The Docker-engine is the official package from the Docker Corporation for Ubuntu-based systems. In the next section, we will see how to check for the version of Docker that was installed. Docker Version. To see the version of Docker running, you can issue the following command − Syntax docker version Options. When the Docker for Mac application starts up, it copies the ~/.docker/certs.d folder on your Mac to the /etc/docker/certs.d directory on Moby (the Docker for Mac xhyve virtual machine). You need to restart Docker for Mac after making any changes to the keychain or to the ~/.docker/certs.d directory in order for the changes to take effect.
$ docker run hello-world Unable to find image 'hello-world:latest' locally latest: Pulling from library/hello-world ca4f61b1923c: Pull complete Digest: sha256:ca0eeb6fb05351dfc8759c20733c91def84cb8007aa89a5bf606bc8b315b9fc7 Status: Downloaded newer image for hello-world:latest Hello from Docker! This message shows that your installation appears to be working correctly. Start a Dockerized web server. Like the hello-world image above, if the image is not found locally, Docker pulls it from Docker Hub. $ docker run -detach -publish =80:80 -name =webserver nginx. In a web browser, go to to view the nginx homepage.
Because we specified the default HTTP port, it isn’t necessary to append:80 at the end of the URL. Early beta releases used docker as the hostname to build the URL. Now, ports are exposed on the private IP addresses of the VM and forwarded to localhost with no other host name set. View the details on the container while your web server is running (with docker container ls or docker ps): $ docker container ls CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 90 nginx 'nginx -g 'daemon off' About a minute ago Up About a minute 0.0.0.0:80-80/tcp, 443/tcp webserver. Stop and remove containers and images with the following commands. Use the “all” flag ( -all or -a) to view stopped containers.
$ docker container ls $ docker container stop webserver $ docker container ls -a $ docker container rm webserver $ docker image ls $ docker image rm nginx Preferences menu Choose → Preferences from the menu bar and configure the runtime options described below. General General settings are:. Start Docker when you log in: Uncheck this option if you don’t want Docker to start when you open your session. Automatically check for updates notifies you when an update is available. Click OK to accept and install updates (or cancel to keep the current version). If you disable this option, you can still find out about updates manually by choosing → Check for Updates. Include VM in Time Machine backups backs up the Docker for Mac virtual machine.
(Disabled by default.). Securely store Docker logins in MacOS keychain stores your Docker login credentials. (Enabled by default.). Send usage statistics — Send diagnostics, crash reports, and usage data to Docker. This information helps Docker improve the application and get more context for troubleshooting problems.
(Enabled by default.) File sharing Choose which local directories to share with your containers. File sharing is required for volume mounting if the project lives outside of the /Users directory. In that case, share the drive where the Dockerfile and volume are located.
Otherwise, you get file not found 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. There are some limitations on the directories that can be shared:. They cannot be a subdirectory of an already shared directory. They cannot already exist inside of Docker. For more information, see:. in the topic on.) Advanced On the Advanced tab, you can limit resources available to Docker. Advanced settings are: CPUs: By default, Docker for Mac 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 for Mac is set to use 2 GB runtime memory, allocated from the total available memory on your Mac. To increase 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 Specify the Disk image location of the Linux volume, where containers and images are stored. You can also move the disk image location. If you attempt to move the 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. Proxies Docker for Mac detects HTTP/HTTPS Proxy Settings from macOS and automatically propagates these to Docker and to your containers.
For example, if you set your proxy settings to Docker uses this proxy when pulling containers. When you start a container, your proxy settings propagate into the containers. $ docker run -it alpine env PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin HOSTNAME=b7edf988b2b5 TERM=xterm HOME=/root HTTPPROXY=httpproxy=noproxy=.local, 169.254/16 You can see from the above output that the HTTPPROXY, httpproxy, and noproxy environment variables are set. When your proxy configuration changes, Docker restarts automatically to pick up the new settings. If you have containers that you wish to keep running across restarts, you should consider using.
Daemon You can configure options on the Docker daemon that determine how your containers run. Select Basic to configure the daemon with interactive settings, or select Advanced to edit the JSON directly. Experimental features Both Docker for Mac Stable and Edge releases have experimental features enabled on Docker Engine, as described. If you uncheck experimental mode, Docker for Mac uses the current generally available release of Docker Engine.
Don’t enable experimental features in production Experimental features are not appropriate for production environments or workloads. They are meant to be sandbox experiments for new ideas. Some experimental features may become incorporated into upcoming stable releases, but others may be modified or pulled from subsequent Edge releases, and never released on Stable. 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.). $ kubectl config get-contexts $ kubectl config use-context docker-for-desktop If you installed kubectl with Homebrew, or by some other method, and experience conflicts, remove /usr/local/bin/kubectl. To enable Kubernetes support and install a standalone instance of Kubernetes running as a Docker container, select Enable Kubernetes, choose the and click the Apply button.
An Internet connection is required. Images required to run the Kubernetes server are downloaded and instantiated as containers, and the /usr/local/bin/kubectl command is installed on your Mac. When Kubernetes is enabled and running, an additional status bar item displays at the bottom right of the Docker for Mac Preferences dialog. The status of Kubernetes shows in the Docker menu and the context points to docker-for-desktop. By default, Kubernetes containers are hidden from commands like docker service ls, because managing them manually is not supported. To make them visible, select Show system containers (advanced) and click Apply and restart. Most users do not need this option.
To disable Kubernetes support at any time, deselect Enable Kubernetes. The Kubernetes containers are stopped and removed, and the /usr/local/bin/kubectl command is removed. For more about using the Kubernetes integration with Docker for Mac, see. Reset Select - Preferences from the menu bar, then click Reset to reset factory defaults, restart the Docker daemon, or uninstall. Reset settings are:. Restart - Select to restart the Docker daemon. Remove all data - This option removes/resets all Docker data without a reset to factory defaults (which would cause you to lose settings).
Reset to factory defaults - Choose this option to reset all options on Docker for Mac to its initial state, the same as when it was first installed. Uninstall - Choose this option to remove Docker for Mac from your system. Uninstall Docker for Mac from the commandline To uninstall Docker from Mac from a terminal, run: -uninstall. If your instance is installed in the default location, this command provides a clean uninstall. $ /Applications/Docker.app/Contents/MacOS/Docker -uninstall Docker is running, exiting. Docker uninstalled successfully.
You can move the Docker application to the trash. You might want to use the command-line uninstall if, for example, you find that the app is non-functional, and you cannot uninstall it from the menu. 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 for Mac 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 for Mac.
To manually add a custom, self-signed certificate, start by adding the certificate to the macOS keychain, which is picked up by Docker for Mac. Here is an example. $ security add-trusted-cert -d -r trustRoot -k /Library/Keychains/login.keychain ca.crt See also,. Note: You need to restart Docker for Mac 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.
Add client certificates You can put your client certificates in /.docker/certs.d/:/client.cert and /.docker/certs.d/:/client.key. When the Docker for Mac application starts up, it copies the /.docker/certs.d folder on your Mac to the /etc/docker/certs.d directory on Moby (the Docker for Mac xhyve virtual machine). You need to restart Docker for Mac 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 for Mac 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//.docker/certs.d/ └──: ├── 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 in the Docker Engine topics. Install shell completion Docker for Mac comes with scripts to enable completion for the docker, docker-machine, 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 To activate completion for Docker commands, these files need to be copied or symlinked to your bashcompletion.d/ directory.
For example, if you installed bash via. Etc =/Applications/Docker.app/Contents/Resources/etc ln -s $etc/docker.zsh-completion /usr/local/share/zsh/site-functions/docker ln -s $etc/docker-machine.zsh-completion /usr/local/share/zsh/site-functions/docker-machine ln -s $etc/docker-compose.zsh-completion /usr/local/share/zsh/site-functions/docker-compose Give feedback and get help To get help from the community, review current user topics, join or start a discussion, log on to our. To report bugs or problems, log on to, where you can review community reported issues, and file new ones. See for more details. To give us feedback on the documentation or update it yourself, use the Feedback options at the bottom of each docs page.
Docker Hub You can access your account from within Docker for Mac. From the Docker for Mac menu, sign in to Docker Hub with your Docker ID, or create one. Then use the Docker for Mac menu to create, view, or navigate directly to your Cloud resources, including organizations, repositories, and swarms. Check out these to learn more:. Where to go next.
Try out the walkthrough at. Dig in deeper with example walkthroughs and source code.
For a summary of Docker command line interface (CLI) commands, see. Check out the blog post,.
Status: Deprecated This article is deprecated and no longer maintained. See Instead This article may still be useful as a reference, but may not work or follow best practices. We strongly recommend using a recent article written for the operating system you are using. The latest version of this article is available at. Introduction The provided use cases are limitless and the need has always been there.
Is here to offer you an efficient, speedy way to port applications across systems and machines. It is light and lean, allowing you to quickly contain applications and run them within their own secure environments (via Linux Containers: LXC). In this DigitalOcean article, we aim to thoroughly introduce you to Docker: one of the most exciting and powerful open-source projects to come to life in the recent years. Docker can help you with so much it’s unfair to attempt to summarize its capabilities in one sentence. The Docker Project and its Main Parts 3. Docker Elements.
Docker Containers. Docker Images. Dockerfiles 4. How to Install Docker 5. How To Use Docker. Beginning.
Working with Images. Working with Containers Docker Whether it be from your development machine to a remote server for production, or packaging everything for use elsewhere, it is always a challenge when it comes to porting your application stack together with its dependencies and getting it to run without hiccups. In fact, the challenge is immense and solutions so far have not really proved successful for the masses. In a nutshell, docker as a project offers you the complete set of higher-level tools to carry everything that forms an application across systems and machines - virtual or physical - and brings along loads more of great benefits with it.
Docker achieves its robust application (and therefore, process and resource) containment via Linux Containers (e.g. Namespaces and other kernel features). Its further capabilities come from a project's own parts and components, which extract all the complexity of working with lower-level linux tools/APIs used for system and application management with regards to securely containing processes. The Docker Project and its Main Parts Docker project (open-sourced by dotCloud in March '13) consists of several main parts (applications) and elements (used by these parts) which are all mostly built on top of already existing functionality, libraries and frameworks offered by the Linux kernel and third-parties (e.g. LXC, device-mapper, aufs etc.). Main Docker Parts. docker daemon: used to manage docker (LXC) containers on the host it runs.
docker CLI: used to command and communicate with the docker daemon. docker image index: a repository (public or private) for docker images Main Docker Elements. docker containers: directories containing everything-your-application.
docker images: snapshots of containers or base OS (e.g. Ubuntu) images. Dockerfiles: scripts automating the building process of images Docker Elements The following elements are used by the applications forming the docker project.
Docker Containers The entire procedure of porting applications using docker relies solely on the shipment of containers. Docker containers are basically directories which can be packed (e.g. Tar-archived) like any other, then shared and run across various different machines and platforms (hosts). The only dependency is having the hosts tuned to run the containers (i.e.
Have docker installed). Containment here is obtained via Linux Containers (LXC). LXC (Linux Containers) Linux Containers can be defined as a combination various kernel-level features (i.e. Things that Linux-kernel can do) which allow management of applications (and resources they use) contained within their own environment. By making use of certain features (e.g. Namespaces, chroots, cgroups and SELinux profiles), the LXC contains application processes and helps with their management through limiting resources, not allowing reach beyond their own file-system (access to the parent's namespace) etc. Docker with its containers makes use of LXC, however, also brings along much more.
Docker Containers Docker containers have several main features. They allow;. Application portability. Isolating processes. Prevention from tempering with the outside. Managing resource consumption and more, requiring much less resources than traditional virtual-machines used for isolated application deployments.
They do not allow;. Messing with other processes. Causing 'dependency hell'. Or not working on a different system. Being vulnerable to attacks and abuse all system's resources and (also) more.
Being based and depending on LXC, from a technical aspect, these containers are like a directory (but a shaped and formatted one). This allows portability and gradual builds of containers. Each container is layered like an onion and each action taken within a container consists of putting another block (which actually translates to a simple change within the file system) on top of the previous one.
And various tools and configurations make this set-up work in a harmonious way altogether (e.g. Union file-system). What this way of having containers allows is the extreme benefit of easily launching and creating new containers and images, which are thus kept lightweight (thanks to gradual and layered way they are built).
Since everything is based on the file-system, taking snapshots and performing roll-backs in time are cheap (i.e. Very easily done / not heavy on resources), much like version control systems (VCS).
Each docker container starts from a docker image which forms the base for other applications and layers to come. Docker Images Docker images constitute the base of docker containers from which everything starts to form. They are very similar to default operating-system disk images which are used to run applications on servers or desktop computers. Having these images (e.g. Ubuntu base) allow seamless portability across systems. They make a solid, consistent and dependable base with everything that is needed to run the applications.
When everything is self-contained and the risk of system-level updates or modifications are eliminated, the container becomes immune to external exposures which could put it out of order - preventing the dependency hell. As more layers (tools, applications etc.) are added on top of the base, new images can be formed by committing these changes. When a new container gets created from a saved (i.e. Committed) image, things continue from where they left off. And the, brings all the layers together as a single entity when you work with a container.
These base images can be explicitly stated when working with the docker CLI to directly create a new container or they might be specified inside a Dockerfile for automated image building. Dockerfiles Dockerfiles are scripts containing a successive series of instructions, directions, and commands which are to be executed to form a new docker image. Each command executed translates to a new layer of the onion, forming the end product. They basically replace the process of doing everything manually and repeatedly. When a Dockerfile is finished executing, you end up having formed an image, which then you use to start (i.e. Create) a new container. How To Install Docker At first, docker was only available on Ubuntu.
Nowadays, it is possible to deploy docker on RHEL based systems (e.g. CentOS) and others as well.
Let's quickly go over the installation process for Ubuntu. Note: Docker can be installed automatically on your Droplet by adding to its User Data when launching it. Check out to learn more about Droplet User Data.