Fix MCP Gateway mount propagation in large-payload-tester workflow#731
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Fix MCP Gateway mount propagation in large-payload-tester workflow#731
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Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>
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[WIP] Fix large-payload-tester functionality
Fix MCP Gateway mount propagation in large-payload-tester workflow
Feb 5, 2026
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Pull request overview
This PR fixes a mount propagation issue in the large-payload-tester workflow where the MCP Gateway container couldn't access the /tmp/mcp-test-fs directory to mount it into the filesystem MCP server. The gateway launches backend MCP servers via Docker-in-Docker, requiring host directory access to propagate mounts to child containers.
Changes:
- Added
/tmp/mcp-test-fs:/tmp/mcp-test-fs:romount tosandbox.mcp.mountsconfiguration - Recompiled lock file with updated Docker command and frontmatter hash
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
.github/workflows/large-payload-tester.md |
Added read-only mount for /tmp/mcp-test-fs to gateway container sandbox configuration |
.github/workflows/large-payload-tester.lock.yml |
Updated compiled Docker command to include new mount and refreshed frontmatter hash |
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The large-payload-tester workflow creates test data in
/tmp/mcp-test-fsand expects the filesystem MCP server to read it, but the gateway container had no access to mount it through.Changes
/tmp/mcp-test-fs:/tmp/mcp-test-fs:rotosandbox.mcp.mountsin workflow frontmatterFlow
Gateway launches backend MCP servers via Docker-in-Docker. Without host directory access, it can't propagate mounts to child containers.
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