[MESOS-6467] Build a Container I/O Switchboard

• Type: Task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0
• Labels: debugging mesosphere
• Target Version/s: 1.2.0
• Epic Link: Mesos Container Attach/Exec
• Sprint: Mesosphere Sprint 47
• Story Points: 3
• Assignee: Kevin Klues
• Reporter: Kevin Klues
• Shepherd: Jie Yu
• Created: 24/Oct/16 22:42
• Updated: 06/Dec/16 23:19
• Resolved: 01/Dec/16 20:10

Description

In order to facilitate attach operations for a running container, we plan to introduce a new component into Mesos known as an “I/O switchboard”. The goal of this switchboard is to allow external components to dynamically interpose on the stdin, stdout and stderr of the init process of a running Mesos container. It will be implemented as a per-container, stand-alone process launched by the mesos containerizer at the time a container is first launched.

Each per-container switchboard will be responsible for the following:

• Accepting a single dynamic request to register an fd for streaming data to the stdin of a container’s init process.
• Accepting multiple dynamic requests to register fds for streaming data from the stdout and stderr of a container’s init process to those fds.
• Allocating a pty for the new process (if requested), and directing data through the master fd of the pty as necessary.
• Passing the actual set of file descriptors that should be dup’d onto the stdin, stdout and stderr of a container’s init process back to the containerizer.

The idea being that the switchboard will maintain three asynchronous loops (one each for stdin, stdout and stderr) that constantly pipe data to/from a container’s init process to/from all of the file descriptors that have been dynamically registered with it.

Issue Links

• relates to: MESOS-6469 Build an Attach Container Actor