Have a visual issue dependency graph

When creating a hierarchy of issues with Blocker Issues it might be nice to have a dependency graph like used in Phabricator for example:

This is a follow-up from #29914.

mentioned in issue #29914

changed the description

mentioned in issue gitlab-org/quality/triage-reports#650 (closed)

mentioned in issue gitlab-org/quality/triage-reports#652 (closed)

added devopsplan groupproject management typefeature labels

added sectiondev label

mentioned in issue gitlab-org/quality/triage-reports#797 (closed)

mentioned in issue gitlab-org/quality/triage-reports#874 (closed)

mentioned in issue gitlab-org/quality/triage-reports#949 (closed)

mentioned in issue gitlab-org/quality/triage-reports#1050 (closed)

mentioned in issue gitlab-org/quality/triage-reports#1104 (closed)

There are other nice visual examples for an issue dependency graph in #29914 #33587 (closed) and from GitLab itself at #15452 (comment 214822008)

Unfortunately some of those issues only depict those as belonging to Epics and Roadmaps, which as enterprise features are not interesting to us.

Additional to the third party examples in #223035 (comment 541531936), there is also https://sourceforge.net/projects/kanbanara/ which does a good job at visualising dependencies between cards in notable ways.

@brendan Found a HN thread on the Phabricator shutdown with your question & response, matching this feature proposal. https://news.ycombinator.com/item?id=27336818

cc @gweaver @sytses

@cdybenko @uhlexsis FYI this is a common request from customers that I speak with and is related to your current work on thinking through relationships and hierarchies for work items.

Agreed, we should name this view and start thinking about having it as an option.

@cdybenko @gweaver I've worked with dependency graph implementations in my past monitoring OSS project, and how to prevent circular loops or performance issues - may need query caching, or pre-calculated tree leaves. Happy to help with brainstorming ideas and design.

Naming proposal: {Issue,MR,Epic} Link Graph similar to the Git commit graph in Repository > Graph. Link because it summarizes relations and blocks described in the docs.

Another less linear example from Phabricator can be taken from https://phabricator.wikimedia.org/T214557, which highlights how and where this is useful in displaying task dependencies of large epics. (Not to conflate with #223035)

Please also take this paper's investigation and conclusion below as a suggestion to try out multiple ways of visualising ticket dependency in the long run:

Selectable and searchable text:

Our findings suggest that matrix layouts are the best layouts to investigate direct causal relationships, with matrix-out-degree the fastest, while node-link diagrams with hierarchical layout is the most promising for mediated causation. For identifying causal structures, radial was the most promising layout, with its performance increasing with the size of graphs. This suggests that causal inference could benefit from visualisation tools that provide multiple coordinated views [26], thus supporting users in a range of different tasks for understanding causation. Further investigation that considers cognitive and visual processes would help in explaining the results of our experiment, and better understanding of the principles of visual causal inference will assist in developing readable and informative causal graphs.

Vo, D.-B. , Lazarova, K., Purchase, H. C. and McCann, M. (2020) Visual Causality: Investigating Graph Layouts for Understanding Causal Processes. In: 11th International Conference on the Theory and Application of Diagrams (Diagrams 2020), Tallinn, Estonia, 24-28 Aug 2020, pp. 332-347.

mentioned in issue #356724 (closed)

We have a customer interested in this feature:

• https://gitlab.zendesk.com/agent/tickets/281623 (internal)
• https://gitlab.my.salesforce.com/0014M00001wWxavQAC (internal)

added customer label