Fix URL. It was printing an error message on startup:
```
2015/11/13 15:49:21 [ERR] fingerprint.env_aws: Error querying AWS Metadata URL, skipping
```
By the way is it safe to use latest? Is there a chance that Amazon decides to change the format of the metadata? It could be safer to use something like `http://169.254.169.254/2014-11-05/meta-data`