Migrate Azure Web Site to Azure Cloud Service

问题

I have a project and I'm planning to start the web app as an Azure Web Site and then migrate it to an Azure Cloud Service (also called Hosted Service) if it is needed as a scale strategy.

The decision is because I read that Azure Web Sites are more simple and fast to develop with almost no Azure-specific configurations or code. So starting fast and simple is a good starting point for the project.

But, is that a good starting point for you? Is migrating an Azure Web Site to an Azure Cloud Service the same as you were migrating a normal ASP.NET Website to an Azure Cloud Service? Would you start with an Azure Cloud Service right from the beginning? If yes, why?

Thanks for your time.

回答1:

There are benefits to both deployment models, it will eventually come down to what you are trying to achieve and ultimately the success of your application.

Below I've outlined the Pros and Cons of each of the models to ensure that you're making the right choice for your applications goals.

Windows Azure Web Sites

You have properly identified that Windows Azure Web Sites is a great starting point for an application, however you could also consider that Web Sites does offer enough scalability for many solutions.

Pros

• 10 Free sites during preview [Free for 12 months]
• Easy Deployment (use Git, TFS, Web Deploy or FTP)
• Quick Scalability (You can move to your own dedicated cluster [aka reserved standard])
• Simple Development (Supports Classic ASP, ASP.NET, Node.js, Python & PHP)
• Persistent Environment (most people are used to this)

Cons

• No SSL Support on Custom Domains
• in Preview (currently no SLA)

Windows Azure Cloud Services

Cloud Services (formerly known as Hosted Services) is definitely the vision for the future of Web Applications. It is built with resiliency in mind to keep the cost of applications affordable by scaling to meet demand, and dial back capacity when your traffic slows.

Pros

• Increased control over the cost of your application (if architected correctly)
• Flexibility (You have full control over the environment)
  • SSL Support
  • Language Agnostic
  • Web Server Agnostic (although IIS is available by default)
• Auto Management of Servers

Cons

• Architecture should be carefully considered
• Deployment time is slower (Slows development cycle)

Things to consider for Portability

The items above might have given you enough to plan the immediate future of the application and it is very likely that you might want to consider Cloud Services in the future (it fits a number of application scenarios better in the long run).

Here is a list of things to help portability between Web Sites to Cloud Services:

1. Start thinking Stateless

   Windows Azure Web Sites is nice as it is a persistent environment, which means you are able to store things like session state and assets to the disk.

   Although this is a good feature, it's best to start planning towards a stateless application, if your end goal is to be in Cloud Services. Here are a few things you can do to start thinking stateless:

   • Don't rely on Session State
     • If you need it, come up with a strategy to make it scale (Caching Service, SQL, or Storage)
   • Use the Storage Service
     • Assets such as Static HTML, css, javascript and images are better placed in Storage
       • Avoids additional bandwidth on your Web Site (potentially stay shared longer for lower cost)
       • Can be CDN Enabled, provides a better experience for International markets
       • Easier to update web assets when application is migrated to Cloud Services
     • Storing User content
       • If your application already stores to the Storage Service, there is one less code modification in the future when moving to cloud services.

2. Make it easy to discover patterns in your Data

   The benefit of Cloud Services is it enables you to reduce cost by only scaling what needs scaled. Starting the process of identifying your scale units i.e. How you partition your database or Tables in Storage.

回答2:

Azure is a great place to have your app, but there are some considerations you need to know before start migrating it.

• Azure Websites and Hosted Services are really trivial to deploy. With Visual studio you generate the package and simply upload it. Then you have a Development environment to check it. If it's ok for you, swap ips. If it's not ok for you, upgrade again.

• Your instances have some properties that could be annoying. For example, you cannot be sure about your IP. Then if your app works with some provider using IP restriction, you will need to figure out how to proceed.

• More considerations. Your "server" could be reimaged at any moment. If you store something on the local disc, that file could go away at any moment.

• Azure works very nice if you have at least 2 instances or more for each website. Maybe your app is not prepared for that. The first step will be managing the sessions with the appFabric. Is really easy, just a change on your web config. Be careful because this session state doesn't work exactly as the "old one". You cannot store non-serializable objects (should be easy to adapt) or a very large objects (more than 8MB).

If you are going to develop something from zero, I suggest you to start into azure from the beginning. The reason is simple: it's really cheap to start and you will not pay serious money until the app have lot's of visits. It's also very cheap to setup a SQLAzure and a storage account. One you have all in place, it's easy to add more instances or scale up.

Example:

Imagine you have an idea and you wish to show up to some possible investors.

You start setting up a little SQLAzure database (1GB ), $9,99 monthly.

Then you build a site and you put 2 extra small instances, $18,72 monthly.

Let's say you need 100 GB of space (images, backups, ...), $12,50 monthly.

At his point, you have all in place to start your business paying less than $50 monthly.

If you site have exit and the visits starts to come, you change your instances for small instances (it's really dangerous to have production environment with extra small instances, because do not have cpu reservation). Then you change the extra small cost ($18,71) up to $57,60. Maybe you need more space to that SQL Azure? etc...

prices calculated from here: http://www.windowsazure.com/en-us/pricing/calculator/?scenario=web .

Those are few tips, there is a lot more. My advice is to start a trial account and play with it.

Final advice: Its very easy to solve everything just purchasing more resources. Sometimes you need to refactor and optimize your code. If you simply add more resources each time you have a problem, you could end with a huge bill and a very messy code.

Hope it helps!

回答3:

I read all post and all of them are very helpful. In addition to all post , I found an info on msdn : Windows Azure Websites, Cloud Services, and VMs: When to use which?

With Windows Azure Websites you can:

• Build highly scalable web sites on Windows Azure.
• Quickly and easily deploy sites to a highly scalable cloud environment that allows you to start small and scale as needed.
• Use the languages and open source applications of your choice then deploy with FTP, Git or TFS, and easily integrate Windows Azure services like SQL Database, Caching, CDN and Storage.

With Cloud Services you can:

• Build or extend your enterprise applications on Windows Azure.
• Create highly-available, scalable applications and services using a rich PaaS environment. Support advanced multi-tier scenarios, automated deployments and elastic scale. Deliver great SaaS solutions to customers anywhere around the world.

And also there is summarizes the option on msdn :

And comparing some features Web Sites and Cloud Services on msdn:

回答4:

Another advantage of Windows Azure Cloud Services over Web Sites is that a cloud service can be added to an Azure Virtual Network. This can give it access to on-premises resources like databases. So if your requirements are such that you need the scalability offered by Azure but need to keep your data on-premises due to security restrictions, cloud services is a better choice.

Azure web sites cannot be part of an Azure virtual network. To access on-premises resources mechanisms such as Azure Service Bus Relay must be configured.

回答5:

We've had our web site running on PHP on some hosting and at some point decided to move it to Azure (where sits main part of our service). We've started with Azure Web Sites which was great from development point of view (mainly integration with git). But after about a week of testing (when we've decided to actually move the production web site) we've found that currently

1. No SSL for custom domains
2. Custom domains are available only for reserved instances (no shared infrastructure)
3. SLA

So we moved to Hosted Service. The main problem for us was lack of ability of simple deployment (need to build package and upload whole package of the web site), and found solution was to use dropbox - as a startup task for role, we're installing dropbox service on the machine, which takes all the web site from dropbox, which in turn have SVN checked out folder, so site updates became very easy.

来源：https://stackoverflow.com/questions/11681488/migrate-azure-web-site-to-azure-cloud-service