AWS S3 Integration with Grails

I’ve been playing with the S3 plugin for a Grails project and wanted to share how I set it up, as the documentation on the site doesn’t cover an example.

First, in my model I added a byte array field and made it transient. Transient basically means it doesn’t add the bytes to the database, but just keeps the data in memory. This means you can take advantage of all of the automatically generated controllers and view classes which are created from the model without having to really deal with the contents.

class ImageHolder{
byte[] image
String imageUri
static transients = ['image']
}

In the controller we use the request object to get the file and save it to disk, removing any spaces that may have crept in. Then we start using the plugin, and create a S3Asset from the file and put it into the asset service class. The assetService must also be declared at the top, and it’s injected via Spring from the plugin.

def s3AssetService
....
def imageholder = new ImageHolder(params)
....
def mhsr = request.getFile('image')
def fileName = mhsr.getOriginalFilename().replace(' ','_')
def ext = fileName.substring(fileName.lastIndexOf(".")+1);
def file = new File(fileName)
if (!mhsr?.empty && mhsr.size < 1024*200){
mhsr.transferTo(file)
def asset = new S3Asset(file)
asset.mimeType = ext
s3AssetService.put(asset)
imageholder.imageUri = asset.url()
imageholder.save()
}

What this does, is now uses the async service to put the file into S3, so your request returns very quickly. You can see that the image URI is now persisted into the domain object, but the content isn’t.

One final thing is to configure AWS in config.groovy. I set the flag to not add a prefix to the bucket name, as I’m using reverse DNS/package style bucket name to ensure uniqueness.

aws {
domain="s3.amazonaws.com"
accessKey="YOURACCESSKEY"
secretKey="YOURSECRETKEY"
bucketName="your.bucket.name"
prefixBucketWithKey=false
timeout=3000
}