lua script and lambda function to update Route53 record

ddns.lua

-- 設定項目
wan_if = "pp 1"
hosted_zone_id = "Z1234567890ABC"
name = "ddns.example.com"

-- SORACOM Funk 呼び出し
function funk(payload)
    req_table = {
        url = "http://funk.soracom.io/",
        method = "POST",
        post_text = payload,
        content_type= 'application/json'
    }
    rsp_t = rt.httprequest(req_table)
    debug(tostring(rsp_t.code)..":"..rsp_t.body)
end

function debug(message)
--    print(message)
    rt.syslog("info", message)
end

function get_if_addr(interface)
    local rtn, str, addr
    local cmd = "show status " .. interface
    local ptn = "PP IP Address Local: ([%d%.]+),"
    rtn, str = rt.command(cmd)
    addr = string.match(str,ptn,1)
    return addr
end

local addr, sleep_time
sleep_time=0
for i=1, 5 do
    addr = get_if_addr(wan_if)
    if (addr) then
        break
    end
    sleep_time = sleep_time + i
    debug(string.format('could not get interface address for "%s". retry after %d sec.', wan_if, sleep_time))
    rt.sleep(sleep_time)
end
if (addr) then
    funk(string.format('{"hosted_zone_id":"%s","name":"%s","ip_address":"%s"}',hosted_zone_id, name, addr))
else
    debug(string.format('could not get interface address for "%s". aborting...' , wan_if))
end

lambda_function.py

import boto3,json
client = boto3.client('route53')

def register(config):
    if(config.get('hosted_zone_id') and config.get('name') and config.get('ip_address')):
        response = client.change_resource_record_sets(
            HostedZoneId=config.get('hosted_zone_id'),
            ChangeBatch={
                'Changes':[
                    {
                        'Action': 'UPSERT',
                        'ResourceRecordSet': {
                            'Name': config.get('name'),
                            'Type': 'A',
                            'ResourceRecords':[ {'Value': config.get('ip_address')} ],
                            'TTL': 60
                        }
                    }
                ]
            }
        )
        print(response)
        return 'OK' if (response.get('ResponseMetadata').get('HTTPStatusCode') == 200) else 'NG'
    else:
        return "invalid parameters" + json.dump(config)

def lambda_handler(event, context):
    print(json.dumps(event))
    return register(event)