This is a way of tying together several different blob-stores to operate as one.

The module exports a single function taking in a config object, and returns a blob-store. The properties of the config object correspond to the methods available on blob-stores (i.e. createReadStream, createWriteStream, exists, remove). If exists is omitted, the blob-store for createReadStream is used instead for those calls. remove also defers to createWriteStream in the same way. Each of these can either be a blob store to forward the calls for that method to, or an array of arrays that's used to match keys to blob-stores based on regular expressions. For example:

var metaStore = MetaBlobStore({
    createReadStream: [
        [/^foo/, blobStore1],
        [/.*/, blobStore2]
    ],
    createWriteStream: blobStore3
});

In this example, for createReadStream and exists calls, the call will be sent to blobStore2 except when the key in the arguments starts with foo, in which case the call will be sent to blobStore1. All calls to createWriteStream and remove are sent to blobStore3.

One thing this doesn't cover is cases where you want to send the calls to more than one blob store. This is farily complex since there are many cases. Do you want to write to both all the time or alternate? Do you want to read from both and append one to the other? Or some other stream multiplexing? Different use cases call for different solutions here, so this is left as an exercise.

This all allows for some pretty complicated routing of your blobs, so be careful!

MIT. See LICENSE.txt