Nudge users to enable incremental prebuilds when prebuilds duration is more than 10 minutes on average

[gtsiolis]

Problem to solve

Currently, incremental prebuilds exist inside project settings as a toggle option users can enable for a project.

However, this feature is only referenced in one changelog entry[1] and slightly documented (see section in prebuilds docs).

See also relevant discussion (internal). Cc @atduarte @geropl @jankeromnes

Proposal

MVC Step 1

Similarly to #9232, we could detect when project prebuilds on average take longer than 10 minutes and nudge users to enable incremental prebuilds using an alert within the project prebuilds page.

We could use:

1. A help alert component if this contains simply a tip that does not take into account usage but promotes a new feature, etc.
2. An information alert component if this contains neutral information that could take into account product usage, etc.
3. A warning alert component to help a user avoid an issue, in case skipping this could lead to excessive charging, see relevant discussion (internal).

Help Alert	Information Alert	Warning Alert

MVC Step 2

Additionally, although prebuilds eventually will be available to enable only via Projects, we could surface a similar alert on the workspace start page for repositories that have not been added as projects yet, nudging users to create a project and enable incremental prebuilds.

TBD (To be discussed)

[gtsiolis]

Cross-posting from a relevant discussion (internal):

@jankeromnes: However, we should probably avoid this right now, especially for European pro[j]ects, because incremental will double the amount of network transfer when creating new prebuilds, and since prebuilds all run in the US, doubling our expensive EU-US network traffic could be expensive.

See also #6650 and https://github.com/gitpod-io/ops/issues/2595 (internal).

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[jankeromnes]

I believe this issue should now be rewritten to:

• nudge users to enable "Use Last Successful Prebuild" instead
• when their typical prebuild duration is more than their shortest time between new pushes

Then we could also try to suggest a reasonable "Skip Prebuilds" value, e.g.

• if your prebuilds take 10min, and during a busy day you push a new change every 10min, then a "Skip Prebuilds" of 0 or 1 is fine
• however, if your prebuilds take 45min, and during a busy day you push a new change every 5min, then you might want a "Skip Prebuilds" value of 9 or 10