SPARK-2166 - Listing of instances to be terminated before the prompt

[j-martin]

Will list the EC2 instances before detroying the cluster.
This was added because it can be scary to destroy EC2
instances without knowing which one will be impacted.

[AmplabJenkins]

Can one of the admins verify this patch?

[mateiz]

Jenkins, test this please

[AmplabJenkins]

Merged build triggered. Build is starting -or- tests failed to complete.

[AmplabJenkins]

Merged build started. Build is starting -or- tests failed to complete.

[AmplabJenkins]

Merged build finished. All automated tests passed.

[AmplabJenkins]

All automated tests passed.
Refer to this link for build results: https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/13582/

[pwendell]

Very minor - but it might be slightly nicer to write this using string interpolation and also just using two different print statements instead of putting a newline directly in there (since you'll get python's system-dependent line delimiter).

print "Are you sure you want to destroy the cluster %s?" % cluster_name
print "The following instances will be terminated:"

[pwendell]

Made some minor comments. Overall, this seems like a great thing to have.

[pwendell]

@j-martin one other thing. Would you mind creating a brief JIRA to describe this feature? You can just create an account on the site. Many people follow our issue tracker so we try to have JIRA's for new things:

https://issues.apache.org/jira/browse/SPARK

[j-martin]

I created the issue. https://issues.apache.org/jira/browse/SPARK-2166

I will also apply the recommendations to the PR shortly.

[pwendell]

@j-martin Seems like this doesn't merge cleanly. Do you mind up-merging it?

[pwendell]

This was actually a pretty tough merge since we changed the spacing around a lot in spark_ec2 recently. I went ahead and manually dealt with the merge. I also made two minor changes on merge.