Download directly from MinIO from R Shiny

[david-wavrock]

This was posted on slack already but at Blair's request I am posting it here

Download daaas_storage.R which serves as a workaround for accessing MinIO files using the R package aws.s3 and put it in the same shiny folder as the server, ui and global files.

In the global file, include:

library(aws.s3)

source('~/project_folder/shiny/daaas_storage.R')
daaas_storage.minimal()

minio_filist <- get_bucket(bucket='shared', use_https=FALSE, region='', prefix='your-name/.../minio-project_folder/')

The character string for prefix should link to the folder where files are stored which you wish to download via the shiny app. minio_filist is of class s3_bucket.

In the server file, include:

output$downloadFile <- downloadHandler(
    filename = 'download.zip'

    content = function(filename){
        save_object('your-name/.../minio-project_folder/target_file.zip',bucket=minio_filist,
        use_https=FALSE, region='',
        file=filename)
    }
)

I found that I had to specify the full filepath from 'shared' in MinIO in order to get the download to work. 'download.zip' is the default name for which the file will be saved and is passed as an argument to the function specified in content.

Calling downloadFile in your ui file occurs as normal:

downloadButton('downloadFile','Download')