This article is an extension to what has been talked about in the above post. The code snippet to read Azure Key Vault Secret to set <set-header> under <inbound> <policies> in Azure API Management along with caching the secret for 60 secs has been given below
Code-Snippet for copy paste:
<policies>
<inbound>
<base />
<!--Look for secret in the cache -->
<cache-lookup-value key="cached-user-secret" variable-name="cached-user-secret" />
<!-- If API Management doesn’t find it in the cache, fetch it from Key Vault -->
<choose>
<when condition="@(!context.Variables.ContainsKey("cached-user-secret"))">
<!-- Retrieve secret from Key Vault -->
<send-request mode="new" response-variable-name="cached-user-secret" timeout="20" ignore-error="false">
<set-url>https://{{kvname}}.vault.azure.net//secrets/{{secret-name}}/?api-version=7.0</set-url>
<set-method>GET</set-method>
<authentication-managed-identity resource="https://vault.azure.net" />
</send-request>
<!-- Store response body in context variable as a string -->
<set-variable name="cached-user-secret" value="@((((IResponse)context.Variables["cached-user-secret"]).Body.As<JObject>()).Property("value").Value.ToString())" />
<!-- Store result in cache -->
<cache-store-value key="cached-user-secret" value="@((string)context.Variables["cached-user-secret"])" duration="60" />
</when>
</choose>
<set-header name="User-secret" exists-action="append">
<value>@((string)context.Variables["cached-user-secret"])</value>
</set-header>
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
</outbound>
<on-error>
<base />
</on-error>
</policies>
Performance numbers:
Inbound (268+ ms) - 1st time
api-inspector (0.259ms)
api-inspector (0.003ms)
cors (0.024ms)
cache-lookup-value (0.006ms)
cache-lookup-value (0.934ms)
choose (0.024ms)
set-method (0.025ms)
authentication-managed-identity (0.253ms)
authentication-managed-identity (0.005ms)
send-request (0.078ms)
send-request (267.616ms) -> Key Vault call for User Secret
send-request (0.034ms)
response-variable-handler (0.010ms)
response-variable-handler (11.223ms)
set-variable (0.118ms)
set-variable (0.014ms)
cache-store-value (0.005ms)
cache-store-value (0.065ms)
cache-store-value (0.087ms)
