Let users know if Crunch hit cloud capacity
If Crunch hits some cloud capacity limit, then any user who is starting or running a workflow may want to know about that—not just the user(s) whose workflows were directly affected.
If Crunch recently hit one or more instance capacity limits in the last 8 hours (number bikesheddable), Workbench should display a red warning banner just under the top bar with a message like:
Arvados has been unable to create some instance types in the cloud recently:
- t0.example (as of DATETIME)
Workflow execution may be delayed until resources are available again.
Repeat the list items for each affected instance type in the last 8 hours.
If Crunch hit a cloud-wide capacity problem like network limit, the message can say:
Arvados has been unable to create new compute nodes as of DATETIME. Workflow execution may be delayed until resources are available again.
The banner can be dismissed. Once it is dismissed, it remains dismissed for the duration of the user's session, unless the error type changes (like a new instance type becomes unavailable, or we go from an instance problem to a cloud-wide problem). If that happens, the banner reappears with the new error information.
DATETIME should be rendered the same way all other absolute datetimes are rendered in Workbench.