Here is my simplified Azure architecture:
ResourceGroup1 => AppServicePlan
ResourceGroup2 -> AppService1, AppService2
Once this architecture is in place, I remove the apps one by one. When i delete (tried in portal and with PowerShell as well) the last app, the plan gets also deleted...
Is it by design or a bug ?
It is by design. The reason it was done that way is to avoid continuing to charge for an unused Plan, which would take some customers by surprise if they don't fully grasp the distinction between Plan and Web App.
So the only time a Plan can be empty is right after it's created. After that, any transition from 1 to 0 contained Web Apps triggers the deletion of the Plan.
If you want to avoid this behavior, the simplest workaround is to include a 'dummy' Web App in the Plan to keep it alive. You can stop that Web App, so it doesn't consume any resources on the VMs.
Related
As I understand there is no concept of update domain in App Services (and in other PaaS offerings). I am wondering how Azure is handling OS updates if I have only a single instance of an App Service app. Do I need to plan for two and more instances if I want to avoid such cases when an app goes down during the OS/other updates or this is handled without downtime? According to docs App Service has 99.95% SLA - is this time reserved here?
First of all, welcome to the community.
Your application will not become unavailable when App Services is patching the OS, you don't have to worry about that. Imagine if that would be the case, it would be a huge problem. Instead, the PaaS service will make sure your application is replicated to an updated worker node before that happens.
But you should have multiple instances, as a best practice listed in this article:
To avoid a single point-of-failure, run your app with at least 2-3 instances.
Running more than one instance ensures that your application is available when App Service moves or upgrades the underlying VM instances
Have a look at this detailed blog post:
https://azure.github.io/AppService/2018/01/18/Demystifying-the-magic-behind-App-Service-OS-updates.html
When the update reaches a specific region, we update available instances without apps on them, then move the apps to the updated instances, then update the offloaded instances.
The SLA is the same regardless the number of instances, even if you select "1 instance":
We guarantee that Apps running in a customer subscription will be available 99.95% of the time
Have a look at Hyper-V and VMWare, it will give you a rough idea on how App Services handle that.
If you're looking for zero-downtime deployments with App Services, what you are looking for are deployment slots.
Managing versions can be confusing, take a look at this issue I opened, it gives you a detailed how-to approach about managing different slot versions, which is not clearly described by Microsoft docs.
I have a very simple asp.net core hosted blazor wasm application on a S1 App Service with 2 slots: Integration and production. When I just publish into my integration slot that takes around 50 seconds. But when I swap the integration with the production slot it takes over 7 minutes. Both apps slots are after that very slow, often taking over a minute before they react again. During the swap both are not responding at all.
There are only 2 settings and the connection string to change. And I don't have any manual warmup.
Is the swap functionality just not really meant the be used on such a low configuration or can I adjust something in my configuration to speed things up?
Adding some information here regarding Azure App service deployment slot swap might be helpful:
Some apps might require custom warm-up actions before the swap. The applicationInitialization configuration element in web.config lets you specify custom initialization actions. The swap operation waits for this custom warm-up to finish before swapping with the target slot.
During the swap operation the Web App’s worker process may get restarted in order for some settings to take effect. Even though the swap does not proceed until the restarted worker process comes back online on every VM instance, it may still not be enough for application to be completely ready to take on production traffic.
Try enabling Application Initialization Module to completely warm up your application prior to swapping it into production.
More detailed explanation of that process is available at How to warm up Azure Web App during deployment slots swap
To add to this if the swap operation takes a long time to complete, you can also get information on the swap operation in the activity log. On your app's resource page in the portal, in the left pane, select Activity log. A swap operation appears in the log query as Swap Web App Slots. You can expand it and select one of the sub operations or errors to see the details.
Please refer to below links for more details on this:
https://learn.microsoft.com/en-us/azure/app-service/deploy-staging-slots#what-happens-during-a-swap
https://ruslany.net/2017/11/most-common-deployment-slot-swap-failures-and-how-to-fix-them/
https://ruslany.net/2019/06/azure-app-service-deployment-slots-tips-and-tricks/
I've created Azure function using Visual Studio as library project, have single project with 12 functions
e.g.
As of now my function hosted in Dedicated AppService Plan and one of function (EventHub listener) processes millions of message per-day, hence it utilizes 90%+ CPU all the time.
So we are planning to scale or Separate App Service plan for that single function. I see following possible solutions
Change dedicated app service plant to consumption. (not sure about pricing impact or SLA).
Create a new project, move single function in that project and deploy that function in a separate app service plan. (required code and CI/CD pipeline changes.)
Deploy same function dlls in 2 AppService Plan and remove functions according to scale. (not sure this is possible with Azure DevOps or not).
would like to know the better approach, if customer does not agree on consumption plan.
The advantage of a dedicated plan over a consumption plan is predictability. Running a workload on a consumption plan will usually work out faster and cheaper than running the same workload on a dedicated plan, but using a dedicated plan does prevent unexpected spikes in usage from leading to unexpected spikes in cost and also prevents cold start issues.
If you switch to the consumption model (option 1), you're paying for individual function execution so whether you run one or two function apps makes no difference from that point of view. You should decide how to split your functions based on how independent they are. If you'll only be deploying them as a single unit then stick to one function app, but if you may want to update the listener separately, put it in a separate project.
If you split into two apps running on separate dedicated service plans, creating a new project (option 2) is certainly the cleanest way to go about it. However, deploying the same project to both apps (option 3) is technically possible - you just need to disable the functions that shouldn't run on each app using app settings. Create settings named AzureWebJobs.MyFunction.Disabled with value true (see https://learn.microsoft.com/en-gb/azure/azure-functions/disable-function#functions-2x---all-languages).
wont help you, it scales all the functions in the function app
that will work
its the same as version, just with 2 app service plans, not one.
Better approach is - isolate this function into a single Azure Function App and then you can scale it independently.
I have one Resource Group. In it:
I have two Web Applications (A and B).
I have two Application Service Plans (PlanA and PlanB).
Each Web Application is alone in its Application Service plan. (A in PlanA, B in PlanB)
Both A and B consume between 1 and 9 GB of disk space each.
When I set both PlanA and PlanB to level B1, both A and B run fine.
When I stop the service for B, A continues to run fine, and B is shut down.
When I scale PlanB down to the Free level (and thus exceed its quota), B does not run.
However - Web App A (which is running in Service Plan PlanA) throws out of disk errors. These errors go away when I change PlanB back to B1. I thought the whole idea of Application Service Plans was to separate resource consumption between groups of applications. What am I missing here?
I thought the whole idea of Application Service Plans was to separate resource consumption between groups of applications.
Firstly, the resource group is just a container that holds related resources for an Azure solution. It is used to easily manage your resources and deploy. The service plan in the resource group will not affect another service plan.
Secondly, the service plan will not affect another service plan. Each service plan use its own physical server resources.
Besides, an app in App Service can be associated with only one App Service plan at any given time.
So the plan B will not affect the plan A.
I guess there maybe another reason causes the plan A web app show disk error.
I suggest you could firstly check the quota of your web app to make sure there are enough disk space to run your wen app. More details about how to check it, you could refer to this article.
If the service plan has enough disk and still show this error. I suggest you could try to scale up the service plan A then scale down.
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.