ssm_getparameter.php

<?php
require 'vendor/autoload.php';

function getSsmParameter($paths)
{
    $sharedConfig = [
    'region' => 'ap-northeast-1',
    'version' => 'latest'
    ];

    $client = new Aws\Ssm\SsmClient($sharedConfig);
    $result = $client->getParametersByPath(
        [
        'Path' => $paths,
        'WithDecryption' => true
        ]
    );

    $count = 0;

    foreach ($result['Parameters'] as $v) {
        $name = $v['Name'];
        $params[$name] = $v['Value'];
        $param_name = explode('/', $name);
        $env_values[$count] = $param_name[3] . "=" . $params[$name];
        $count++;
    }
    return $env_values;
}

$env_values = getSsmParameter('/MyService/Test/');

$fp = fopen(".env", "w");
foreach ($env_values as $v){
    fwrite($fp, $v);
    fwrite($fp, "\n");
}

fclose($fp);