Add entrypoint and entrypointArgs support for MCP Gateway container configuration

[Copilot]

The MCP Gateway specification lacked fields to configure custom entrypoints for backend MCP server containers. This prevented overriding container default entrypoints and passing custom startup arguments.

Changes

Core types (pkg/types/mcp.go, pkg/workflow/tools_types.go)

• Added Entrypoint string field to BaseMCPServerConfig
• Updated mcpServerConfigToMap() to serialize entrypoint field

Parsing & validation

• Extended getMCPConfig() with optional transformContainer parameter to control docker command transformation
• Added entrypoint extraction in tools_parser.go and validation in mcp_config_validation.go

Rendering system (pkg/workflow/mcp-config.go, pkg/workflow/copilot_mcp.go)

• Added PreserveContainerFields flag to MCPConfigRenderer to conditionally preserve container fields
• When MCP Gateway is enabled (shouldGenerateMCPGateway()), container/entrypoint/entrypointArgs are preserved in JSON format for gateway processing
• When gateway is disabled, fields are transformed to docker commands with --entrypoint flag for backward compatibility

Documentation (docs/src/content/docs/reference/mcp-gateway.md)

• Added entrypoint field specification and usage examples

Behavior

Gateway mode (preserves container fields):

tools:
  custom-mcp:
    container: ghcr.io/example/server
    entrypoint: /custom/entrypoint.sh
    entrypointArgs: ["--verbose"]

Generates config for gateway:

{
  "container": "ghcr.io/example/server",
  "entrypoint": "/custom/entrypoint.sh",
  "entrypointArgs": ["--verbose"]
}

Non-gateway mode (transforms to docker command):

{
  "command": "docker",
  "args": ["run", "--rm", "-i", "--entrypoint", "/custom/entrypoint.sh", 
           "ghcr.io/example/server", "--verbose"]
}

Original prompt

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This section details on the original issue you should resolve

<issue_title>MCP Gateway spec does not allow container volume mount points to be specified</issue_title>
<issue_description>Recent changes to the MCP Gateway do not allow it to configure the volume mounts and other configuration for the backend mcp server containers that it launches.

We need a more structured way to specify these options in the json config passed to the MCP Gateway.

https://github.com/githubnext/gh-aw/blob/main/docs/src/content/docs/reference/mcp-gateway.md</issue_description>

<agent_instructions>Please take a look at this issue and create a PR with a fix.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes MCP Gateway spec does not allow container volume mount points to be specified #9388

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[lpcox]

@copilot please do not add network and port options to the configuration. just add volume mounts.

[Copilot]

@copilot please do not add network and port options to the configuration. just add volume mounts.

Done! Removed the network and ports options, keeping only the mounts (volume mounts) configuration. The gateway now uses the default --network host mode.

Updated in commit 9595db1.

[lpcox]

Looks good