Simple Dynamic DNS client

Warning: This works for me. It's really rough, does very little error checking and isn't customizable. I'm open to PRs, as long as it still works for me. Throw it into a crontab and run however often you want.

Requirements

Mikrotik router
DNS hosted with AWS Route53
My route53-util and routeros-utils in your path

How it works

Using routeros-utils, query the router for the external IP address
Check against cache to see if that is different from what we expected
If necessary, use route53-util to update the appropriate Route53 record with the new IP address and save that address to our cache

Configuration

The default configuration file is located at ~/.config/dyndns-settings. You can override this by setting the environment variable DYNDNS_SETTINGS_FILE.

Technically, the configuration file is simply a bunch of environment variables that are sourced by the script, which also means that you could set them some other way and it will work just fine.

Required variables

ROUTEROS_HOST - Hostname or IP address of Mikrotik router
ROUTEROS_USERNAME - Username with API access to router
ROUTEROS_PASSWORD - Password for user
R53_REGION - AWS region to use for Route53
R53_PROFILE - AWS Profile to use (for loading credentials)
R53_DNS_NAME - DNS record to update
R53_ZONE_ID - Route53 Hosted Zone ID

Optional Variables

DYNDNS_CACHE - Cache file to store IP Address - defaults to ~/.cache/dyndns
R53_TTL - TTL of the A record to be created/updated - defaults to 60

IAM Permissions

I run this with an IAM User that has only the following policy statements:

{
    "Sid": "Route53GetChange",
    "Effect": "Allow",
    "Action": [
        "route53:GetChange"
    ],
    "Resource": [
        "arn:aws:route53:::change/*"
    ]
},
{
    "Sid": "Route53Zone",
    "Effect": "Allow",
    "Action": [
        "route53:ListResourceRecordSets",
        "route53:ChangeResourceRecordSets"
    ],
    "Resource": [
        "arn:aws:route53:::hostedzone/<ZONE ID HERE>"
    ]
}

Running in Docker

After building, you will need to mount an AWS credentials file, the settings file, and probably the cache file, and set the respective environment variables. For example:

docker container run --rm -it \
    -v ~/aws-dns-creds.txt:/root/.aws/credentials \
    -v ~/dyndns-settings.txt:/dyndns-settings.txt \
    -e DYNDNS_SETTINGS_FILE=/dyndns-settings.txt \
    -v ~/dyndns-cache:/dyndns-cache \
    -e DYNDNS_CACHE=/dyndns-cache/ip.txt \
    container:tag

abatkin / dyndns-cache