Get last modified object from S3 using AWS CLI
Amazon Web-ServicesAmazon Ec2Amazon S3Amazon Web-Services Problem Overview
I have a use case where I programmatically bring up an EC2 instance, copy an executable file from S3, run it and shut down the instance (done in user-data). I need to get only the last added file from S3.
Is there a way to get the last modified file / object from a S3 bucket using the AWS CLI tool?
Amazon Web-Services Solutions
Solution 1 - Amazon Web-Services
You can list all the objects in the bucket with aws s3 ls $BUCKET --recursive
:
$ aws s3 ls $BUCKET --recursive
2015-05-05 15:36:17 4 an_object.txt
2015-06-08 14:14:44 16322599 some/other/object
2015-04-29 12:09:29 32768 yet-another-object.sh
They're sorted alphabetically by key, but that first column is the last modified time. A quick sort
will reorder them by date:
$ aws s3 ls $BUCKET --recursive | sort
2015-04-29 12:09:29 32768 yet-another-object.sh
2015-05-05 15:36:17 4 an_object.txt
2015-06-08 14:14:44 16322599 some/other/object
tail -n 1
selects the last row, and awk '{print $4}'
extracts the fourth column (the name of the object).
$ aws s3 ls $BUCKET --recursive | sort | tail -n 1 | awk '{print $4}'
some/other/object
Last but not least, drop that into aws s3 cp
to download the object:
$ KEY=`aws s3 ls $BUCKET --recursive | sort | tail -n 1 | awk '{print $4}'`
$ aws s3 cp s3://$BUCKET/$KEY ./latest-object
Solution 2 - Amazon Web-Services
Updated answer
After a while there is a small update how to do it a bit elegant:
aws s3api list-objects-v2 --bucket "my-awesome-bucket" --query 'sort_by(Contents, &LastModified)[-1].Key' --output=text
Instead of extra reverse
function we can get last entry from the list via [-1]
Old answer
This command just do the job without any external dependencies:
aws s3api list-objects-v2 --bucket "my-awesome-bucket" --query 'reverse(sort_by(Contents, &LastModified))[:1].Key' --output=text
Solution 3 - Amazon Web-Services
aws s3api list-objects-v2 --bucket "bucket-name" |jq -c ".[] | max_by(.LastModified)|.Key"
Solution 4 - Amazon Web-Services
If this is a freshly uploaded file, you can use Lambda to execute a piece of code on the new S3 object.
If you really need to get the most recent one, you can name you files with the date first, sort by name, and take the first object.
Solution 5 - Amazon Web-Services
Following is bash script, that downloads latest file from a S3 Bucket. I used AWS S3 Synch command instead, so that it would not download the file from S3 if already existing.
--exclude, excludes all the files
--include, includes all the files matching the pattern
#!/usr/bin/env bash
BUCKET="s3://my-s3-bucket-eu-west-1/list/"
FILE_NAME=`aws s3 ls $BUCKET | sort | tail -n 1 | awk '{print $4}'`
TARGET_FILE_PATH=target/datdump/
TARGET_FILE=${TARGET_FILE_PATH}localData.json.gz
echo $FILE_NAME
echo $TARGET_FILE
aws s3 sync $BUCKET $TARGET_FILE_PATH --exclude "*" --include "*$FILE_NAME*"
cp target/datdump/$FILE_NAME $TARGET_FILE
p.s. Thanks @David Murray