IS_OFFLINE is not set with --useDocker for go1.x

[MackJM]

Bug Report

From my understanding reading the docs at npmjs, I should be seeing the environment variable IS_OFFLINE while running my lambda. This is not the case for me.

Current Behavior

No variable called IS_OFFLINE is set

Sample Code

isoff := os.Getenv("IS_OFFLINE")
fmt.Println("is_off ", isoff)

Prints:
is_off

plugins:

• serverless-manifest-plugin
• serverless-pseudo-parameters
• serverless-plugin-stage-variables
• serverless-cloud-conformity
• serverless-offline
• serverless-dynamodb-local

provider:
runtime: go1.x
stage: dev

Expected behavior/code

IS_OFFLINE should return the value of true

Environment

• serverless version: serverless@1.67.0
• serverless-offline version: serverless-offline@6.3.1
• node.js version: v12.16.1
• OS: macOS 10.15.3
  optional, if you are using any of the following frameworks to invoke handlers

Possible Solution
I can manually set IS_OFFLINE in my serverless.yaml and it works fine

Additional context/Screenshots
I'm using --useDocker

[dustinsgoodman]

Looks like this was removed via the v6 alpha changes: #768 (comment)

Update: Opened a PR to remove it from the README #1018