How to override AspNetCore LogLevel from aspsettings.json on Azure App Service?

Here is a post about something which is very dumb  yet it cost me a few hours to figure it out – how to override the Logging configuration from appsettings.json file on the Azure App Service settings?

Basically, you might have your AspNetCore app configured like this

  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Error" 

It is very simple config – do not show any logs for anything which is less than error (for AspNetCore logs) and nothing below the Information for the rest of the code logging traces.

The problem is that you may have in your code things like this

this.logger.LogDebug("[Group]:message" + JsonConvert.SerializeObject(creationEvent, Formatting.Indented));

You want to take a quick look but without redeploying the app – how to do that?

After 2 hours of searching, it turns out to be quite simple rule for overriding ANY setting.

Replace every { in the appsettings.json file with : in azure app settings

So just add a new Azure App Service setting  with key Logging:LogLevel:Default  and set it to Debug value and once done remove it.

How to use Azure Traffic manager with custom domains and SSL?


Here is a short „lessons learned“ blog post about a thing which: a) seems not have an updated blog post, stack overflow etc, b) wasted a day of my life and c) turned to be quite trivial once I figured out how to do it.

Basically, as Scott Hanselman blogged about a long time ago you might have users distributed around the globe in which case you would like them to use resources which are close to them and improve their perf. Or another use case is that auto-scale up/out capabilities of the single App Service are not enough and you would like to use multiple app services supporting your website.

Well if this sounds interesting, I have good news – like many other things with Azure this one turns out to be quite simple so let me show you how to set up SSL balancing with custom names using Azure Trafic manager.

Step 1 – create app services which will distribute the load

For the purpose of this blog post, I will create two app service: one in US and one in Europe data center with the idea that all of the users who are in US will be hitting the US app service and all the other users will use the EU app service.

There are many other use cases other than the typical geo distribution one like for example auto scale-out capabilities of a single app service are not sufficient, getting phased rollouts without using the slots, a/b tests, complying with the data sovereignty mandates etc…

Step 2 – create azure traffic manager endpoint

We need a single URL address which will then route traffic to the app services and one way to achieve that in Azure is by using the Azure Traffic Manager.

Hit that little plus, search for Traffic and – voila!

Two important things on this screen:

  • name – defines the unique public URL which will be called by service consumers and which will then go to individual app services
  • routing method  – there are 4 different ways how the app service routing can be driven where the most commonly used is the performance one but just for the kicks, I am going to use in my post Geographic one.

Now open traffic manager endpoint and do yourself a favor, open configuration and enable https only traffic

Step 3 – map the app services to the traffic manager

We need to inform traffic manager where it can redirect the traffic – go to the Endpoints/Add

And there define what app service should be used by which geographical area.

As we said for this example US service will handle North America traffic and EU service the rest of the world.

This definition is specific to Geographic routing and it can be specified to smaller geographic areas – for example, you can have app service for the state of New York 

Now quickly the other app service which should take all the traffic which is not from North America

And that’s it – if you would hit the traffic manager endpoint from different parts of the world you would see that different app services are handling the traffic

Is that it?

Well on most of the blogs this will be sufficient but as I always take care of both of my blog subscribers I will explain here how to take the things explained so far and elevate them to something really usefull in real world 🙂

Step 4 – Define CNAME mapping for the traffic manager

While you can use the url with its domain for demos, it is totally lame to use it in production for your product so we are going to define a CNAME mapping which will allow us to access it through our domain.

Here is how that setting looks like with my DNS provider

So everyone hitting will be hitting the which will then route traffic to the app services.

Step 5 – magic (define custom names for all of the app services)

In this step, we are going open all of the app services  which are mapped to traffic manager and set their custom names to the same one mapped through DNS in step #5

The fact this works is magical as there were no DNS mapping defined for the app service itself but the validation passes. This works due to the fact that traffic manager is not a real load balancer but more of another DNS entry so the DNS mappings defined for the manager are valid also for the app services mapped to it!

Step 6 – add SSL bindings to the app service

We then go through each one of the app services and upload SSL certificate (Scott Hanselman recently blogged on how to get a free SSL cert for your site) 

Once the SSL certificate is uploaded to the app service, we can define app service SSL binding

Step 7 – a final test that everything works fine

If you did all the steps, you should be done and you can hit your custom domain using https and verify the app service balancing of your custom domain using the

That’s it folks!

What is the best way to store secrets using Azure Key Vault?

As I said already, you should NEVER store passwords in any file going to your Git repo – there is a circle in Dante’s hell just for people doing that 🙂

Up until recently you had a few options to store secrets where the most used one was to store them in Application settings of your Azure App Service (there is another circle for people still using cloud service/VMs in 2018) and then during the runtime app service will override the local dev settings with the appropriate environment ones.  That is a bit better as now you don’t have to be afraid of anyone having access to your repo that just about anyone having access to the Azure Portal with services.

To make this even safer Microsoft created a secure storage called Azure Key Vault to which you move all the secrets from Application Settings and now only folks who have access to Azure Key Vault can see them.

The problem is now how to authenticate with Key Vault and the only solution up until a few  months ago was to  use Azure Key Vault from a web app using client secret which basically meant that you have to store your Key Vault password into the Application settings which kind of made the whole purpose of Key Vault questionable as anyone having access to App settings will get the password for Key Vault and 3 minutes later access to the secrets there.

Alas, do not despair, my dear reader, as little thinker fairies from Microsoft Azure team invented Azure Active Directory Managed Service Identity (MSI) just so we can secure our secrets in a worry-free way.

So what is MSI and how it helps with the problem?

Good question!

Basically, the idea is here that you make an AAD account for your app service with secret credentials not shown anywhere on the portal and then you grant Azure Key Vault access rights to that account so without any secrets stored anywhere your app service will be authorized for Key Vault access.

How to create AAD account for your app service?

Easy peasy! Open your app service and scroll the settings until you find Manage service identity one click On and Save – that’s it.
Here is how I did that on my app service called keyvault-demo

How to authorize managed service identity to access Key Vault?

Also easy (you have to love new MS/Azure stack – superb simple and strong stuff) – open or create Key Vault, click on Access Policies and then click on Add.

Here is how I did that on my key vault called nivatech-demo

On the Add access policy first select the template what the app service should have access too (I’ve given it in this blog post access to everything (keys, secrets and certs) , then click Select principal list item and in the search box on the right side enter the name of app service MSI you want to authorize (in this blog post keyvault-demo) and then click Select.

Don’t forget to click Save on the next screen 🙂

Et voila! Your app service can now access key vault and read keys/secrets/certs.

Can I see the sample of the code reading the value from Key Vault using this MSI thingy?

Oh, sure – it is quite simple.

Let say we want to store in our key vault a secret which will be used for JWT authorization in a key called jwt-secret-key and with value Y31n55o835dv2CpSAKsErqVUqkNb42P0.

In Key Vault find Secrets and click Generate/Import button.

And then fill the fields with the key name and value

(The story about the need of rotating keys will have to wait for some other time so we will not set any expiration date here)

How can I retrieve the value from Key Vault in my service?

The best way is to add KeyVault as a configuration provider and then the value will come out of the simple usage of IConfiguration as all the other config values.

The way how I do this in Papiri application is by modifying Program.cs file to be something like this

public class Program
    public static void Main(string[] args)
        var builder = WebHost.CreateDefaultBuilder(args);

        //Add CacheKey Vault to configuration pipeline
        builder.ConfigureAppConfiguration((context, configBuilder) =>
            // vault host address - you can get the value from app settings
            var vaultHost = "";
            //Create Managed Service Identity token provider
            var tokenProvider = new AzureServiceTokenProvider();
            //Create the CacheKey Vault client
            var kvClient = new KeyVaultClient((authority, resource, scope) => 
                            tokenProvider.KeyVaultTokenCallback(authority, resource, scope));
            //Add CacheKey Vault to configuration pipeline
            configBuilder.AddAzureKeyVault(vaultHost, kvClient, new DefaultKeyVaultSecretManager());


and that’s pretty much it – anywhere in your code you can do now

var keyFromVault = this.configuration.GetValue<string>("jwt-secret-key");

Wow, this is super cool but how can I run this code on my dev box?

I don’t use KeyVault locally (I prefer user secrets) but if you want to use it it is easy and all it is need is a few steps:

  1. Go to Key Vault / Access Policies / Add New and add yourself.

    My subscription is tied to my Microsoft Account (MSA) and I use the same to login to my dev box but this works the same if you are using AAD accounts.
  2. Install on your dev machine azure CLI 2.0
  3. Then run az login  command on your dev box to and login with the same account from #1 to your Azure subscription
az login

That’s it – the code snippet from above should now work on your local box too!

Questions/Comments/Corrections/Suggestions – more then welcome 🙂

(In some of the future posts I will share how I secure in my Papiri application using MSI secret access to blob storage and service bus)

How to run Azure app service with Asp.Net Core 2.2 Preview?

So, you like Asp.Net Core 2.2 Preview as much as I do and you want to deploy your website to Azure as app service – easy peasy, right?

Not so fast cowboy! 🙂

Asp.Net Core 2.2 is ATM still in Preview and in order to be able to deploy it to Azure service you need to add 2.2 runtime extension.

First, open your app service and find Extensions section and click add

Then you find Asp.Net  Core 2.2 Runtime extension select it and accept EULA

After a few seconds, the extension is installed and your 2.2 websites are working fine now deployed on Azure.

So go and get that cup of coffee you deserve for a job well done!

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