Troubleshooting

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Estimated reading time: 6 minutes

Typically, the QuickStart works out-of-the-box, but some scenarios can cause problems.

Example errors

You might get errors when attempting to connect to a machine (such as with docker-machine env default) or pull an image from Docker Hub (as with docker run hello-world).

The errors you get might be specific to certificates, like this:

  Error checking TLS connection: Error checking and/or regenerating the certs: There was an error validating certificates for host "192.168.99.100:2376": dial tcp 192.168.99.100:2376: i/o timeout

Others explicitly suggest regenerating certificates:

  Error checking TLS connection: Error checking and/or regenerating the certs: There was an error validating certificates for host "192.168.99.100:2376": x509: certificate is valid for 192.168.99.101, not 192.168.99.100
  You can attempt to regenerate them using 'docker-machine regenerate-certs [name]'.
  Be advised that this will trigger a Docker daemon restart which will stop running containers.

Or, indicate a network timeout, like this:

  bash-3.2$ docker run hello-world
  Unable to find image 'hello-world:latest' locally
  Pulling repository docker.io/library/hello-world
  Network timed out while trying to connect to https://index.docker.io/v1/repositories/library/hello-world/images. You may want to check your internet connection or if you are behind a proxy.
  bash-3.2$

Solutions

Here are some quick solutions to help get back on track. These examples assume the Docker host is a machine called default.

Regenerate certificates

Some errors explicitly tell you to regenerate certificates. You might also try this for other errors that are certificate and/or connectivity related.

  $ docker-machine regenerate-certs default
    Regenerate TLS machine certs?  Warning: this is irreversible. (y/n): y
    Regenerating TLS certificates

Restart the Docker host

$ docker-machine restart default

After the machine starts, set the environment variables for the command window.

$ eval $(docker-machine env default)

Run docker-machine ls to verify that the machine is running and that this command window is configured to talk to it, as indicated by an asterisk for the active machine (*).

$ docker-machine ls
NAME             ACTIVE   DRIVER         STATE     URL                         SWARM   DOCKER    ERRORS
default          *        virtualbox     Running   tcp://192.168.99.101:2376           v1.10.1

Stop the machine, remove it, and create a new one.

$ docker-machine stop default
  Stopping "default"...
  Machine "default" was stopped.

$ docker-machine rm default
  About to remove default
  Are you sure? (y/n): y
  Successfully removed default

You can use the docker-machine create command with the virtualbox driver to create a new machine called default (or any name you want for the machine).

$ docker-machine create --driver virtualbox default
  Running pre-create checks...
  (default) Default Boot2Docker ISO is out-of-date, downloading the latest release...
  (default) Latest release for github.com/boot2docker/boot2docker is v1.10.1
  (default) Downloading
  ...
  Docker is up and running!
  To see how to connect your Docker Client to the Docker Engine running on this virtual machine, run: docker-machine env default

Set the environment variables for the command window.

$ eval $(docker-machine env default)

Run docker-machine ls to verify that the new machine is running and that this command window is configured to talk to it, as indicated by an asterisk for the active machine (*).

HTTP proxies and connectivity errors

A special brand of connectivity errors can be caused by HTTP proxy. If you install Docker Toolbox on a system using a virtual private network (VPN) that uses an HTTP proxy (such as a corporate network), you might encounter errors when the client attempts to connect to the server.

Here are examples of this type of error:

  $ docker run hello-world
  An error occurred trying to connect: Post https://192.168.99.100:2376/v1.20/containers/create: Forbidden

  $ docker run ubuntu echo "hi"
  An error occurred trying to connect: Post https://192.168.99.100:2376/v1.20/containers/create: Forbidden

Configure HTTP proxy settings on Docker machines

When Toolbox creates virtual machines (VMs) it runs start.sh, where it gets values for HTTP_PROXY, HTTPS_PROXY, and NO_PROXY, and passes them as create options to create the default machine.

You can reconfigure HTTP proxy settings for private networks on already-created Docker machines, such as the default machine, then change the configuration when you are using the same system on a different network.

Alternatively, you can modify proxy settings on your machine(s) manually through the configuration file at /var/lib/boot2docker/profile inside the VM, or configure proxy settings as a part of a docker-machine create command.

Both solutions are described below.

Update /var/lib/boot2docker/profile on the Docker machine

One way to solve this problem is to update the file /var/lib/boot2docker/profile on an existing machine to specify the proxy settings you want.

This file lives on the VM itself, so you need to ssh into the machine, then edit and save the file there.

You can add your machine addresses as values for a NO_PROXY setting, and also specify proxy servers that you know about and you want to use. Typically setting your Docker machine URLs to NO_PROXY solves this type of connectivity problem, so that example is shown here.

  1. Use ssh to log in to the virtual machine. This example logs in to the default machine.

     $ docker-machine ssh default
 docker@default:~$ sudo vi /var/lib/boot2docker/profile

  2. Add a NO_PROXY setting to the end of the file similar to the example below.

     # replace with your office's proxy environment
 export "HTTP_PROXY=http://PROXY:PORT"
 export "HTTPS_PROXY=http://PROXY:PORT"
 # you can add more no_proxy with your environment.
 export "NO_PROXY=192.168.99.*,*.local,169.254/16,*.example.com,192.168.59.*"

  3. Restart Docker.

    After you modify the profile on your VM, restart Docker and log out of the machine.

     docker@default:~$ sudo /etc/init.d/docker restart
 docker@default:~$ exit

Re-try Docker commands. Both Docker and Kitematic should run properly now.

When you move to a different network (for example, leave the office’s corporate network and return home), remove or comment out these proxy settings in /var/lib/boot2docker/profile and restart Docker.

Create machines manually using --engine env to specify proxy settings

Rather than reconfigure automatically-created machines, you can delete them and create your default machine and others manually with the docker-machine create command, using the --engine env flag to specify the proxy settings you want.

Here is an example of creating a default machine with proxies set to http://example.com:8080 and https://example.com:8080, and a N0_PROXY setting for the server example2.com.

docker-machine create -d virtualbox \
--engine-env HTTP_PROXY=http://example.com:8080 \
--engine-env HTTPS_PROXY=https://example.com:8080 \
--engine-env NO_PROXY=example2.com \
default

To learn more about using docker-machine create, see the create command in the Docker Machine reference.

 

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