cloud watch events support

[kapilt]

Issue #1124

Support subscribing functions to cloud watch events.

with this pr the intent is that you can now subscribe to any of the dozen of event types that are sent through cloud watch events https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/EventTypes.html

Example usage, in this case subscribing to ec2 instance state change notifications

@sample_app.on_cw_event({'source': ['aws.ec2']})
def instance_change(event, context):
    print(event)

[codecov-io]

Codecov Report

Merging #1126 into master will increase coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1126      +/-   ##
==========================================
+ Coverage   95.98%   96.03%   +0.05%     
==========================================
  Files          28       28              
  Lines        5176     5218      +42     
  Branches      658      665       +7     
==========================================
+ Hits         4968     5011      +43     
+ Misses        135      134       -1     
  Partials       73       73

Impacted Files	Coverage Δ
chalice/awsclient.py	94.62% <100%> (+0.06%)	⬆️
chalice/app.py	97.43% <100%> (+0.02%)	⬆️
chalice/deploy/deployer.py	98.32% <100%> (+0.03%)	⬆️
chalice/package.py	100% <100%> (ø)	⬆️
chalice/deploy/planner.py	97.11% <100%> (+0.12%)	⬆️
chalice/deploy/models.py	100% <100%> (+0.56%)	⬆️

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[kyleknap]

Looks good! I still need to pull it down and try it out. Otherwise had some comments and suggestions. I think this will be really useful. Also we will probably need to do some rebasing to fix some conflicts.

[kyleknap]

Other thing I forgot... It would be good to add a changelog entry for this. You can add it under a new Next Release section in the CHANGELOG.rst file

[kyleknap]

I tried it out and it worked well. I just had a couple more bits of feedback on the documentation after trying to use it to test out the feature

[kyleknap]

Looks great. Just had one small comment. Otherwise, I say we rebase off of master, add a changelog entry, and we can get this one merged too.

[kapilt]

rebased and added changelog and terraform packaging support.

[kyleknap]

Nice! Looks good. Just one a little picky comment: I noticed in the updated docs and in the code, CloudWatch is being spelled out as two words. Could we update it to make it one word (i.e. CloudWatch instead of CloudWatch in the docs and cloudwatch instead of cloud_watch in the code) to make it consistent with the official service branding and how it is exposed in boto3? Otherwise, it should be good to merge.

[kapilt]

wrt to cloudwatch, updated docs and code to reflect the product marketing name.

[kyleknap]

Looks good. Thanks!