Fix critical validation gap for run volume parameters

[cyberkunju]

Summary

The registry validator had a blind spot: while isConfigEnvValid() enforces that environment variable templates are namespaced with the server name, there was no equivalent guard for server.Run.Volumes. As a result, any volume mapping could reference parameters from a completely different server and still pass validation, only to explode later at runtime with an opaque Docker error.

Problem

Here’s the kind of misconfiguration we were silently accepting:

name: my-server
image: mcp/my-server
type: server
run:
  volumes:
    - '{{wrong-name.storage_path}}:/app/data'  # Wrong prefix!
config:
  parameters:
    type: object
    properties:
      storage_path:
        type: string

Because nothing double-checked server.Run.Volumes, {{wrong-name.storage_path}} skated by unchecked. When Docker spun up the container it couldn’t resolve that parameter and failed with a cryptic message.

Impact

More than twenty production servers rely on templated volumes today, including:

• arxiv-mcp-server → {{arxiv-mcp-server.storage_path}}:/app/papers
• markdownify → {{markdownify.paths|volume|into}}
• aks → {{aks.azure_dir}}:/home/mcp/.azure

Any typo in those prefixes would have slipped through CI and landed in the registry, leaving operators to discover the failure only after deployment.

Solution

• Introduced isRunVolumesValid() to mirror the existing environment validation rules.
• Enforce that every template is prefixed with the current server name, whether it’s a bare parameter ({{server.param}}) or a filtered expression ({{server.param|filter|into}}).
• Emit clear, actionable error messages that call out the expected prefix versus what we actually saw.

Before

$ go run ./cmd/validate --name my-server
✅ Config env is valid
✅ License validation skipped
# Invalid volume parameter silently accepted!

After

$ go run ./cmd/validate --name my-server
✅ Config env is valid
2025/10/10 volume parameter must be prefixed with "my-server." but found "wrong-name.storage_path" in: "{{wrong-name.storage_path}}:/app/data"
exit status 1

Testing

• New coverage: Unit tests spanning valid prefixes, filter expressions, and edge cases.
• Stability fixes: Cleaned up existing tests to assert on the improved error handling.
• Validation sweep: Confirmed arxiv-mcp-server, markdownify, and aks all pass with the new guardrails.

This closes the validation gap and surfaces configuration mistakes where they belong—in CI, not in production.

[Copilot]

Pull request overview

This PR addresses a critical validation gap where volume parameter templates in server configurations could reference parameters from different servers without validation, leading to runtime failures. The fix introduces server name prefix validation for volume parameters, matching the existing validation pattern used for environment variables.

Key Changes:

• Added isRunVolumesValid() function to validate volume parameter prefixes
• Integrated volume validation into the main validation flow
• Added comprehensive test coverage for volume validation scenarios

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
cmd/validate/main.go	Implements isRunVolumesValid() to enforce server name prefix requirements for volume parameters and integrates it into the validation pipeline
cmd/validate/main_test.go	Adds test coverage for volume validation and updates Test_areSecretsValid with proper working directory setup

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[Copilot]

The comment should follow Go conventions by starting with the function name. Change to: // isRunVolumesValid checks volume parameter usage is valid

Suggested change

	// Check volume parameter usage is valid
	// isRunVolumesValid checks volume parameter usage is valid

[Copilot]

The comment on line 294 is misleading - the code doesn't skip filter expressions but rather handles them specially. Update to: // Handle filter expressions (contains |) by extracting the parameter name before the first |

[Copilot]

The directory setup logic is duplicated between Test_areSecretsValid and Test_isRunVolumesValid. Consider extracting this into a helper function or using t.TempDir() with test fixtures to improve maintainability.