Break the Docker for Mac host-to-container networking

This repo has code that reproducibly breaks the host-to-container networking of Docker for Mac.

See docker/for-mac#3487 for background and discussion.

Note:

This code reproducibly breaks the host-to-container networking of Docker for Mac. It runs a MariaDB container and then accesses that container in a way that breaks Docker's host-to-container networking. If the code succeeds, the symptom will be that all new network connections from the host to any running container fail with a timeout error. You will have to restart the Docker engine and the running containers.

Prerequisites

You will need the following installed on your Mac:

• Docker for Mac 2.0.0.3 (Docker engine 18.09.2)
• or
• Docker for Mac 2.0.0.2 (Docker engine 18.09.1)
• NodeJS version 8.12 or higher
• npm version 6.4.1 or higher
• bash version 3.2.57 or higher

bash-3.2$ docker --version
Docker version 18.09.2, build 6247962

bash-3.2$ node --version
v8.12.0

bash-3.2$ npm --version
6.4.1

bash-3.2$ bash --version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin17)
Copyright (C) 2007 Free Software Foundation, Inc.

How to use

Docker for Mac must be running. No process can be listening on port 23456.

To break the Docker engine, run the shell script ./go.sh in a terminal. It will need you to confirm that you want to try to break the Docker engine. If so, hit Return and wait patiently for up to 60 seconds.

It starts a MariaDB container. It builds a tiny NodeJS app to talk to the DB container. It runs the NodeJS app. Log messages from both a MariaDB container and various shell and NodeJs processes will be interleaved, including failed connection messages.

Be patient.

A successful breakage of the Docker engine will be indicated by logging messages in the terminal that end with something like this:

  ...

sequelize: created table
sequelize: created model
AttachmentBlob: Executing (e9bf39e0-d14f-4457-939d-710f57d68d95): START TRANSACTION;
AttachmentBlob: Executing (e9bf39e0-d14f-4457-939d-710f57d68d95): SELECT `documentIdentifier`, `documentBlob`, `createdAt`, `updatedAt` FROM `AttachmentBlobs` AS `AttachmentBlob` WHERE `AttachmentBlob`.\
`documentIdentifier` = 'a1444c70d63e03af60867b1f05ec6cc4da24fd9a2820bf7b6c9814f43edbd4ac' AND `AttachmentBlob`.`documentBlob` = X'494433030000000f3729505249560000200f00007777772e616d617a6f6e2e636f6d003c\
3f786d6c2076657273696f6e3d22312e302220656e636f64696e673d225554462d38223f3e0a3c756974733a5549545320786d6c6e733a7873693d226874 ... for 31107060 characters
2019-01-27 18:50:41 11 [Warning] Aborted connection 11 to db: 'docker' user: 'docker' host: '172.17.0.1' (Got a packet bigger than 'max_allowed_packet' bytes)
AttachmentBlob: Executing (e9bf39e0-d14f-4457-939d-710f57d68d95): COMMIT;
succeeded to find trouble: SequelizeDatabaseError: This socket has been ended by the other party

*** fail *** : code 1 : .../go.sh

The smoking-gun part is this:

Got a packet bigger than 'max_allowed_packet' bytes

If you run go.sh again, it will eventually fail with a connection timeout. This is the symptom that the Docker engine's host-to-container networking is broken. If you get a connection refusal, that suggests the Docker engine isn't even running (not an expected outcome). You can also run any other image/container and you should get a timeout error when trying to connect to an exposed port from the host.

go.sh will create a couple of Untracked directories:

  mysql/
  node_modules/

go.sh will leave a Docker container running MariaDB.

docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
a8893615e84d        mariadb:10.3        "docker-entrypoint.s…"   13 minutes ago      Up 13 minutes       0.0.0.0:23456->3306/tcp   dockerbug

You can kill it with ./stop.sh

You will have to restart the Docker engine via the Restart menu item under the Docker icon.

Details

• go.sh [fileName] -- kills running containers, starts the MariaDB container, runs npm install, runs go.js fileName
• go.js -- loads a blob from a file, connects to the DB with Sequelize, creates a table for blobs, sends the blob to the DB, boom!
• stop.sh -- stops the running MariaDB container, if any

Read the code.