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Deploying Multi-OS applications with Docker Enterprise

Docker Enterprise 3.0 is the first Containers-as-a-Service platform to offer production-level support for the integrated management and security of both Linux and Windows Server Containers. It is also the first platform to support both Docker Swarm and Kubernetes orchestration.

In this lab we'll use a Docker Enterprise cluster. You will have an environment that is either Linux only, comprised of Windows and Linux nodes. We'll deploy both a Java web app on Linux and a multi-service application that includes both Windows and Linux components using Docker Swarm. Then we'll take a look at securing and scaling the application. Finally, we will then deploy the app using Kubernetes.

Difficulty: Intermediate (assumes basic familiarity with Docker) If you're looking for a basic introduction to Docker, check out https://training.play-with-docker.com

Time: Approximately 75 minutes

Introduction:

Tasks:

Understanding the Play With Docker Interface

This workshop is only available to people in a pre-arranged workshop. That may happen through a Docker Meetup, a conference workshop that is being led by someone who has made these arrangements, or special arrangements between Docker and your company. The workshop leader will provide you with the URL to a workshop environment that includes Docker Enterprise Edition. The environment will be based on Play with Docker.

If none of these apply to you, contact your local Docker Meetup Chapter and ask if there are any scheduled workshops. In the meantime, you may be interested in the labs available through the Play with Docker Classroom.

There are three main components to the Play With Docker (PWD) interface.

1. Console Access

Play with Docker provides access to the 4 Docker Enterprise hosts in your Cluster. These machines are:

  • A Linux-based Docker Enterprise 19.XX Manager node
  • Three Linux-based Docker Enterprise 19.XX Worker nodes
  • A Windows Server 2019-based Docker Enterprise XX.XX Worker Node

In some cases, your workshop organizer will have requested a Linux only environment. In that case, just skip the Windows sections of the workshop.

By clicking a name on the left, the console window will be connected to that node.

2. Access to your Universal Control Plane (UCP) and Docker Trusted Registry (DTR) servers

Additionally, the PWD screen provides you with a one-click access to the Universal Control Plane (UCP) web-based management interface as well as the Docker Trusted Registry (DTR) web-based management interface. Clicking on either the UCP or DTR button will bring up the respective server web interface in a new tab.

3. Session Information

Throughout the lab you will be asked to provide either hostnames or login credentials that are unique to your environment. These are displayed for you at the bottom of the screen.

Document conventions

  • When you encounter a phrase in between < and > you are meant to substitute in a different value.

    For instance if you see <dtr hostname> you would actually type something like ip172-18-0-7-b70lttfic4qg008cvm90.direct.ee-workshop.play-with-docker.com

  • When you see the Linux penguin all the following instructions should be completed in your Linux console

  • When you see the Windows flag all the subsequent instructions should be completed in your Windows console. You can skip these sections if you have a Linux only environment.

Introduction

Docker Enterprise provides an integrated, tested and certified platform for apps running on enterprise Linux or Windows operating systems and cloud providers. Docker Enterprise is tightly integrated to the the underlying infrastructure to provide a native, easy to install experience and an optimized Docker environment. Docker Certified Infrastructure, Containers and Plugins are exclusively available for Docker Enterprise with cooperative support from Docker and the Certified Technology Partner.

Overview of Orchestration

While it is easy to run an application in isolation on a single machine, orchestration allows you to coordinate multiple machines to manage an application, with features like replication, encryption, load-balancing, service discovery and more. If you've read anything about Docker, you have probably heard of Kubernetes and Docker Swarm mode. Docker Enterprise allows you to use either Docker Swarm mode or Kubernetes for orchestration.

Both Docker Swarm mode and Kubernetes are declarative: you declare your cluster's desired state, and applications you want to run and where, networks, and resources they can use. Docker Enterprise simplifies this by taking common concepts and moving them to the a shared resource.

Overview of Docker Swarm mode

A Swarm is a group of machines that are running Docker and joined into a cluster. After that has happened, you continue to run the Docker commands you’re used to, but now they are executed on a cluster by a Swarm manager. The machines in a Swarm can be physical or virtual. After joining a Swarm, they are referred to as nodes.

Swarm mode uses managers and workers to run your applications. Managers run the Swarm cluster, making sure nodes can communicate with each other, allocate applications to different nodes, and handle a variety of other tasks in the cluster. Workers are there to provide extra capacity to your applications. In this workshop, you have one manager and three workers.

Overview of Kubernetes

Kubernetes is available in Docker Enterprise 3.0 and included in this workshop. Kubernetes deployments tend to be more complex than Docker Swarm, and there are many component types. UCP simplifies a lot of that, relying on Docker Swarm to handle shared resources. We'll concentrate on Pods and Load Balancers in this workshop, but there's plenty more supported by UCP 2.XX.

Task 1: Configure the Docker Enterprise Cluster

The Play with Docker (PWD) environment is almost completely set up, but before we can begin the labs, we need to do two more steps. First we'll add a Windows node to the cluster. We've left the node unjoined so you can see how easy it is to do. Then we'll create two repositories in Docker Trusted Registry. (The Linux worker nodes are already added to the cluster)

Task 1.1: Accessing PWD

  1. Navigate in your web browser to the URL the workshop organizer provided to you.

  2. Fill out the form, and click submit. You will then be redirected to the PWD environment.

    It may take a few minutes to provision out your PWD environment. After this step completes, you'll be ready to move on to task 1.2: Install a Windows worker node

Task 1.2: Join a Windows worker node

Let's start by adding our 3rd node to the cluster, a Windows Server 2016 worker node. This is done using Docker Swarm.

  1. From the main PWD screen click the UCP button on the left side of the screen

    Note: Because this is a lab-based install of Docker Enterprise we are using the default self-signed certs. Because of this your browser may display a security warning. It is safe to click through this warning.

    In a production environment you would use certs from a trusted certificate authority and would not see this screen.

  2. When prompted enter your username and password (these can be found below the console window in the main PWD screen). The UCP web interface should load up in your web browser.

    Note: Once the main UCP screen loads you'll notice there is a red warning bar displayed at the top of the UCP screen, this is an artifact of running in a lab environment. A UCP server configured for a production environment would not display this warning

  3. From the main dashboard screen, click Add a Node on the bottom left of the screen

  4. Select node type "Windows", check the box, that you followed the instructions and copy the text from the dark box shown on the Add Node screen. Don't select a custom listen or advertise address.

    Note There is an icon in the upper right corner of the box that you can click to copy the text to your clipboard

    Note: You may notice that there is a UI component to select Linux or Windowson the Add Node screen. In a production environment where you are starting from scratch there are a few prerequisite steps to adding a Windows node. However, we've already done these steps in the PWD environment. So for this lab, just leave the selection on Linux and move on to step 2

  5. Switch back to the PWD interface, and click the name of your Windows node. This will connect the web-based console to your Windows Server 2016 Docker Enterprise host.

  6. Paste the text from Step 4 at the command prompt in the Windows console. (depending on your browser, this can be tricky: try the "paste" command from the edit menu instead of right clicking or using keyboard shortcuts)

    You should see the message This node joined a Swarm as a worker. indicating you've successfully joined the node to the cluster.

  7. Switch back to the UCP server in your web browser and click the x in the upper right corner to close the Add Node window

  8. You will be taken back to the UCP Dashboard. In the left menu bar, click Shared Resources, and select Nodes.

    You should be taken to the Nodes screen and will see 4 worker nodes listed at the bottom of your screen.

    Initially the new worker node will be shown with status down. After a minute or two, refresh your web browser to ensure that your Windows worker node has come up as healthy

Congratulations on adding a Windows node to your UCP cluster. Now you are ready to use the worker in either Swarm or Kubernetes. Next up we'll create a few repositories in Docker Trusted registry.

Task 1.3: Create Three DTR Repositories

Docker Trusted Registry is a special server designed to store and manage your Docker images. In this lab we're going to create three different Docker images, and push them to DTR. But before we can do that, we need to setup repositories in which those images will reside. Often that would be enough.

However, before we create the repositories, we do want to restrict access to them. Since we have two distinct app components, a Java web app (with a database), and a .NET API, we want to restrict access to them to the team that develops them, as well as the administrators. To do that, we need to create two users and then two organizations.

  1. In the PWD web interface click the DTR button on the left side of the screen.

    Note: As with UCP before, DTR is also using self-signed certs. It's safe to click through any browser warning you might encounter.

  2. From the main DTR page, click users and then the New User button.

  3. Create a new user, java_user and give it a password you'll remember. I used user1234. Be sure to save the user.

    Then do the same for a dotnet_user.

  4. Select the Organization button.

  5. Press New organization button, name it java, and click save.

    Then do the same with dotnet and you'll have two organizations.

  6. Now you get to add a repository! Click on the java organization, select repositories and then Add repository

  7. Name the repository java_web.

    Note the repository is listed as "Public" but that means it is publicly viewable by users of DTR. It is not available to the general public.

  8. Now it's time to create a team so you can restrict access to who administers the images. Select the java organization and the members will show up. Press Add user and start typing in java. Select the java_user when it comes up.

  9. Next select the java organization and press the Team button to create a web team.

  10. Add the java_user user to the web team and click save.

  11. Next select the web team and select the Repositories tab. Select Add Existing repository and choose the java_webrepository. You'll see the java account is already selected. Then select Read/Write permissions so the web team has permissions to push images to this repository. Finally click save.

  12. Now add a new repository also owned by the web team and call it database. This can be done directly from the web team's Repositories tab by selecting the radio button for Add New Repository. Be sure to grant Read/Write permissions for this repository to the web team as well.

  13. Repeat 4-11 above to create a dotnet organization with a repository called dotnet_api, the dotnet_user, and a team named api (with dotnet_user as a member). Grant read/write permissions for the dotnet_api repository to the api team.

  14. From the main DTR page, click Repositories, you will now see all three repositories listed.

  15. (optional) If you want to check out security scanning in Task 5, you should turn on scanning now so DTR downloads the database of security vulnerabilities. In the left-hand panel, select System and then the Security tab. Select ENABLE SCANNING and Online.

Congratulations, you have created three new repositories in two new organizations, each with one team and a user each.

Task 2: Deploy a Java Web App with Universal Control Plane

Now that we've completely configured our cluster, let's deploy a web app. The Signup application is a basic Java CRUD (Create, Read, Update, Delete) application that uses Spring and Hibernate to transact queries against MySQL. It runs in Tomcat.

Task 2.1: Clone the Demo Repo

  1. From PWD click on the worker1 link on the left to connnect your web console to the UCP Linux worker node.

  2. Before we do anything, let's configure an environment variable for the DTR URL/DTR hostname. You may remember that the session information from the Play with Docker landing page. Select and copy the the URL for the DTR hostname.

  3. Set an environment variable DTR_HOST using the DTR host name defined on your Play with Docker landing page:

    $ export DTR_HOST=<dtr hostname>
$ echo $DTR_HOST

  4. Now use git to clone the workshop repository.

    $ git clone https://github.com/dockersamples/hybrid-app.git

    You should see something like this as the output:

    Cloning into 'hybrid-app'...
remote: Counting objects: 389, done.
remote: Compressing objects: 100% (17/17), done.
remote: Total 389 (delta 4), reused 16 (delta 1), pack-reused 363
Receiving objects: 100% (389/389), 13.74 MiB | 3.16 MiB/s, done.
Resolving deltas: 100% (124/124), done.
Checking connectivity... done.

    You now have the necessary demo code on your worker host.

Task 2.2: Build and Push the Linux Web App Images

  1. Change into the java-app directory.

    $ cd ./hybrid-app/java-app/

  2. Use docker build to build your Docker image.

    $ docker build -t $DTR_HOST/java/java_web .

Note the final "." in the above command. The "." is the build context, specifically the current directory. One of the most common mistakes even experienced users make is leaving off the build context.

The -t tags the image with a name. In our case, the name indicates which DTR server and under which organization's respository the image will live.

Note: Feel free to examine the Dockerfile in this directory if you'd like to see how the image is being built.

There will be quite a bit of output. The Dockerfile describes a two-stage build. In the first stage, a Maven base image is used to build the Java app. But to run the app you don't need Maven or any of the JDK stuff that comes with it. So the second stage takes the output of the first stage and puts it in a much smaller Tomcat image.

  1. Log into your DTR server from the command line.

    First use the dotnet_user, which isn't part of the java organization

    $ docker login $DTR_HOST
Username: <your username>
Password: <your password>
Login Succeeded

    Use docker push to upload your image up to Docker Trusted Registry.

    $ docker push $DTR_HOST/java/java_web
    $ docker push $DTR_HOST/java/java_web
The push refers to a repository [.<dtr hostname>/java/java_web]
8cb6044fd4d7: Preparing
07344436fe27: Preparing
...
e1df5dc88d2c: Waiting
denied: requested access to the resource is denied

    As you can see, the access control that you established in the Task 1.3 prevented you from pushing to this repository.

  2. Now try logging in using java_user, and then use docker push to upload your image up to Docker Trusted Registry.

    $ docker push $DTR_HOST/java/java_web

    The output should be similar to the following:

    The push refers to a repository [<dtr hostname>/java/java_web]
feecabd76a78: Pushed
3c749ee6d1f5: Pushed
af5bd3938f60: Pushed
29f11c413898: Pushed
eb78099fbf7f: Pushed
latest: digest: sha256:9a376fd268d24007dd35bedc709b688f373f4e07af8b44dba5f1f009a7d70067 size: 1363

    Success! Because you are using a user name that belongs to the right team in the right organization, you can push your image to DTR.

  3. In your web browser head back to your DTR server and click View Details next to your java_web repo to see the details of the repo.

    Note: If you've closed the tab with your DTR server, just click the DTR button from the PWD page.

  4. Click on Tags from the horizontal menu. Notice that your newly pushed image is now on your DTR.

  5. Next, build the MySQL database image. Change into the database directory.

	$ cd ../database

  1. Use docker build to build your Docker image.

    $ docker build -t $DTR_HOST/java/database .

Note the final "." in the above command. The "." is the build context, specifically the current directory. One of the most common mistakes even experienced users make is leaving off the build context.

  1. Use docker push to upload your image up to Docker Trusted Registry.

    $ docker push $DTR_HOST/java/database

  2. In your web browser head back to your DTR server and click Tags from the horizontal menu in your database repo to see the details of the repo. Notice that your newly pushed image is now on your DTR.

Task 2.3: Deploy the Web App using UCP

The next step is to run the app in Swarm. As a reminder, the application has two components, the web front-end and the database. In order to connect to the database, the application needs a password. If you were just running this in development you could easily pass the password around as a text file or an environment variable. But in production you would never do that. So instead, we're going to create an encrypted secret. That way access can be strictly controlled.

  1. Go back to the first Play with Docker tab. Click on the UCP button. You'll have the same warnings regarding https that you have before. Click through those and log in. You'll see the Universal Control Panel dashboard.

  2. There's a lot here about managing the cluster. You can take a moment to explore around. When you're ready, click on Swarm and select Secrets.

  3. Click the Create button and you'll see a Create Secret screen. Type mysql_password in Name and Dockercon!!! in Content. Then click Create in the lower right. Obviously you wouldn't use this password in a real production environment. You'll see the content box allows for quite a bit of content, you can actually create structured content here that will be encrypted with the secret.

  4. Next we're going to create two networks. First click on Networks under Swarm in the left panel, and select Create in the upper right. You'll see a Create Network screen. Name your first network back-tier. Leave everything else the default and click Create in the lower right.

  5. Repeat step 4 but with a new network front-tier.

  6. Now we're going to use the fast way to create your application: Stacks. In the left panel, click Shared Resources, Stacks and then Create Stack in the upper right corner.

  7. Name your stack java_web and select Swarm Services for your Mode. Then click Next. Below you'll see we've included a .yml file. Before you paste that in to the Compose.yml edit box, note that you'll need to make a quick change. Each of the images is defined as <dtr hostname>/java/<something>. You'll need to change the <dtr hostname> to the DTR Hostname found on the Play with Docker landing page for your session. It will look something like this: ip172-18-0-21-baeqqie02b4g00c9skk0.direct.ee-beta2.play-with-docker.com You can do that right in the edit box in UCP but wanted to make sure you saw that first.

    Here's the Compose file. Once you've copy and pasted it in, and made the changes, click Create in the lower right corner.

    version: "3.3"

services:

  database:
    image: <dtr hostname>/java/database
    # set default mysql root password, change as needed
    environment:
      MYSQL_ROOT_PASSWORD: mysql_password
    # Expose port 3306 to host. 
    ports:
      - "3306:3306" 
    networks:
      - back-tier

  webserver:
    image: <dtr hostname>/java/java_web
    ports:
      - "8080:8080" 
    networks:
      - front-tier
      - back-tier

networks:
  back-tier:
    external: true 
  front-tier:
    external: true 

secrets:
  mysql_password:
    external: true

    Then click Done in the lower right.

  8. You've deployed your app! Now go and see it. Open a new tab or browser window and enter the UCP Hostname. Then add the :8080/java-web to the end of the URL, you will see the app loaded.

  9. Delete the java_web stack.

Task 3: Deploy the next version with a Windows node

Now that we've moved the app and updated it, we're going to add in a user sign-in API. For fun, and to show off the cross-platform capabilities of Docker Enterprise, we are going to do it in a Windows container.

If your workshop organizer requested a Windows only environment, you can skip to Task 4.

Task 3.1: Clone the repository

  1. Because this is a Windows container, we have to build it on a Windows host. Switch back to the main Play with Docker page, select the name of the Windows worker.

    First make sure Docker is running - it runs as a background Windows Service:

    Start-Service docker

    Then clone the repository again onto this host:

    PS C:\> git clone https://github.com/dockersamples/hybrid-app.git

  2. Set an environment variable for the DTR host name. Much like you did for the Java app, this will make a few step easier. Copy the DTR host name again and create the environment variable. For instance, if your DTR host was ip172-18-0-17-bajlvkom5emg00eaner0.direct.ee-beta2.play-with-docker.com you would type:

    PS C:\> $env:DTR_HOST="ip172-18-0-17-bajlvkom5emg00eaner0.direct.ee-beta2.play-with-docker.com"

Task 3.2: Build and Push Windows Images to Docker Trusted Registry

  1. CD into the c:\hybrid-app\netfx-api directory.

    Note you'll see a dotnet-api directory as well. Don't use that directory. That's a .NET Core api that runs on Linux. We'll use that later in the Kubernetes section.

    PS C:\> cd c:\hybrid-app\netfx-api\

  2. Use docker build to build your Windows image.

    PS C:\hybrid-app\netfx-api> docker build -t $env:DTR_HOST/dotnet/dotnet_api .

    Note the final "." in the above command. The "." is the build context, specifically the current directory. One of the most common mistakes even experienced users make is leaving off the build context.

    Note: Feel free to examine the Dockerfile in this directory if you'd like to see how the image is being built.

    Your output should be similar to what is shown below

    PS C:\hybrid-app\netfx-api> docker build -t $env:DTR_HOST/dotnet/dotnet_api .

Sending build context to Docker daemon  415.7kB
Step 1/8 : FROM microsoft/iis:windowsservercore-10.0.14393.1715
 ---> 590c0c2590e4

<output snipped>

Removing intermediate container ab4dfee81c7e
Successfully built d74eead7f408
Successfully tagged <dtr hostname>/dotnet/dotnet_api:latest

    Note: It will take a few minutes for your image to build.

  3. Log into Docker Trusted Registry

    PS C:\hybrid-app\netfx-api> docker login $env:DTR_HOST
Username: dotnet_user
Password: user1234
Login Succeeded

  4. Push your new image up to Docker Trusted Registry.

    PS C:\hybrid-app\netfx-api> docker push $env:DTR_HOST/dotnet/dotnet_api
The push refers to a repository [<dtr hostname>/dotnet/dotnet_api]
5d08bc106d91: Pushed
74b0331584ac: Pushed
e95704c2f7ac: Pushed
669bd07a2ae7: Pushed
d9e5b60d8a47: Pushed
8981bfcdaa9c: Pushed
25bdce4d7407: Pushed
df83d4285da0: Pushed
853ea7cd76fb: Pushed
55cc5c7b4783: Skipped foreign layer
f358be10862c: Skipped foreign layer
latest: digest: sha256:e28b556b138e3d407d75122611710d5f53f3df2d2ad4a134dcf7782eb381fa3f size: 2825

  5. You may check your repositories in the DTR web interface to see the newly pushed image.

Task 3.3: Deploy the Java web app

  1. First we need to update the Java web app so it'll take advantage of the .NET API. Switch back to worker1 and change directories to the java-app-v2 directory. Repeat steps 1,2, and 4 from Task 2.2 but add a tag :2 to your build and pushes:

    $ docker build -t $DTR_HOST/java/java_web:2 .
$ docker push $DTR_HOST/java/java_web:2

    Note the final "." in the above docker build command. The "." is the build context, specifically the current directory. One of the most common mistakes even experienced users make is leaving off the build context.

    This will push a different version of the app, version 2, to the same java_web repository.

  2. Next repeat the steps 6-8 from Task 2.3, but use this Compose file instead:

    version: "3.3"

services:

  database:
    image: <dtr hostname>/java/database
    # set default mysql root password, change as needed
    environment:
      MYSQL_ROOT_PASSWORD: mysql_password
    # Expose port 3306 to host. 
    ports:
      - "3306:3306" 
    networks:
      - back-tier

  webserver:
    image: <dtr hostname>/java/java_web:2
    ports:
      - "8080:8080" 
    networks:
      - front-tier
      - back-tier
    environment:
      BASEURI: http://dotnet-api/api/users

  dotnet-api:
    image: <dtr hostname>/dotnet/dotnet_api
    ports:
      - "57989:80"
    networks:
      - front-tier
      - back-tier

networks:
  back-tier:
    external: true
  front-tier:
    external: true

secrets:
  mysql_password:
    external: true

  3. Once tested, delete the stack.

Task 4: Deploy to Kubernetes

Now that we have built, deployed and scaled a multi OS application to Docker Enterprise using Swarm mode for orchestration, let's learn how to use Docker Enterprise with Kubernetes.

Docker Enterprise lets you choose the orchestrator to use to deploy and manage your application, between Swarm and Kubernetes. In the previous tasks we have used Swarm for orchestration. In this section we will deploy the application to Kubernetes and see how Docker Enterprise exposes Kubernetes concepts.

Before moving forward we need to make sure that our cluster worker nodes can schedule kubernetes workloads. If go to the nodes section, you'll notice that the scheduler type of worker2 and worker3 is set to Swarm.

Click on the worker2 node and change it's orchestration type to mixed using the gear icon on the top right corner. Repeat the same step for worker3.

Now your cluster is configured to run both kuberentes and Swarm workloads

Task 4.1: Build .NET Core app instead of .NET

For now Kubernetes does not support Windows workloads in production, so we will start by porting the .NET part of our application to a Linux container using .NET Core.

  1. From the Play with Docker landing page, click on worker1 and CD into the hybrid-app/dotnet-api directory.

    $ cd ~/hybrid-app/dotnet-api/

  2. Use docker build to build your Linux image.

    $ docker build -t $DTR_HOST/dotnet/dotnet_api:core .

    Note the final "." in the above command. The "." is the build context, specifically the current directory. One of the most common mistakes even experienced users make is leaving off the build context.

    Note: Feel free to examine the Dockerfile in this directory if you'd like to see how the image is being built. Also, we used the :core tag so that the repository has two versions, the original with a Windows base image, and this one with a Linux .NET Core base image.

    Your output should be similar to what is shown below

    Sending build context to Docker daemon   29.7kB
Step 1/10 : FROM microsoft/aspnetcore-build:2.0.3-2.1.2 AS builder
2.0.3-2.1.2: Pulling from microsoft/aspnetcore-build
723254a2c089: Pull complete

	<output snipped>

Removing intermediate container 508751aacb5c
Step 7/10 : FROM microsoft/aspnetcore:2.0.3-stretch
2.0.3-stretch: Pulling from microsoft/aspnetcore

Successfully built fcbc49ef89bf
Successfully tagged ip172-18-0-8-baju0rgm5emg0096odmg.direct.ee-beta2.play-with-docker.com/dotnet/dotnet_api:latest

    Note: It will take a few minutes for your image to build.

  3. Log into Docker Trusted Registry

    $ docker login $DTR_HOST
Username: dotnet_user
Password: user1234
Login Succeeded

  4. Push your new image up to Docker Trusted Registry.

    $ docker push $DTR_HOST/dotnet/dotnet_api:core
The push refers to a repository [<dtr hostname>/dotnet/dotnet_api]
5d08bc106d91: Pushed
74b0331584ac: Pushed
e95704c2f7ac: Pushed
669bd07a2ae7: Pushed
d9e5b60d8a47: Pushed
8981bfcdaa9c: Pushed
25bdce4d7407: Pushed
df83d4285da0: Pushed
853ea7cd76fb: Pushed
55cc5c7b4783: Skipped foreign layer
f358be10862c: Skipped foreign layer
latest: digest: sha256:e28b556b138e3d407d75122611710d5f53f3df2d2ad4a134dcf7782eb381fa3f size: 2825

  5. You may check your repositories in the DTR web interface to see the newly pushed image.

Task 4.2: Examine the Docker Compose File

Docker Enterprise lets you deploy native Kubernetes applications using Kubernetes deployment descriptors, by pasting the yaml files in the UI, or using the kubectl CLI tool.

However many developers use docker-compose to build and test their application, and having to create Kubernetes deployment descriptors as well as maintaining them in sync with the Docker Compose file is tedious and error prone.

In order to make life easier for developers and operations, Docker Enterprise lets you deploy an application defined with a Docker Compose file as a Kubernetes workloads. Internally Docker Enterprise uses the official Kubernetes extension mechanism by defining a Custom Resource Definition (CRD) defining a stack object. When you post a Docker Compose stack definition to Kubernetes in Docker Enterprise, the CRD controller takes the stack definition and translates it to Kubernetes native resources like pods, controllers and services.

We'll use a Docker Compose file to instantiate our application, and it's the same file as before, except that we will switch the .NET Docker Windows image with the .NET Core Docker Linux image we just built. One other change we have to make is to create a new secret mysql-secret with DockerCon!!! as the password. Follow the instructions above but use - instead of _ because Kubernetes doesn't allow underscores.

Let's look at the Docker Compose file in app/docker-stack.yml.

Change the images for the dotnet-api and java-app services for the ones we just built. And remember to change <dtr hostname> to the long DTR hostname listed on the landing page for your Play with Docker instance.

version: '3.3'

services:
  database:
    deploy:
      placement:
        constraints:
        - node.platform.os == linux
    image: <dtr hostname>/java/database
    environment:
      MYSQL_ROOT_PASSWORD: mysql-password
    networks:
      back-tier:
    ports:
    - published: 32768
      target: 32768

  dotnet-api:
    deploy:
      placement:
        constraints:
        - node.platform.os == linux
    image: <dtr hostname>/dotnet/dotnet_api:core
    networks:
      back-tier:
    ports:
    - published: 32769
      target: 80

  java-web:
    deploy:
      placement:
        constraints:
        - node.platform.os == linux
    image: <dtr hostname>/java/java_web:2
    environment:
      BASEURI: http://dotnet-api/api/users
    networks:
      back-tier:
      front-tier:
    ports:
    - published: 32770
      target: 8080

networks:
  back-tier:
    external: true
  front-tier:
    external: true

secrets:
  mysql-password:
    external: true

Task 4.3: Deploy to Kubernetes using the Docker Compose file

Login to UCP, go to Shared resources, Stacks.

Click create Stack. Fill name: hybrid-app, mode: Kubernetes Workloads, namespace: default.

You should see the stack being created.

Click on it to see the details.

Task 4.4: Verify the app

Go to Kubernetes / Pod. See the pods being deployed.

Go to Kubernetes / Controllers. See the deployments and ReplicaSets.

Go to Kubernetes / Load Balancers. See the Kubernetes services that have been created.

Click on java-web-published to the the details of the public load balancer created for the Java application.

The Node Port 32770 is exposed. Note this is different than previous implementations because of Kubernetes NodePort range limitations. Open a new browser tab, paste in the UCP Hostname from the Play with Docker landing page and add :32770/java-web/ at the end of the url. You should be led to the running application.

Task 5: Security Scanning

Security is crucial for all organizations. And it is a complicated topic, too indepth to go through in detail here. We're going to look at just one of the features that Docker Enterprise has to help you build a secure software supply chain: Security Scanning.

  1. If you turned on security in Task 1.3 step 14 you can skip this step. Otherwise, turn on scanning now so DTR downloads the database of security vulnerabilities. In the left-hand panel, select System and then the Security tab. Select ENABLE SCANNING and Online.

    This will take awhile so you may want to take a break by reading up on Docker Security.

  2. Once the scanning database has downloaded, you can scan individual images. Select a repository, such as java/java_web, and then select the Tags tab. If it hasn't already scanned, select Start scan. If it hasn't scanned already, this can take 5-10 minutes or so.

    You see that in fact there are alot of vulnerabilities! That's because we deliberately chose an old version of the tomcat base image. Also, most operating systems and many libraries contain some vulnerabilities. The details of these vulnerabilites and when they come into play are important. You can select View details to get more information. You can see which layers of your image introduced vulnerabilities.

    And by selecting Components you can see what the vulnerabilities are and what components introduced the vulnerabilies. You can also select the vulnerabilies and examine them in the Common Vulnerabilies and Exploits database.

  3. One way you can reduce your vulnerabilities is to identify where the vulnerabilities are coming from. For instance, you can see that in java_web:latest, 1 Critical and 9 Major issues were introduced with the Spring Framework. Time to upgrade that framework! Of course, upgrading the app is out of scope for this workshop, but you can see how it would give you the information you need to mitigate vulnerabilities.

  4. You can also choose newer base images. For instance, you can go back to the Dockerfile in the ~/hybrid-app/java-app directory, and change the second base image to 9.0.13-jre11-slim. Slim images in official images are generally based on lighter-weight operating systems like Alpine Linux or Debian, which have reduced attack space. Then check the scanning again (this may again take 5-10 minutes). You'll still see vulnerabilites, but far fewer.

  5. DTR also allows you to Sign Images and Create promotion policies which prevent users from using images in production that don't meet whatever criteria you set, including blocking images with critical and/or major vulnerabilities.

Common Issues

  • Confirm that you are setting the environmental variable DTR_HOST to the DTR hostname.

Conclusion

In this lab we've looked how Docker Enterprise can help you manage both Linux and Windows workloads whether they be traditional apps you've modernized or newer cloud-native apps, leveraging Swarm or Kubernetes for orchestration.

You can find more information on Docker Enterprise at http://www.docker.com as well as continue exploring using our hosted trial at https://dockertrial.com

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