s3cmd with Multiple AWS Accounts

Awhile back I was doing a lot of work involving Amazon’s Simple Storage Service (aka Amazon S3).

And while tools like Panic’s Transmit, the Firefox S3Fox extension, or even Amazon’s own S3 Management Console make it easy to use, sometimes you really just want a command-line tool.

There’s a lot of good tools out there, but the one I’ve been using is s3cmd. This tool is written in Python and is well documented. Installation on Linux or OS X is simple as is its configuration. And as a longtime Unix command-line user it’s syntax is simple. Some examples:

To list your buckets:

~ $ s3cmd ls
2010-04-28 23:50 s3://g5-images
2011-01-21 06:42 s3://g5-mongodb-backup
2011-03-21 21:23 s3://g5-mysql-backup
2010-06-03 17:45 s3://g5-west-images
2010-09-02 15:57 s3://g5engineering

List the size of a bucket with “human readable” units:

~ $ s3cmd du -H s3://g5-mongodb-backup
1132G s3://g5-mongodb-backup/

List the contents of a bucket:

~ $ s3cmd ls s3://g5-mongodb-backup
2011-08-08 14:43 3273232889 s3://g5-mongodb-backup/mongodb.2011-08-08-06.tar.gz
2011-08-08 21:12 3290592536 s3://g5-mongodb-backup/mongodb.2011-08-08-12.tar.gz
2011-08-09 03:16 3302734859 s3://g5-mongodb-backup/mongodb.2011-08-08-18.tar.gz
2011-08-09 09:09 3308369423 s3://g5-mongodb-backup/mongodb.2011-08-09-00.tar.gz
2011-08-09 14:51 3285753739 s3://g5-mongodb-backup/mongodb.2011-08-09-06.tar.gz

Show the MD5 hash of an asset:

~ $ s3cmd ls --list-md5 s3://g5-mongodb-backup/mongodb.2011-08-09-06.tar.gz
2011-08-09 14:51 3285753739 07747e3de16138799d9fe1846436a3ce \
s3://g5-mongodb-backup/mongodb.2011-08-09-06.tar.gz

Transferring a file to a bucket uses the get and put commands. And if you
forget an option or need a reminder of usage the very complete s3cmd –help
output will likely be all the help you need.

One problem I have with most tools for AWS is managing multiple accounts. Most
of these tools assume you have just one account, but I work with multiple
accounts and switching between them can be cumbersome.

Here’s how I work with multiple AWS accounts using s3cmd.

By default s3cmd puts its configuration file in ~/.s3cfg, but you can
override this and specify a configuration file with the -c option.

What I do is create a separate config file with the appropriate credentials for
each account I work with and give them unique names:

~ $ ls -1 .s3cfg*
.s3cfg-g5
.s3cfg-tcp

Another option is to keep the credentials for the account you use most often in
the standard ~/.s3cfg file and use the -c option when/if you need another
account. I don’t like this option because it’s too easy to mistakenly use the
wrong account. For example, without a ~/.s3cfg this is what happens when I use
s3cmd without specifying a configuration:

~ $ s3cmd ls
ERROR: /Users/mike/.s3cfg: No such file or directory
ERROR: Configuration file not available.
ERROR: Consider using --configure parameter to create one.

So, what to do? Using the -c all the time is a PITA. Answer: use Bash aliases!

Here’s a subset of the s3cmd aliases I have in my ~/.bashrc file:

# s3cmd aliases for different s3 accounts
alias s3g5='s3cmd -c ~/.s3cfg-g5'
alias s3tcp='s3cmd -c ~/.s3cfg-tcp'

Now, to list the buckets in my personal account I just do:

~ $ s3tcp ls
2011-07-01 06:10 s3://mikesisk-img
2011-07-05 23:16 s3://www.tcpipranch.com
2011-07-01 22:55 s3://www.watch4rocks.com

And I can still pass arguments:

~ $ s3tcp -H --list-md5 ls s3://mikesisk-img/me.jpg
2011-07-01 06:09 5k 13d7c86bccd8915dd93b085985305394 \
s3://mikesisk-img/me.jpg

Just keep in mind that calls to bash aliases from scripts and cronjobs might not work. Plus it’s bad form and will come back to bite you one of these days. Just use the long form with -c in these places and keep the aliases for your own interactive command-line usage.