fix: allow Bedrock provider to use AWS SDK default credential chain

Remove hard requirement for explicit AWS credentials in Bedrock provider.
When access key and secret key are not provided, the AWS SDK automatically
falls back to its default credential chain (env vars, instance profile,
ECS task role, EKS IRSA, SSO).

Closes #3694

Signed-off-by: majiayu000 <1835304752@qq.com>

Author: majiayu000

apps/sim/blocks/blocks/agent.ts

@@ -367,9 +367,9 @@ Return ONLY the JSON array.`,
       title: 'AWS Access Key ID',
       type: 'short-input',
       password: true,
-      placeholder: 'Enter your AWS Access Key ID',
+      placeholder: 'Optional - uses AWS default credential chain if empty',
       connectionDroppable: false,
-      required: true,
+      required: false,
       condition: {
         field: 'model',
         value: providers.bedrock.models,
@@ -380,9 +380,9 @@ Return ONLY the JSON array.`,
       title: 'AWS Secret Access Key',
       type: 'short-input',
       password: true,
-      placeholder: 'Enter your AWS Secret Access Key',
+      placeholder: 'Optional - uses AWS default credential chain if empty',
       connectionDroppable: false,
-      required: true,
+      required: false,
       condition: {
         field: 'model',
         value: providers.bedrock.models,

apps/sim/providers/bedrock/index.ts

@@ -50,14 +50,6 @@ export const bedrockProvider: ProviderConfig = {
   executeRequest: async (
     request: ProviderRequest
   ): Promise<ProviderResponse | StreamingExecution> => {
-    if (!request.bedrockAccessKeyId) {
-      throw new Error('AWS Access Key ID is required for Bedrock')
-    }
-
-    if (!request.bedrockSecretKey) {
-      throw new Error('AWS Secret Access Key is required for Bedrock')
-    }
-
     const region = request.bedrockRegion || 'us-east-1'
     const bedrockModelId = getBedrockInferenceProfileId(request.model, region)
 
@@ -67,13 +59,18 @@ export const bedrockProvider: ProviderConfig = {
       region,
     })
 
-    const client = new BedrockRuntimeClient({
-      region,
-      credentials: {
-        accessKeyId: request.bedrockAccessKeyId || '',
-        secretAccessKey: request.bedrockSecretKey || '',
-      },
-    })
+    const clientConfig: {
+      region: string
+      credentials?: { accessKeyId: string; secretAccessKey: string }
+    } = { region }
+    if (request.bedrockAccessKeyId && request.bedrockSecretKey) {
+      clientConfig.credentials = {
+        accessKeyId: request.bedrockAccessKeyId,
+        secretAccessKey: request.bedrockSecretKey,
+      }
+    }
+
+    const client = new BedrockRuntimeClient(clientConfig)
 
     const messages: BedrockMessage[] = []
     const systemContent: SystemContentBlock[] = []