Improve mock support for AWS SDK

[karlsnyder0]

Improves the describeEndpoint mock (Serverless Offline)

https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/Iot.html#describeEndpoint-property

Add mocks for getCallerIdentity and assumeRole.

https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/STS.html https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/STS.html#assumeRole-property https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/STS.html#getCallerIdentity-property

Add Support for Redis Host, Port and Database.

[mvayngrib]

@karlsnyder0 thanks for the PR! A few questions and comments:

• Fix describeEndpoint. Good catch, I wasn't aware there were two signatures for that method. However, you broke the single-argument variant. It's not in their documentation, but it is in their typescript def :)
• Add STS mocks - is there a reason they need to be in this module? Seems like something users can mock individually for their particular use cases.
• Add support for redis host, port, db. I like the direction, but currently the opts to createBroker are passed through directly to the mosca broker constructor, so it would be better to differentiate between this module's options and mosca's. Maybe createBroker should have two options hashes, e.g. createBroker({ ascoltatore, mosca })

[karlsnyder0]

@mvayngrib

• I'll investigate the single parameter of describeEndpoint.
• When this plugin is used in Serverless offline any calls to the AWS STS object fail. STS is used in combination with IoT to generate AWS IoT tokens. When this is mocked in this plugin it allows a developer to contain their Serverless code with what should work with the AWS SDK and when running Serverless Offline that same code should still work which is what I thought the main goal of this plugins was to achieve. See- https://serverless.com/blog/serverless-notifications-on-aws/
• Two options, good point. I'll create two options.

BTW, I have another PR coming for adding secure communication and self signed certificate support. You see, we are using the AWS Device Client to communicate with AWS IoT. The AWS Device Client does not allow non-secure communication.

[mvayngrib]

@karlsnyder0 cool, looking forward to the next PR!

the main issue I have with the STS mocking bit is that STS is used for all kinds of identity-related scenarios, not limited to Iot. If serverless-offline decides to mock it too (which i hope they won't for the same reason this module doesn't), or some other plugin does, or the user themselves, those mocks will conflict with each other, or just error out. On the other hand, it's relatively easy for the user to add the mocks in their setup, e.g. conditioned on the NODE_ENV or IS_OFFLINE env vars. That's what I currently do in my project - have a bunch of additional mocks that are specific to my use cases. Does that make sense?

[karlsnyder0]

@mvayngrib Please review the latest changes.

If you would prefer the STS Mocks be left out I can certainly do that. It seemed to make sense to me that this would be completely isolated from the implementation however I can certainly create another plugin to mock STS. Are you sure you don't want STS in this plugin?

[mvayngrib]

@karlsnyder0 how about let's make it optional, and add a mockSTS config flag, which defaults to false

[karlsnyder0]

@mvayngrib I've removed the STS mocks.

[karlsnyder0]

@mvayngrib fyi- I'm planning to propose to Serverless Offline that they add AWS Mocks so that the AWS SDK works with offline.

[karlsnyder0]

I can definitely see as this grows there should be a separate method in charge of building the mosca backend config. See latest changes.

[karlsnyder0]

@mvayngrib Please review when you get the chance. Thanks!

[mvayngrib]

@karlsnyder0 lgtm. Fix the README and I'll merge?

[mvayngrib]

@karlsnyder0 thanks! Released in 1.3.0

[karlsnyder0]

@mvayngrib Thanks! I'll followup with my next PR.