Set-AzApiManagementPolicy with a value from a function - azure

Question

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.

Answer 1

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

Answer 2

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:
$policyString = '
<policies>
<inbound>
<base />
<set-variable name="sasToken" value="#{
string resourceUri = "$(azure.servicebusqueueendpoint)";
string keyName = "$(azure.servicebusaccesspolicykey)";
string key = "$(azure.servicebusaccesspolicyvalue)";
TimeSpan sinceEpoch = DateTime.UtcNow - new DateTime(1970, 1, 1);
var expiry = Convert.ToString((int)sinceEpoch.TotalSeconds + 120);
string stringToSign = System.Uri.EscapeDataString(resourceUri) + "\n" + expiry;
HMACSHA256 hmac = new HMACSHA256(Encoding.UTF8.GetBytes(key));
var signature = Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
var sasToken = String.Format("SharedAccessSignature sr={0}&sig={1}&se={2}&skn={3}",
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<string>
to make it work otherwise it conflicts with the xml
Thanks mclayton for pointing me in the right direction.