Mac os docker volumes path

Docker Desktop for Mac user manual

Estimated reading time: 16 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.

Use Docker Compose V2: Select this option to enable the docker-compose command to use Docker Compose V2. For more information, see Docker Compose V2.

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:

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.)

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

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.

Software Updates

The Software Updates section notifies you of any updates available to Docker Desktop. You can choose to download the update right away, or click the Release Notes option to learn what’s included in the updated version.

If you are on a Docker Team or a Business subscription, you can turn off the check for updates by clearing the Automatically Check for Updates checkbox in the General settings. This will also disable the notification badge that appears on the Docker Dashboard.

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:

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

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

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:

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

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

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.

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Using volumes in Docker Compose

Posted on Jan 16, 2018. Updated at Jun 21, 2020

Purpose

The purpose of this post is to review how we can use volumes in Docker and Docker Compose. These are some possible scenarios:

• Use one/various volumes by one service/container.
• Use one/various volumes by one set of services (defined in the same docker-compose.yml file).
• Use one/various volumes across the Docker installation.

Before you begin

In this tutorial, we’ll learn how to use Docker Compose volumes. A GNU Linux/Mac OS/Windows machine with Docker and Docker Compose installed is required to follow this tutorial.

How to declare volumes in Docker

There are two ways of declaring volumes in Docker: The imperative way (Docker client) and the declarative way (Docker Compose yaml file or Docker Dockerfile).

In the this post you’ll see only how to do it in a declarative manner using a docker-compose file. But it’s worth mention that is also possible to declare volumes in Docker using their command line client:

Types of volumes in Docker

1. Docker host-mounted volumes

Syntax: /host/path : /container/path

Host path can be defined as an absolute or as a relative path.

2. Docker named volumes

Syntax: named_volume_name : /container/path

Named volumes can be defined as internal (default) or external.

2.1. Docker internal named volumes

Docker compose internal named volumes have the scope of a single Docker-compose file and Docker creates them if they don’t exist.

Docker Compose file example with a named volume web_data :

TIP 1: From Docker Compose version 3.4 the name of the volume can be dynamically generated from environment variables placed in an .env file (this file has to be in the same folder as docker-compose.yml is).

TIP 2: To increase the security in our system we can mount the volume as read-only if the container only needs to read the mounted files. This will prevent an attacker to modify or create new files in the host of the server for example.

Example of .env file:

Example of a Docker Compose file with and internal docker named volume based on an environment variable:

docker-compose up will generate a volume called my_volume_001.

2.2. Docker external named volumes

Docker compose external named volumes can be used across the Docker installation and they need to be created by the user (otherwise fails) using the docker volume create command.

Defines web_data volume:

docker-compose.yml file with a named volume web_data defined externally:

There are different volume types like nfs, btrfs, ext3, ext4 and also 3rd party plugins to create volumes.

External named volumes can be defined dynamically from environment variables using a name section as we did in the previous example.

3. Sharing volumes

Syntax: —volumes-from container_name

We can start a new container using volumes defined in another. Similar to -v or —volume but without having to define a volume or mounting paths.

Note: —volumes-from make sense if we are using just Docker. For Docker-compose we can use top-level volumes as we did in previous section and make them available to more than one service. Example sharing web_data to app and app2:

Remove Docker volumes

If you followed this tutorial you might have lots of Docker populated volumes. If you need to delete them, you can use the following post to delete the existing Docker volumes running in your system.

Final thoughts

One of the main benefits of using Docker volumes is the ability of changing the content/configuration of a container without the need of recreating it.

You should take into account that if the content of a container will never change probably is better to copy content once you are building its Docker image.

Finally, if you need to provide changes to a container that has no volumes attached with it and it is not possible to recreate it, there is always the option of copy files directly to a running container.

Recommended books to expand your Docker knowledge:

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