Amazon CloudWatch query runners

[arikfr]

What type of PR is this? (check all applicable)

• New Query Runner (Data Source)

Description

Query runner for Amazon CloudWatch and CloudWatch Insights.

• Implement Insights query runner.
• Update names & types.
• Add logos.
• Implement Test Connection.

[rauchy]

LGTM. I just have a couple of questions:

1. How do you decide if a helper function is inside or outside a class scope? For example, I'm not sure why CloudWatch._get_client is inside the CloudWatch scope, but parse_response is outside. I know it's not a big deal, but if it's just arbitrary, then a unified approach would make the code slightly easier to step into.

2. How do you pick between list comprehensions and building with for loops? For example, the for block in parse_response under cloudwatch.py could easily be represented with a list comprehension. Again, not a big deal, but having a rule to follow (for example - 'prefer list comprehensions unless they look like a pile of manure') might make things easier.

[arikfr]

1. How do you decide if a helper function is inside or outside a class scope? For example, I'm not sure why CloudWatch._get_client is inside the CloudWatch scope, but parse_response is outside.

_get_client uses values from the instance, hence it's a class method. parse_response doesn't so it's outside.

2. How do you pick between list comprehensions and building with for loops?

Mostly habit thing. When the for loop is simple I use list comprehensions, but when it's multi line I usually do a for loop.

[rauchy]

_get_client uses values from the instance, hence it's a class method. parse_response doesn't so it's outside.

Yeah, but encapsulating is about knowledge, not access to memory. parse_response is tightly coupled to CloudWatch's knowledge and not at all portable. It's as related to CloudWatch as _get_client...

[arikfr]

I'm looking at it not at the class level, but the module level. redash.query_runner.cloudwatch is a module about accessing CloudWatch metrics. It has the CloudWatch class which is the Redash driver/interface and parse_response which is used to parse responses coming from the API.

There is also a benefit in testing: it makes it trivial to test parse_response without having to go through the whole CloudWatch class. Of course it could be a staticmethod on the CloudWatch class, but I don't see much benefit in doing so.

[kangzj]

@arikfr Hi mate, good job & great effort
I'm a newbie to redash. May I ask how to query from CloudWatch? It doesn't seem to work the normal way. Thanks

[susodapop]

Hey @kangzj, the CloudWatch query runner documentation is underway. The associated issue is getredash/website#453. This data source is part of V9 which is still in beta. The doc should be ready before the full release.

The short answer is that you don't use SQL to query CloudWatch. It uses a YAML query (similar to the JSON query source or MongoDB).