Azure-sdk-for-js: Check whether a storage container or blob already exists

[ricklang]

Is there an easy way to check whether a storage container already exists? Same for a blob.

[bterlson]

Maybe the easiest way today is calling getProperties on BlobClient and checking for a 404 status code. I think we should implement exists, however! /cc @XiaoningLiu @jeremymeng

[XiaoningLiu]

Agree

Maybe the easiest way today is calling getProperties on BlobClient and checking for a 404 status code. I think we should implement exists, however! /cc @XiaoningLiu @jeremymeng

[bterlson]

I confirmed with @JeffreyRichter that exists makes some sense, but there's a concern that exists encourages coding patterns that might seem reliable but aren't in practice. For example, upload-if-not-exists might be implemented as if (!(await client.exists())) { await client.upload() } but another node might be running the same check at the same time and the uploads will still clobber each other.

It's still worth implementing exists, though, I think. Python will likely be adding it as well.

[Gtonizuka]

hey guys has this ever been implemented?

[cpwr]

yeah, has it?

[jeremymeng]

implemented in #5333