[MCP Bundle] Make MonologBundle optional #864

camilleislasse · 2025-11-13T07:45:25Z

Q	A
Bug fix?	yes
New feature?	no
Docs?	no
Issues	Fix #830
License	MIT

This PR makes MonologBundle optional dependency for McpBundle. Without it installed, the container compilation was failing with "Parent definition' monolog.logger_prototype' does not exist."

Changes

Wrap monolog.logger.mcp service creation in class_exists() check
Add ->nullOnInvalid() to setLogger() call in services.php
Uniformize logger references: both McpCommand and McpController now use monolog.logger.mcp with NULL_ON_INVALID_REFERENCE
Update test to skip when MonologBundle is not installed

Credits

Builds on the initial work in #849 by @WebMamba. That PR protected service creation but the service was still referenced without protection. This PR completes the fix by also protecting the service usage.

@WebMamba

Fixes symfony#830 - Wrap monolog.logger.mcp service creation in class_exists() check - Add ->nullOnInvalid() to setLogger() call - Uniformize logger references in McpCommand and McpController - Update test to skip when MonologBundle is not installed Builds on symfony#849 by @WebMamba

WebMamba

Thanks @camilleislasse to give me a hand on this.

WebMamba · 2025-11-14T13:05:50Z

src/mcp-bundle/tests/DependencyInjection/McpBundleTest.php

+        if (!class_exists(MonologBundle::class)) {
+            $this->markTestSkipped('MonologBundle is not installed');
+        }
+


Since monolog is never installed on the ci, this test will be always skipped, so the rest of the test is useless. What do you think about requiring monolog on dev then?

WebMamba · 2025-11-14T13:14:45Z

src/mcp-bundle/config/services.php

            ->call('setPaginationLimit', [param('mcp.pagination_limit')])
            ->call('setInstructions', [param('mcp.instructions')])
-            ->call('setLogger', [service('monolog.logger.mcp')])
+            ->call('setLogger', [service('monolog.logger.mcp')->nullOnInvalid()])


The function setLogger can't have a nullable as argument see:
https://github.com/modelcontextprotocol/php-sdk/blob/7a3b473c405411aca8be14c0c6e12d2493752d61/src/Server/Builder.php#L254.
So I don't think this can work... Maybe to have an if condition before the call can be better ?

Yes and another error probably here :

ai/src/mcp-bundle/src/Command/McpCommand.php

Line 27 in 1e69969

private readonly LoggerInterface $logger,

I'm not entirely happy with this solution ecea6d6 - conditionally instantiating transports with/without the logger parameter feels verbose.

The issue: MCP SDK has LoggerInterface $logger = new NullLogger() (non-nullable), so we can't pass null even though there's a default, if you have a better idea @WebMamba

Can change if modelcontextprotocol/php-sdk#152 is correct

…ts, and handle nullable logger in McpCommand/McpController by conditionally passing it to Transports. When MonologBundle is absent, Server and Transports use their default NullLogger.

OskarStark · 2025-11-15T08:18:01Z

I tend more and more to require the logger

camilleislasse · 2025-11-15T08:28:58Z

I tend more and more to require the logger

Me too, I feel like we’re making things unnecessarily complicated 😂

WebMamba

Also, it’s not really the point of this PR, but one of the key parts of this bundle is to build/instantiate the mcp.server.builder, and we don’t have any tests to secure this part. It seems important to me to add tests to cover it. The first commit of this PR had the CI green even if the builder wasn’t working.

WebMamba · 2025-11-16T15:33:26Z

src/mcp-bundle/src/Controller/McpController.php

+                $this->httpMessageFactory->createRequest($request),
+                $this->responseFactory,
+                $this->streamFactory,
+                logger: $this->logger,


Same here you can pass the NullLogger instead ?

OskarStark · 2025-11-16T15:41:54Z

Makes sense, open for a PR bringing in some tests?

WebMamba · 2025-11-16T15:41:45Z

src/mcp-bundle/src/Command/McpCommand.php

+        $transport = $this->logger
+            ? new StdioTransport(logger: $this->logger)
+            : new StdioTransport();


what do you thinks instead of having the NullLogger logic here: https://github.com/modelcontextprotocol/php-sdk/pull/152/files to have it here ?

Suggested change

$transport = $this->logger

? new StdioTransport(logger: $this->logger)

: new StdioTransport();

$transport = new StdioTransport(logger: $this->logger === null ? NullLogger() : $this->logger)

Sorry the reviews are in the wrong order I miss clicked 😅

WebMamba · 2025-11-16T15:50:07Z

But yes, to sum up my thought, you can either:

require Monolog
or if Monolog is not installed, instantiate a NullLogger

After some reflection, I’m leaning more toward the NullLogger option 😇

camilleislasse · 2025-11-16T16:30:30Z

But yes, to sum up my thought, you can either:

require Monolog

or if Monolog is not installed, instantiate a NullLogger

After some reflection, I’m leaning more toward the NullLogger option 😇

Maybe wait the review of modelcontextprotocol/php-sdk#152 ? If it's merged, I can pass the logger (which can be null via ContainerInterface::NULL_ON_INVALID_REFERENCE) directly to the transport without ternary operators.

camilleislasse · 2025-11-16T17:05:26Z

Makes sense, open for a PR bringing in some tests?

@OskarStark Shouldn't lint:container have caught this? I'm not sure if it's possible to run it independently on each bundle though - they each have their own dependencies, right?

camilleislasse requested review from Nyholm, OskarStark and chr-hertel as code owners November 13, 2025 07:45

carsonbot added Bug Something isn't working Status: Needs Review labels Nov 13, 2025

carsonbot changed the title ~~Make MonologBundle optional in McpBundle~~ Make MonologBundle optional in McpBundle Nov 13, 2025

OskarStark added the MCP Bundle Issues & PRs about the MCP SDK integration bundle label Nov 13, 2025

carsonbot changed the title ~~Make MonologBundle optional in McpBundle~~ [MCP Bundle] Make MonologBundle optional in McpBundle Nov 13, 2025

OskarStark changed the title ~~[MCP Bundle] Make MonologBundle optional in McpBundle~~ [MCP Bundle] Make MonologBundle optional Nov 13, 2025

OskarStark approved these changes Nov 13, 2025

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carsonbot added Status: Reviewed and removed Status: Needs Review labels Nov 13, 2025

OskarStark mentioned this pull request Nov 13, 2025

[MCP Bundle] Fix services when monolog is not installed #849

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WebMamba reviewed Nov 14, 2025

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camilleislasse added 2 commits November 14, 2025 18:18

Conditionally call Builder->setLogger() only when MonologBundle exis…

ecea6d6

…ts, and handle nullable logger in McpCommand/McpController by conditionally passing it to Transports. When MonologBundle is absent, Server and Transports use their default NullLogger.

Add MonologBundle to require-dev to ensure tests run in CI

a8500ca

WebMamba reviewed Nov 16, 2025

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