In my recent talk at Leeds Sitecore User Group this month, I demoed the Sitecore Publishing Service running in Docker and discussed how we can harness that for easy roll-out and migration to developers, through test environments and to the Cloud.
What is Docker?
Docker has really taken hold in the last few years with a massive amount of time and money being invested in the technology. I won’t go into detail here as there are hundreds of resources readily available online.
Microsoft are embracing Docker and investing heavily in it’s future with their .NET Core and Azure implementations. Their Docker documentation is definitely one of the better resources and a worthwhile read:
Not everyone is a fan of Docker and not everything needs ‘Dockerising.’ However Docker containers can be useful when you need:
- Consistency between environments with no variations between instances
- Portability – An ability to share an environment
- Isolation – You want your environment to be agnostic of, and isolated from the host machine / Operating System
- Repeatability – When you have a lot of people wanting to set up the same thing
Why use Docker for the Publishing Service?
The Publishing Service is a good candidate for containerisation. For large development teams or teams with masses of infrastructure, individually setting up the SPS can mean a large investment in time and resources. As long as your environment supports it, Docker can reduce that cost significantly.
Building the image
First up: clone the repo here: https://github.com/mjftechnology/Sitecorium.Docker.PublishingService
The instructions are present in the Readme.md file but for your convenience:
- Download the SPS service zip file version that matches your requirements and place in the assets folder
- Rename the zip to “Sitecore Publishing Service.zip”
- Edit the Connection strings in the Docker-compose.yml file to a SQL Server instance the image can access. (It will install the SPS table schema in these DBs)
- Edit the hostname in the Docker-compose.yml file to a hostname of your choice or leave the default
- Open a command prompt and type: docker-compose up –build -d. After some time the image should be built and the container will be started with the name publishingservice.
- Add the hostname sitecore.docker.pubsvc (or your custom host) to your hosts file
- From here on in you can run or tear down the container with two easy commands:
docker-compose up -d and docker-compose down
How does it work?
The example consists of 2 main parts:
- The docker-compose YAML file
- The Dockerfile
Docker Compose is a handy tool for orchestrating containers. It’s not mandatory in order to use the SPS but I find it useful for supplying parameters to a Dockerfile and makes it easier to add companion containers later on. The docker-compose.yml file in the repo should be customised, allowing you to enter your Sitecore database connection strings and desired hostname for the Publishing Service instance.
The Dockerfile (text based instructions Docker uses to construct an image) used in my demo is where the heavy lifting takes place. It is based on the .NET Framework image from Microsoft which out of the box gives us:
- Windows Server Core as the base OS
- IIS 10 as the Web Server
- .NET Framework
- .NET Extensibility for IIS
*Note*
As the Publishing Service currently has a dependency on the .NET Framework and is therefore not fully cross platform we must use a windows image as a base. There is a plan for version 5 to be built on top of Sitecore Host (Sitecore’s service architecture going forward). In theory this will be fully .NET Core based and thus cross platform. This means we will be able to use a much smaller linux container as a base image. Until then we’re stuck with bloated Windows!
On top of this base Windows image the Dockerfile then instructs Docker to:
- Install the .NET Core Hosting Bundle which in turn installs the .NET Core runtime, library and ASP.NET Core module. It also allows us to run the SPS in IIS.
- Copy the SPS zip file from the assets folder into the image and unzip it.
- Set the connection strings to the Sitecore databases using the values passed in from the docker-compose file.
- Upgrade the database schema as per the SPS install instructions
- Install the SPS into IIS using the hostname in the compose file.
Running the container
Once the container is up and running, your host entry is set and the Sitecore config updated you should be able to view the container status page in the usual manner by navigating to the status URL in a browser to ensure the service is up and running:
http://<your host>/api/publishing/operations/status
If the service is running you should see a status response of zero a la:
{ "status": 0 }
Time to try a publish!
