CloudWatch EC2 - Finding EC2 Server's Instance ID and Instance Name

I have a custom CloudWatch metric that I am reporting. My call looks like:

$dimensions = array(
    array(
        "Name" => "InstanceId",
        "Value" => "need instance id here"
    ),
    array(
        "Name" => "InstanceName",
        "Value" => "need instance name here"
    )
);

// API call to save cpu usage
$client->putMetricData(array(
    "Namespace" => "mynamespace",
    "MetricData" => array(
        array(
            "MetricName" => "CPU_Usage",
            "Value" => $cpu_usage,
            "Unit" => "Percent",
            "Timestamp" => time(),
            "Dimensions" => $dimensions
        )
    )
));

I want to populate InstanceId and InstanceName with values corresponding to the server running the script.

Is there a way to do this through CloudWatch API?