<set-header name=”Authorization” exists-action=”override”>
<value>@(“Bearer ” + (string)context.Variables[“managed-id-access-token”])</value>
</set-header>​

Subscriptions in Azure API Management are a way to control access to APIs. When you publish APIs through APIM, you can secure them using subscription keys. Here’s a quick overview:

Subscriptions: These are containers for a pair of subscription keys (primary and secondary). Developers need a valid subscription key to call the APIs. 
Subscription IDs: Each subscription has a unique identifier called a Subscription ID. 

How does Subscription relate to the APIM resource though?

Scope of Subscriptions: Subscriptions can be associated with different scopes within an APIM instance:

Product Scope: Subscriptions can be linked to a specific product, which is a collection of one or more APIs. Developers subscribe to the product to access all APIs within it.
API Scope: Subscriptions can also be associated with individual APIs, allowing more granular control over access.

}
resource apimDiagnostics ‘diagnostics@2023-05-01-preview’ = {
name: ‘applicationinsights’ // Use a supported diagnostic identifier
properties: {
loggerId: ‘/subscriptions/${subscriptionId}/resourceGroups/${resourceGroup().name}/providers/Microsoft.ApiManagement/service/${apimService.name}/loggers/${apimLogger.name}’
metrics: true
}
}
}

// Creating a product for the API. Products are used to group APIs and apply policies to them
resource product ‘Microsoft.ApiManagement/service/products@2020-06-01-preview’ = {
parent: apimService
name: productName
properties: {
displayName: productName
description: productDescription
state: ‘published’
subscriptionRequired: true
}
}

// Create PRODUCT-API association the API with the product
resource productApi1 ‘Microsoft.ApiManagement/service/products/apis@2020-06-01-preview’ = {
parent: product
name: api1.name
}

// Creating a user for the API Management service
resource user ‘Microsoft.ApiManagement/service/users@2020-06-01-preview’ = {
parent: apimService
name: ‘userName’
properties: {
firstName: ‘User’
lastName: ‘Name’
email: ‘user@example.com’
state: ‘active’
}
}

// Creating a subscription for the API Management service
// NOTE: the subscription is associated with the user and the product, AND the subscription ID is what will be used in the request to authenticate the calling client
resource subscription ‘Microsoft.ApiManagement/service/subscriptions@2020-06-01-preview’ = {
parent: apimService
name: ‘subscriptionAIProduct’
properties: {
displayName: ‘Subscribing to AI services’
state: ‘active’
ownerId: user.id
scope: product.id
}
}

return fetch(URL_CHAT, {
method: “POST”,
headers: {
“api-key”: process.env.SUBSCRIPTION_KEY,
“Content-Type”: “application/json”
},
body: JSON.stringify(body)
})