A module that contains logic to send/publish event messages to specified Azure Event Hub.

AzureEventHub.psm1

function Get-SASToken
{
    <#
    .DESCRIPTION
    Compute a valid SAS-token for accessing an Azure Event Hub / Service Bus
    .PARAMETER EventHubNamespace
    The Azure Event Hub Namespace
    .PARAMETER EventHubName
    Name of the of the Azure Event Hub
    .PARAMETER AccessPolicyName
    Name of the access policy
    .PARAMETER AccessPolicyKey
    Key for the access policy 
    .PARAMETER TokenTimeOut
    Timeout in seconds for the SAS-token (default 1800 seconds)
    .EXAMPLE
    Get-SASToken -EventHubNamespace 'YourEventHubNamespace' -EventHubName 'YourEventHubName' -AccessPolicyName "YourSendPolicyName" -AccessPolicyKey "RVZFTlRfSFVCX0FDQ0VTU19QT0xJQ1lfS0VZIQ=="
    .NOTES
    Author: Jeff Tong
    Reference: https://learn.microsoft.com/en-us/rest/api/eventhub/generate-sas-token
    #>
    PARAM(
        [Parameter(Mandatory=$True)]
        [string] $EventHubNamespace,
        [Parameter(Mandatory=$True)]
        [string] $EventHubName,
        [Parameter(Mandatory=$True)]
        [string] $AccessPolicyName,
        [Parameter(Mandatory=$True)]
        [string] $AccessPolicyKey,
        [int] $TokenTimeOut=1800
    )
    [Reflection.Assembly]::LoadWithPartialName("System.Web")| out-null
    
    $URI="$eventHubNamespace.servicebus.windows.net/$eventHubName"
    
    $Expires=([DateTimeOffset]::Now.ToUnixTimeSeconds()) + $TokenTimeOut
    $SignatureString=[System.Web.HttpUtility]::UrlEncode($URI)+ "`n" + [string]$Expires
    $HMAC = New-Object System.Security.Cryptography.HMACSHA256
    $HMAC.key = [Text.Encoding]::ASCII.GetBytes($AccessPolicyKey)
    $Signature = $HMAC.ComputeHash([Text.Encoding]::ASCII.GetBytes($SignatureString))
    $Signature = [Convert]::ToBase64String($Signature)
    $SASToken = "SharedAccessSignature sr=" + [System.Web.HttpUtility]::UrlEncode($URI) + "&sig=" + [System.Web.HttpUtility]::UrlEncode($Signature) + "&se=" + $Expires + "&skn=" + $AccessPolicyName
    return $SASToken
}

function Send-EventHubMessage
{
    <#
    .DESCRIPTION
    Send a message to an Azure Event Hub
    .PARAMETER EventHubNamespace
    The Azure Event Hub Namespace
    .PARAMETER EventHubName
    Name of the of the Azure Event Hub
    .PARAMETER SASToken
    A valid SAS authorization token (see Get-SASToken)
    .PARAMETER Message
    Message send to the specified eventhub Event Hub in json format. E.g.: { "key":"123456789", "value":"123.00"}
    .PARAMETER TimeOut
    The Timeout for this post with default of 30 seconds.
    .PARAMETER PublisherId
    Send the message to specific publisher by ID.  Default is null.
    .PARAMETER APIVersion
    API-version string. Default is null.
    .EXAMPLE
    Send-EventHubMessage -EventHubNamespace 'yourEventHubNamespace' -EventHubName 'yourEventHubName' -SASToken $SASToken -Message ' { "key":"123456789", "value":"123.00"}'
    .NOTES
    Author: Jeff Tong
    Reference: https://learn.microsoft.com/en-us/rest/api/eventhub/send-event
    #>
    PARAM(
        [Parameter(Mandatory=$True)]
        [string] $EventHubNamespace,
        [Parameter(Mandatory=$True)]
        [string] $EventHubName,
        [Parameter(Mandatory=$True)]
        [string] $SASToken,
        [Parameter(Mandatory=$True)]
        [string] $Message,
        [Parameter(Mandatory=$False)]
        [int] $TimeOut=30,
        [Parameter(Mandatory=$False)]
        [string] $PublisherId=$null,
        [Parameter(Mandatory=$False)]
        [string] $APIVersion=$null
    )
    
    $headers = @{
        "Authorization"=$SASToken;
        "Content-Type"="application/atom+xml;type=entry;charset=utf-8";
    }
    
    $Uri = "https://$($EventHubNamespace).servicebus.windows.net/$($EventHubName)"
    
    if ([string]::IsNullOrWhitespace($PublisherId))
    {
      $Uri = $Uri + "/messages?timeout=$($TimeOut)"
    }
    else 
    {
      $Uri = $Uri + "/publishers/$(PublisherId)/messages?timeout=$($TimeOut)"
    }
    
    if (-not [string]::IsNullOrWhitespace($APIVersion))
    {
      $Uri = "$($Uri)&api-version=$($APIVersion)"
    }
    
    # Should see a 202 - Created
    return Invoke-WebRequest -Method POST -Uri $Uri -Header $headers -Body $Message
}

If 404 - Unauthorized is received when sending the event message, double check the access key and access key policy name. Also ensure that your IP Address is added/allowed to the Event Hub Namespace resource if Firewall is enabled (Networking -> Firewall).