What exactly is Docker on Feiniu NAS? Once I understood the terms mirroring, port mapping, and directory mounting, I went from being confused to installing eight containers

when I first installed Feiniu, I saw people chatting enthusiastically in the group: things like "Docker deploying a photo album" or "setting up a downloader container," as casual as eating and drinking. When I opened the tutorial myself, the screen was full of 'pull image', 'map port', and 'mount directory'—I couldn't understand a single sentence, so I just closed the page and pretended to be dead. It was so stuck for over a week until one day I wanted to install a movie library and couldn't avoid it. I forced myself to break down those terms and figure them out, only to realize that the principle behind Docker was ridiculously simple—the hardest part was all in jargon. Now, my N100 has been running 8 containers for over a year. In this article, I'll explain the words that stuck me in plain language—so you can start working after reading.

first get to the two most complicated words: an image is an installation package, and a container is a running program

The two most discouraging terms in

Docker circle are actually easy to understand by analogy: a image is a pre-packaged that packages the program, runtime, and dependencies. Others prepare it online and you download it to use; container is the program that runs after installation, packaging, and . A single image can open several containers at once, just like an installation package can be installed on several computers.

go deeper, the biggest difference between containers and regular software is "one-time." Traditional software can't be fully uninstalled once installed, with registry files and leftover folders in complete mess; Containers are different. delete it, it's just a deleted one. It's clean and . When you want to use it again, you can reopen it from the mirror and it's ready in ten seconds. The first time I experienced this satisfaction was installing a toolbox: if you install a wrong one, delete it directly, recreate and change two parameters. It takes less than a minute, completely eliminating the frustration of traditional Windows software uninstalling.

there's another word called 'tag'—you can't avoid it when choosing a mirror. There are many versions of the same software image, with the most common tag being latest, which means the latest version. Sounds pretty good, right? The trap is here—the last test changes. Today it's v2.5, and next month, when the image author updates, if you recreate the container, it will become v3.0, and the configuration method might change completely. I later suffered a setback. Now, if you can lock a specific version number, you lock the version. For example, clearly select the 2.5.0 tag, and upgrade yourself when you need to upgrade, so don't let mirror authors decide for you.

The most critical column when

containers is the directory mounted; if you don't attach data, you lose

If I could only remember one thing in this article, I'd choose this one. containers are disposable lunch boxes, so never put your data in container. The downloader and album programs you run in the container, the files it downloads and the generated configurations are all stored inside the container by default—once the container is deleted, everything is gone. This isn't a bug; it's the design.

solution is to "mount": when installing the container, specify a correspondence and connect a folder on the NAS hard drive into the container as its data directory. This way, the program thinks it's writing files to the container, but in reality, the files end up on your NAS hard drive. You can delete or rebuild containers however you like; the data remains untouched in external folders.

specifically, fill in the "left path corresponds to the right path": the left side should be the real folder on your NAS, for example, if I set the download directory in the downloads folder on the first drive; On the right, enter the internal path recognized by the container program. Each software is different, so you need to check its documentation. For example, some downloaders require you to fill in /config for configuration and /downloads for downloads. The most painful experience I've experienced was installing a downloader in the early days. The configuration directory wasn't mounted, and after two months, after rebuilding the container, all download records, categories, and seed information were gone—two months of sorting for nothing. Later, I learned my lesson: whenever I installed a new container, the configuration directory was always displayed . By the way, this folder needs to be created first on the hard drive you've already mounted. How do you mount a hard drive? I previously wrote a complete on Feiniu to attach the second hard drive. If you haven't figured it out, check that first.

port mapping: who is on the left or right; if occupied, switch to another

programs in the container also listen for ports, for example, Jellyfin defaults to 8096. But containers are hidden in an isolated small environment. If you enter the NAS IP directly from the browser, you can't find it. You have to do a "mapping" during installation: forwarding a port on the NAS to the port inside the container.

is written as "left: right," the left side is the NAS's external port, and the right side is the container's internal port . You can modify the left side however you like, but the right side generally can't be touched—the program listens to that opening inside the container, and if you change it, it can't hear it. When accessing, use the NAS IP plus the port on the left. Here's a real example from my home: when installing the toolbox, it defaulted to 8080, but after creating it, it wouldn't open. Upon checking, 8080 was occupied by another container, so I changed the left side to 18080, but the right side didn't move, and it worked immediately. So remember this: If it won't open, suspect port conflicts. Try switching to the account on the left—the cost is zero.

there's also something called 'network mode,' which is common in graphical interfaces: bridge and host. Beginners should remember: "Bridge is the default, and the port mapping set is designed for it; The host is the container that directly uses the NAS's own network, so no mapping is needed, but ports tend to conflict." I used Bridge the whole time, never had any online troubles, so you should use this one first.

Where to find

mirrors and how to choose: Don't copy tutorials just because they see them

software installation, ranked by difficulty level:

my approach is top-down: for the first two months, I relied entirely on the App Center, then when the app center I wanted wasn't available, I switched to the Docker admin interface to create it myself—searched for the software name in the registry, glanced at the list that appeared: prioritized those with official logos, then checked download numbers and recent update times, and beware of old images that hadn't been updated for months. If you can't find it, try a different name and search. Many apps on Docker Hub use a combination of the author's name and the software name, so it's normal to find no results directly by the software name.

online tutorials often throw you a docker run command to copy, but when you break it down, it's basically the same thing mentioned earlier: -p is followed by port mapping, -v is followed by directory mounting. Once you recognize these two letters, 90% of tutorials will understand what they're doing, and when copying, you'll know which paths to switch to your own. For large projects like the film library, I previously wrote the entire process of installing Jellyfin using Docker in this —just follow the instructions; A more advanced approach is to have AI automatically find and download videos. Check out in this article.

the three cars I overturned, you just detoured

first car: once the container is too large, the memory can't hold up. 8 container sounds like not much, but every program consumes memory. My small PC is 4GB, and when it runs all at once, it takes up 80% of the time, making web pages slow to load. Later, I cleared the two large memory-consuming devices in front of the surveillance cameras, then stopped the useless containers (they didn't delete them after stopping, started them as needed), and only then did they return to a comfortable water level. Whether to upgrade memory and to what size, I tested it in my on NAS memory, and concluded that 4GB is enough for most people, so don't spend money first.

second car: I thought the container was running and I just ignored it. container thing stops and won't call you. One day, I found my album hadn't been backed up for several days. When I checked the management interface, I saw the container had already crashed. The reason for restarting was a power outage that didn't automatically reboot up. My current habit is to check the container list every few days to see if anything has turned red; For important containers, I will study the "auto-restart" switch; after power outages, I get back up on my own.

Third car: Charging without even calculating the battery. this is a hidden cost. If you have more containers, hard drives can't sleep and your machine runs year-round, electricity bills will go up. In my tests, it only adds a few yuan per month, so I don't mind, but if you load a bunch of "interesting-looking" containers and they gather dust, that's basically working for the meter. I calculated the specific expenses in the of the NAS electricity bill article. If you want to know more, check it out. By the way, this Docker approach isn't exclusive to Feiniu; Synology can also play it. I compared the differences between the two in on choosing between Synology and Feiniu. Both aspects of the Docker ecosystem are sufficient, so there's no need to worry about choosing a model.

Conclusion: In what order should beginners get started

My advice is just three steps: don't skip grades:

• first month: Only use the App Center to master the basic NAS drive—storage, sharing, backup, these are the foundation
• Second month: Create the first container from the Docker management interface, choose a simple toolbox software to practice, focusing on practicing the "mount directory" action
• afterwards: install whatever you need, The number of containers is kept within what the machine can handle, and each container displays the data

core is basically one thing: images can be freely removed, containers can be deleted freely, and data will always hang on the NAS hard drive . Once you understand this sentence, Docker is like a software warehouse you can install and disassemble on your own. If it goes wrong, you just delete and start over, with no sunk cost. This is also my biggest impression from playing for over half a year—half the fun of NAS lies in the hardware, and the other half is really fiddling with these containers in Docker.