Closes https://github.com/coder/internal/issues/369
We can't know whether a replacement (i.e. drift of terraform state
leading to a resource needing to be deleted/recreated) will take place
apriori; we can only detect it at `plan` time, because the provider
decides whether a resource must be replaced and it cannot be inferred
through static analysis of the template.
**This is likely to be the most common gotcha with using prebuilds,
since it requires a slight template modification to use prebuilds
effectively**, so let's head this off before it's an issue for
customers.
Drift details will now be logged in the workspace build logs:
Plus a notification will be sent to template admins when this situation
arises:
A new metric - `coderd_prebuilt_workspaces_resource_replacements_total`
- will also increment each time a workspace encounters replacements.
We only track _that_ a resource replacement occurred, not how many. Just
one is enough to ruin a prebuild, but we can't know apriori which
replacement would cause this.
For example, say we have 2 replacements: a `docker_container` and a
`null_resource`; we don't know which one might
cause an issue (or indeed if either would), so we just track the
replacement.
---------
Signed-off-by: Danny Kopping <dannykopping@gmail.com>
PR contains:
- fix for claiming & deleting prebuilds with immutable params
- unit test for claiming scenario
- unit test for deletion scenario
The parameter resolver was failing when deleting/claiming prebuilds
because a value for a previously-used parameter was provided to the
resolver, but since the value was unchanged (it's coming from the
preset) it failed in the resolver. The resolver was missing a check to
see if the old value != new value; if the values match then there's no
mutation of an immutable parameter.
---------
Signed-off-by: Danny Kopping <dannykopping@gmail.com>
