Docker Desktop for Mac user manual

Estimated reading time: 15 minutes

Welcome to Docker Desktop! The Docker Desktop for Mac user manual provides information on how to configure and manage your Docker Desktop settings.

For information about Docker Desktop download, system requirements, and installation instructions, see Install Docker Desktop.

Preferences

The Docker Preferences menu allows you to configure your Docker settings such as installation, updates, version channels, Docker Hub login, and more.

Choose the Docker menu > Preferences from the menu bar and configure the runtime options described below.

General

On the General tab, you can configure when to start and update Docker:

• Automatically check for updates: By default, Docker Desktop is configured to check for newer versions automatically. If you have installed Docker Desktop as part of an organization, you may not be able to update Docker Desktop yourself. In that case, upgrade your existing organization to a Team plan and clear this checkbox to disable the automatic check for updates.

• Start Docker Desktop when you log in: Automatically starts Docker Desktop when you open your session.

• Include VM in Time Machine backups: Select this option to back up the Docker Desktop virtual machine. This option is disabled by default.

• Use gRPC FUSE for file sharing: Clear this checkbox to use the legacy osxfs file sharing instead.

• Send usage statistics: Docker Desktop sends diagnostics, crash reports, and usage data. This information helps Docker improve and troubleshoot the application. Clear the check box to opt out.

• Show weekly tips: Displays useful advice and suggestions about using Docker.

• Open Docker Desktop dashboard at startup: Automatically opens the dashboard when starting Docker Desktop.

Resources

The Resources tab allows you to configure CPU, memory, disk, proxies, network, and other resources.

Advanced

On the Advanced tab, you can limit resources available to Docker.

Advanced settings are:

• CPUs: By default, Docker Desktop is set to use half the number of processors available on the host machine. To increase processing power, set this to a higher number; to decrease, lower the number.

• Memory: By default, Docker Desktop is set to use 2 GB runtime memory, allocated from the total available memory on your Mac. To increase the RAM, set this to a higher number. To decrease it, lower the number.

• Swap: Configure swap file size as needed. The default is 1 GB.

• Disk image size: Specify the size of the disk image.

• Disk image location: Specify the location of the Linux volume where containers and images are stored.

You can also move the disk image to a different location. If you attempt to move a disk image to a location that already has one, you get a prompt asking if you want to use the existing image or replace it.

File sharing

Use File sharing to allow local directories on the Mac to be shared with Linux containers. This is especially useful for editing source code in an IDE on the host while running and testing the code in a container. By default the /Users, /Volume, /private, /tmp and /var/folders directory are shared. If your project is outside this directory then it must be added to the list. Otherwise you may get Mounts denied or cannot start service errors at runtime.

File share settings are:

• Add a Directory: Click + and navigate to the directory you want to add.

• Apply & Restart makes the directory available to containers using Docker’s bind mount (-v) feature.

Tips on shared folders, permissions, and volume mounts

• Share only the directories that you need with the container. File sharing introduces overhead as any changes to the files on the host need to be notified to the Linux VM. Sharing too many files can lead to high CPU load and slow filesystem performance.

• Shared folders are designed to allow application code to be edited on the host while being executed in containers. For non-code items such as cache directories or databases, the performance will be much better if they are stored in the Linux VM, using a data volume (named volume) or data container.

• If you share the whole of your home directory into a container, MacOS may prompt you to give Docker access to personal areas of your home directory such as your Reminders or Downloads.

• By default, Mac file systems are case-insensitive while Linux is case-sensitive. On Linux, it is possible to create 2 separate files: test and Test, while on Mac these filenames would actually refer to the same underlying file. This can lead to problems where an app works correctly on a Mac (where the file contents are shared) but fails when run in Linux in production (where the file contents are distinct). To avoid this, Docker Desktop insists that all shared files are accessed as their original case. Therefore, if a file is created called test, it must be opened as test. Attempts to open Test will fail with the error No such file or directory. Similarly, once a file called test is created, attempts to create a second file called Test will fail. For more information, see Volume mounting requires file sharing for any project directories outside of /Users.)

Proxies

Docker Desktop detects HTTP/HTTPS Proxy Settings from macOS and automatically propagates these to Docker. For example, if you set your proxy settings to http://proxy.example.com, Docker uses this proxy when pulling containers.

Your proxy settings, however, will not be propagated into the containers you start. If you wish to set the proxy settings for your containers, you need to define environment variables for them, just like you would do on Linux, for example:

$ docker run -e HTTP_PROXY=http://proxy.example.com:3128 alpine env

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=b7edf988b2b5
TERM=xterm
HOME=/root
HTTP_PROXY=http://proxy.example.com:3128

For more information on setting environment variables for running containers, see Set environment variables.

Network

You can configure Docker Desktop networking to work on a virtual private network (VPN). Specify a network address translation (NAT) prefix and subnet mask to enable Internet connectivity.

Docker Engine

The Docker Engine page allows you to configure the Docker daemon to determine how your containers run.

Type a JSON configuration file in the box to configure the daemon settings. For a full list of options, see the Docker Engine dockerd commandline reference.

Click Apply & Restart to save your settings and restart Docker Desktop.

Command Line

On the Command Line page, you can specify whether or not to enable experimental features.

Experimental features provide early access to future product functionality. These features are intended for testing and feedback only as they may change between releases without warning or can be removed entirely from a future release. Experimental features must not be used in production environments. Docker does not offer support for experimental features.

For a list of current experimental features in the Docker CLI, see Docker CLI Experimental features.

You can toggle the experimental features on and off in Docker Desktop. If you toggle the experimental features off, Docker Desktop uses the current generally available release of Docker Engine.

You can see whether you are running experimental mode at the command line. If Experimental is true, then Docker is running in experimental mode, as shown here. (If false, Experimental mode is off.)

> docker version

Client: Docker Engine - Community
 Version:           19.03.1
 API version:       1.40
 Go version:        go1.12.5
 Git commit:        74b1e89
 Built:             Thu Jul 25 21:18:17 2019
 OS/Arch:           darwin/amd64
 Experimental:      true

Server: Docker Engine - Community
 Engine:
  Version:          19.03.1
  API version:      1.40 (minimum version 1.12)
  Go version:       go1.12.5
  Git commit:       74b1e89
  Built:            Thu Jul 25 21:17:52 2019
  OS/Arch:          linux/amd64
  Experimental:     true
 containerd:
  Version:          v1.2.6
  GitCommit:        894b81a4b802e4eb2a91d1ce216b8817763c29fb
 runc:
  Version:          1.0.0-rc8
  GitCommit:        425e105d5a03fabd737a126ad93d62a9eeede87f
 docker-init:
  Version:          0.18.0
  GitCommit:        fec3683

Kubernetes

Docker Desktop includes a standalone Kubernetes server that runs on your Mac, so that you can test deploying your Docker workloads on Kubernetes. To enable Kubernetes support and install a standalone instance of Kubernetes running as a Docker container, select Enable Kubernetes.

For more information about using the Kubernetes integration with Docker Desktop, see Deploy on Kubernetes.

Reset

Reset and Restart options

On Docker Desktop Mac, the Restart Docker Desktop, Reset to factory defaults, and other reset options are available from the Troubleshoot menu.

For information about the reset options, see Logs and Troubleshooting.

Dashboard

The Docker Desktop Dashboard enables you to interact with containers and applications and manage the lifecycle of your applications directly from your machine. The Dashboard UI shows all running, stopped, and started containers with their state. It provides an intuitive interface to perform common actions to inspect and manage containers and existing Docker Compose applications. For more information, see Docker Desktop Dashboard.

Add TLS certificates

You can add trusted Certificate Authorities (CAs) (used to verify registry server certificates) and client certificates (used to authenticate to registries) to your Docker daemon.

Add custom CA certificates (server side)

All trusted CAs (root or intermediate) are supported. Docker Desktop creates a certificate bundle of all user-trusted CAs based on the Mac Keychain, and appends it to Moby trusted certificates. So if an enterprise SSL certificate is trusted by the user on the host, it is trusted by Docker Desktop.

To manually add a custom, self-signed certificate, start by adding the certificate to the macOS keychain, which is picked up by Docker Desktop. Here is an example:

$ sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain ca.crt

Or, if you prefer to add the certificate to your own local keychain only (rather than for all users), run this command instead:

$ security add-trusted-cert -d -r trustRoot -k ~/Library/Keychains/login.keychain ca.crt

See also, Directory structures for certificates.

Note: You need to restart Docker Desktop after making any changes to the keychain or to the ~/.docker/certs.d directory in order for the changes to take effect.

For a complete explanation of how to do this, see the blog post Adding Self-signed Registry Certs to Docker & Docker Desktop for Mac.

Add client certificates

You can put your client certificates in ~/.docker/certs.d/<MyRegistry>:<Port>/client.cert and ~/.docker/certs.d/<MyRegistry>:<Port>/client.key.

When the Docker Desktop application starts, it copies the ~/.docker/certs.d folder on your Mac to the /etc/docker/certs.d directory on Moby (the Docker Desktop xhyve virtual machine).

• You need to restart Docker Desktop after making any changes to the keychain or to the ~/.docker/certs.d directory in order for the changes to take effect.

• The registry cannot be listed as an insecure registry (see Docker Engine. Docker Desktop ignores certificates listed under insecure registries, and does not send client certificates. Commands like docker run that attempt to pull from the registry produce error messages on the command line, as well as on the registry.

Directory structures for certificates

If you have this directory structure, you do not need to manually add the CA certificate to your Mac OS system login:

/Users/<user>/.docker/certs.d/
└── <MyRegistry>:<Port>
   ├── ca.crt
   ├── client.cert
   └── client.key

The following further illustrates and explains a configuration with custom certificates:

/etc/docker/certs.d/        <-- Certificate directory
└── localhost:5000          <-- Hostname:port
   ├── client.cert          <-- Client certificate
   ├── client.key           <-- Client key
   └── ca.crt               <-- Certificate authority that signed
                                the registry certificate

You can also have this directory structure, as long as the CA certificate is also in your keychain.

/Users/<user>/.docker/certs.d/
└── <MyRegistry>:<Port>
    ├── client.cert
    └── client.key

To learn more about how to install a CA root certificate for the registry and how to set the client TLS certificate for verification, see Verify repository client with certificates in the Docker Engine topics.

Install shell completion

Docker Desktop comes with scripts to enable completion for the docker and docker-compose commands. The completion scripts may be found inside Docker.app, in the Contents/Resources/etc/ directory and can be installed both in Bash and Zsh.

Bash

Bash has built-in support for completion To activate completion for Docker commands, these files need to be copied or symlinked to your bash_completion.d/ directory. For example, if you installed bash via Homebrew:

etc=/Applications/Docker.app/Contents/Resources/etc
ln -s $etc/docker.bash-completion $(brew --prefix)/etc/bash_completion.d/docker
ln -s $etc/docker-compose.bash-completion $(brew --prefix)/etc/bash_completion.d/docker-compose

Add the following to your ~/.bash_profile:

[ -f /usr/local/etc/bash_completion ] && . /usr/local/etc/bash_completion

OR

if [ -f $(brew --prefix)/etc/bash_completion ]; then
. $(brew --prefix)/etc/bash_completion
fi

Zsh

In Zsh, the completion system takes care of things. To activate completion for Docker commands, these files need to be copied or symlinked to your Zsh site-functions/ directory. For example, if you installed Zsh via Homebrew:

etc=/Applications/Docker.app/Contents/Resources/etc
ln -s $etc/docker.zsh-completion /usr/local/share/zsh/site-functions/_docker
ln -s $etc/docker-compose.zsh-completion /usr/local/share/zsh/site-functions/_docker-compose

Fish-Shell

Fish-shell also supports tab completion completion system. To activate completion for Docker commands, these files need to be copied or symlinked to your Fish-shell completions/ directory.

Create the completions directory:

mkdir -p ~/.config/fish/completions

Now add fish completions from docker.

ln -shi /Applications/Docker.app/Contents/Resources/etc/docker.fish-completion ~/.config/fish/completions/docker.fish
ln -shi /Applications/Docker.app/Contents/Resources/etc/docker-compose.fish-completion ~/.config/fish/completions/docker-compose.fish

Give feedback and get help

To get help from the community, review current user topics, join or start a discussion, log on to our Docker Desktop for Mac forum.

To report bugs or problems, log on to Docker Desktop for Mac issues on GitHub, where you can review community reported issues, and file new ones. See Logs and Troubleshooting for more details.

For information about providing feedback on the documentation or update it yourself, see Contribute to documentation.

Docker Hub

Select Sign in /Create Docker ID from the Docker Desktop menu to access your Docker Hub account. Once logged in, you can access your Docker Hub repositories and organizations directly from the Docker Desktop menu.

For more information, refer to the following Docker Hub topics:

• Organizations and Teams in Docker Hub
• Builds

Two-factor authentication

Docker Desktop enables you to sign into Docker Hub using two-factor authentication. Two-factor authentication provides an extra layer of security when accessing your Docker Hub account.

You must enable two-factor authentication in Docker Hub before signing into your Docker Hub account through Docker Desktop. For instructions, see Enable two-factor authentication for Docker Hub.

After you have enabled two-factor authentication:

1. Go to the Docker Desktop menu and then select Sign in / Create Docker ID.

2. Enter your Docker ID and password and click Sign in.

3. After you have successfully signed in, Docker Desktop prompts you to enter the authentication code. Enter the six-digit code from your phone and then click Verify.

After you have successfully authenticated, you can access your organizations and repositories directly from the Docker Desktop menu.

Where to go next

• Try out the walkthrough at Get Started.

• Dig in deeper with Docker Labs example walkthroughs and source code.

• For a summary of Docker command line interface (CLI) commands, see Docker CLI Reference Guide.

• Check out the blog post, What’s New in Docker 17.06 Community Edition (CE).