Function function_handler

examples/basic-s3-thumbnail/src/main.rs:21–66

This lambda handler * listen to file creation events * downloads the created file * creates a thumbnail from it * uploads the thumbnail to bucket "[original bucket name]-thumbs". Make sure that * the created png file has no strange characters in the name * there is another bucket with "-thumbs" suffix in the name * this lambda only gets event from png file creation

(
    event: LambdaEvent<S3Event>,
    size: u32,
    client: &T,
)

    * this lambda has permission to put file into the "-thumbs" bucket
*/
pub(crate) async fn function_handler<T: PutFile + GetFile>(
    event: LambdaEvent<S3Event>,
    size: u32,
    client: &T,
) -> Result<(), Error> {
    let records = event.payload.records;

    for record in records.into_iter() {
        let (bucket, key) = match get_file_props(record) {
            Ok(touple) => touple,
            Err(msg) => {
                tracing::info!("Record skipped with reason: {}", msg);
                continue;
            }
        };

        let image = match client.get_file(&bucket, &key).await {
            Ok(vec) => vec,
            Err(msg) => {
                tracing::info!("Can not get file from S3: {}", msg);
                continue;
            }
        };

        let thumbnail = match get_thumbnail(image, size) {
            Ok(vec) => vec,
            Err(msg) => {
                tracing::info!("Can not create thumbnail: {}", msg);
                continue;
            }
        };

        let mut thumbs_bucket = bucket.to_owned();
        thumbs_bucket.push_str("-thumbs");

        // It uploads the thumbnail into a bucket name suffixed with "-thumbs"
        // So it needs file creation permission into that bucket

        match client.put_file(&thumbs_bucket, &key, thumbnail).await {
            Ok(msg) => tracing::info!(msg),
            Err(msg) => tracing::info!("Can not upload thumbnail: {}", msg),
        }
    }

    Ok(())
}

fn get_file_props(record: S3EventRecord) -> Result<(String, String), String> {
    record