I was setting up a environment that had MAAS as its provider. bootstrap said this:
$ juju -v bootstrap
2013/04/25 21:32:12 INFO environs: reading tools with major version 1
2013/04/25 21:32:12 INFO environs: falling back to public bucket
2013/04/25 21:32:12 ERROR command failed: no tools available
error: no tools available
A hint on IRC got me to try sync-tools:
$ juju -v sync-tools
2013/04/25 21:46:20 INFO environs/ec2: opening environment "juju-public"
2013/04/25 21:46:20 ERROR failed to initialize the official bucket environment
2013/04/25 21:46:20 ERROR command failed: environment has no access-key or secret-key
error: environment has no access-key or secret-key
Setting AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY in the shell made sync-tools succeed and I could make progress. But it's pretty obscure.