I am new to cloud platform.
I know that various cloud vendor have a mechanism wherein if the VM crashes and cannot be brought up, it can spin a new VM
In such a case, how is the code deployed on the new VM that the Cloud provider spins?
In such a case does the application owner has to deal with the deployment or is it taken care of by the Provider
For PaaS, you upload a package and configuration (cspkg and cscfg from your build) to the cloud service, this is deployed by Azure automatically, you can specify how many (and size) machines you want your application to be deployed over, and it's configurable via the Portal (and outside using PowerShell/REST) if you want to.
In your solution you specify the size in the csdef:
<ServiceDefinition name="MyWebRole.CloudService"
<WebRole name="MyWebRole" vmsize="Small">
And the number of instances in the cscfg:
<Role name="MyWebRole" vmName="WebRole">
<Instances count="2" />
You should make sure you have a minimum of 2 instances running for your app, if one goes down then your app won't fail straight away. Microsoft may need to tear it down or update it without telling you (and you shouldn't notice apart from any logs etc), if your app cannot cope on a single instance then make sure you have 3 (so in the event of a server going down you still have a minimum of 2).
Via the Azure Portal you can both reboot and reimage (deploy your package/config to a completely new machine), the package/config are retained in Azure so you don't need to deploy them again, the same thing happens when you scale your service up/down, the package/config already exist in Azure so it "just does it" (expecting a busy day? Add some machines to your service, or set it to auto scale based on a metric).
IaaS is very much the same as your usual VM scenario, you spin them up, remote onto them and do whatever is necessary! You can turn them on and off via the portal. Installations, OS issues/config, patching, are your own problems (potentially joined to a domain so policies/DSC can be used if that's what your familiar with), so if you have something that needs to be installed via an exe etc or used with a GUI, then VM's work for this scenario. As a side note, I've only every once seen an issue in Azure with a VM getting knackered (blue screen -> insert cd error), if you think you have a problem with the platform you can do things like delete the VM (but keep the disks!) and create a new one with the same disks.
Another thing to look into is WebApps/AppServices, they are kind of like Cloud Services, except they take away some of the issues such as having actual underlying VMs.
Related
i am a newbie and am planning to host iis server for my client in azure with auto-scale functionality.
we will test modules and update once in a week in iis server, my question is how to sync the files between vms while on auto-scaling and if we can use auto-scale only for identicals vms, then please suggest me the solution for this scenario. we will start min 2 max 10 vms in auto-scale.
Regards,
Kumar B
I first would ask why a VM, things do get more complicated using VMs. Scale Set would help support this however you still will have issues when you want to deploy new code. You said IIS so I am presuming Windows. Desired State Configuration is a great choice you can make a PowerShell script that will "configure" your VM for you, and potentially pull in any code updates. This is also where things like chef/puppet/salt can come into play to ensure the server is configured.
You could look at creating a custom image that every time you deploy new code gets baked into the image. Then you are basically doing a rolling update where you spin up a new server and then destroy one until they all have been updated. Technically this could be done, either way, just if they are baked into the image you would have a quicker start time.
https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-deploy-app
https://adamtheautomator.com/azure-vm-scale-sets-powershell/
Automatic - VMs may be rebooted in a random order even taking all VMs temporarily down at the same time.
Rolling - The scale set deploys updates to instances in batches with an optional pause time between batches.
Manual - Nothing happens to existing VMs when an update is initiated.
What files are you trying to sync if they are not code files, Azure Files would be a great fit as that supports SMB or you could just use cloud storage.
You can deploy your application to a virtual machine scale set using desired state configuration. See: https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-deploy-app
Not what you asked, but you should consider why you are hosting your app in IIS on VMs. If you are using Azure, then Azure App Service may be a better fit. See: https://learn.microsoft.com/en-us/azure/app-service/
I thought one of the advantages of Azure was that I could turn services on and off depending on when I want them to be available.
However I cant see how to pause my App Service Plan.
Is it possible?
I want to use the S1 tier so that I can play with what it offers. However I want to be able to pause the cost accumulation when I am not using it.
I see from the app service pricing help that an app will still be billed for even though it is in the stopped state.
Yet the link also clearly states that I only pay for what I use. So how does that work?
If you put your hosting plan onto the free tier, you will stop being charged for it. However if you have things like deployment slots and certificates these will be deleted.
The ability to turn services on and off, is more to do with being able to scale services, so if you need 50 servers for an hour you can easily do that.
What you can do to make your solution temporary is to create a deployment script, using Powershell or Resource manager Templates then you can deploy your solution for exactly as long as you need it and then delete it again when you don't. In this sense you can turn your services on and off at a whim.
Azure provides building blocks for you to create the solution you need, it is up to you to figure out how to best use those building blocks to create the solution you seek.
Edited to answer extended question.
If you want to use the S1 pricing plan, and not have it charge when you are not using it, the only way of achieving that is by using automation. Fortunately, this is reasonably trivial to achieve.
If you look at this template it is pretty much all configured to deploy a website from Github to Azure on demand. If you edit that to configure it to your needs you can have a new Azure website online with 2 minutes of running the script.
Then you would have another script that deleted it once you had finished.
Doing it this way you would loose no functionality, and probably learn quite a bit about what is possible with Azure along the way.
App Service Plan
An app service plan is the hardware that a web app runs on. In the free and shared tier your web apps share an instance with other web apps. In the other tiers you have a dedicated virtual machine. It is this virtual machine that you pay for. In that case it is irrelevant whether or not you have web apps running on your app service or not, you still have a virtual machine running and you will be charged for that.
To change the App Service Plan via PowerShell, you can run the following command
Set-AzureRmAppServicePlan -ResourceGroupName $rg -Name $AppServicePlan -Tier Free
I was able to accomplish this using the dashboard by selecting the App Service Plan, clicking Scale up (App Service Plan), and then from there if you click Dev/Test you can select the Free tier.
As others have mentioned, you need to script this. Fortunately, I created a repository with one-click deployment to your Azure resources.
https://github.com/jraps20/jrap-AzureVerticalScaling
The steps are intended to be as simple and generic as possible:
Execute the one-click deployment from the repo readme
Select the subscription, resource group etc.
Deploy resource to Azure
Set up your schedule to scale up and scale down as-needed
The scripting relies on runbooks and variables to maintain the previous state of each App Service Plan and App Services within those plans. Some App Services cannot be scaled due to specific settings being used (AlwaysOn, Use32BitWOrkerProcess, ClientCertEnabled, etc.). In those cases, the previous values are stored as variables prior to down scaling and then the original values are reapplied when the services are scaled up.
For more clarity, I have written a blog post that goes into detail. The post is pertaining to Sitecore, but applies to any App Service setup- Drastically Reduce Azure PaaS Hosting Costs in Non-Prod Environments With Scheduled Vertical Scaling. It also includes a brief video tutorial to show its use case.
Myself and others have been using this repository/approach for well over a year and it works great. I mostly use it for POC's to reduce costs when I'm not actively working on something. However, its main intention was for targeting non-prod environments to save costs during non-work hours.
Azure App Service Plan is just an logical concept of a set of features and capacity that you can share across multiple apps. I don`t think you can "pause" a plan, instead you can pause your service. and depends on billing model of each service, you might or might not get charged.
Pausing = Delete or lower tier.
Scripting is the key.
Design Diagram
Use scripts to create (also consider shared resources)
Delete using scripts
Use scripts to recreate.
eg: If we use resource group properly per environment then
Export-AzureRmResourceGroup will create a template for us (everything in the resource group will be pulled out as script). So we can delete it and recreate it anytime.
To pause a VM and stop billing you need to shut is down and deallocate it. Just shutting down still has the capacity reserved as if its running.
Storage can't be shutdown - it can be moved to lower cost tiers.
We currently have a window service which send some notification emails to users after doing some processing on database(SQL database). Runs once in day.
We want to move this on azure cloud. One alternate is to put it on Azure VM as is. but I am finding some other best possible solution for that.
I study about recurring and on demand Web jobs but I am not sure is this is best solution.
Also is there any possibility to update configuration of service code in App.config without re-deploy the code of service on cloud. I means we can manage configuration from Azure portal.
Thanks in advance.
Update 11/4/2016
Since this was written, there are 2 additional features available in Azure that are both excellent choices depending on what functionality you need:
Azure Functions (which was based on the WebJobs described below): Serverless code that can be trigger/invoked in various ways, and has scaling support.
Azure Service Fabric: Microservice platform, with support for actor model, stateful and stateless services.
You've got 3 basic options:
Windows service running on VM
WebJob
Cloud service
There's a lot of information out there on the tradeoffs between these choices, but here's a brief summary.
VM - Advantages: you can move your service basically as it is without having to change much or any of your code. They also have the easiest connectivity with other resources in Azure (blob storage, virtual networks, etc). The disadvantage is you're giving up all the of PaaS advantages and are still stuck managing your own VM infrastructure
WebJob - Advantages: Multiple invocation options (queues, blobs, manually, queue receive loops, continuous while-loop style, etc), scheduled (would cover your case). Easy to deploy (can go with website, as a console app, automatically through Kudu), has some built in logging in Azure portal - and yes, to answer your question, you can alter the configuration in the portal itself for connection strings and app settings.
Disadvantages - you'll need to update code, you don't have access to underlying resources (if you need that), and more of something to keep in mind than a disadvantage - it uses the same resources as the webapp it's deployed with.
Web Jobs are the newest of the options, but at the same time appear to have active development going on to increase the functionality and usefulness.
Cloud Service - like a managed VM, has some deployment options, access to underlying VM if needed. Would require some code changes from your existing service.
There's nothing you've mentioned in your use case that makes me think a Web Job shouldn't be first thing you try.
(Edit: Troy Hunt has a great and relatively recent blog post illustrating most of the points I've mentioned about Web Jobs above: http://www.troyhunt.com/2015/01/azure-webjobs-are-awesome-and-you.html)
My understanding of the VMs involved in Azure Cloud Services is that at least some parts of it are not meant to persist throughout the lifetime of the service (unlike regular VMs that you can create through Azure).
This is why you must use Startup Tasks in your ServiceDefinition.csdef file in order to configure certain things.
However, after playing around with it for a while, I can't figure out what does and does not persist.
For instance, I installed an ISAPI filter into IIS by logging into remote desktop. That seems to have persisted across deployments and even a reimaging.
Is there a list somewhere of what does and does not persist and when that persistence will end (what triggers the clearing of it)?
See http://blogs.msdn.com/b/kwill/archive/2012/10/05/windows-azure-disk-partition-preservation.aspx for information about what is preserved on an Azure PaaS VM in different scenarios.
In short, the only things that will truly persist are things packaged in your cscfg/cspkg (ie. startup tasks). Anything else done at runtime or via RDP will eventually be removed.
See - How to: Update a cloud service role or deployment - in most cases, an UPDATE to an existing deployment will preserve local data while updating the application code for your cloud service.
Be aware that if you change the size of a role (that is, the size of a virtual machine that hosts a role instance) or the number of roles, each role instance (virtual machine) must be re-imaged, and any local data will be lost.
Also if you use the standard deployment practice of creating a new deployment in the staging slot and then swapping the VIP, you will also lose all local data (these are new VMs).
The company I work for is looking to develop a few apps against the cloud.
An ASP.NET Web Api application hosted in an Azure web role.
A Windows Server type application hosted in an Azure worker role.
We are completely new to web or cloud development and would like to know the following:
When being served to the consumer, is the same instance of the application being served to all, is it one per request or are multiple roles being created and served to consumers?
When being served to the consumer, is the same instance of the application being served to all?
That depends on how many instances you've asked Azure to run your application on. If you've only deployed to 1 instance, then it will of course be the same instance that responds to all requests. But if you deploy to multiple instances, requests will be load-balanced, which means you have no guarantee that multiple requests from the same user will be handled by the same instance.
When you're asking this question, it could be because you might be tempted to store local data on the machine running the instance. However, this is not a good idea. Windows Azure can at any time tear down your instance and start your application on a completely different machine. They call this "healing", because it usually happens because Windows Azure tries to be helpful and avoid any potential problem that could mean downtime for your instance. But it also happens if your machine for some reason locks up or something else bad happens. This process of healing means that anything that's not part of your deployment package will be lost. So for example, if you're logging to a file on the disk, this log will be lost if Azure "heals" your instance.
is it one per request or are multiple roles being created and served to consumers?
I'm not completely sure what you mean here, so I'll take a guess and risk interpreting your question wrongly. My guess is that you're asking if there will be one instance per user request. No, there will only be the number of instances that you have decided. Remember that you have to pay per instance that's running, so it's only fair that the number of instances running is dictated by you.
When you have your application packaged and ready to be deployed to Windows Azure, you can decide how many instances of each role you want to have running. You set this number in the deployment package, so that when your package is deployed, Azure will automatically start the requested number of instances. However, you can change the number of running instances of each role after deployment and on-the-fly. This makes it possible for you to scale with more instances within minutes.
I hope this helps and that I understood your questions correctly. :-)
Azure Web and Worker roles in an Azure Cloud Service are deployed on at least one instance (managed VM). Azure allows you to size (memory, CPU) and scale (number of instances). Azure actually lets you scale dynamically, i.e. add more instances on demand. You pay by the hour for the size & number of instances deployed.
For example, a Cloud service can have a single instance of a worker role (background processing) and multiple instances of the Web role. Multiple instances are handled behind a load balancer and the client is unaware of what instance they are using (all instances are created equal).
An Azure role instance is a VM with some specific payload.
For example, in your service you declare you want three instances of "Frontend" web role and two instances of "Backend" worker role. When Azure deploys your service it starts five VMs and three of them will run "Frontend" payload and have IIS started and two of them will run "Backend" payload and have no IIS started.
Now until you ask Azure to change that configuration it remains persistent no matter what requests come and what load occurs. You have five VMs with 3+2 configurations. To change the configuration you need some action on your part.
There're two way to have the configuration changed. You can use Management Portal or an external program to change the "instance count" in either or both roles. You can also add auto-scaling code that will gather metrics and make Management API requests to alter the "instance count". Either way when "instance count" goes up Azure starts more VMs with the same payload and when it goes down it stops some of the VMs.