Add support for dockerized DynamoDBLocal

[henhal]

This adds a new option which if true starts DynamoDB using docker.
Enabling support for docker resolves some issues with running the DynamoDB Java server on incompatible
architectures such as Apple M1.

If the option docker is truthy, instead of spawning a java process, a docker process is spawned, such as

docker run -d -p 8000:8000 amazon/dynamodb-local -jar DynamoDBLocal.jar -port 8000 -sharedDb -inMemory

The same arguments are supported as when running DynamoDBLocal using java on the localhost.

Customization:

The following environment variables may be used to customize the docker behaviour:

• DOCKER_PATH - the path to the docker executable. Default: 'docker'
• DOCKER_IMAGE - the name of the docker image. Default: 'amazon/dynamodb-local'

[henhal]

Fixes #63.
Whipped together for feedback and discussion. Works fine for me to start on MacBook Pro M1 2021 after installing Docker Desktop.
No tests created (if applicable).

[henhal]

If this is accepted, I intend to make a PR on https://github.com/99x/serverless-dynamodb-local/blob/v1/index.js to support docker as an argument for the SLS plugin as well.

Would it be more desirable to have the option as an object, such as

docker: {
   enabled: true,
   image: 'amazon/dynamodb-local', // optional
   path: '/usr/bin/local/docker' // optional
}

... or are you find with a simple docker: true and advanced options through environment variables? It occurred to me that envs are not ideal to use from the SLS plugin, it would be clearer if those options could be passed as part of the options object passed to dynamodb-localhost.

Updates to README.md are also needed, happy to append that once discussion topics are settled. :)

[ixartz]

I'm also interested by this PR. It could be great if it can be merged.

Maybe we should tag here the maintainer. They also put an email adresss in the README file?

[henhal]

@AshanFernando

[henhal]

@AshanFernando In order to proceed with 99x/serverless-dynamodb-local#279 I need a new released version of dynamodb-localhost. Could you please publish e.g. 0.1.0?

[AshanFernando]

@henhal Can you approve the below version bump
#65

[lsalazarm99]

Hello. I know that the new versions of this plugin and dynamodb-localhost are not released in NPM yet, so I installed both of them directly from their git repositories.

I tried serverless dynamodb start --docker, as the docs states, but it says it doesn't recognize the docker argument. It works if I set the docker parameter in my serverless config.

[henhal]

@lsalazarm99 Sorry if a stupid suggestion, but did you confirm that the unreleased version was in use? I mean, did serverless-dynamodb-local's package.json also reference the unreleased "pre-version"?

I did try this use-case successfully using npm link during development, which ensures my local version was used both from my test package and transitively from serverless-dynamodb-local. Just thinking your temporary setup might have had two versions in node_modules like this?

node_modules
|- serverless-dynamodb-local <- unreleased version directly from git
   |- node_modules
      |- dynamodb-localhost <-- official version referenced by package.json
|- dynamodb-localhost <- unreleased version directly from git

[henhal]

Doh, I missed the part about how it worked from serverless.yml but not from the CLI, then my suggestion makes no sense. Sorry.