fix(modal): Support non-main envs in Modal

[kadams54]

Summary

Modal has a hierarchy of workspaces -> environments. The default environment is main. If you stick with that, the environment doesn't have any impact on Modal's URLs; however, if you use a non-default environment, e.g., prod, that environment name is added into the URL. These changes support generating Modal's URL slug properly to support both main and non-default environments.

Backwards compatibility

• The new modal_environment Terraform variable defaults to main so projects that don't set it will not be impacted.

Docs updated

• docs/GETTING_STARTED.md — updated terraform.tfvars block
• terraform/environments/production/terraform.tfvars.example — updated example to include the new variable

Summary by CodeRabbit

• Documentation

  • Updated getting started guide with expanded Modal prerequisites, now requiring both Workspace and Environment names with guidance on locating them.

• New Features

  • Terraform configuration now includes environment variable support for Modal, enabling flexible workspace configuration across different deployment environments.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR extends Modal workspace configuration to support environment-specific naming. A new modal_environment variable is introduced alongside the existing modal_workspace setting, then conditionally merged into a workspace slug that is applied to both the Modal app module and worker control-plane binding.

Changes

Modal Environment Variable Integration

Layer / File(s)	Summary
Input variable definition, example configuration, and user documentation terraform/environments/production/variables.tf, terraform/environments/production/terraform.tfvars.example, docs/GETTING_STARTED.md	The modal_environment input variable defaults to "main" with validation requiring a non-empty value when sandbox provider is modal. The example tfvars file and getting-started guide are updated to document both workspace and environment configuration.
Conditional workspace slug computation terraform/environments/production/locals.tf	A new modal_workspace_slug local computes the effective workspace name: for the "main" environment, it uses the raw workspace value; for other environments, it appends the environment name as a hyphenated suffix.
Modal app and worker control-plane integration terraform/environments/production/modal.tf, terraform/environments/production/workers-control-plane.tf	Both the modal app module workspace argument and the control-plane worker MODAL_WORKSPACE binding are updated to use the computed modal_workspace_slug instead of the raw workspace variable.

Sequence Diagram

Not applicable; this PR contains configuration and infrastructure variable updates without multi-component runtime interaction.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• ColeMurray/background-agents#529: Related — both PRs modify the same terraform module call in terraform/environments/production/modal.tf but with different purposes.

Poem

🐰 Environments awaken, workspaces align,
Main and satellites dance in a slug design,
Modal now knows where it's meant to be,
Configuration blooms—what unity! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title directly and clearly summarizes the main change: adding support for non-main Modal environments through a new modal_environment variable and conditional workspace slug formatting.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@terraform/environments/production/variables.tf`:
- Around line 75-84: Update the validation block for the Terraform variable
"modal_environment" to also reject colon and slash characters: modify the
existing validation condition in the variable "modal_environment" (currently
referencing var.sandbox_provider and length(var.modal_environment)) to
incorporate a regex check that ensures the value does not contain ":" or "/"
(e.g., using can(regex("^[^:/]+$", var.modal_environment)) in the condition when
sandbox_provider == "modal"), and update the error_message to something like
"modal_environment must not contain colons or slashes." so invalid endpoint
slugs are prevented.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 29cf18c9-edff-40e9-938f-637f10338315

📥 Commits

Reviewing files that changed from the base of the PR and between b52ab9a and 45e3a23.

📒 Files selected for processing (6)

• docs/GETTING_STARTED.md
• terraform/environments/production/locals.tf
• terraform/environments/production/modal.tf
• terraform/environments/production/terraform.tfvars.example
• terraform/environments/production/variables.tf
• terraform/environments/production/workers-control-plane.tf

[ColeMurray]

[Automated Review]
The slug is plumbed into URL construction here, but modal deploy / modal secret create in terraform/modules/modal-app/scripts/{deploy,create-secrets}.sh are invoked without --env (and no MODAL_ENVIRONMENT is exported), so they deploy to the workspace's default environment regardless of var.modal_environment.

Concretely, with modal_environment = "production":

• This module's outputs and the worker's MODAL_WORKSPACE → myworkspace-production--…modal.run
• But modal deploy lands the app at the workspace default (typically main) → myworkspace--…modal.run
• Result: every endpoint 404s.

Suggested fix:

1. Add a modal_environment input to the modal-app module.
2. Pass it as MODAL_ENVIRONMENT in the environment blocks of null_resource.modal_secrets and null_resource.modal_deploy in modules/modal-app/main.tf — Modal CLI reads that var natively.
   (Or alternatively, append --env "${MODAL_ENVIRONMENT}" in both scripts.)

Without this, the feature is half-wired for non-main envs — URLs point one place, deployment lands somewhere else.

[ColeMurray]

see comment regarding modal script