Thursday, September 19, 2013

Special secret stuff with s3cmd

According to my coworker, "Amazon's S3 is the best thing since sliced bread." For working with S3, s3cmd is a handy little tool. It's documentation is a bit on the sparse side, but, what do you expect for free?

One gotcha with S3 is that buckets and the files in them have entirely distinct ACLs. This can lead to scenarios where the owner of a bucket can't work with the files in it. An easy way for this to come about is to log into the S3 console and create a bucket with one set of credentials, then upload files with a tool like s3cmd under another set of credentials.

cd /path/to/files/
s3cmd -v sync . s3://

You can give permissions to the bucket owner like so:

s3cmd setacl --recursive s3://

You might also want to make the files public, so they can be served as a static website.

s3cmd setacl --acl-public --recursive s3://

AWS Command Line Interface

I've been using s3cmd for a while, out of habit, but maybe it's time to try to Amazon's AWS Command Line Interface, which just had their version 1.0 release.

From a brief look, AWS CLI looks nice. You can do the same sync operation as above and make files public in one command:

aws s3 sync . s3:// --acl public-read

Amazon is very mysterious about how to specify the target of a grant of permissions, aka the grantee. I tried to give permission to the owner of a bucket, but kept getting an error. Some more examples in the docs would help! I also get "Invalid Id" for no apparent reason in the permissions section of the web UI for S3, so maybe I'm just clueless.

aws s3api put-object-acl --bucket --grant-full-control --key genindex.html
#> A client error (InvalidArgument) occurred: Argument format not recognized.

As far as I could tell, the AWS CLI tool seems to be missing the --recursive option that we used with s3cmd. That seems like a fairly essential thing.

Also, I couldn't get the profile feature to work:

aws s3 ls s3:// --profile docgenerator
#>The config profile (docgenerator) could not be found

NOTE: Many thanks to Mitch Garnaat, I now know how the --profile switch works. Contrary to the documentation, you need a heading in your config file like this: [profile docgenerator] rather than like this: [docgenerator].

I'm glad Amazon is taking the lead in developing this tool, and I'm sure they'll keep making it better. And, there's a Github repo, so I'm guessing that means they take pull requests.