Azure Function App Push-OutputBinding Adding Subscription Information to JSON Output using Powershell

Question

I have written several Azure Functions over the past year in both powershell and C#. I am currently writing an API that extracts rows from a Storage Account Table and returns that data in a JSON format.

The data pulls fine. The data converts to JSON just fine. A JSON formatted response is displayed - which is fine - but the Push-OutputBinding shoves in additional data to my original JSON data - account information, environment information, subscription information, and tenant information.

I've tried a number of different strategies for getting past this. I gave up on using C# to interact with the Tables because the whole Azure.Data.Tables and Cosmos tables packages are a hot mess with breaking changes and package conflicts and .Net 6 requirements for new functions apps. So please don't offer up a C# solution unless you have a working example with specific versions for packages, etc.

Here is the code: Note that I have verified that $certData and $certJson properly formatted JSON that contain only the data I want to return.

using namespace System.Net

# Input bindings are passed in via param block.
param($Request, $TriggerMetadata)

# Write to the Azure Functions log stream.
Write-Host "PowerShell HTTP trigger function processed a request."

# Interact with query parameters or the body of the request.
$filter = $Request.Query.Filter
if (-not $filter) {
    $filter = "ALL"
}

$certData = GetCerts $filter | ConvertTo-Json

#$certJson = $('{ "CertData":"'  + $certData + '" }')
$body = "${CertData}" 

# Associate values to output bindings by calling 'Push-OutputBinding'.
Push-OutputBinding -Name Response -Value ([HttpResponseContext]@{
        StatusCode = [HttpStatusCode]::OK
        ContentType = "application/json"
        Body = $body
    })

When I call the httpTrigger function, the response looks like this:

{ "CertData":"[
  {
    "Name": "MySubscriptionName blah blah",
    "Account": {
      "Id": "my user id",
      "Type": "User",
      ....
    },
    "Environment": {
      "Name": "AzureCloud",
      "Type": "Built-in",
      ...
    },
    "Subscription": {
      "Id": "SubscriptionID",
      "Name": "SubscriptionName",
      ....
    },
    "Tenant": {
      "Id": "TenandID",
      "TenantId": "TenantId",
      "ExtendedProperties": "System.Collections.Generic.Dictionary`2[System.String,System.String]",
    ...
    },
    "TokenCache": null,
    "VersionProfile": null,
    "ExtendedProperties": {}
  },
  {
    "AlertFlag": 1,
    "CertID": "abc123",
    "CertName": "A cert Name",
    "CertType": "an assigned cert type",
    "DaysToExpire": 666,
    "Domain": "WWW.MYDOMAIN.COM",
    "Expiration": "2033-10-04T21:31:03Z",
    "PrimaryDomain": "WWW.MYDOMAIN.COM",
    "ResourceGroup": "RANDOM-RESOURCES",
    "ResourceName": "SOMERESOURCE",
    "Status": "OK",
    "Subscription": "MYSUBSCRIPTIONNAME",
    "Thumbprint": "ABC123ABC123ABC123ABC123ABC123",
    "PartitionKey": "PARKEY1",
    "RowKey": "ID666",
    "TableTimestamp": "2022-02-03T09:00:28.7516797-05:00",
    "Etag": "W/\"datetime'2022-02-03T14%3A00%3A28.7516797Z'\""
  },
...

Not only does the returned values add data I don't want exposed, it makes parsing the return data that I do want to get when I make API calls problematic.

How do I get rid of the data added by the Push-OutputBinding?

You shouldn't have to serialise anything to send it to Push-OutputBinding. I would hazard a guess that the object being returned from your GetCerts function is what is polluting your object and if you were to check the returned object with $certData | Format-List * that those properties were in fact valid for that object. You may have to use Select-Object to only return the properties that you want from GetCerts On a slightly different note are you using the table storage binding input as you can apply a filter within the function.json instead of making the call yourself. — BrettMiller
– BrettMiller, Commented Feb 3, 2022 at 15:22
You are indeed correct regards GetCerts polluting the data. I'll play with Select-Object to see if I can get the data I want. As for using table storage bindings in the function.json files... all the breaking changes and package conflicts involved in the push to Cosmos has made that a hot mess for both C# and PowerShell. — Valkaryn
– Valkaryn, Commented Feb 3, 2022 at 16:22
Of note, when I was debugging in VSCode, I wasn't seeing the extraneous data in my watched vars or when written out to file. This is why I assumed it had occured in the Push-Outputbinding step. Reviewing that data again, I see where it landed in the mix. Thanks! — Valkaryn
– Valkaryn, Commented Feb 3, 2022 at 16:26
Also, thanks for the info on not having to serialize the data! — Valkaryn
– Valkaryn, Commented Feb 3, 2022 at 16:38
I was able to get table storage working with filtering in the host.json but not at the same time as an optional route parameter so I ended up returning all values and filtering within the function which was fine for a small amount of entities but would quickly get awful if your table was large. Could share a code sample of how I got that working if you require. — BrettMiller
– BrettMiller, Commented Feb 3, 2022 at 17:14

Valkaryn · Accepted Answer · 2022-02-03 16:37:07Z

1

Was able to resolve issue by modifying run.ps1 as follows:

using namespace System.Net

# Input bindings are passed in via param block.
param($Request, $TriggerMetadata)

# Write to the Azure Functions log stream.
Write-Host "PowerShell HTTP trigger function processed a request."

# Interact with query parameters or the body of the request.
$filter = $Request.Query.Filter

if (-not $filter) {
    $filter = "ALL"
}

$certData = ( GetCerts $filter | Select-Object -Skip 1 )
 
#write-information $certData | Format-List

# Associate values to output bindings by calling 'Push-OutputBinding'.
Push-OutputBinding -Name Response -Value ([HttpResponseContext]@{
        StatusCode = [HttpStatusCode]::OK
        Body = $certData
    })

answered Feb 3, 2022 at 16:37

Valkaryn

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