Category: Uncategorized

Getting a bearer token from AAD using Logic Apps

Why?

You can use the built in authentication when calling, for example, external APIs. It is one of the best features of Logic Apps. Sometimes you might need to get the auth token anyway. Such as when you think Logic Apps does not support OAUTH 2.0 (Thank you Mötz Jensen for helping me understand it.)

How?

You need to get the usual things: Client ID, Client Secret and audience, or scope depending on the version of OAUTH you need to use. For version 2.0 you need to use scope. Please replace scope with audience in the examples below.

In my example I will use the following settings (pseudo-real):

Property Value
Client ID 0352cf0f-2e7a-4aee-801d-7f27f8344c77
Client Secret Th15154S3cr32t!
Scope https://api.myhome.com/.default
Tenant ID a2c10435-de68-4994-99b2-13fed13bdadf

Configuring a call

Create a Logic app HTTP step and set the following properties:

Property Setting
Method POST
URI https://login.microsoftonline.com/tenantID/oauth2/v2.0/token
Headers
Key Value
Content-type application/x-www-form-urlencoded

The body is a bit more tricky. You need to create a URL-string with login info. It is not that hard. Just type the property name, set a = sign and the add the property value. Inbetween properties you put a & sign (like a URL).

Using my values from above, the resulting string will look like this:

Client_Id=0352cf0f-2e7a-4aee-801d-7f27f8344c77&Client_Secret=Th15154S3cr32t!&grant_type=client_credentials&scope=https://api.myhome.com/.default

Remember to add the grant_type=client_credentials and you must not use any line breaks. It is just a long string.

Result

Looking at this in logic apps, the step looks like this:

Using the token

To use the token in a call you need to do two things.

  1. Get the token value from the output of the Get Token step.
  2. Add the token as a header to the call you need to make.

Get the token value

To make things easy I used a Parse JSON step and provided this schema:

{
    "properties": {
        "access_token": {
            "type": "string"
        },
        "expires_in": {
            "type": "integer"
        },
        "ext_expires_in": {
            "type": "integer"
        },
        "token_type": {
            "type": "string"
        }
    },
    "type": "object"
}

Use the token value

In this case I am calling an API that expects an OAUTH 2.0 token. I configured the step like this:

The short-short version

Issue a call to your AAD using an application/x-www-form-urlencoded body. Making sure the body is one long URL-encoded string.

My US Tour :-)

Not exactly. I am going on a trip for work to St Louis and Nashville and since meetup.com is an awesome, global service I reached out to the local groups. They welcomed me and now I have two sessions lined up. Very Happy!

The session: Api management 101

The topic
An introduction to how Azure API management can help you take control of your organization’s APIs.
APIs are built and published everywhere, they can handle different data, authentication, and paths, making your APIs easier to use and re-use. Security, documentation, users, even sign-up can be handled directly.

Who is this aimed at?
Developers or architects working in a mid-to-large organization that uses APIs to exchange data internally or externally. You do not need any prior knowledge about Azure API management.

Friday, December 9th St Louis

Hosted by St Louis Azure User Group

Microsoft Technology Center – @4220
4220 Duncan Ave #501 · St. Louis, MO

Sign up here.

Tuesday, December 13 Nashville

Jointly hosted by Nashville .Net User Group and The Nashville Microsoft Azure Users Group

Vaco Nashville
5501 Virginia Way Suite 120 · Brentwood, TN

Sign up here

The code and labs

All the code shown in the sessions can be found in this handly GitHub Rep.

Azure DiagnosticSettings and Bicep

This is not the explain everything article, but something I wrote as a guide to how I usually solve the issue of DiagnosticSettings.

The basics

I will assume you know what Diagnostics are within Azure and that you know how to create and deploy Bicep. This post aims at showing you how you can solve how to connect Azure Diagnostigs to your resources, using Bicep.

The Scenario

In this scenario I will use something very specific but it will work just as well for your scenario. I am using autoscaling for an Azure Function environment (or Service Plan if you prefer). If the function gets a lot of traffic, the autoscaler will add an additional instance and then remove instances if the traffic goes down.

The autoscaler can alert users whenever it fires. Either by sending emails or using a webhook. However you also need a record of when the autoscaler triggered. That is very useful when you want to analyze traffic and response times.

Bicep and DiagnosticSettings

A diagnostic setting is different compared to, lets say an Azure Storage. Normally, a resource can be deployed by itself but diagnosticsettings need to be connected to an existing resource. This is called Extension Resource.

When deploying an extension resource you simply need to tell it which other resource it is connected to. You do this using the scope property.

Here is an example from my Bicep file:

resource LogAnalyticsConnection 'Microsoft.Insights/diagnosticSettings@2021-05-01-preview' = {
  name: 'scaling'
  scope: FunctionplanElastic_Autoscale
  properties: {...}
}

The FunctionplanElastic_Autoscale is the autoscale I have created for my function.

The problem

When deploying a diagnostic setting you might not always know which metrics are available to you, and in some cases the metrics differ between the portal and the APIs used by Azure for deployment. So using the portal is not the best way, because you get strange errors complaining about different metrics not being available.

Another problem is that diagnostic settings are not exported as a part of the resource, so finding the settings can be really tricky.

A solution

This is in two parts: Finding what resource to scope, and finding what metrics and logs are available to you.

Finding the scope

This is the easy part. When you navigate the Azure Portal you connect diagnostic settings to a resource. That is the scope you are looking for. If you need it for an Azure Storage, that storage is the scope. In my case, I needed it for an autoscaling resource which in turn is connected to an Azure function. In this case, the diagnostic settings should be connected to the autoscaler.

Finding the Logs and Metrics

There is an API for this called Diagnostic Settings – List!
If you call the API you will get the possible diagnostic settings for that particular resource, including syntax. Using the API is a little tricky but here goes:

Authenticating the API

The caller needs to have read access to the resource. I recommend you use my “Login as yourself” post to manage the API authorization.

Setting up the URI

This is the tricky part. Here is the documentation version GET https://management.azure.com/{resourceUri}/providers/Microsoft.Insights/diagnosticSettings?api-version=2021-05-01-preview.

The tricky part is the resourceUri. Here is my version from Postman.

https://management.azure.com/subscriptions/:subscriptionId/resourcegroups/:resourcegroupName/providers/:provider/:resourceName/providers/Microsoft.Insights/diagnosticSettings?api-version=2021-05-01-preview

The resourceUri has 4 different parts:
– The subscriptionId: I think you know what this is.
– The resourceGroupName: Yeah, you know this too.
Provider this is the provider name of the resource type you are trying to access.
The easiest way to find this is to look in the URL when you access the resource in the Azure Portal. This always contains a /, for instance Microsoft.DataFactory/factories.
ResourceName: This is simply the name of the resource you are trying to access.

In my scenario: https://management.azure.com/subscriptions/XXXX-YYYY-zzzz-eeee-wuertweuygfdu/resourcegroups/SYS001-Identifier-RG/providers/microsoft.insights/autoscalesettings/MyAutoscaler/providers/Microsoft.Insights/diagnosticSettings?api-version=2021-05-01-preview

This replies back with this body:

{
    "value": [
        {
            ...
                "metrics": [
                    {
                        "category": "AllMetrics",
                        "enabled": false,
                        "retentionPolicy": {
                            "enabled": false,
                            "days": 0
                        }
                    }
                ],
                "logs": [
                    {
                        "category": "AutoscaleEvaluations",
                        "categoryGroup": null,
                        "enabled": false,
                        "retentionPolicy": {
                            "enabled": false,
                            "days": 0
                        }
                    },
                    {
                        "category": "AutoscaleScaleActions",
                        "categoryGroup": null,
                        "enabled": true,
                        "retentionPolicy": {
                            "enabled": false,
                            "days": 0
                        }
                    }
                ],
                "logAnalyticsDestinationType": null
            },
            "identity": null
        }
    ]
}

Note! There is two small issues here.
1. If you have selected any logging, then that is the configuration that will show up. To know which features are available, the option has to be unconfigured.
2. If you have not added any diagnostic settings before, the APIs returns an empty list.

So now I know which features are available. I need both logging options, so I will add allLogs to my Bicep.

Updating the Bicep file

My finished Bicep looks like this:

param logAnalyticsResourceId string
...
resource LogAnalyticsConnection 'Microsoft.Insights/diagnosticSettings@2021-05-01-preview' = {
  name: 'scaling'
  scope: FunctionplanElastic_Autoscale
  properties: {
    workspaceId: logAnalyticsResourceId
    logs: [
      { 
        enabled: true
        categoryGroup: 'allLogs'
        retentionPolicy: {
          days: 30
          enabled:true 
        }
      }
    ]
  }
}

Conclusion

Adding diagnostic settings needs to be done using another process since they cannot be downloaded. You can access and API to get the settings available to you.

If you need the files used in this scenario you can find them in my GitHub Repo.

The parts of a SAS Key

Whenever I generated a SAS key for allowing access to a storage I have always wondered what all the different parts actually mean, today I found out.

(Source: MS Learn I added some information)

Lets look at this generated key: https://myaccount.blob.core.windows.net/?restype=service&comp=properties&sv=2021-06-08&ss=bf&st=2015-04-29T22%3A18%3A26Z&se=2015-04-30T02%3A23%3A26Z&srt=s&sp=rw&sip=168.1.5.60-168.1.5.70&spr=https&sig=F%6GRVAZ5Cdj2Pw4tgU7IlSTkWgn7bUkkAg8P6HESXwmf%4B

Parameter Example Description
Resource URI https://myaccount.blob.core.windows.net/?restype=service&comp=properties Defines the Azure Storage endpoint and other parameters. This example defines an endpoint for Blob Storage and indicates that the SAS applies to service-level operations. When the URI is used with GET, the Storage properties are retrieved. When the URI is used with SET, the Storage properties are configured
Storage version sv=2015-04-05 For Azure Storage version 2012-02-12 and later, this parameter indicates the version to use. This example indicates that version 2015-04-05 (April 5, 2015) should be used.
Storage service ss=bf Specifies the Azure Storage to which the SAS applies. This example indicates that the SAS applies to Blob Storage (b) and Azure Files (f). Also available are Queue (q) and Table (t)
Start time st=2015-04-29T22%3A18%3A26Z (Optional) Specifies the start time for the SAS in UTC time. This example sets the start time as April 29, 2015 22:18:26 UTC. If you want the SAS to be valid immediately, omit the start time.
Expiry time se=2015-04-30T02%3A23%3A26Z Specifies the expiration time for the SAS in UTC time. This example sets the expiry time as April 30, 2015 02:23:26 UTC.
Allowed resource type srt=s Specifies which resource types are accessible via the SAS. This example specifies that the accessible resource is in Blob Storage. Service (s), Container (c) and Object (o).
Permissions sp=rw Lists the permissions to grant. This example grants access to read (r) and write (w) operations.
IP range sip=168.1.5.60-168.1.5.70 Specifies a range of IP addresses from which a request is accepted. This example defines the IP address range 168.1.5.60 through 168.1.5.70.
Protocol spr=https Specifies the protocols from which Azure Storage accepts the SAS. This example indicates that only requests by using HTTPS are accepted, and why should you accept anything else?
Signature sig=F%6GRVAZ5Cdj2Pw4tgU7IlSTkWgn7bUkkAg8P6HESXwmf%4B Specifies that access to the resource is authenticated by using an HMAC signature. The signature is computed over a string-to-sign with a key by using the SHA256 algorithm, and encoded by using Base64 encoding.

Since permissions (sp) is a little more complex I listed them in a separate table.

Allowed persmission Description
r Read
w Write
d Delete
l List
a Add
c Create
u Update
p Process
i Immutable storage
y Permanently delete
x Enable deletion of versions
t Read/Write blob index
f Filter Blog index

Now I can finally decrypt a signature to find out which access rights have been assigned.

Pitfall when deploying Azure Function v4 and .net 6

I was tasked with setting up a Function environment. The Function was supposed to be hosted as a version 4 (~4) and was written in .net 6. No problem, right? Wrong!

The error

This was the error I got:

Your app is pinned to an unsupported runtime version for '~4'. For better performance, we recommend using one of our supported versions instead: ~3.

To me that seems like a you problem but as ever Azure says it’s mine.

The hunt

I used Bicep to deploy the Azure function, but in order to find all the settings that might be needed I opened the JSON view of the Function in the Azure Portal. The Function was pushed to development by the developer and it was up to me to deploy it in TEST and PROD.

The JSON view is an awesome feature. On the overview page of almost all services, you will find it up and to the right. It’s just a link:

If you click it, you get the JSON/ARM representation of the service:

You can find all the settings that you might want to look up, such as Always On or which server farm it is connected to.

The find

I found this article from Microsoft, which I recommend, but at the same time it should not have to exists. It addresses all kinds of issues you can encounter when using Azure Functions 4.

The solution

You need to tell Azure what version of dotnet you are using. This only needs to be done when using version 4 and .net 6.
Add this setting to your Bicep:

properties: {
     siteConfig: {
         netFrameworkVersion: 'v6.0'
     }
 }

Then redeploy and the error message dissappears.

The grief

Now the pitfall part is that if you look into the JSON view of the Function and try to find that setting … it is null. Even after your redeploy.

So, how are we supposed to know that needs to be set?

Boo! Boo I say.