Archivematica @ Wellcome Collection
  • Introduction
  • High-level design
  • Storing born-digital files
    • Creating a transfer package
    • Upload a transfer package to S3
    • Check a package was stored successfully
    • Downloading a package from the storage service
    • Following a package in the dashboard
  • Service architecture
    • How does Archivematica work?
      • The Archivematica apps
      • Microservices, tasks and jobs
      • Gearman, ElastiCache, and the MCP server/client
    • How is our deployment unusual?
      • What are our extra services?
      • ECS containers on EC2, not Fargate
      • Why we forked Archivematica
    • How it fits into the wider platform
  • About our deployment
    • Using Wellcome catalogue identifiers
    • Different environments
    • Working storage: MySQL, Redis, and EBS
  • Administering Archivematica
    • Bootstrapping a new Archivematica stack
    • User management
      • How to add or remove users
      • Authentication with Azure AD
    • Upgrading to a new version of Archivematica
    • Running an end-to-end test
    • Clearing old transfers from the dashboard
  • Debugging Archivematica
    • Where to find application logs
    • Troubleshooting known errors
      • Timeout waiting for network interface provisioning to complete
      • 401 Unauthorized when the s3_start_transfer Lambda tries to run
      • "pull access denied" when running containers (and other ECS agent issues)
      • "Unauthorized for url" when logging in
      • "gearman.errors.ExceededConnectionAttempts: Exceeded 1 connection attempt(s)" in MCP server
      • NotADirectoryError in the Extract zipped transfer stage
    • Restarting services if a task is stuck
    • SSH into the Archivematica container hosts
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  1. Debugging Archivematica
  2. Troubleshooting known errors

"gearman.errors.ExceededConnectionAttempts: Exceeded 1 connection attempt(s)" in MCP server

We have seen errors like this from MCP server, alongside packages stalling at the "Extract zipped transfer" job:

gearman.errors.ExceededConnectionAttempts: Exceeded 1 connection attempt(s)

This can be fixed by restarting the MCP server task.

My hypothesis: the MCP server relies on Gearman, and I think it might struggle when it can't connect to it – that is, when there aren't any Gearman tasks running. Even when Gearman comes back, it can't regain its connection.

The Gearman service should persist through a blue-green deployment, but there may be times when it goes down properly – for example, if we restart all the ECS tasks by hand. If so, it's important to ensure that the MCP server task starts after Gearman.

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Last updated 2 years ago