Question 105722 in Azure Question posted in
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Azure – Set-AzApiManagementPolicy with a value from a function

I am trying to use Azure Pipeline to build my API Management infrastructure automatically and have successfully added the API and API Operation but having trouble defining the Operation specific Policy.

I have this policy that I based on a very useful article https://www.serverlessnotes.com/docs/expose-service-bus-queue-through-api-management

<policies>
    <inbound>
        <base />
        <set-variable name="sasToken" value="@{            
            return "bob";
        }" />
        <set-header name="Authorization" exists-action="override">
            <value>@(context.Variables.GetValueOrDefault<string>("sasToken"))</value>
        </set-header>
        <set-header name="Content-type" exists-action="override">
            <value>application/json</value>
        </set-header>
        <set-header name="Ocp-Apim-Subscription-Key" exists-action="delete" />
        <set-header name="BrokerProperties" exists-action="override">
            <value>@{                
                return string.Format("{{"SessionId":"{0}"}}", "bob");
            }</value>
        </set-header>
        <set-backend-service base-url="https://i365intfnapidevtbcoresb.servicebus.windows.net/i365intfnapidevtbcoresbqueue" />
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
    </outbound>
    <on-error>
        <base />
    </on-error>
</policies>

There is actually more code in the value bits, but for illustration I’ve removed them.

However if I put this in a separate file (or even an inline variable) and run the Azure Powershell command

Set-AzApiManagementPolicy -Context $apim_context -ApiId $apiId -OperationId addmessage -PolicyFilePath <path to policy xml file>

Where the $ values are variables I declared previously.

I get the error

Error Details:
        [Code= ValidationError, Message= 'bob' is an unexpected token. Expecting white space. Line 5, position 21., Target=
representation]

Basically, I cant work out how to format the function thats in the value attribute or value elements. The bit starting with @{}.

I can enter the policy via the Azure API Management screen no problem, but cant do it via the Set-AzApiManagementPolicy command.

Any ideas on how to format it.

Thanks.

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    Solved it in the end, You have to encode some of the characters to make it work. For example @quot; instead of "

    So I have in my Azure Powershell script:

      $policyString = '
            <policies>
                <inbound>
                    <base />
                    <set-variable name="sasToken" value="@{
                        string resourceUri = &quot;$(azure.servicebusqueueendpoint)&quot;;
                        string keyName = &quot;$(azure.servicebusaccesspolicykey)&quot;;
                        string key = &quot;$(azure.servicebusaccesspolicyvalue)&quot;;
                        TimeSpan sinceEpoch = DateTime.UtcNow - new DateTime(1970, 1, 1);
                        var expiry = Convert.ToString((int)sinceEpoch.TotalSeconds + 120);
                        string stringToSign = System.Uri.EscapeDataString(resourceUri) + &quot;n&quot; + expiry;
                        HMACSHA256 hmac = new HMACSHA256(Encoding.UTF8.GetBytes(key));
                        var signature = Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
                        var sasToken = String.Format(&quot;SharedAccessSignature sr={0}&amp;sig={1}&amp;se={2}&amp;skn={3}&quot;, 
                                        System.Uri.EscapeDataString(resourceUri),
                                        System.Uri.EscapeDataString(signature), expiry, keyName);
                        return sasToken;
                    }" />
                    <set-header name="Authorization" exists-action="override">
                        <value>@((string)context.Variables.GetValueOrDefault("sasToken"))</value>
                    </set-header>
                    <set-header name="Content-type" exists-action="override">
                        <value>application/json</value>
                    </set-header>
                    <set-header name="Ocp-Apim-Subscription-Key" exists-action="delete" />
                    <set-header name="BrokerProperties" exists-action="override">
                        <value>@{
                          return string.Format("{{"SessionId":"{0}"}}", "1");
                        }</value>
                    </set-header>
                    <set-backend-service base-url="$(azure.servicebusqueueendpoint)" />
                </inbound>
                <backend>
                    <base />
                </backend>
                <outbound>
                    <base />
                </outbound>
                <on-error>
                    <base />
                </on-error>
            </policies>
          '

Set-AzApiManagementPolicy -Context $apim_context -ApiId $apiId -OperationId addmessage -Policy $policyString

    and this now seems to do the trick.

    You would probably also need to do the same for c# things like:

    context.Variables.GetValueOrDefault<string>

    would be

    context.Variables.GetValueOrDefault&lt;string&gt;

    to make it work otherwise it conflicts with the xml

    Thanks mclayton for pointing me in the right direction.


  2. 0

    It will escape it for you if you use the Format parameter.

    Set-AzApiManagementPolicy -Context $apim_context -Format "application/vnd.ms-azure-apim.policy.raw+xml" -ApiId $apiId -OperationId addmessage -Policy $policyString
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