check returns the most recent LastModified timestamp

This allows us to version a whole bucket.
Closes #5

README.md

@@ -68,3 +68,5 @@ Requires [Docker](https://www.docker.com/).
   * Exclude the `s3://` prefix/protocol for `bucket`.
 
 1. Run `./test/out </full/path/to/dir>`.
+1. Run `./test/in </full/path/to/dir>`.
+1. Run `./test/check`.

assets/check

@@ -4,5 +4,15 @@
 
 set -e
 
-# pretend that "the given version is already the latest"
+# parse incoming config data
-echo "[]"
+payload=`cat`
+bucket=$(echo "$payload" | jq -r '.source.bucket')
+
+# export for `aws` cli
+export AWS_ACCESS_KEY_ID=$(echo "$payload" | jq -r '.source.access_key_id')
+export AWS_SECRET_ACCESS_KEY=$(echo "$payload" | jq -r '.source.secret_access_key')
+
+# Consider the most recent LastModified timestamp as the most recent version.
+timestamps="$(aws s3api list-objects --bucket $bucket --query 'Contents[].{LastModified: LastModified}')"
+recent="$(echo $timestamps | jq -r 'max_by(.LastModified)')"
+echo "[$recent]"