If the content not Found, you must refresh this page manually. Docker for Windows Join Docker experts and the broader container community for thirty-six -in depth sessions, hang out with the Docker Captains in the live hallway track, and go behind the scenes with exclusive interviews with theCUBE. For example, Docker images do not ship with 6 different shells for you to choose from - they usually ship with a single minimalist shell, or no shell at all.
Learning by Google searches and Stack Overflow will lead to bad habits, misunderstandings, and gaps in knowledge. The whole reason for me writing this book is to help you get started with Docker and containers! This can be anything from your laptop, a bare metal server in your data center, all the way up to an instance the public cloud. It then packages them into a software construct called a virtual machine VM. We then take those VMs and install an operating system and application on each one.
Things are a bit different in the container model. When the server is powered on, your chosen OS boots. In the Docker world this can be Linux, or a modern version of Windows that has support for the container primitives in its kernel. Similar to the VM model, the OS claims all hardware resources. On top of the OS, we install a container engine such as Docker. The container engine then takes OS resources such as the process tree, the filesystem, and the network stack, and carves them up into secure isolated constructs called containers.
Each container looks smells and feels just like a real OS. Inside of each container we can run an application. This is shown in Figure 7. At a high level, we can say that hypervisors perform hardware virtualization — they carve up physical hardware resources into virtual versions.
On the other hand, containers perform OS virtualization — they carve up OS resources into virtual versions. We started out with a single physical server and the requirement to run 4 business applications. So far the models are almost identical.
But this is where the similarities stop. The VM model then carves low-level hardware resources into VMs. As such, every VM needs its own OS to claim, initialize, and manage all of those virtual resources. And sadly, every OS comes with its own set of baggage and overheads.
Most need their own licenses as well as people and infrastructure to patch and upgrade them. Each OS also presents a sizable attack surface. The container model has a single kernel running in the host OS.
A single OS that needs licensing. A single OS that needs upgrading and patching. And a single OS kernel presenting an attack surface. All in all, a single OS tax bill! That might not seem a lot in our example of a single server needing to run 4 business applications. Another thing to consider is start times. None of that is needed when starting a container! The single shared kernel, down at the OS level, is already started! Net result, containers can start in less than a second. This all amounts to the container model being leaner and more efficient than the VM model.
We can pack more applications onto less resources, start them faster, and pay less in licensing and admin costs, as well as present less of an attack surface to the dark side. Checking the Docker daemon The first thing I always do when I log on to a Docker host is check that Docker is running. As long as you get a response back in the Client and Server sections you should be good to go.
Starting a simple container The simplest way to start a container is with the docker container run command. The following command starts a simple container that will run a containerized version of Ubuntu Linux.
We started with docker container run, this is the standard command to start a new container. We then used the -it flags to make the container interactive and attach it to our terminal. Finally, we told it to run the Bash shell in the Linux example, and the PowerShell app in the Windows example.
It could, so it pulled it locally and stored it in its local cache. Once the image was pulled, the daemon created the container and executed the specified app inside of it.
Try executing some basic commands inside of the container. You might notice that some commands do not work. This is because the images we used, like almost all container images, are highly optimized for containers.
The following example shows a couple of commands — one succeeds and the other one fails. As shown in the output above, the ping utility is not included as part of the official Ubuntu image. This makes the Bash shell the one and only process running inside of the container. You can see this by running ps -elf from inside the container. The first process in the list, with PID 1, is the Bash shell we told the container to run. The second process is the ps -elf command we ran to produce the list.
This is a short-lived process that has already exited by the time the output is displayed. Note: Windows containers are slightly different and tend to run quite a few processes. This means that if you type exit, to exit the Bash shell, the container will also exit terminate.
This is also true of Windows containers — killing the main process in the container will also kill the container. Doing this will place you back in the shell of your Docker host and leave the container running in the background.
You can use the docker container ls command to view the list of running containers on your system. As you can see, the shell prompt has changed back to the container. If you run the ps command again you will now see two Bash or PowerShell processes. This is because the docker container exec command created a new Bash or PowerShell process and attached to that. This means that typing exit in this shell will not terminate the container, because the original Bash or PowerShell process will continue running.
It will still be running. If you are following along with the examples on your own Docker host, you should stop and delete the container with the following two commands you will need to substitute the ID of your container.
They can! The following examples will be from a Linux Docker host running an Ubuntu container. From within the shell of your new container, follow the procedure below to write some data to a new file in the tmp directory and verify that the write operation succeeded. Press Ctrl-PQ to exit the container without killing it. Now use the docker container stop command to stop the container and put in on vacation.
Now run a docker container ls command to list all running containers. The container is not listed in the output above because you put it in the stopped state with the docker container stop command.
Run the same command again, only this time add the -a flag to show all containers, including those that are stopped. Now we can see the container showing as Exited 0. Stopping a container is like stopping a virtual machine. The stopped container is now restarted. Time to verify that the file we created earlier still exists. Connect to the restarted container with the docker container exec command.
Your shell prompt will change to show that you are now operating within the namespace of the container. Verify that the file you created earlier is still there and contains the data you wrote to it. As if by magic, the file you created is still there and the data it contains is exactly how you left it! This proves that stopping a container does not destroy the container or the data inside of it. While this example illustrates the persistent nature of containers, I should point out that volumes are the preferred way to store persistent data in containers.
But at this stage of our journey I think this is an effective example of the persistent nature of containers. It is possible to delete a running container with a single command by passing the -f flag to docker container rm. More on this in a second. The next example will stop the percy container, delete it, and verify the operation.
The container is now deleted — literally wiped off the face of the planet. If it was a good container, it becomes a serverless function in the afterlife. If it was a naughty container, it becomes a dumb terminal :-D To summarize the lifecycle of a container… You can stop, start, pause, and restart a container as many times as you want. But the container and its data will always be safe. Stopping containers gracefully Most containers in the Linux world will run a single process.
In the Windows world they run a few processes, but the following rules still apply. The procedure is quite violent — a bit like sneaking up behind the container and shooting it in the back of the head. Once the docker stop command returns, you can then delete the container with docker container rm. As we just said, this gives the process a chance to clean things up and gracefully shut itself down. This is effectively the bullet to the head.
But hey, it got 10 seconds to sort itself out first! Like we said a second ago, this is like creeping up from behind and smashing it over the head. Restart policies are applied per-container, and can be configured imperatively on the command line as part of docker-container run commands, or declaratively in Compose files for use with Docker Compose and Docker Stacks.
At the time of writing, the following restart policies exist:. The always policy is the simplest. It will always restart a stopped container unless it has been explicitly stopped, such as via a docker container stop command. An easy way to demonstrate this is to start a new interactive container with the -- restart always policy, and tell it to run a shell process.
When the container starts you will be attached to its shell. We show this in the following example. Notice that the container was created 35 seconds ago, but has only been up for 1 second.
This is because we killed it when we issued the exit command from within the container, and Docker has had to restart it. An interesting feature of the --restart always policy is that a stopped container will be restarted when the Docker daemon starts. For example, you start a new container with the --restart always policy and then stop it with the docker container stop command. At this point the container is in the Stopped Exited state.
However, if you restart the Docker daemon, the container will be automatically restarted when the daemon comes back up. The main difference between the always and unless-stopped policies is that containers with the --restart unless-stopped policy will not be restarted when the daemon restarts if they were in the Stopped Exited state. The process for restarting Docker is different on different Operating Systems. This example shows how to stop Docker on Linux hosts running systemd.
To restart Docker on Windows Server use restart-service Docker. Once Docker has restarted, you can check the status of the containers. The on-failure policy will restart a container if it exits with a non-zero exit code. It will also restart containers when the Docker daemon restarts, even containers that were in the stopped state. If you are working with Docker Compose or Docker Stacks, you can apply the restart policy to a service object as follows:.
The image runs an insanely simple web server on port Use the docker container stop and docker container rm commands to clean up any existing containers on your system. Then run the following docker container run command. This is because we started this container in the background with the -d flag. Starting a container in the background does not attach it to your terminal. We know docker container run starts a new container. But this time we give it the -d flag instead of -it.
After that, we name the container and then give it -p The -p flag maps ports on the Docker host to ports inside the container. This means that traffic hitting the Docker host on port 80 will be directed to port inside of the container.
This means our container will come up running a web server listening on port This image is not kept up-to-date and will contain vulnerabilities! Running a docker container ls command will show the container as running and show the ports that are mapped. Up 2 mins 0. Now that the container is running and ports are mapped, we can connect to the container by pointing a web browser at the IP address or DNS name of the Docker host on port The same docker container stop, docker container pause, docker container start, and docker container rm commands can be used on the container.
Also, the same rules of persistence apply — stopping or pausing the container does not destroy the container or any data stored in it. Yet the container ran a simple web service. How did this happen? It also forces a default behavior and is a form of self documentation for the image — i.
Be warned though, the procedure will forcible destroy all containers without giving them a chance to clean up. This should never be performed on production systems or systems running important containers. Run the following command from the shell of your Docker host to delete all containers. In this example, we only had a single container running, so only one was deleted 6efacd We already know the docker container rm com- mand deletes containers. The -f flag forces the operation so that running containers will also be destroyed.
Net result… all containers, running or stopped, will be destroyed and removed from the system. The above command will work in a PowerShell terminal on a Windows Docker host. In its simplest form, it accepts an image and a command as arguments. The image is used to create the container and the command is the application you want the container to run.
If you add the -a flag you will also see containers in the stopped Exited state. For this to work, the image used to create your container must contain the Bash shell. You can give docker container start the name or ID of a container. You can specify con- tainers by name or ID. It is recommended that you stop a container with the docker container stop command before deleting it with docker container rm. It accepts container names and container IDs as its main argument.
Chapter summary In this chapter, we compared and contrasted the container and VM models. We looked at the OS tax problem inherent in the VM model, and saw how the container model can bring huge advantages in much the same way as the VM model brought huge advantages over the physical model.
We saw how to use the docker container run command to start a couple of simple containers, and we saw the difference between interactive containers in the foreground versus containers running in the background.
We know that killing the PID 1 process inside of a container will kill the container. We finished the chapter using the docker container inspect command to view detailed container metadata. So far so good! The process of containerizing an app looks like this:. Start with your application code.
Create a Dockerfile that describes your app, its dependencies, and how to run it. Feed this Dockerfile into the docker image build command. Figure 8. Containerize a single-container app The rest of this chapter will walk you through the process of containerizing a simple single-container Node. The process is the same for Windows, and future editions of the book will include a Windows example.
Cloning into 'psweb' The clone operation creates a new directory called psweb. Change directory into psweb and list its contents. This directory contains all of the application source code, as well as subdirectories for views and unit tests.
Feel free to look at the files - the app is extremely simple. Notice that the repo has a file called Dockerfile. This is the file that describes the application and tells Docker how to build it into an image.
The directory containing the application is referred to as the build context. To describe the application 2. To tell Docker how to containerize the application create an image with the app inside.
Do not underestimate the impact of the Dockerfile as a from of documentation! It has the ability to help bridge the gap between development and operations! It also has the power to speed up on-boarding of new developers etc.
This is because the file accurately describes the application and its dependencies in an easy-to-read format. As such, it should be treated as code, and checked into a source control system. This will be the base layer of the image, and the rest of the app will be added on top as additional layers. At this point, the image looks like Figure 8.
Labels are simple key-value pairs and are an excellent way of adding custom metadata to an image. Note: I will not be maintaining this image. The RUN apk add --update nodejs nodejs-npm instruction uses the Alpine apk package manager to install nodejs and nodejs-npm into the image. The RUN instruction installs these packages as a new image layer on top of the alpine base image created by the FROM alpine instruction.
The image now looks like Figure 8. The COPY. It copies these files into the image as a new layer. The image now has three layers as shown in Figure 8. This directory is relative to the image, and the info is added as metadata to the image config and not as a new layer. Then the RUN npm install instruction uses npm to install application dependencies listed in the package.
The image now has four layers as shown in Figure 8. This is added as image metadata and not an image layer. This is also added as metadata and not an image layer. The following command will build a new image called web:latest. Onto production! Nigel explained k8s in a simple and accessible way emphasizing the architecture side.
Highly recommended for starting your journey with K8s. Concise, easy to follow, and good reads to get get started. If you're new to Kubernetes, and need a quick "get-up-to-speed" book with hands-on demos, then this is the book for you!
He does an amazing job all in under pages! I started just two months ago and now I can dockerize an app, build and publish images and use these images in k8s deployment.
You helped me a lot to get a better understanding of Docker and K8s. I started from scratch with your courses on the Pluralsight platform and I continue to practice with reading your books - thank you. Nigel's books in additional languages. For India and the sub-continent. Get the books here. For China. Get Docker Deep Dive in simplified Chinese here. Get The Kubernetes Book in simplified Chinese here. For Russia. Get in Russian here. In producing this edition, I've gone through every page and every example to make sure everything is up-to-date with the latest versions of Docker and the latest trends in the cloud-native ecosystem.
Docker Deep Dive - This course will cover Docker Web Commerce. Digital Banking. Web Business. Web Development. Content Management. Go Programming. Google Development.
Service-Oriented Architecture. Social Media. Web Applications. Web Design. Web Programming. Web Services. Web Usability. Career Development.
Soft Skills. Bundle Offers. Special Discount. Free Shipping Free Shipping. Docker Deep Dive Updated May MRP: Rs. Price in points: points. Reward points: points. ISBN: Availability: In stock. Buy Add to wish list Compare. Check C. D availability for your pincode. Description Features. If you want to learn the basics of Docker, this book is for you. If you want to be a pro with Docker, this book is for you.
Key features include: Extensive coverage of Docker architecture Deep dive into core concepts such as images and containers Networking, volumes, and security Docker Certified Associate DCA coverage Nigel is passionate about teaching Docker and this is reflected in this book. Books Author 4: Nigel Poulton.
Binding: Paperback.
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