Continuous Delivery with Containers – Azure CLI Command for Creating a Docker Release Pipeline with VSTS Part 2

Posted by Graham Smith on March 14, 2017No CXomments (click here to comment)

In my previous post I described my experience of working through Microsoft's Continuous Integration and Deployment of Multi-Container Docker Applications to Azure Container Service tutorial which is a walkthrough of how to use an Azure CLI 2.0 command to create a VSTS deployment pipeline to push Docker images to an Azure Container Registry and then deploy and run them on an Azure Container Service running a DC/OS cluster. Whilst it's great to be able to issue some commands and have stuff magically appear it's unlikely that you would use this approach to create production-grade infrastructure: having precise control over naming things is one good reason. Another problem with commands that create infrastructure is that you don't always get a good sense of what they are up to, and that's what I found with the az container release create command.

So I spent quite a bit of time ‘reverse engineering' az container release create in order to understand what it's doing and in this post I describe, step-by-step, how to build what the command creates. In doing so I gained first-hand experience of what I think will be an import pattern for the future -- running VSTS agents in a container. If your infrastructure is in place it's quick and easy to set up and if you want more agents it takes just seconds to scale to as many as you need. In fact, once I had figured what was going on I found that working with Azure Container Service and DC/OS was pretty straightforward and even a great deal of fun. Perhaps it's just me but I found being able to create 50 VSTS agents at the ‘flick of a switch' put a big smile on my face. Read on to find out just how awesome all this is...

Getting Started

If you haven't already worked through Microsoft's tutorial and my previous post I strongly recommend those as a starting point so you understand the big picture. Either way, you'll need to have the Azure CLI 2.0 installed and also to have forked the sample code to your own GitHub account and renamed it to something shorter (I used TwoSampleApp). My previous post has all the details. If you already have the Azure CLI installed do make sure you've updated it (pip install azure-cli --upgrade) since version 2.0 was recently officially released.

Creating the Azure Infrastructure

You'll need to create the following infrastructure in Azure:

  • A dedicated resource group (not strictly necessary but helps considerably with cleaning up the 30+ resources that get created).
  • An Azure container registry.
  • An Azure container service configured with a DC/OS cluster.

The Azure CLI 2.0 commands to create all this are as follows:

The az acs create command in particular is doing a huge amount of work behind the scenes, and if configuring a container service for a production environment you'd most likely want greater control over the names of all the resources that are created. I'm not worried about that here and the output of these commands is fine for my research purposes. If you do want to delve further you can examine the automation script for the top level resources these commands create.

Configuring VSTS

Over in your VSTS account you'll need to attend to the following items:

  • Create a new team project (I called mine TwoServiceApp) configured for Git. (A new project isn't strictly necessary but it helps when cleaning up.)
  • Create an Agent Pool called TwoServiceApp. You can get to the page that manages agent pools from the agent queues tab of your team project:
  • Create a service endpoint of type Github that grants VSTS access to your GitHub account. The procedure is detailed here -- I used the personal access token method and called the connection TwoServiceAppGh.
  • Create a service endpoint of type Docker Registry that grants access to the Azure container registry created above. I describe the process in this blog post and called the endpoint TwoServiceAppAcr.
  • Create a personal access token (granting permission to all scopes) and store the value for later use.
  • Ensure the Docker Integration extension is installed from the Marketplace.

Create a VSTS Agent

This is where the fun begins because we're going to create a VSTS agent in DC/OS using a Docker container. Yep -- you read that right! If you've only ever created an agent on ‘bare metal' servers then you need to forget everything you know and prepare for awesomeness. Not least because if you suddenly feel that you want a dozen agents a quick configuration setting will have them created for you in a flash!

The first step is to configure your workstation to connect to the DC/OS cluster running in your Azure container service. There are several ways to do this but I followed these instructions (Connect to a DC/OS or Swarm clusterCreate an SSH tunnel on Windows) to configure PuTTY to create an SSH tunnel. The host name will be something like azureuser@twoserviceappacsmgmt.westeurope.cloudapp.azure.com (you can get the master FQDN from the overview blade of your Azure container service and the default login name used by az acr create is azureuser) and you will need to have created a private key in .ppk format using PuTTYGen. Once you have successfully connected (you actually SSH to a DC/OS master VM) you should be able to browse to these URLs:

  • DC/OS -- http://localhost
  • Marathon -- http://localhost/marathon
  • Mesos -- http://localhost/mesos

If you followed the Microsoft tutorial then much of what you see will be familiar, although there will be nothing configured of course. To create the application that will run the agent you'll need to be in Marathon:

Clicking Create Application will display the configuration interface:

Whilst it is possible to work through all of the pages and enter in the required information, a faster way is to toggle to JSON Mode and paste in the following script (overwriting what's there):

You will need to amend some of the settings for your environment:

  • id -- choose an appropriate name for the application (note that /vsts-agents/ creates a folder for the application).
  • VSTS_POOL -- the name of the agent pool created above.
  • VSTS_TOKEN -- the personal access token created above.
  • VSTS_ACCOUNT -- the name of your VSTS account (ie if the URL is https://myvstsaccount.visualstudio.com then use myvstsaccount).

It will only take a few seconds to create the application after which you should see something that looks like this:

For fun, click on the Scale Application button and enter a number of instances to scale to. I scaled to 50 and it literally took just a few seconds to configure them all. This resulted in this which is pretty awesome in my book for just a few seconds work:

Scaling down again is even quicker -- pretty much instant in Marathon and VSTS was very quick to get back to displaying just one agent. With the fun over, what have we actually built here?

The concept is that rather than configure an agent by hand in the traditional way, we are making use of one of the Docker images Microsoft has created specifically to contain the agent and build tools. You can examine all the different images from this page on Docker Hub. Looking at the Marathon configuration code above in the context of the instructions for using the VSTS agent images it's hopefully clear that the configuration is partially around hosting the image and creating the container and partially around passing variables in to the container to configure the agent to talk to your VSTS account and a specific agent pool.

Create a Build Definition

We're now at a point where we can switch back to VSTS and create a build definition in our team project. Most of the tasks are of the Docker Compose type and you can get further details here. Start with an empty process and name the definition TwoServiceApp. On the Options tab set the Default agent queue to be TwoServiceApp. On the tasks tab in Get sources configure the build to point to your GitHub account:

Now add and configure the following tasks (only values that need adding or amending, or which need a special mention are listed):

Task #1 -- Docker Compose
  • Display name = Build repository
  • Docker Registry Connection = TwoServiceAppAcr (or the name of the Docker Registry endpoint created above if different)
  • Docker Compose File = **/docker-compose.ci.build.yml
  • Action = Run a specific service image
  • Service name = ci-build

Save the definition and queue a build. The source code will be pulled down and then the instructions in the ci-build node of docker-compose.ci.build.yml will be executed which will cause service-b to be built.

Task #2 -- Docker Compose
  • Display name = Build service images
  • Docker Registry Connection = TwoServiceAppAcr (or the name of the Docker Registry endpoint created above if different)
  • Docker Compose File = **/docker-compose.yml
  • Qualify Image Names = checked
  • Action = Build service images
  • Additional Image Tags = $(Build.BuildId) $(Build.SourceBranchName) $(Build.SourceVersion) (on separate lines)
  • Include Source Tags = checked
  • Include Latest Tag = checked

Save the definition and queue a build. The addition of this task causes causes Docker images to be created in the agent container for service-a and service-b.

Task #3 -- Docker Compose
  • Display name = Push service images
  • Docker Registry Connection = TwoServiceAppAcr (or the name of the Docker Registry endpoint created above if different)
  • Docker Compose File = **/docker-compose.yml
  • Qualify Image Names = checked
  • Action = Push service images
  • Additional Image Tags = $(Build.BuildId) $(Build.SourceBranchName) $(Build.SourceVersion) (on separate lines)
  • Include Source Tags = checked
  • Include Latest Tag = checked

Save the definition and queue a build. The addition of this task causes causes the Docker images to be pushed to the Azure container registry.

Task #4 -- Docker Compose
  • Display name = Write service image digests
  • Docker Registry Connection = TwoServiceAppAcr (or the name of the Docker Registry endpoint created above if different)
  • Docker Compose File = **/docker-compose.yml
  • Qualify Image Names = checked
  • Action = Write service image digests
  • Image Digest Compose File = $(Build.StagingDirectory)/docker-compose.images.yml

Save the definition and queue a build. The addition of this task creates immutable identifiers for the previously built images which provide a guaranteed way of referring back to a specific image in the container registry. The identifiers are stored in a file called docker-compose.images.yml, the contents of which will look something like:

Task #5 -- Docker Compose
  • Display name = Combine configuration
  • Docker Registry Connection = TwoServiceAppAcr (or the name of the Docker Registry endpoint created above if different)
  • Docker Compose File = **/docker-compose.yml
  • Additional Docker Compose Files = $(Build.StagingDirectory)/docker-compose.images.yml
  • Qualify Image Names = checked
  • Action = Combine configuration
  • Remove Build Options = checked

Save the definition and queue a build. The addition of this task creates a new docker-compose.yml that is a composite of the original docker-compose.yml and docker-compose.images.yml. The contents will look something like:

This is the file that is used by the release definition to deploy the services to DC/OS.

Task #6 -- Copy Files
  • Display name = Copy Files to: $(Build.StagingDirectory)
  • Contents = **/docker-compose.env.*.yml
  • Target Folder = $(Build.StagingDirectory)

Save the definition but don't bother queuing a build since as things stand this task doesn't have any files to copy over. Instead, the task comes in to play when using environment files (see later).

Task #7 -- Publish Build Artifacts
  • Display name = Publish Artifact: docker-compose
  • Path to Publish = $(Build.StagingDirectory)
  • Artifact Name = docker-compose
  • Artifact Type = Server

Save the definition and queue a build. The addition of this task creates the build artefact containing the contents of the staging directory, which happen to be docker-compose.yml and docker-compose.images.yml, although only docker-compose.yml is needed. The artifact can be downloaded of course so you can examine the contents of the two files for yourself.

Create a Release Definition

Create a new empty release definition and configure the Source to point to the TwoServiceApp build definition, the Queue to point to the TwoServiceApp agent queue and check the Continuous deployment option:

With the definition created, edit the name to TwoServiceApp, rename the default environment to Dev and rename the default phase to AcsDeployPhase:

Add Docker Deploy task to the AcsDeployPhase and configure as follows (only values that need changing are listed):

  • Display Name = Deploy to ACS DC/OS
  • Docker Registry Connection = TwoServiceAppAcr (or the name of the Docker Registry endpoint created above if different)
  • Target Type = Azure Container Service (DC/OS)
  • Docker Compose File = **/docker-compose.yml
  • ACS DC/OS Connection Type = Direct

The final result should be as follows:

Trigger a release and then switch over to DC/OS (ie at http://localhost) and the Services page. Drill down through the Dev folder and the three services defined in docker-compose.yml should now be deployed and running:

To complete the exercise the Dev environment can now be cloned (click the ellipsis in the Dev environment to show the menu) to create Test and Production environments with manual approvals. If you want to view the sample application in action follow the View the application instructions in the Microsoft tutorial.

At this point there is no public endpoint for the production instance of TwoServiceApp. To remedy that follow the Expose public endpoint for production instructions in the Microsoft tutorial. Additionally, you will need to amend the production version of the Docker Deploy task so the Additional Docker Compose Files section contains docker-compose.env.production.yml.

Final Thoughts

Between Microsoft's tutorial and my two posts relating to it you have seen a glimpse of the powerful tools that are available for hosting and orchestrating containers. Yes, this has all been using Linux containers but indications are that similar functionality -- if perhaps not using exactly the same tools -- is on the way for Windows containers. Stay tuned!

Cheers -- Graham

Continuous Delivery with Containers – Azure CLI Command for Creating a Docker Release Pipeline with VSTS Part 1

Posted by Graham Smith on January 30, 20172 Comments (click here to comment)

One of the aims of my blog series on Continuous Delivery with Containers is to try and understand how best to use Visual Studio Team Services with Docker, so I was very interested to learn that Azure CLI 2.0 has a command to create a VSTS deployment pipeline to push Docker images to an Azure Container Registry and then deploy and run them on an Azure Container Service running a DC/OS cluster. Even better, Microsoft have written a tutorial (Continuous Integration and Deployment of Multi-Container Docker Applications to Azure Container Service) on how to use this command.

Whilst I'm somewhat sceptical about using generic scaffolding tooling to create production-ready workloads (I find that the naming conventions used are usually unsuitable for example) there is no doubt that they are great for quickly building proof of concepts and also for learning (what are hopefully!) best practices. It was with this aim that, armed with a large cup of tea, I sat down one afternoon to plough my way through the tutorial. It was a great learning experience, however I went down some blind alleys to get the pipeline working and then ended up doing quite a lot of head scratching (due to my ignorance I hasten to add) to fully understand what had been created.

So in this post I'm writing-up my experience of working through the tutorial with notes that I hope will help anyone else using it. In a follow-up post I'll attempt to document what the az container release create command actually creates and configures. Just a reminder that with this tutorial we're still very much in the Linux container world. Whilst this might be frustrating for those eager to see advanced tutorials based on Windows containers the learning focus here is mostly Docker and VSTS so the fact that the containers are running Linux shouldn't put you off.

On a final note before we get started, I'm using a Windows 10 Professional workstation with the beta version (1.13.0 at the time of writing) of Docker for Windows installed and running.

Getting Started with the Azure CLI

The tutorial requires version 2.0 of Azure CLI which is based on Python. The Azure CLI installation documentation suggests running Azure CLI in Docker but don't go down that path as it's a dead end as far as the tutorial is concerned. Instead follow these installation steps:

  1. Install the latest version of Python from here.
  2. From a command prompt upgrade pip (package management system for Python) using the python -m pip install --upgrade pip command.
  3. Install Azure CLI 2.0 using pip install azure-cli. (If you have previously installed Azure CLI 2.0 you should check for an upgrade using pip install azure-cli --upgrade.)
  4. Check Azure CLI is working using the az command. You should see this:

The next step is to actually log in to the Azure CLI. The process is as follows:

  1. At a command prompt type az login.
  2. Navigate to https://aka.ms/devicelogin in a browser.
  3. Supply the one-time authentication code supplied by the az login command.
  4. Complete the authentication process using your Azure credentials.

If you have multiple subscriptions you may need to set the default subscription:

  1. At the command prompt type az account list to show details of all your accounts.
  2. Each account has an isDefault property which will tell you the default account.
  3. If you need to make a change use az account set --subscription <Id> -- you can copy and paste the subscription Id from the accounts list.

Creating the Azure Container Service Cluster with DC/OS

This step is pretty straightforward and the tutorial doesn't need any further explanation. My commands to create the resource group and the ACS cluster were:

Be aware that the az acs create command results in a request to provision 18 cores. This might exceed your quota for a given region, even if you have previously contacted Microsoft Support to request an increase in the total number of cores allowed for your subscription (which you might have to do anyway if you have cores already provisioned). I found that choosing a region where I didn't have any cores provisioned fixed a quotaExceeded exception that I was getting.

For simplicity I used the --generate-ssh-keys option to save having to do this manually. This creates id_rsa and id_rsa.pub files (ie a private / public key pair) in C:\Users\<username>\.ssh.

A word of warning -- if you are using an Azure subscription with MSDN credits be aware that an ACS cluster will eat your credits at an alarming rate. As of the time of writing this post I've not found a reliable way of turning everything off and turning it back on again with everything fully working (specifically the build agent). Consequently I tend to delete the resource group and the VSTS project when I'm finished using them and then recreate them from scratch when I next need them. If you do this do be aware that if you have multiple Azure subscriptions the az account set --subscription <Id> command to set the default subscription can't be relied upon to be ‘sticky', and you can find yourself creating stuff in a different subscription by mistake.

Working with the Sample Code

The tutorial uses sample code that consists of an Angular.js-based web app (with a Node.js backend) that calls a separate .NET Core application, and these are deployed as two separate services. The problem I found was that the name of the GitHub repo (container-service-dotnet-continuous-integration-multi-container) is extremely long and is used to name some of the artefacts that get created by the Azure CLI container release command. This makes for some very unwieldy names which I found somewhat irksome. You can fix this as follows:

  1. Fork the sample code to your own GitHub account.
  2. Switch to the Settings tab:
  3. Use the Rename option to give the forked repo a more manageable name -- I chose TwoServiceApp.
  4. Clone the repo to your workstation in your preferred way -- for me this involved opening a command prompt at C:\Source\GitHub and running git clone https://github.com/GrahamDSmith/TwoServiceApp.git.

At this point it's probably a good idea to get the sample app working locally which will help with understanding how multi-container Docker deployments work. If you want to examine the source code then Visual Studio Code is an ideal tool for the job. To run the application the first step is to build the .NET Core component. At a command prompt at the root of the application run the following command:

This runs docker-compose with a specific .yml file, and executes the instructions at the ci-build node. The really neat thing about this command is that it uses a Docker container to build the .NET Core app (service-b), which means your workstation doesn't need the .NET Core to be installed for this to work. Looking at the key parts of the docker-compose.ci.build.yml file:

  • image: microsoft/dotnet:1.0.0-preview2.1-sdk -- this specifies that this particular Microsoft official Docker image for .NET Core on Linux should be used.
  • volumes: -- ./service-b:/src -- this causes the local service-b folder on your workstation to be ‘mirrored' to a folder named src in the container that will be created from the microsoft/dotnet:1.0.0-preview2.1-sdk image.
  • working_dir: /src -- set the working directory in the container to src.
  • command: /bin/bash -c "dotnet restore && dotnet publish -c Release -o bin ." -- this is the command to build and publish service-b.

Because the service-b folder on your workstation is mirrored to the src folder in the running container the result of the build command is copied from the container to your workstation. Pretty nifty!

To actually run the application now run this command:

By convention docker-compose will look for a docker-compose.yml file so there is no need to specify it. On examining docker-compose.yml it should be pretty easy to see what's going on -- three services (service-a, service-b and mycache) are specified and service-a and service-b are built according to their respective Dockerfile instructions. Both service-a and service-b containers are set to listen on port 80 at runtime and in addition service-a is accessible to the host (ie your workstation) on port 8080. Consequently, you should be able to navigate to http://localhost:8080 in your browser and see the app running.

Creating the Deployment Pipeline

This step is straightforward and the tutorial doesn't need any further explanation. One extra step I included was to create an Azure Container Registry instance in the same resource group used to create the Azure Container Service. Despite repeated attempts, for some reason I couldn't create this at the command line so ended up creating it through the portal. The command though should look similar to this:

To facilitate easy teardown I also created a dedicated project in VSTS called TwoServiceApp. The command to create the pipeline (GitHub token made up of course) was then as follows:

This command results in the creation of build and release definitions in VSTS (along with other supporting items) and a deploy of the image to a Dev environment.

Viewing the Application

To view the application as deployed to the Dev environment you need to launch the DC/OS dashboard. The tutorial instructions are easy to follow, however you might get tripped-up by the instructions for configuring Pageant since the instructions direct you to "Launch PuttyGen and load the private SSH key used to create the ACS cluster (%homepath%\id_rsa)". On my machine at least the id_rsa file was created at %homepath%\.ssh\id_rsa rather than %homepath%\id_rsa. If you persist with the instructions you eventually end up running the application in the Dev environment, but if like me you are new to cluster technologies such as DC/OS it all feels like some kind of sorcery.

A final observation here is that the configuration to launch the DC/OS dashboard requires your browser's proxy to be set. This knocked-out the Internet connection for all my other browser tabs, and was the cause of alarm for a few seconds when I realised that the tab I was using to edit my WordPress blog wouldn't save. If you launched the DC/OS dashboard from the command line (using az acs dcos browse --name TwoServiceAppAcs --resource-group TwoServiceAppRg) you need to use CTRL+C from the command line to close the session. In an emergency head over to Windows Settings > Network & Internet > Proxy to reset things back to normal.

Until Next Time

That concludes the write-up of my notes for use with the Continuous Integration and Deployment of Multi-Container Docker Applications to Azure Container Service tutorial. If you work through the tutorial and have any further tips that might be of use please do post in the comments.

In the next post I'll start to document what the what the az container release create command actually creates and configures.

Cheers -- Graham

Continuous Delivery with Containers – Amending a VSTS / Docker Hub Deployment Pipeline with Azure Container Registry

Posted by Graham Smith on December 1, 2016No CXomments (click here to comment)

In this blog series on Continuous Delivery with Containers I'm documenting what I've learned about Docker and containers (both the Linux and Windows variety) in the context of continuous delivery with Visual Studio Team Services. It's a new journey for me so do let me know in the comments if there is a better way of doing things!

In the previous post in this series I explained how to use VSTS and Docker to build and deploy an ASP.NET Core application to a Linux VM running in Azure. It's a good enough starting point but one of the first objections anyone working in a private organisation is likely to have is publishing Docker images to the public Docker Hub. One answer is to pay for a private repository in the Docker Hub but for anyone using Azure a more appealing option might be the Azure Container Registry. This is a new offering from Microsoft -- it's still in preview and some of the supporting tooling is only partially baked. The core product is perfectly functional though so in this post I'm going to be amending the pipeline I built in the previous post with Azure Container Registry to find out how it differs from Docker Hub. If you want to follow along with this post you'll need to make sure  you have a working pipeline as I describe in my previous post.

Create an Azure Container Registry

At the time of writing there is no PowerShell experience for ACR so unless you want to use the CLI 2.0 it's a case of using the portal. I quite like the CLI but to keep things simple I'm using the portal. For some reason ACR is a marketplace offering so you'll need to add it from New > Marketplace > Containers > Container Registry (preview). Then follow these steps:

  1. Create a new resource group that will contain all the ACR resources -- I called mine PrmAcrResourceGroup.
  2. Create a new standard storage account for the ACR -- I called mine prmacrstorageaccount. Note that at the time of writing ACR is only available in a few regions in the US and the storage account needs to be in the same region. I chose West US.
  3. Create a new container registry using the resource group and storage account just created -- I called mine PrmContainerRegistry. As above, the registry and storage account need to be in the same location. You will also need to enable the Admin user:
    azure-portal-create-container-registry

Add a New Docker Registry Connection

This registry connection will be used to replace the connection made in the previous post to Docker Hub. The configuration details you need can be found in the Access key blade of the newly created container registry:

azure-portal-container-registry-access-key-blade

Use these settings to create a new Docker Registry connection in the VSTS team project:

vsts-services-endpoints-azure-container-registry

Amend the Build

Each of the three Docker tasks that form part of the build need amending as follows:

  • Docker Registry Connection = <name of the Azure Container Registry connection>
  • Image Name = aspnetcorelinux:$(Build.BuildNumber)
  • Qualify Image Name = checked

One of the most crucial amendments turned out to be the Qualify Image Name setting. The purpose of this setting is to prefix the image name with the registry hostname, but if left unchecked it seems to default to Docker Hub. This causes an error during the push as the task tries to push to Docker Hub which of course fails because the registry connection has authenticated to ACR rather than Docker Hub:

vsts-docker-push-error

It was obvious once I'd twigged what was going on but it had me scratching my head for a little while!

Final Push

With the amendments made you can now trigger a new build, which should work exactly as before except now the docker image is pushed to -- and run from -- your ACR instance rather than Docker Hub.

Your next question is probably going to be how can I get a list of the repositories I've created in ACR? Don't bother looking in the portal since -- at the time of writing at least -- there is no functionality there to list repositories. Instead one of the guys at Microsoft has created a separate website which, once authenticated, shows you this information:

acr-portal

If you want to do a bit more you can use the CLI 2.0. The syntax to list repositories for example is az acr repository list -n <Azure Container Registry name>.

It's early days yet however the ACR is looking like a great option for anyone needing a private container registry and for whom an Azure option makes sense. Do have a look at the documentation and also at Steve Lasker's Connect(); video here.

Cheers -- Graham

Continuous Delivery with Containers – Use Visual Studio Team Services and Docker to Build and Deploy ASP.NET Core to Linux

Posted by Graham Smith on October 27, 20166 Comments (click here to comment)

In this blog series on Continuous Delivery with Containers I'm documenting what I've learned about Docker and containers (both the Linux and Windows variety) in the context of continuous delivery with Visual Studio Team Services. The Docker and containers world is mostly new to me and I have only the vaguest idea of what I'm doing so feel free to let me know in the comments if I get something wrong.

Although the Windows Server Containers feature is now a fully supported part of Windows it is still extremely new in comparison to containers on Linux. It's not surprising then that even in the world of the Visual Studio developer the tooling is most mature for deploying containers to Linux and that I chose this as my starting point for doing something useful with Docker. As I write this the documentation for deploying containers with Visual Studio Team Services is fragmented and almost non-existent. The main references I used for this post were:

However to my mind none of these blogs cover the whole process to any satisfactory depth and in any case they are all somewhat out of date. In this post I've therefore tried to piece all of the bits of the jigsaw together that form the end-to-end process of creating an ASP.NET Core app in Visual Studio and debugging it whilst running on Linux, all the way through to using VSTS to deploy the app in a container to a target node running Linux. I'm not attempting to teach the basics of Docker and containers here and if you need to get up to speed with this see my Getting Started post here.

Install the Tooling for the Visual Studio Development Inner Loop

In order to get your development environment properly configured you'll need to be running a version of Windows that is supported by Docker for Windows and have the following tooling installed:

You'll also need a VSTS account and an Azure subscription.

Create an ASP.NET Core App

I started off by creating a new Team Project in VSTS and called Containers and then from the Code tab creating a New repository using Git called AspNetCoreLinux:

vsts-code-new-repository

Over in Visual Studio I then cloned this repository to my source control folder (in my case to C:\Source\VSTS\AspNetCoreLinux as I prefer a short filepath) and added .gitignore and .gitattributes files (see here if this doesn't make sense) and committed and synced the changes. Then from File > New > Project I created an ASP.NET Core Web Application (.NET Core) application called AspNetCoreLinux using the Web Application template (not shown):

visual-studio-create-new-asp-net-core-application

Visual Studio will restore the packages for the project after which you can run it with F5 or Ctrl+F5.

The next step is to install support for Docker by right-clicking the project and choosing Add > Docker Support. You should now see that the Run dropdown has an option for Docker:

visual-studio-run-dropdown

With Docker selected and Docker for Windows running (with Shared Drives enabled!) you will now be running and debugging the application in a Linux container. For more information about how this works see the resources on the Visual Studio Tools for Docker site or my list of resources here. Finally, if everything is working don't forget to commit and sync the changes.

Provision a Linux Build VM

In order to build the project in VSTS we'll need a build machine. We'll provision this machine in Azure using the Azure driver for Docker Machine which offers a very neat way for provisioning a Linux VM with Docker installed in Azure. You can learn more about Docker Machine from these sources:

To complete the following steps you'll need the Subscription ID of the Azure subscription you intend to use which you can get from the Azure portal.

  1. At a command prompt enter the following command:

    By default this will create a Standard A2 VM running Ubuntu called vstsbuildvm (note that "Container names must be 3-63 characters in length and may contain only lower-case alphanumeric characters and hyphen. Hyphen must be preceded and followed by an alphanumeric character.") in a resource group called VstsBuildDeployRG in the West US datacentre (make sure you use your own Azure Subscription ID). It's fully customisable though and you can see al the options here. In particular I've added the option for the VM to be created with a static public IP address as without that there's the possibility of certificate problems when the VM is shut down and restarted with a different IP address.
  2. Azure now wants you to authenticate. The procedure is explained in the output of the command window, and requires you to visit https://aka.ms/devicelogin and enter the one-time code:
    command-prompt-docker-machine-create
    Docker Machine will then create the VM in Azure and configure it with Docker and also generate certificates at C:\Users\<yourname>\.docker\machine. Do have a poke a round the subfolders of this path as some of the files are needed later on and it will also help to understand how connections to the VM are handled.
  3. This step isn't strictly necessary right now, but if you want to run Docker commands from the current command prompt against the Docker Engine running on the new VM you'll need to configure the shell by first running docker-machine env vstsbuildvm. This will print out the environment variables that need setting and the command (@FOR /f "tokens=*" %i IN (‘docker-machine env vstsbuilddeployvm') DO @%I) to set them. These settings only persist for the life of the command prompt window so if you close it you'll need to repeat the process.
  4. In order to configure the internals of the VM you need to connect to it. Although in theory you can use the docker-machine ssh vstsbuildvm command to do this in practice the shell experience is horrible. Much better is to use a tool like PuTTY. Donovan Brown has a great explanation of how to get this working about half way down this blog post. Note that the folder in which the id_rsa file resides is C:\Users\<yourname>\.docker\machine\machines\<yourvmname>. A tweak worth making is to set the DNS name for the server as I describe in this post so that you can use a fixed host name in the PuTTY profile for the VM rather than an IP address.
  5. With a connection made to the VM you need to issue the following commands to get it configured with the components to build an ASP.NET Core application:
    1. Upgrade the VM with sudo apt-get update && sudo apt-get dist-upgrade.
    2. Install .NET Core following the instructions here, making sure to use the instructions for Ubuntu 16.04.
    3. Install npm with sudo apt -y install npm.
    4. Install Bower with sudo npm install -g bower.
  6. Next up is installing the VSTS build agent for Linux following the instructions for Team Services here. In essence (ie do make sure you follow the instructions) the steps are:
    1. Install the Ubuntu pre-requisites using sudo apt-get install -y libunwind8 libcurl3.
    2. Create and switch to a downloads folder using sudo mkdir Downloads && cd Downloads.
    3. At the Get Agent page in VSTS select the Linux tab and the Ubuntu 16.04-x64 option and then the copy icon to copy the URL download link to the clipboard:
      vsts-download-agent-get-agent
    4. Back at the PuTTY session window type sudo wget followed by a space and then paste the URL from the clipboard. Run this command to download the agent to the Downloads folder.
    5. Go up a level using cd .. and then make and switch to a folder for the agent using sudo mkdir myagent && cd myagent.
    6. Extract the compressed agent file to myagent using sudo tar zxvf ~/Downloads/vsts-agent-ubuntu.16.04-x64-2.108.0.tar.gz (note the exact file name will likely be different).
    7. Configure the agent using ./config.sh after first making sure you have created a personal access token to use. I created my agent in a pool I created called Linux.
    8. Configure the agent to run as a service using sudo ./svc.sh install and then start it using sudo ./svc.sh start.

If the procedure was successful you should see the new agent showing green in the VSTS Agent pools tab:

vsts-agent-pools

Provision a Linux Target Node VM

Next we need a Linux VM we can deploy to. I used the same syntax as for the build VM calling the machine vstsdeployvm:

Apart from setting the DNS name for the server as I describe in this post there's not much else to configure on this server except for updating it using sudo apt-get update && sudo apt-get dist-upgrade.

Gearing Up to Use the Docker Integration Extension for VSTS

Configuration activities now shift over to VSTS. The first thing you'll need to do is install the Docker Integration extension for VSTS from the Marketplace. The process is straightforward and wizard-driven so I won't document the steps here.

Next up is creating three service end points -- two of the Docker Host type (ie our Linux build and deploy VMs) and one of type Docker Registry. These are created by selecting Services from the Settings icon and then Endpoints and then the New Service Endpoint dropdown:

vsts-services-endpoints-docker

To create a Docker Host endpoint:

  1. Connection Name = whatever suits -- I used the name of my Linux VM.
  2. Server URL = the DNS name of the Linux VM in the format tcp://your.dns.name:2376.
  3. CA Certificate = contents of C:\Users\<yourname>\.docker\machine\machines\<yourvmname>\ca.pem.
  4. Certificate = contents of C:\Users\<yourname>\.docker\machine\machines\<yourvmname>\cert.pem.
  5. Key = contents of C:\Users\<yourname>\.docker\machine\machines\<yourvmname>\key.pem.

The completed dialog (in this case for the build VM) should look similar to this:

vsts-services-endpoints-docker-host

Repeat this process for the deploy VM.

Next, if you haven't already done so you will need to create an account at Docker Hub. To create the Docker Registry endpoint:

  1. Connection Name = whatever suits -- I used my name
  2. Docker Registry = https://index.docker.io/v1/
  3. Docker ID = username for Docker Hub account
  4. Password = password for Docker Hub account

The completed dialog should look similar to this:

vsts-services-endpoints-docker-hub

Putting Everything Together in a Build

Now the fun part begins. To keep things simple I'm going to run everything from a single build, however in a more complex scenario I'd use both a VSTS build and a VSTS release definition. From the VSTS Build & Release tab create a new build definition based on an Empty template. Use the AspNetCoreLinux repository, check the Continuous integration box and select Linux for the Default agent queue (assuming you create a queue named Linux as I've done):

vsts-create-new-build-definition

Using Add build step add two Command Line tasks and three Docker tasks:

vsts-add-tasks

In turn right-click all but the first task and disable them -- this will allow the definition to be saved without having to complete all the tasks.

The configuration for Command Line task #1 is:

  • Tool = dotnet
  • Arguments = restore -v minimal
  • Advanced > Working folder = src/AspNetCoreLinux (use the ellipsis to select)

Save the definition (as AspNetCoreLinux) and then queue a build to make sure there are no errors. This task restores the packages specified in project.json.

The configuration for Command Line task #2 is:

  • Tool = dotnet
  • Arguments = publish -c $(Build.Configuration) -o $(Build.StagingDirectory)/app/
  • Advanced > Working folder = src/AspNetCoreLinux (use the ellipsis to select)

Enable the task and then queue a build to make sure there are no errors. This task publishes the application to$(Build.StagingDirectory)/app (which equates to home/docker-user/myagent/_work/1/a/app).

The configuration for Docker task #1 is:

  • Docker Registry Connection = <name of your Docker registry connection>
  • Action = Build an image
  • Docker File = $(Build.StagingDirectory)/app/Dockerfile
  • Build Context = $(Build.StagingDirectory)/app
  • Image Name = <your Docker ID>/aspnetcorelinux:$(Build.BuildNumber)
  • Docker Host Connection = vstsbuildvm (or your Docker Host name for the build server)
  • Working Directory = $(Build.StagingDirectory)/app

Enable the task and then queue a build to make sure there are no errors. If you run sudo docker images on the build machine you should see the image has been created.

The configuration for Docker task #2 is:

  • Docker Registry Connection = <name of your Docker registry connection>
  • Action = Push an image
  • Image Name = <your Docker ID>/aspnetcorelinux:$(Build.BuildNumber)
  • Advanced Options > Docker Host Connection = vstsbuildvm (or your Docker Host name for the build server)
  • Advanced Options > Working Directory = $(System.DefaultWorkingDirectory)

Enable the task and then queue a build to make sure there are no errors. If you log in to Docker Hub you should see the image under your profile.

The configuration for Docker task #3 is:

  • Docker Registry Connection = <name of your Docker registry connection>
  • Action = Run an image
  • Image Name = <your Docker ID>/aspnetcorelinux:$(Build.BuildNumber)
  • Container Name = aspnetcorelinux$(Build.BuildNumber) (slightly different from above!)
  • Ports = 80:80
  • Advanced Options > Docker Host Connection = vstsdeployvm (or your Docker Host name for the deploy server)
  • Advanced Options > Working Directory = $(System.DefaultWorkingDirectory)

Enable the task and then queue a build to make sure there are no errors. If you navigate to the URL of your deployment sever (eg http://vstsdeployvm.westus.cloudapp.azure.com/) you should see the web application running. As things stand though if you want to deploy again you'll need to stop the container first.

That's all for now...

Please do be aware that this is only a very high-level run-through of this toolchain and there many gaps to be filled: how does a website work with databases, how to host a website on something other than the Kestrel server used here and how to secure containers that should be private are just a few of the many questions in my mind. What's particularly exciting though for me is that we now have a great solution to the problem of developing a web app on Windows 10 but deploying it to Windows Server, since although this post was about Linux, Docker for Windows supports the same way of working with Windows Server Core and Nanao Server (currently in beta). So I hope you found this a useful starting point -- do watch out for my next post in this series!

Cheers -- Graham