azd up fails: BCP420 in infra/core/host/container-apps.bicep - ternary module scope no longer compiles on Bicep 0.36.1+

[hemarina]

Describe the bug

azd up fails during provisioning because infra/core/host/container-apps.bicep no longer compiles with current versions of the Bicep CLI:

ERROR: Your Bicep template has an error.

error executing step command 'provision': deployment failed: initializing provisioning manager:
failed to compile bicep template: failed running bicep build: exit code: 1, stdout: , stderr:
infra\core\host\container-apps.bicep(28,10) : Error BCP420: The scope could not be resolved at
compile time because the supplied expression is ambiguous or too complex. Scoping expressions must
be reducible to a specific kind of scope without knowledge of parameter values.
[https://aka.ms/bicep/core-diagnostics#BCP420]
infra\main.bicep(218,22) : Error BCP104: The referenced module has errors.
[https://aka.ms/bicep/core-diagnostics#BCP104]

The BCP104 in main.bicep is just the cascade from the single real error. The rest of the bicep build output is pre-existing warnings (BCP318 / BCP037 / BCP187 / linter), which are unrelated to the failure.

Root cause

infra/core/host/container-apps.bicep:28 sets a module scope with a ternary that returns two different scope expressions:

module containerRegistry 'container-registry.bicep' = {
  name: '${name}-container-registry'
  scope: !empty(containerRegistryResourceGroupName) ? resourceGroup(containerRegistryResourceGroupName) : resourceGroup()
  ...
}

Bicep turned this pattern into a hard compile error (BCP420) in v0.36.1 (June 2025). A scope: expression must now reduce to a specific scope kind without knowledge of parameter values.

References:

• Error BCP420: The scope could not be resolved at compile time because the supplied expression is ambiguous or too complex. Scoping expressions must be reducible to a specific kind of scope without knowledge of parameter values Azure/bicep#17325
• BCP420 is breaking modules with conditional scope Azure/bicep#17288

This compiled fine when the template was authored, so nothing changed in this repo — the toolchain moved. Notably there is no "pin an older Bicep" workaround for azd users: azd pins Bicep 0.45.15 and automatically upgrades any older local copy it manages (cli/azd/pkg/tools/bicep/bicep.go), so every user hits this.

This file is the legacy infra/core/ shared library used across many azd samples, so other templates carrying the same copy of core/host/container-apps.bicep are likely affected too.

To Reproduce

1. azd init -t Azure-Samples/APICenter-Reference
2. azd up

Or, without deploying anything:

bicep build infra/main.bicep

Expected behavior

azd up succeeds.

Suggested fix

Collapse the ternary so a single resourceGroup() call determines the scope kind and only the name varies:

module containerRegistry 'container-registry.bicep' = {
  name: '${name}-container-registry'
  scope: resourceGroup(!empty(containerRegistryResourceGroupName) ? containerRegistryResourceGroupName : resourceGroup().name)
  ...
}

I verified this against Bicep 0.45.15 (the version azd pins): the original expression reproduces BCP420 at the same line/column, and the revised expression compiles cleanly (exit code 0).

Additional context

• OS: Windows 11
• Reported downstream in the Awesome AZD gallery: API Center template has bicep error Azure/awesome-azd#954