[SPARK-8863] [EC2] Check aws access key from aws credentials if there is no boto config

'spark_ec2.py' use boto to control ec2.
And boto can support '~/.aws/credentials' which is AWS CLI default configuration file.

We can check this information from ref of boto.

"A boto config file is a text file formatted like an .ini configuration file that specifies values for options that control the behavior of the boto library. In Unix/Linux systems, on startup, the boto library looks for configuration files in the following locations and in the following order:
/etc/boto.cfg - for site-wide settings that all users on this machine will use
(if profile is given) ~/.aws/credentials - for credentials shared between SDKs
(if profile is given) ~/.boto - for user-specific settings
~/.aws/credentials - for credentials shared between SDKs
~/.boto - for user-specific settings"

* ref of boto: http://boto.readthedocs.org/en/latest/boto_config_tut.html
* ref of aws cli : http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-started.html

However 'spark_ec2.py' only check boto config & environment variable even if there is '~/.aws/credentials', and 'spark_ec2.py' is terminated.

So I changed to check '~/.aws/credentials'.

cc rxin

Jira : https://issues.apache.org/jira/browse/SPARK-8863

Author: JPark <JPark@JPark.me>

Closes #7252 from JuhongPark/master and squashes the following commits:

23c5792 [JPark] Check aws access key from aws credentials if there is no boto config

1 files changed, 10 insertions, 8 deletions

diff --git a/ec2/spark_ec2.py b/ec2/spark_ec2.py
index dd0c12d259..ae4f2ecc5b 100755
--- a/ec2/spark_ec2.py
+++ b/ec2/spark_ec2.py
@@ -325,14 +325,16 @@ def parse_args():
     home_dir = os.getenv('HOME')
     if home_dir is None or not os.path.isfile(home_dir + '/.boto'):
         if not os.path.isfile('/etc/boto.cfg'):
-            if os.getenv('AWS_ACCESS_KEY_ID') is None:
-                print("ERROR: The environment variable AWS_ACCESS_KEY_ID must be set",
-                      file=stderr)
-                sys.exit(1)
-            if os.getenv('AWS_SECRET_ACCESS_KEY') is None:
-                print("ERROR: The environment variable AWS_SECRET_ACCESS_KEY must be set",
-                      file=stderr)
-                sys.exit(1)
+            # If there is no boto config, check aws credentials
+            if not os.path.isfile(home_dir + '/.aws/credentials'):
+                if os.getenv('AWS_ACCESS_KEY_ID') is None:
+                    print("ERROR: The environment variable AWS_ACCESS_KEY_ID must be set",
+                          file=stderr)
+                    sys.exit(1)
+                if os.getenv('AWS_SECRET_ACCESS_KEY') is None:
+                    print("ERROR: The environment variable AWS_SECRET_ACCESS_KEY must be set",
+                          file=stderr)
+                    sys.exit(1)
     return (opts, action, cluster_name)