How to upload to s3 from ec2 log files through lambda & boto3 – Amazon web services

I want to upload only Ec2 log files through lambda.

I have code for this

import json
import os
import datetime as dt
import boto3
import socket

region = 'ap-northeast-2'
instances = []
ec2_r = boto3.resource('ec2')
ec2 = boto3.client('ec2', region_name=region)

for instance in ec2_r.instances.all():
    for tag in instance.tags:
        if tag['Key'] == 'Log-Archive':
            if tag['Value'] == 'True':
                instances.append(instance.id)
             
def lambda_handler(event, context):
    s3 = boto3.client("s3")   
    dir_path = "/log"
    bucket = 'mybucket'
    x = dt.datetime.now()
    date = x.strftime("%Y%m%d")
    def log(in_path):
        for (dir_path, dir, files) in os.walk(in_path):
            for file in files:
                if date in file:
                    yield os.path.join(dir_path, file)
                    
    for file_name in log(dir_path):
        key = socket.gethostname() + '/' + file_name
        res = s3.upload_file(file_name, bucket, key)

    return {
        'statusCode': 200,
    }

When I tested this code it returned 200 code. but nothing in my bucket.
And I tested this code on my local ec2 without lambda code, and It works

33

Response
{
  "statusCode": 200
}

Function Logs
START RequestId: 39f63d4f-e154-48b8-9fb3-51b98f927a30 Version: $LATEST
END RequestId: 39f63d4f-e154-48b8-9fb3-51b98f927a30
REPORT RequestId: 39f63d4f-e154-48b8-9fb3-51b98f927a30  Duration: 51.61 ms  Billed Duration: 52 ms  Memory Size: 128 MB Max Memory Used: 89 MB

Request ID
39f63d4f-e154-48b8-9fb3-51b98f927a30

Can I take some advices? thanks for all answers.