chore: add template toggle to disable module caching by Emyrk · Pull Request #21931 · coder/coder

Emyrk · 2026-02-04T21:24:38Z

There exists use cases to disable the new module caching behavior of workspace builds. This was the legacy behavior.

Emyrk · 2026-02-04T21:26:04Z

coderd/database/migrations/000416_workspace_module_reuse_toggle.up.sql

@@ -0,0 +1,16 @@
+DROP VIEW template_with_names;
+ALTER TABLE templates ADD COLUMN disable_module_cache BOOL NOT NULL DEFAULT false;


Make users opt into the legacy behavior.

TBH I prefer having configuration flags being positive as opposed to negative, so enable_module_cache with default true would be my suggestion. Not a blocker though.

coder-tasks · 2026-02-04T21:27:12Z

Documentation Check

New Documentation Needed

This PR adds a new template setting that allows disabling Terraform module caching. Documentation should be added to help template admins understand when and why to use this feature.

Update docs/admin/templates/managing-templates/dependencies.md - Add a section explaining the new disable_module_cache template setting
- Explain that Coder caches Terraform modules by default for performance (already documented)
- Document the new toggle available in template settings
- Explain when to disable module caching (e.g., for debugging, testing new module versions, or when module behavior needs to change frequently)
- Note that disabling caching will impact build performance and require downloading modules on every build
- Show where to find this setting in the UI (Template Settings > General)
Consider adding to docs/admin/templates/troubleshooting.md - Add troubleshooting guidance
- Add a troubleshooting entry about module caching issues
- Recommend trying the "Disable module cache" setting if workspace builds are using stale module versions
- Link back to the dependencies.md documentation

Why Documentation is Needed

New feature: This is a new template-level configuration option that template admins need to know about
Performance impact: Disabling module caching has performance implications that should be clearly documented
Use cases: The PR description mentions "use cases to disable the new module caching behavior" but doesn't specify what those are - docs should clarify
Discovery: Users need to know this option exists when troubleshooting module-related issues
Connection to existing docs: The existing dependencies.md page discusses module caching benefits but doesn't mention how to disable it if needed

Automated review via Coder Tasks

johnstcn · 2026-02-05T09:25:04Z

coderd/database/migrations/000416_workspace_module_reuse_toggle.up.sql

@@ -0,0 +1,16 @@
+DROP VIEW template_with_names;
+ALTER TABLE templates ADD COLUMN disable_module_cache BOOL NOT NULL DEFAULT false;


TBH I prefer having configuration flags being positive as opposed to negative, so enable_module_cache with default true would be my suggestion. Not a blocker though.

johnstcn · 2026-02-05T09:26:00Z

coderd/provisionerdserver/provisionerdserver.go

-		}
-		if err == nil && tfvals.CachedModuleFiles.Valid {
-			versionModulesFile = tfvals.CachedModuleFiles.UUID.String()
+		if !template.DisableModuleCache {


This is what I mean, the other way round it would be

if template.EnableModuleCache { ... }

Aside, the below comment is also a bit confusing as it implies that the logic is related to DisableModuleCache being true?

I will delete that comment, it provides no help.

I do agree the inversion is not great. But I like that the zero value in golang is the correct default

site/src/pages/TemplateSettingsPage/TemplateGeneralSettingsPage/TemplateSettingsForm.tsx

Emyrk · 2026-02-05T18:26:29Z

TBH I prefer having configuration flags being positive as opposed to negative, so enable_module_cache with default true would be my suggestion. Not a blocker though.

I agree, but I also want the Golang zero value to be the default

…ast_workspaces

johnstcn

I'm OK with this change, besides the things I've already mentioned.
(Also, the unrelated golden file changes)

johnstcn · 2026-02-05T20:01:11Z

provisioner/terraform/testdata/resources/devcontainer/converted_state.state.golden

+              "id": "eb9b7f18-c277-48af-af7c-2a8e5fb42bab"
            },
            {
              "workspace_folder": "/workspace2",
              "config_path": "/workspace2/.devcontainer/devcontainer.json",
              "name": "dev2",
-              "id": "964430ff-f0d9-4fcb-b645-6333cf6ba9f2",
-              "subagent_id": "40a59d56-d3df-488f-b07d-331c0b774bac"
+              "id": "964430ff-f0d9-4fcb-b645-6333cf6ba9f2"
            }


not part of this change

I don't know what is going on. Fresh workspace, git clean -xfd, make gen -B 🤔

coder-tasks · 2026-02-05T20:24:13Z

Documentation Check

Updates Needed

docs/tutorials/best-practices/speed-up-templates.md - Add section explaining the disable_module_cache template setting and when to use it. The current "Set up Terraform provider caching" section discusses provider caching but not module caching behavior. Should explain:
- Default behavior: modules are cached at template import (introduced in chore!: send modules archive over the proto messages #21398)
- How to opt out per-template using the new disable_module_cache setting
- Trade-offs: performance vs always fetching latest unpinned modules
- Link to template settings page for configuration
docs/admin/templates/extending-templates/modules.md - Add note about module caching behavior:
- Explain that modules are cached by default during template import/update
- Mention the disable_module_cache template setting as an opt-out
- Clarify that this affects how often modules are re-downloaded from registries/git

Context

This PR adds a disable_module_cache boolean field to templates (defaults to false). It allows templates to opt out of the module caching behavior introduced in PR #21398, which caches Terraform modules at template import time to speed up workspace builds.

The API documentation and audit logs are already updated in this PR. User-facing documentation should explain:

What module caching is and why it improves performance
The behavior change from chore!: send modules archive over the proto messages #21398 (modules cached at import vs downloaded per build)
How to configure the setting via the template settings UI
When you might want to disable it (e.g., development workflows needing latest module versions)

Automated review via Coder Tasks

Emyrk · 2026-02-05T20:27:16Z

Documentation Check

I'm not going to document a feature I don't want people to use. The warning label in the product is enough imo.

How I tell the tasks bot "No"?

Emyrk · 2026-02-05T20:33:12Z

The chromatic failures are unrelated to my change

johnstcn · 2026-02-05T20:34:12Z

@Emyrk I'm not going to document a feature I don't want people to use. The warning label in the product is enough imo.

I think you can just ignore it?

Emyrk · 2026-02-05T20:38:38Z

@Emyrk I'm not going to document a feature I don't want people to use. The warning label in the product is enough imo.

I think you can just ignore it?

Ah, it is not required. I'm merging in spite of docs and chromatic

Emyrk added 3 commits February 4, 2026 13:47

chore: add template toggle to disable module caching

39b6441

chore: add fontend toggle option

a234bf6

honor the disable

f66a881

github-actions bot assigned Emyrk Feb 4, 2026

Emyrk commented Feb 4, 2026

View reviewed changes

add unit test:

afdb13e

Emyrk requested a review from johnstcn February 4, 2026 21:34

johnstcn reviewed Feb 5, 2026

View reviewed changes

Emyrk added 3 commits February 5, 2026 12:28

wording

66fb354

Merge remote-tracking branch 'origin/main' into stevenmasley/opt_in_f…

8f4770b

…ast_workspaces

bump migration

664a49c

johnstcn approved these changes Feb 5, 2026

View reviewed changes

Emyrk and others added 3 commits February 5, 2026 20:11

make gen

3cd5865

remove diffs

d5ad8ad

down mig

f9ac35c

Emyrk merged commit efd98bd into main Feb 5, 2026
29 of 32 checks passed

Emyrk deleted the stevenmasley/opt_in_fast_workspaces branch February 5, 2026 20:38

github-actions bot locked and limited conversation to collaborators Feb 5, 2026

		@@ -0,0 +1,16 @@
		DROP VIEW template_with_names;
		ALTER TABLE templates ADD COLUMN disable_module_cache BOOL NOT NULL DEFAULT false;

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Emyrk commented Feb 4, 2026

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coder-tasks bot commented Feb 4, 2026

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Emyrk commented Feb 5, 2026

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Emyrk commented Feb 5, 2026

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Emyrk commented Feb 5, 2026

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johnstcn commented Feb 5, 2026

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coder-tasks bot commented Feb 5, 2026 •

edited by Emyrk

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