Also add some clarification about the lack of database constraints for
soft template deletion.
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Signed-off-by: Danny Kopping <dannykopping@gmail.com>
Co-authored-by: Danny Kopping <dannykopping@gmail.com>
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.
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Signed-off-by: Danny Kopping <dannykopping@gmail.com>
`Collect()` is called whenever the `/metrics` endpoint is hit to
retrieve metrics.
The queries used in prebuilds metrics collection are quite heavy, and we
want to avoid having them running concurrently / too often to keep db
load down.
Here I'm moving towards a background retrieval of the state required to
set the metrics, which gets invalidated every interval.
Also introduces `coderd_prebuilt_workspaces_metrics_last_updated` which
operators can use to determine when these metrics go stale.
See https://github.com/coder/coder/pull/17789 as well.
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Signed-off-by: Danny Kopping <dannykopping@gmail.com>
