Reads PowerShell environment variables file to upload to AWS Lambda

.env_lambda.ps1

<#
.SYNOPSIS
    Reads PowerShell environment variables file to upload to AWS Lambda

.DESCRIPTION
    The .env_lambda script is made of the following steps:
    1. Skips the first three lines of the .env file
    2. Retrieves the contents of each line after the first ":"
    3. Joins all variables into a comma-separated string
    4. Uploads variables up to AWS Lambda

.PARAMETER EnvVars
    File containing PowerShell environment variable to upload to AWS Lambda.
    See example for file format.

.PARAMETER SkipLines
    Number of lines to skip from the start of the file.
    Defaults to 0.

.PARAMETER LambdaFunction
    Name of AWS Lambda Function to upload environment variables to.        

.EXAMPLE
    Example source .env.ps1 file:
    -----------------------------
    $env:PROJECT_HOME="C:\Users\naaman\Documents\Code\pythagoras"
    cd $env:PROJECT_HOME
    .\venv\Scripts\activate.ps1
    $env:DEV_S3_BUCKET_NAME="pythagoras-dev-static.example.id.au"
    $env:DEV_STATIC_PATH="https://pythagoras-dev-static.example.id.au/static"
    -----------------------------    
    PS C:\Users\naaman> .\.env_lambda.ps1 -EnvVars .env.ps1 -SkipLines 3 -LambdaFunction pythagoras-app-dev
    ...
    aws lambda update-function-configuration --function-name=pythagoras-app-dev --environment Variables='{DEV_S3_BUCKET_NAME="pythagoras-dev-static.example.id.au", DEV_STATIC_PATH="https://pythagoras-dev-static.example.id.au/static"}'    
#>
[cmdletbinding()]
Param (

    # Read from supplied environment variables filename
    [Parameter(Mandatory = $true)]
    [String] $EnvVars,

    # Skip number of lines from top of environment variables file
    [Parameter(Mandatory = $false)]
    [String] $SkipLines = 0,

    # Skip number of lines from top of environment variables file
    [Parameter(Mandatory = $true)]
    [String] $LambdaFunction    

)

$lines = Get-Content $EnvVars | Select-Object -skip $SkipLines | %{$_.Split(':', 2)[1]}
$variables = @{}
foreach($line in $lines) {
    $key_val = $line.Split('=')
    $variables.Add($key_val[0],$key_val[1].trim("`""))
}
Update-LMFunctionConfiguration -FunctionName $LambdaFunction -Environment_Variable $variables