expire azure token as needed (#615)

packages/cli/src/azuretoken.ts

@@ -1,10 +1,20 @@
 import { AZURE_OPENAI_TOKEN_SCOPES } from "../../core/src/constants"
 
-export async function createAzureToken(signal: AbortSignal): Promise<string> {
+export interface AuthenticationToken {
+    token: string
+    expiresOnTimestamp: number
+}
+
+export async function createAzureToken(
+    signal: AbortSignal
+): Promise<AuthenticationToken> {
     const { DefaultAzureCredential } = await import("@azure/identity")
     const azureToken = await new DefaultAzureCredential().getToken(
         AZURE_OPENAI_TOKEN_SCOPES.slice(),
         { abortSignal: signal }
     )
-    return azureToken.token
+    return {
+        token: azureToken.token,
+        expiresOnTimestamp: azureToken.expiresOnTimestamp,
+    }
 }

packages/cli/src/nodehost.ts

@@ -41,7 +41,7 @@ import {
 import { AbortSignalOptions, TraceOptions } from "../../core/src/trace"
 import { logVerbose, unique } from "../../core/src/util"
 import { parseModelIdentifier } from "../../core/src/models"
-import { createAzureToken } from "./azuretoken"
+import { AuthenticationToken, createAzureToken } from "./azuretoken"
 import { LanguageModel } from "../../core/src/chat"
 import { errorMessage } from "../../core/src/error"
 
@@ -144,7 +144,7 @@ export class NodeHost implements RuntimeHost {
     }
     clientLanguageModel: LanguageModel
 
-    private _azureToken: string
+    private _azureToken: AuthenticationToken
     async getLanguageModelConfiguration(
         modelId: string,
         options?: { token?: boolean } & AbortSignalOptions & TraceOptions
@@ -158,10 +158,13 @@ export class NodeHost implements RuntimeHost {
             !tok.token &&
             tok.provider === MODEL_PROVIDER_AZURE
         ) {
-            if (!this._azureToken)
+            if (
+                !this._azureToken ||
+                this._azureToken.expiresOnTimestamp >= Date.now()
+            )
                 this._azureToken = await createAzureToken(signal)
             if (!this._azureToken) throw new Error("Azure token not available")
-            tok.token = "Bearer " + this._azureToken
+            tok.token = "Bearer " + this._azureToken.token
         }
         if (!tok && this.clientLanguageModel) {
             return <LanguageModelConfiguration>{