24 Jan 2017
In round 8 of the Service Fabric Q&A, they announced a “common questions” page to hopefully answer the frequently asked questions they’ve gotten almost every time.
https://docs.microsoft.com/en-us/azure/service-fabric/service-fabric-common-questions
Update: Another gem I became aware of in this session is Microsoft.Diagnostic.EventFlow which allows you to log to Microsoft.Extensions.Logging and have it persist to Elasticsearch (and the ELK stack more specifically.)
20 Dec 2016
I’ve been playing with Azure Service Fabric and testing out
the latest preview
with Windows container support. My goal is to deploy a stateless OWIN self-hosted Web API in a container to
service fabric. I saw a cool demo of an application upgrade, so I stole the idea of an API that simply returns a color (blue.)
Version 2 of the service returns a different color (red), so you can actually watch the rolling upgrade across the cluster
as the color changes from blue to red in several load-balanced clients.
Program.cs
using Microsoft.Owin.Hosting;
using System;
using System.Threading;
namespace ColorPicker
{
class Program
{
static void Main(string[] args)
{
string baseAddress = "http://*:80/";
using (WebApp.Start<Startup>(url: baseAddress))
{
Console.WriteLine($"ColorPicker listening at {baseAddress}");
Thread.Sleep(Timeout.Infinite);
}
}
}
}
Startup.cs
using Owin;
using System.Web.Http;
namespace ColorPicker
{
public class Startup
{
public void Configuration(IAppBuilder app)
{
HttpConfiguration config = new HttpConfiguration();
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
config.Formatters.Remove(config.Formatters.XmlFormatter);
app.UseWebApi(config);
}
}
}
ColorController.cs
using System.Web.Http;
namespace ColorPicker
{
public class ColorController : ApiController
{
public string Get()
{
return "#0000FF";
}
}
}
Dockerfile
FROM microsoft/windowsservercore
ADD . /app
WORKDIR /app
ENTRYPOINT ["cmd.exe", "/k", "ColorPicker.exe"]
Docker Registry
The service manifest only lets you specify the name of the container, which means you have to deploy it to a registry. I don’t
want to push anything to DockerHub, so instead I decided to give Docker Registry a try.
I’m using a macbook, so I followed the quick guide to run the registry as a container.
PS C:\> docker run -d -p 5000:5000 --name registry registry:2
I’m running Windows in a VM and tried pushing my Windows docker image to the registry running on the mac host.
PS C:\> docker build -t colorpicker .
PS C:\> docker tag colorpicker 10.211.55.2:5000/colorpicker
PS C:\> docker push 10.211.55.2:5000/colorpicker
This surprisingly worked, but gave me a TLS error:
The push refers to a repository [10.211.55.2:5000/colorpicker]
Get https://10.211.55.2:5000/v2/: http: server gave HTTP response to HTTPS client
Make it insecure
It turns out the docker client requires TLS by default, but the docs also explain how to run it insecurely for testing. To disable security, you have to edit the docker config file on the client, and whitelist the insecure registry you want to connect to.
The instructions tell you to edit the docker file directly, which only applies to *nix clients. I dug a little deeper into how to configure this for both Docker for Mac and Windows.
Docker for Mac
Docker for Mac provisions a HyperKit VM based on Alpine Linux. They do some interesting stuff with git to modify files in the docker app (such as a daemon.json file,) and then reload the VM. However, they have since added an option in the advanced settings dialog to add insecure registries.
If you still wish to connect to the host (for debugging, or other reasons,) you have to use screen rather than ssh. Found that little nugget on this blog. Any changes to the host will be lost whenever the daemon is restarted.
Press enter to get a prompt. Disconnect with ctrl+a d.
$ screen ~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/tty
Docker for Windows
Docker for Windows lets you run Linux containers on Windows 10 by provisioning a minimal Linux VM using Hyper-V. I’m not aware of any way to access the host environment, and the stable version of docker does not expose any settings to configure the docker file.
But I want to push my windows container, not a linux container. Why would I need Docker for Windows? As luck would have it, I needed to install the beta release in order to get the option to switch between linux and windows containers. The beta settings dialog includes daemon options which lets you set insecure registries. This is not currently available in the stable release.
Another point worth mentioning is that the docker daemon would not start on my Windows VM when set to use linux containers, which has something to do with nested virtualization (running a VM inside a VM.) Since I don’t really care about linux containers at the moment, I simply switched to windows containers, and slowly backed into the bushes.
Let’s try again…
Now that our client is configured to trust our insecure registry, let’s try the push again.
PS C:\> docker push 10.211.55.2:5000/colorpicker
The push refers to a repository [10.211.55.2:5000/colorpicker]
242b7a69a21f: Pushed
0281ebf270fd: Pushed
4777122753b8: Pushed
de57d9086f9a: Skipped foreign layer
f358be10862c: Skipped foreign layer
latest: digest: sha256:7d3ff34231abec035813d36f1cfe48c737e15ba9b6db9dd238e5c1f166bcb73d size: 1570
Success!
12 Dec 2016
SFNuGet is a NuGet package that allows you to “easily share, discover and reuse Service Fabric services as NuGet packages.”
In the world of Microservices, one of the greatest things is Docker Hub, where you can find thousands of reusable images that you can easily incorporate into your own applications. Service Fabric is still fairly new, so there isn’t such a vibrant community yet - I hope SFNuGet is a start.
With SFNuGet, developers like you can easily create and share great services with the entire community. If you come from the Docker world, you can think Service Fabric NuGet packages as Docker images, while Service Fabric application manifests as Docker compose files. And if I dare to dream, the parallel concepts create opportunities for bridging the two in the future.
http://haishibai.blogspot.com/2016/08/sharing-your-service-fabric-services-as.html?m=1
There isn’t much available yet on nuget, but this may help to manage a large fabric application composed of services from multiple teams.
12 Dec 2016
Coordinating loosely-coupled, distributed teams that develop microservices, comes down to agreeing on and enforcing a contract.
As each team continuously delivers each service, ideally multiple times a day, integration and end-to-end tests become unwieldy.
Rather than trying to tame the beast that is a distributed architecture, and bringing all the pieces together, simply document expectations so that breaking changes become apparent.
Pact provides a contract ‘between service consumers and providers, enabling consumer driven contract testing.”
This video from Atlassian gives a visual explanation of how this type of testing is integral to a successful microservices architecture.
11 Dec 2016
I’m a big fan of online editors that generate graphs as you type pseudocode DSL. They update as you type, and re-arrange themselves to best fit the screen. The ones I frequent include:
And the latest discovery
- viz.js - graphs using GraphViz
I’ll update this post if I come across any more.
