Use the Edge SDK on an Azure virtual machine

An application on an Azure virtual machine (VM) can prove its identity with the Azure Instance Metadata Service (IMDS). IMDS provides a signed attested data document for the VM. The Edge SDK reads that document and presents it to your in Aembit, which verifies it. You configure the SDK client and request a credential.

How an Azure VM proves its identity

An Azure VM requests an attested data document from IMDS at 169.254.169.254 with the Metadata: true header. The request carries a 10-digit nonce, and the SDK uses the current Unix timestamp by default. IMDS returns a Base64-encoded PKCS#7 signature that holds the signed document and its certificate chain.

The Edge SDK sends that signature, its encoding, and the nonce to Aembit. Aembit verifies the signature and validates its certificate chain against pinned Microsoft and DigiCert root certificates, and rejects a document whose timeStamp.expiresOn has passed. When your Trust Provider has , Aembit then compares the nonce you sent with the nonce inside the signed document. It then evaluates the match rules against the VM ID, subscription ID, and image SKU in the document. Without match rules, Aembit skips both checks. Because the signed document is the evidence, no credential or token has to exist on the VM ahead of time.

For the request and response shapes behind that exchange, see Edge API authentication with Azure Instance Metadata Service.

Before you start

An with at least Read Only permission for Trust Providers.
An for the service your application reaches.
An Azure Instance Metadata Service Trust Provider with match rules on the VM ID, subscription ID, or image SKU of your VM.
An Azure VM with IMDS reachable at 169.254.169.254, running Node.js 20 or later for TypeScript, or Python 3.10 or later for Python.

Get your Edge SDK Client ID

Your application needs the from the Azure Instance Metadata Service Trust Provider whose match rules identify your VM.

Log in to your Aembit Tenant.
Go to the Trust Providers section in the left sidebar.
Select the Trust Provider you want to use for Edge API authentication.
In the TRUST PROVIDER section, find the Edge SDK Client ID field.
Copy the Edge SDK Client ID to use in your authentication requests.

Wire up the SDK

The example collects every value you change into one EXAMPLE_CONFIG object at the top of the file. The Azure Instance Metadata Service Trust Provider takes no configuration of its own, because the SDK reads what it needs from IMDS at runtime.

TypeScript
Python

import { EdgeClient, trustProviders } from "@aembit/edge-sdk"

const EXAMPLE_CONFIG = {
  baseUrl: "https://<tenant>.ec.<stack>.aembit.io",
  clientId: "your-edge-sdk-client-id",
  serverHost: "target.example.com",
  serverPort: 443,
  credentialType: "ApiKey",
  resourceSet: undefined as string | undefined
}

const trustProvider = trustProviders.azureMetadataService()

const client = new EdgeClient({
  baseUrl: EXAMPLE_CONFIG.baseUrl,
  clientId: EXAMPLE_CONFIG.clientId,
  trustProvider,
  resourceSet: EXAMPLE_CONFIG.resourceSet
})

async function main() {
  const credential = await client.getCredential({
    server: { host: EXAMPLE_CONFIG.serverHost, port: EXAMPLE_CONFIG.serverPort },
    credentialType: EXAMPLE_CONFIG.credentialType
  })

  console.log(
    JSON.stringify({
      credentialType: credential.credentialType ?? null,
      expiresAt: credential.expiresAt ?? null,
      dataKeys: Object.keys(credential.data)
    })
  )
}

main().catch((error: unknown) => {
  console.error(error)
  process.exitCode = 1
})

from typing import Any

from aembit_edge import CredentialServerRef, EdgeClient, EdgeClientConfig, GetCredentialInput
from aembit_edge.trust_providers import AzureMetadataServiceTrustProvider

EXAMPLE_CONFIG: dict[str, Any] = {
    "base_url": "https://<tenant>.ec.<stack>.aembit.io",
    "client_id": "your-edge-sdk-client-id",
    "server_host": "target.example.com",
    "server_port": 443,
    "credential_type": "ApiKey",
    "resource_set": None,
}


def main() -> None:
    trust_provider = AzureMetadataServiceTrustProvider()

    client = EdgeClient(
        EdgeClientConfig(
            base_url=EXAMPLE_CONFIG["base_url"],
            client_id=EXAMPLE_CONFIG["client_id"],
            trust_provider=trust_provider,
            resource_set=EXAMPLE_CONFIG["resource_set"],
        )
    )

    credential = client.get_credential(
        GetCredentialInput(
            server=CredentialServerRef(
                host=EXAMPLE_CONFIG["server_host"],
                port=EXAMPLE_CONFIG["server_port"],
            ),
            credential_type=EXAMPLE_CONFIG["credential_type"],
        )
    )

    print(f"Payload Keys: {list(credential.data.keys())}")


if __name__ == "__main__":
    main()

Where each value comes from in Aembit:

TypeScript value	Python value	Where it comes from
`baseUrl`	`base_url`	The Edge API base URL in your Aembit Tenant profile. See Get your Aembit Edge API base URL.
`clientId`	`client_id`	The Edge SDK Client ID you copied from the Trust Provider.
`serverHost` and `serverPort`	`server_host` and `server_port`	The Host and Port under Service Endpoint on your , which Aembit uses to find the Access Policy. Port must be equal, and Host must be equal or match a `*` wildcard.
`credentialType`	`credential_type`	The credential type your returns.
`resourceSet`	`resource_set`	Leave unset unless your Access Policy lives in a non-default Resource Set. It takes the Resource Set ID, not its name.

Run the example

The Edge SDK repository carries an example of this integration for each language, including how to copy it to a VM and run it.

Azure IMDS VM example (TypeScript)TypeScript example for the Azure Instance Metadata Service Trust Provider.

Azure IMDS VM example (Python)Python example for the Azure Instance Metadata Service Trust Provider.

Troubleshooting

Every error the Edge SDK raises carries a kind, which narrows the failure to one side of the exchange. Alongside kind, each error carries statusCode, apiCode, and requestId when Aembit supplies them, and retryable to report whether another attempt might succeed. The Python SDK names these fields status_code, api_code, request_id, and retryable.

The SDK can’t read the attested document

The SDK raises a trust_provider error when it can’t read an attested data document from IMDS, and it never contacts Aembit. The SDK waits 1 second for IMDS before the request times out. Confirm the application runs on the Azure VM itself and can reach 169.254.169.254.

Authentication fails

The SDK raises an error with the auth kind when Aembit rejects the authentication request. Aembit records no access authorization event for an authentication request, so the status code and these checks are the evidence you have.

A 400 status means Aembit couldn’t read the Client ID or the Resource Set ID in the request. Copy the Edge SDK Client ID from the Trust Provider again, and confirm resourceSet holds a Resource Set ID as the third check in the following list describes.

A 401 status carries the same message whichever check failed. Work through the checks in order:

Confirm clientId (Python client_id) holds the Edge SDK Client ID of the Trust Provider you set up for this workload. The value ends with that Trust Provider’s ID, so compare the last segment with the ID field in the Trust Provider editor. If they differ, copy the Edge SDK Client ID from the right Trust Provider.
Confirm the Trust Provider’s toggle reads Active. If it reads Inactive, switch it on in the Trust Provider editor. The change saves at once, after a confirmation dialog when the Trust Provider is in use.
Confirm the Trust Provider belongs to the Resource Set the request names. resourceSet (Python resource_set) takes the Resource Set ID, not its name. When you leave it unset, the Trust Provider must belong to the Default Resource Set. To find the ID, select Administration ☰ Resource Sets and hover over the Resource Set name, or open the Resource Set and copy Resource Set ID. To see which Resource Set holds the Trust Provider, select each Resource Set in the selector at the top of the Trust Providers page.

Contact Aembit support to enable this feature.
Confirm the identity evidence passes the Trust Provider’s validation, using the checks after this list where your Trust Provider type has them. Aembit evaluates match rules only after the token or document passes validation, so a validation failure looks like a match rule failure.
Confirm the Trust Provider’s match rules hold this workload’s values. Aembit groups the rules by Attribute, and by Key for custom claim rules, and each group needs a matching rule. A Value containing * matches any run of characters in that position. Any other value must match exactly, including case, unless your Trust Provider’s checks after this list say otherwise. A rule with an empty Value fails the Trust Provider, so fill in the Value or delete the rule. A Trust Provider with no match rules accepts any workload whose evidence passes validation. Compare each rule’s Value with the matching field in real evidence from this workload, and correct the rule.

For an Azure Instance Metadata Service Trust Provider, the subscriptionId, vmId, and sku attributes compare fields of the signed attested document. vmId ignores case, and the other two must match exactly unless the Value contains *.

The credential request raises an error

The SDK raises an error with the credential kind when the credential request returns an error status. The error’s message holds the message from Aembit’s response. When the response carries none, the message reads Edge API request failed with status followed by the status code.

An error with no statusCode (Python status_code) whose message names server.host or server.port comes from the SDK, which checks those values before it contacts Aembit. Set server.host to a non-empty string and server.port to a whole number from 1 to 65535.

A 404 status. Aembit identified the Client Workload and the Server Workload, then couldn’t settle on one Access Policy or one Credential Provider. The response carries no message, so check each cause:

No active Access Policy holds this Server Workload and a Client Workload that matches this workload, or more than one does. More than one Client Workload can match one workload. Count the active Access Policies across every matching Client Workload, and keep exactly one. A new Access Policy saved with Save Policy stays inactive until you switch on its toggle, while Save Policy & Activate saves it as active.
The Access Policy holds Credential Providers of different types. Keep Credential Providers of one type on the Access Policy.
connectionMetadata (Python connection_metadata) selected none of the Access Policy’s Credential Providers, or more than one. Aembit chooses by connectionMetadata when it carries a filled value: accountName, accessKeyId, both headerName and headerValue, or both httpBodyFieldPath and httpBodyFieldValue. It chooses this way even when the Access Policy holds one Credential Provider. Leave it unset when the Access Policy holds one Credential Provider, and otherwise set it to values that select exactly one.
The Credential Provider the request selected is inactive. Switch its toggle to Active. Aembit records no access authorization event for this cause.

A 400 status. When the message is Aembit’s own, Aembit failed while it selected or fetched the credential, and the message says why. Examples include an error status from the service the Credential Provider calls, and a key missing from a secret the Credential Provider reads. Correct the Credential Provider or the service it calls, then retry. An Access Policy with more than one Credential Provider also returns 400 when connectionMetadata carries no filled value, or the request carries no connectionMetadata. An AWS Secrets Manager Value or Azure Key Vault Value Credential Provider with Private Network Access switched on returns 400 for every credential type the SDK requests. Switch Private Network Access off on that Credential Provider to retrieve its secret through the Edge SDK. A 400 whose message reads Edge API request failed with status 400 means Aembit rejected the request before it looked for a credential. Confirm credentialType (Python credential_type) is a valid credential type, such as ApiKey or OAuthToken. When you set certSigningRequest (Python cert_signing_request), confirm it’s valid base64. When you set resourceSet (Python resource_set), confirm it’s the ID of a Resource Set in your Aembit Tenant.

A 401 status after authentication succeeds. Confirm baseUrl (Python base_url) is the Edge API base URL from your Aembit Tenant profile, exactly. In TypeScript, a 307 or 308 redirect to another host drops the Authorization header from the credential request.

The credential comes back empty

Aembit returns status 200 for these responses, so the SDK raises no error, and the field your code reads in the credential’s data is empty. The credential’s credentialType (Python credential_type) tells the two causes apart.

credentialType matches the type you requested. Aembit doesn’t compare the requested type with the Credential Provider’s type. The requested type picks which fields of data Aembit fills, and the response repeats it. When the two types differ, the credential can arrive in a field your code doesn’t read or come back with no value. Some Credential Providers raise a 400 credential error instead. When the Server Workload uses Authentication Method HTTP Authentication with Authentication Scheme Basic, a Username & Password Credential Provider returns the base64-encoded username:password value in both username and password. Request the type that matches the Credential Provider on the Access Policy:

Credential Provider	`credentialType`	Fields in `data`
API Key	`ApiKey`	`apiKey`
Username & Password	`UsernamePassword`	`username`, `password`
AWS Secrets Manager Value (username and password)	`UsernamePassword`	`username`, `password`
AWS Secrets Manager Value (plain text or single value)	None	None, because the Edge API can’t return this secret
Azure Key Vault Value (username and password)	`UsernamePassword`	`username`, `password`
AWS Security Token Service Federation	`AwsStsFederation`	`awsAccessKeyId`, `awsSecretAccessKey`, `awsSessionToken`
X.509-SVID Certificate	`X509Svid`	`certificate`
Any other type except AWS Secrets Manager Value	`OAuthToken`	`token`

A request with no credentialType gets OAuthToken. An X509Svid request also needs certSigningRequest (Python cert_signing_request).

credentialType is Unknown. Aembit authenticated the workload but returned no credential. Find the request’s event in Reporting, as Retrieving Access Authorization Event data describes. The event records a result for the Client Workload, the Server Workload, the Access Policy, each Trust Provider, and each Access Condition, and NotFound marks one Aembit couldn’t identify. Fix the first one that didn’t succeed:

Server Workload: Aembit compares server.host and server.port with Host and Port under Service Endpoint, not with Forward to Port. Host matches when it equals server.host, and a * in Host matches any run of characters. Aembit doesn’t compare Transport Protocol or the TLS settings. The Server Workload must also be Active and belong to an active Access Policy.
Client Workload: each identifier type under Client Identification must match this workload. Rows of the same type are alternatives, except OIDC ID Token rows with different Claim Name values, which must each match. The Client Workload must also be Active and belong to an active Access Policy. The identifier types that fit this platform appear at the end of this section.
Trust Provider with the result Unauthorized: Aembit checks the workload’s evidence again on every credential request. Every active Trust Provider on the Access Policy must attest the workload, and Aembit stops at the first that fails. A Trust Provider this workload can’t satisfy, such as one for another platform, fails every request. Switch off its Active toggle, remove it from the Access Policy, or give the workload its own Access Policy. The event’s reason names the check that failed. For MatchRuleFailed, the event also records the attribute, expectedValue or expectedValues, and actualValue, so correct that match rule’s Value. When the Trust Provider validates an identity token and the event records no actualValue, Aembit couldn’t compare the rule. Give each match rule a Value, and confirm the token carries each claim the match rules name. For any other reason, work through the Trust Provider checks in the Authentication fails section of this page.
Access Condition with the result Unauthorized: meet the condition, or remove it from the Access Policy.
Every entity succeeded: confirm the Access Policy has a Credential Provider. When the event’s credentialProvider entry carries a reason, Credential failure lists what each reason means.

When a Client Workload uses the Aembit Client ID identifier, the SDK doesn’t read the CLIENT_WORKLOAD_ID environment variable. Pass the value in your client configuration instead, as clientWorkloadDetails: { os: { environment: { CLIENT_WORKLOAD_ID: "<value>" } } }, or as the same structure in client_workload_details in Python.

For this platform, Azure Subscription Id and Azure VM Id compare values from the attested document.