LLNL security policies, some Axom pull requests cannot be run through all Axom CI checks. The Livermore Computing (LC) Center GitLab systems restrict which GitHub PRs may run automatically through its CI test pipelines. For example, a PR made from branch on a forked repository will not trigger GitLab CI checks. GitLab CI on LC platforms will be run only on PRs that are made from branches in the GitHub Axom repository.


The following process for accepting PR contributions from a fork of the Axom repo must be executed by a member of the Axom team:

To facilitate testing contributions in PRs from forked repositories, we maintain a script to pull a PR branch from a forked repo into the Axom repo. First, identify the number of the PR, which appears at the top of a PR. Then, run a script from the top-level Axom directory:

$ ./scripts/make_local_branch_from_fork_pr -b <PR #>

If successful, this will create a branch in your local copy of the Axom repo labeled pr-from-fork/<PR #> and you will be on that local branch in your checkout space. To verify this, you can run the following command after you run the script:

$ git branch

You will see the new branch in the listing of branches and the branch you are on will be starred.

You can push the new branch to the Axom repo on GitHub:

$ git push <branch-name>

and make a PR for the new branch. It is good practice to reference the original PR in the description of the new PR to track the original PR discussion and reviews.

All CI checks will be triggered to run on the new PR made in the Axom repo. When everything passes and the PR is approved, it may be merged. When it is merged, the original PR from the forked repo will be closed and marked as merged unless it is referenced elsewhere, such as in a GitHub issue. If this is the case, then the original PR (from the forked repo) must be closed manually.

Testing and Code Health

Comprehensive software testing processes and use of code health tools (e.g., static analysis, memory checkers, code coverage) are essential ingredients in the Axom development process.

See Tests and Examples for a description of our software testing process, including continuous integration.

Software Development Tools

In addition to the tools listed above, we use a variety of other tools to help manage and automate our software development processes. The tool philosophy adopted by the Axom project focuses on three central tenets:

  • Employ robust, commonly-used tools and don’t re-invent something that already exists.

  • Apply tools in ways that non-experts find easy to use.

  • Strive for automation and reproducibility.

The main interaction hub for Axom developers is the Atlassian tool suite on the Livermore Computing Collaboration Zone (CZ). These tools can be accessed through the MyLC Portal. Developer-level access to Axom project spaces in these tools requires membership in the LC group ‘axomdev’. If you are not in this group, and need to be, please send an email request to ‘’.

The main tools we use are listed below. Please navigate the links provided for details about how we use them and helpful information about getting started with them.

  • Confluence. We use the Axom Confluence space for team discussion (e.g., hashing out design ideas), maintaining meeting notes, etc.

  • Github. We use the Axom Github project to manage our issues and Git repository which contains the Axom source code, build configurations, scripts, test suites, documentation, etc.

  • Gitlab. We use Gitlab for continuous integration to ensure code quality on our LC systems.: Axom Gitlab project

    • See LC GitLab for more information about how we use Gitlab.

  • Azure Pipelines. We use Azure Pipelines for continuous integration to ensure every code change passes a level of quality before being merged.: Azure Pipelines

    • See Azure Pipelines for more information about how we use Azire Pipelines.