Crear una llave pública de OpenSSH para una VM Ubuntu en Azure usando PuttyGen

En días pasados publiqué como crear una llave pública de OpenSSH para una VM Ubuntu en Azure usando macOS. Esta vez vamos a hacerlo para Windows usando PuttyGen. El proceso de crear la VM en el portal de Azure es exactamente igual, debes ver una pantalla como esta

How many nines? Understanding availability

Most likely you have already experienced a system downtime, either on an application you have worked on or on some service that you consume. It has happened to Amazon, Netflix,  Microsoft, Salesforce, etc. How much did you have to wait? How much did your users?

If you’re building an application and you ask your boss (or your client) what’s the percentage of time  the application should be working correctly, most likely you’ll get an answer like “always” or  “100% (or more)”.

Even though we don’t wan’t bad things to happen, they will surely do; bugs, attacks, power outages, natural disasters, etc., all are scenarios that might affect a system. Expecting them not to happen is naive; it’s better to think on and plan for failure, since it is inevitable.

Availability is the capability of an application to be available after some problem occurs. Again, we are not saying there will be no problems, but how effectively will be able to recover from them instead. This means that we need to a) identify the potential fail points and b) create an strategy to be able to prevent the error becoming a failure affecting the user (this means a tree falling in the forest when no-one is around makes no sound).

Crear una llave pública de OpenSSH para una VM Ubuntu en Azure usando macOS

Cuando se crea una nueva máquina virtual en Windows Azure, tienes la opción de asignar una contraseña o usar una llave pública de SSH como tipo de autenticación.

Creating a new VM

Aunque normalmente estamos acostumbrados a usar contraseñas, sin importar que tan complejas sean, en muchos casos son compartidas con otras personas, adivinadas, escritas en post-its, etc., invalidando las medidas de seguridad que intentaban establecer.

Introducción a Service Fabric (I)

This post is part of Service Fabric series

  1. Introduction to Service Fabric
  2. Creating a WCF Service for Azure Service Fabric

In the beginning (not so far away) it was the local server, and developer’s life was a chaos. IT team (if existing, otherwise the developer itself) was responsible of ensuring the server where the applications was installed worked as needed. It was his fault if this didn’t happen.

Later, whit the use of virtualization the cloud came bringing the ability of give us the chance of blaming transfer the responsibility to someone else.

 

What does all this have to do with this post? Microsoft Azure Service Fabric is a Platform as a Service option, built from scratch for supporting cloud, distributed, high-scale and high-availability applications. It started as a proposal for cloud databases (CloudDB) and currently is being used on rockstar Microsoft Products like Cortana, Skype for Business, Power BI, SQL Azure, etc.

Its main advantages are in the easiness given to developers for managing elements that are beyond functionality, like

  • Rolling updates
  • Logging
  • Monitoring and telemetry from the services
  • Failures
  • Security

This way developer can focus all his efforts and attention in coding.

 

Microservices

Even though it is normally associated with microservices, Service Fabric benefits can be useful in multi-layer applications, APIs, etc. But, what are microservices? Although there is no standard definition, they are normally identified by spliting application functions in small parts. These parts are independently versioned, written in any language or technology and oriented to solve a concrete situation from the problem is intending to tackle. It is important to be clear that monolithic is not bad neither microservices is good; it all depends of the scenario and context.

By being distributed independently in different nodes (containers, servers, virtual machines) within a cluster where the replication and partition process is performed, each microservice can be scaled according to its own needs.

Cluster

Service Fabric can run the same on Microsoft Azure, other clouds providers like AWS and even on private clouds, no matter if it is Linux or Windows. Even at development time, the required components are exactly the same, what makes really easy to move from one environment to the other when it is needed. This is because the components where thought to be standard and is not needed to make modifications according to the environment where it will be executed.

The cluster is a set of nodes components installed and configured to communicate each other; it provides an abstraction level between the application and the infraestructure where it’s executed. The main cluster abilites are

  • Supporting thousand of nodes
  • Dynamic change
  • Isolation unit

Infrastructure Services

Service fabric provides a set of services to help with infrastructure management

Cluster manager

In charge of cluster operations. By default it can be managed using REST through port 19800 with HTTP and with TCP through port 19000 using Powershell.

Failover manager

In charge of detecting when new nodes are added to the cluster, when they are removed, or when a fail occurs in order to re-balance for high availabiliy.

Naming

Maps the services with the endpoints, so the can communicate each other.

Fault Analysis

Helps you to introduce failures to your services so you can test different scenarios in a controlled manner.

Image Store

Contains the actual bits of the services, the master used for creating the copies that are replicated on the nodes.

Upgrade

In charge of updating Service Fabric components, exclusively on Azure.

 

Programming models

When working with Service Fabric, you have 3 options for creating your services

Reliable services

Provides a simple way for integrate with Service Fabric when creating your services, benefiting from the platform tools.

Reliable actors

Built on top of Reliable Services capabilities, it’s a framework that works with single-threaded units called Actors, based on the design pattern with the same name.

Guest executable

It’s just that, an executable that you can deploy to service fabric cluster, without fully integrating with the platform; Service Fabric just ensures the exec stays up and running. The programming language doesn’t matter, so it is a good option for existing applications.

 

Application and services

An applications is basically a set of services, defined in ApplicationManifest.xml file; in Service Fabric terms, we name it Application Type. Based on this type we create an Application Instance, that is the one we hit at runtime; this is very similar to the class and instance concepts in OOP. The same goes for Service Type and Service instance; additionaly it’s composed by 3 parts: code, data and configuration.

Each of this elements has its own version, so we can have an Application with version label 2.1.1 composed by one service with version 1.0.0.


 

That’s it for now; we’ve covered Service Fabric concepts that will be used for our next tutorials.

Fortune cookie app powered by Azure Functions using Twilio and Sendgrid outputs

One of the greatest advantages of working with Azure Functions is being able to prototype easily applications. For this post I will create a simple Fortune cookie app, which will send you a phrase to your email using Sendgrid and phone via SMS using Twilio. The app will be composed of three pieces

  • Front-end web page using HttpTrigger
  • POST request processing with HttpTrigger
  • Queue processing using Azure Queue Storage Trigger