[MCC] Fix validation errors that pointed users at a nonexistent argument

[Denali Cornwell (dcwell)]

🤖 PR Validation — ️✔️ All clear

Breaking Changes
️✔️ None

Related command

az mcc ent node update, az mcc ent node create

Description

Follow-up to #10290. Two user-facing error messages in the mcc extension pointed at the wrong thing. Both were found by an edge-case sweep of every validation path in the extension, run after #10290 merged.

1. Proxy errors named an argument that does not exist

Eight proxy validation messages on az mcc ent node update told the user to set --enable-proxy:

ValidationError: Parameter --enable-proxy is set to "Enabled", must provide --proxy-host and --proxy-port parameter.

enable_proxy is deliberately unregistered (args_schema.enable_proxy._registered = False); the argument the command exposes is --proxy. Following the guidance in the message produced:

ERROR: unrecognized arguments: --enable-proxy Enabled

so the message led to a dead end. All eight now name --proxy. The internal argument name is unchanged.

2. Create reported the cache node when it could not find the MCC resource

MccEntNodeCreate.pre_operations looks up the MCC resource to fill in location, but the failure message reported args.cache_node_name. A bare except: also discarded the underlying error, so a mistyped resource group surfaced as a missing MCC resource.

Before:

ERROR: Cache node resource creation failed. CLI could not find the specified MCC resource with name 'MyCacheNode' that the cache node would be created on.

After:

ERROR: Cache node resource creation failed. CLI could not find the MCC resource 'MyMccResource' in resource group 'MyResourceGroup' that the cache node would be created on. (ResourceGroupNotFound) Resource group 'MyResourceGroup' could not be found.

Both bare except: clauses are now except Exception as ex with raise ... from ex.

Notes

• No behaviour change to validation itself — only the text of the errors and the preservation of the underlying exception.
• 1.0.0b4 has not been published to index.json yet, so these entries fold into the existing 1.0.0b4 block rather than adding a version.

Testing

• azdev linter --include-whl-extensions mcc — PASSED
• azdev style mcc — pylint and flake8 PASSED
• azdev test mcc — 1 passed
• 105-command sweep (69 offline, 28 live against real Azure resources, 8 raw REST comparisons) re-run after the change.

[azure-client-tools-bot-prd]

Hi Denali Cornwell (@dcwell),
Please write the description of changes which can be perceived by customers into HISTORY.rst.
If you want to release a new extension version, please update the version in pyproject.toml (or setup.py, if the extension has not migrated yet) as well.

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[Copilot]

🟢 Approval recommended

The changes are low-risk and align with the PR’s stated goal; remaining feedback is limited to minor user-facing grammar/readability nits in the updated messages.

Pull request overview

Fixes user-facing validation and error messages in the mcc extension so they no longer direct users to nonexistent CLI arguments and so underlying lookup failures are preserved for troubleshooting.

Changes:

• Update proxy-related validation errors to reference --proxy (instead of the unregistered/internal --enable-proxy).
• Improve az mcc ent node create MCC resource lookup failure reporting by including MCC resource name, resource group, and the underlying exception (via exception chaining).
• Record these fixes in HISTORY.rst under the existing 1.0.0b4 entry.

File summaries

File	Description
src/mcc/azext_mcc/custom.py	Updates validation/lookup error messages and replaces bare except: with except Exception as ex plus exception chaining.
src/mcc/HISTORY.rst	Documents the corrected error messages and preserved underlying exception behavior.

Review details

Suppressed comments (2)

src/mcc/azext_mcc/custom.py:441

• Grammar: "Parameter --proxy is set not provided" is ungrammatical and reads like a typo; it should say that --proxy is not provided.

                    if has_value(args.proxy_host) or has_value(args.proxy_port):
                        err_msg = "ValidationError: Parameter --proxy is set not provided and cache node is in proxy state \"Disabled\": --proxy-host and --proxy-port cannot be provided."
                        raise ValidationError(err_msg)

src/mcc/azext_mcc/custom.py:446

• Grammar: the error message says "must provide --proxy-host and --proxy-port parameter" but it requires two parameters; this should be plural to avoid confusion.

            if args.proxy == "Enabled":
                if not has_value(args.proxy_host) or not has_value(args.proxy_port):
                    err_msg = "ValidationError: Parameter --proxy is set to \"Enabled\", must provide --proxy-host and --proxy-port parameter."
                    raise ValidationError(err_msg)

• Files reviewed: 2/2 changed files
• Comments generated: 3
• Review effort level: Lite

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[Aditya Pujara (a0x1ab)]

/azp run

[azure-pipelines]

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Successfully started running 2 pipeline(s).

[Yong Zhang (yonzhan)]

MCC

[Aditya Pujara (a0x1ab)]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 2 pipeline(s).

[Azure CLI Bot (azclibot)]

[Release] Update index.json for extension [ mcc-1.0.0b5 ] : https://dev.azure.com/msazure/One/_build/results?buildId=179975905&view=results