A simple, fast script that searches through your Docker infrastructure and tells you exactly which service is using a given port (based on folder structure).
Built for homelab admins with dozens (or hundreds) of self-hosted services, FindPort makes it easy to resolve mystery ports and maintain Docker hygiene.
In my homelab, I run over 125 Docker containers using a standardized structure:
Each service has its own directory (e.g. /volume1/docker/immich/, /volume1/docker/uptime-kuma/, /volume1/docker/jellystat/) containing a docker-compose.yml file and all persistent data. This setup makes backups and versioning clean and simple.
However, when I forget to document a port assignment, I sometimes run into "mystery ports" during scans with PortNote—a great tool for visualizing port usage. That’s when I needed a way to answer the dreaded question:
“Wait… what’s running on port 3333?”
See the writeup and video tour on my website:
https://jacques.home-lab.site
FindPort scans a directory tree (like /volume1/docker) for docker-compose.yml files.
It searches for the given port number and, when found, returns the name of the parent directory—i.e. the service name.
Since I follow the convention of naming each directory after the service it runs, this script gives me the exact answer I need with zero guesswork.
/docker
├── immich/
│ └── docker-compose.yml
├── vikunja/
│ └── docker-compose.yml
├── jellystat/
│ └── docker-compose.ymlEach directory holds: A single service A docker-compose.yml All persistent volumes/data
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Clone or download this repo.
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Give the script the appropriate permissions
sudo chmod +x findport.sh -
Run the script and pass it an unknown port as your argument:
./findport.sh 3333
Standard GNU tools:
- grep
- awk
- find
NOTE: Tested on Linux (Debian/Ubuntu) and Synology DSM with Docker installed.
Shoutout to PortNote for being a fantastic port documentation tool and the inspiration for this script.