serverless-offline-provider-value-replacer

Serverless plugin for manipulating values under providers while using serverless-offline.

Main use case is for replacing values which would otherwise been imported from cloud formation.

Installation

Installing using npm:

npm i serverless-offline-provider-value-replacer --save-dev

Then inside your serverless.yml, add serverless-offline-provider-value-replacer to your plugins list.

    plugins:
        - serverless-offline-provider-value-replacer

Usage

The plugin is configured with values located at custom.offline.provider-replacements

    offline:
      provider-replacements:
        - path: "$..URL_INGESTED_FROM_CF"
          replaceWith: "http://localhost:9090"

If we take the following yml which will cause issue running locally:

provider:
  name: aws
  stage: local
  environment:
    FOO: !ImportValue my-aws-stack-foo

When running the lambda with serverless offline, the value of FOO when accessed by process.env.FOO will be [Object object].

Using the plugin, we can force the value of FOO to be some other value at run time while using serverless offline. Eg:

    offline:
      provider-replacements:
        - path: "$..FOO"
          replaceWith: "bar"

When the code is then running, the value of process.env.FOO will now be bar.

Depending on how you have serverless.ymls configured, you may not need this plugin. However, in our scenario we had a single map in the yml for cloud formation outputs that would support all of our environments except local. So this allowed us to circumvent not being able to run !ImportValue with our local stack.