AWS Lambda, boto3 - start instances, error while testing (not traceable) - python-3.x

Question

I am trying to create a Lambda function to automatically start/stop/reboot some instances (with some additional tasks in the future).
I created the IAM role with a policy:
{
"Version": "2012-10-17",
"Statement": [
{
"Action": [
"ec2:StartInstances",
"ec2:StopInstances",
"ec2:RebootInstances"
],
"Condition": {
"StringEquals": {
"ec2:ResourceTag/critical":"true"
}
},
"Resource": [
"arn:aws:ec2:*:<12_digits>:instance/*"
],
"Effect": "Allow"
}
]
}
The Lambda function has been granted access to the correct VPC, subnet, and security group.
I assigned the role to a new Lambda function (Python 3.9):
import boto3
from botocore.exceptions import ClientError
# instance IDs copied from my AWS Console
instances = ['i-xx1', 'i-xx2', 'i-xx3', 'i-xx4']
ec2 = boto3.client('ec2')
def lambda_handler(event, context):
print(str(instances))
try:
print('The break occurs here \u2193')
response = ec2.start_instances(InstanceIds=instances, DryRun=True)
except ClientError as e:
print(e)
if 'DryRunOperation' not in str(e):
print("You don't have permission to reboot instances.")
raise
try:
response = ec2.start_instances(InstanceIds=instances, DryRun=False)
print(response)
except ClientError as e:
print(e)
return response
I cannot find anything due to no message in the test output about where the error is. I had thought it had been a matter of time duration, then I set the time limit to 5 mins to be sure if it was a matter of time. For example:
Test Event Name
chc_lambda_test1
Response
{
"errorMessage": "2022-07-30T19:15:40.088Z e037d31d-5658-40b4-8677-1935efd3fdb7 Task timed out after 300.00 seconds"
}
Function Logs
START RequestId: e037d31d-5658-40b4-8677-1935efd3fdb7 Version: $LATEST
['i-xx', 'i-xx', 'i-xx', 'i-xx']
The break occurs here ↓
END RequestId: e037d31d-5658-40b4-8677-1935efd3fdb7
REPORT RequestId: e037d31d-5658-40b4-8677-1935efd3fdb7 Duration: 300004.15 ms Billed Duration: 300000 ms Memory Size: 128 MB Max Memory Used: 79 MB Init Duration: 419.46 ms
2022-07-30T19:15:40.088Z e037d31d-5658-40b4-8677-1935efd3fdb7 Task timed out after 300.00 seconds
Request ID
e037d31d-5658-40b4-8677-1935efd3fdb7
I had tried increasing the Lambda memory too, but it hasn't worked (it is not the case, since Max Memory Used: 79 MB).

Answer 1

The main reason the issue occurred, is the lack of internet access to the subnet assigned to the Lambda function. I have added (as Ervin Szilagyi suggested) an endpoint in the VPC (with an assignment to the subnet and security group).
The next step was to provide authorization - thanks to this idea Unauthorized operation error occurs when using Boto3 to launch an EC2 instance with an IAM role, I added the IAM access key and secret key to the client invocation.
ec2 = boto3.client(
'ec2',
aws_access_key_id=ACCESS_KEY,
aws_secret_access_key=SECRET_KEY,
)
However, please be careful with security settings, I am a new user (and working on my private projects at the moment), therefore, you shouldn't take this solution as secure.