Include deploy history on metric chart for Environments page

Resources

PM @joshlambert | FE @iamphill | UX @pedroms

Description

When viewing the graph of a performance metric in the Environment detail page, it would be helpful to have the deployment timestamps noted on the chart.

Proposal

Add a vertical line that marks the time for each deployment. When hovering the line, complement the time and date info in the tooltip with the commit SHA or tag (if available) that was deployed.