it's not always sunny with podman

I am moving from docker to podman and selinux because I thought that podman is more secure and hence, the future. I thought the transition will be somewhat seamless. I even prepaired containers but once I migrated I still ran into issues.

minor issue: it’s podman-compose instead of podman compose. The hyphen feels like a step back because we moved from docker-compose to docker compose. But thT’s not a real issue.

podman does not autostart containers after boot. You have to manually start them, or write a start script. Or create a systemd unit for each of them.

Spinning up fresh services works most of the time but using old services that worked great with docker are a pain. I am wasting minutes after minutes because I struggle with permissions and other weird issues.

podman can’t use lower number ports such that you have to map the ports outside of the machine and forward them properly.

Documentation and tutorials are “all” for docker. Github issues are “all” for docker. There isn’t a lot of information floating around.

I’m still not done and I really wonder why I should move forward and not go back to docker. Painful experience so far. linuxhandbook.com/docker-vs-podman/ and following pages helped me a lot to get rid of my frustration with podman.

hperrin,

Regarding the low port number thing, that’s just a consequence of not running as root. By default, regular users can’t listen on ports below 1000.

lemmyvore,

1024

hperrin,

You are correct. I’m as bad as hard drive manufacturers.

qaz,

Well hard drive manufacturers are actually correct. A gigabyte (GB) is in base 10 and thus 1000 megabytes, not 1024. Gibibytes (GiB) are base 2 (hence “bi”) and thus 1024 mebibytes.

lemmyingly,

I know it’s technically correct but it still hurts a little inside to admit it each time.

I know the reason is because giga is an SI prefix but all the way through my education, 1 GB was taught to be 1024 MB, so I always want to use this instead of what is correct.

To be fair, the tech industry has been naughty with things like this. I know of two. I wonder how many others there are?

I believe that:

  • The style of characters a user can choose is called a typeface. I think every piece of software calls it a font. I remember hearing it came from Apple/Steve Jobs.
  • I believe the use of setup is incorrect. Setup is a noun, so it refers to an existing configuration. It tends to be used when running an OS or program for the first time though, which I believe set up is the correct term. Set up is an adjective and refers to the act of creating the configuration.

I’ve wondered if these were done due to screen space constraints or aesthetics.

Molecular0079, (edited )

Your issues stem from going rootless. Podman Compose creates rootless containers and that may or may not be what you want. A lot more configuration needs to be done to get rootless containers working well for persistent services that use low ports, like enabling linger for specific users or enabling low ports for non-root users.

If you want the traditional Docker experience (which is rootful) and figure out the migration towards rootless later, I’d recommend the following:

  1. Install podman-docker. This provides a seamless Docker compatibility layer for podman, allowing you to even use regular docker commands that get translated behind the scenes into Podman.
  2. Install regular docker-compose. This will work via podman-docker and gives you the native docker compose experience.
  3. Enable podman.socket and podman-restart.service. First one socket-activates the central Podman daemon, second one restarts any podman containers with a restart-policy of always on boot.
  4. Run your docker-compose commands using sudo, so sudo docker-compose up -d etc. You can run this with sudo podman compose as well if you’re allergic to hyphenation. Podman allows both rootful and rootless containers and the way you choose is by running the commands with sudo or not.

This gets you to a very Docker-like experience and is what I am currently using to host my services. I do plan on getting familiar with rootless and systemd services and Kubernetes files, but I honestly haven’t had the time to figure all that out yet.

GravitySpoiled,

thank you!

qaz,

Enable podman.socket and podman-restart.service. First one socket-activates the central Podman daemon, second one restarts any podman containers with a restart-policy of always on boot.

Thanks, the last time I checked I was told that creating individual systemd services was the only viable solution and I ended up ditching podman because I didn’t think it was worth the hassle. I might try it again with your tips.

Molecular0079,

Definitely not necessary. If that was the case, it wouldn’t live up to it’s claims of being a transparent Docker replacement at all. I think you do need to use systemd if you want to go full rootless, but I haven’t tried it enough to make a solid call on that.

But yeah, with the above steps, I’ve moved seamlessly over to Podman for my self hosting stack and I’ve never looked back. It’s also great because I can take literally any Docker Compose I find on the Internet and it will most likely just work.

johanbcn,

podman does not autostart containers after boot. You have to manually start them, or write a start script. Or create a systemd unit for each of them.

I have not yet tried podman, but I know that podman-compose used to have an option to generate systemd units for your pods: docs.podman.io/…/podman-generate-systemd.1.html

Still, that option has been deprecated in favour of Podman Quadlet docs.podman.io/en/…/podman-systemd.unit.5.html

MigratingtoLemmy,

Almost all of your problems are because you aren’t running as root. These aren’t bugs. They seem like a pain because you’re transitioning from Docker which runs as root (which is ABSOLUTELY INCORRIGIBLE in my opinion).

SELinux is a different story though. Now that’s a hard to tame beast. Things go wrong easily if you don’t know what you’re doing.

I suggest researching more before jumping off into a new technology, you seem like you weren’t anticipating some of these problems which adds to the frustration.

sudneo,

You can run docker rootless too. On local machines running docker with root is a risk that for many is acceptable. On servers and publicly exposed hosts, rootless.

Vent,

Podman is purposefully built to rely on systemd for running containers at startup. It ties in with the daemonless and rootless conventions. It’s also nice because systemd is already highly integrated with the rest of the OS, so doing things like making a container start up after a drive is mounted is trivial.

Podman has a command to generate systemd files for your containers, which you can then use immediately or make some minor tweaks to your liking.

I use podman for my homelab and enjoy it. I like the extra security and that it relies on standard linux systems like systemd and user permissions. It forces me to learn more about linux and things that apply to more than just podman. You can avoid a lot of trouble by running the containers as root and using network=host, but that takes away security and the fun of learning.

xor,

Ooh I didn’t know about the systemd integration, that actually sounds like a really smart approach.

To be honest, until right now I’d pretty much written off podman as docker 2

Molecular0079,

You can avoid a lot of trouble by running the containers as root and using network=host

Root yes, but you can avoid network=host most of the time pretty easily. I am still struggling with going rootless myself tbh.

Helix,

it’s podman-compose instead of podman compose

Don’t use it, it’s not a full replacement. The script is barely maintained and not really “official”.

I think before switching from Docker to Podman you should first get proficient in Docker, because Podman is not for beginners (yet).

possiblylinux127,

Podman compose isn’t really usable for me

Throwaway1234, (edited )

podman does not autostart containers after boot. You have to manually start them, or write a start script. Or create a systemd unit for each of them.

FWIW, I’m on Bluefin-dx (one of uBlue^[1]^'s images) and I’ve noticed that my containers autostart at boot since I’ve rebased from Silverblue to Bluefin-dx. Mind you; I’m not necessarily advocating for you to make the switch to Bluefin-dx, but it’s at least worth finding out how they’ve been able to achieve that and perhaps implement their ways for your own benefit.

  1. Which are mostly Fedora Atomic images with some QoL and thus SELinux, Podman (etc.) are just baked in as you would expect.
DangerousInternet,
@DangerousInternet@lemmy.world avatar

deleted_by_author

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    Throwaway1234,

    run on boot is easy if you run containers via systemd, if service is enabled it auto-starts on boot

    TIL, thank you for that insight!

    if disabled, than you start it manually.

    That’s the peculiar part; some of the containers I’ve had since I was on Silverblue, but back then they never autostarted on boot. Just (relatively) recently, since the rebase to Bluefin-dx, have I experienced that all of the containers -so even the ones that existed prior- autostart on boot.

    DangerousInternet,
    @DangerousInternet@lemmy.world avatar

    deleted_by_author

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    Throwaway1234,

    Could be, but I honestly wouldn’t know 😅. But thanks for sharing these; perhaps these may provide pointers that would help/enable me to better comprehend it.

    j0rge,

    We use quadlets to manage those containers: docs.podman.io/en/…/podman-systemd.unit.5.html

    As others in the thread have pointed out just having systemd manage them is the way to go, it’s a nice combo!

    Throwaway1234,

    Thank you Jorge for chiming in!

    MajinBlayze, (edited )

    Yeah, podman’s networking approach sent me back to docker as well. I have a bunch of services that don’t even expose their ports to the local network, they just connect to each other, and only the reverse proxy is exposed. Switching to podman would require me to reconfigure all my port mappings to make sure there aren’t any conflicts, and then update all the references. It’s not a ton of work, but enough to keep me on docker for the time being.

    edit: It looks like podman’s networking stack has changed since I used it, so this is almost certainly wrong now

    deluxeparrot,

    Is there a difference between networking approaches?

    With rootful podman containers the only difference I noticed is that bridge networks aren’t isolated by default.

    Why would you need to reconfigure the port mappings?

    MajinBlayze,

    Tbh it’s possible I messed something up, iirc the bridge network I was using wouldn’t work, and it seemed like it would only work in host mode, hence the belief that I needed to remap things. This was over a year ago, and tbh I didn’t try very hard to make it work.

    DangerousInternet,
    @DangerousInternet@lemmy.world avatar

    deleted_by_author

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    facelessunit,

    I think you meant to post github.com/k9withabone/podlet

    RandoCalrandian,
    @RandoCalrandian@kbin.social avatar

    I know this isn't the answer you want, but consider switching away from compose entirely
    A local kubernetes instance handles all the routing for me, and since i was using that anyway podman was legitimately a drop in replacement for docker.

    Podman is just the tool that creates the container for me, running it gets handled by something else entirely.

    Also, i can run podman compose up just fine, no hyphen needed. https://docs.podman.io/en/latest/markdown/podman-compose.1.html

    GravitySpoiled,

    thx! maybe I’ll switch to it in a year or so. For now, I am good in learning new containerization technology

    gibson,

    You can make actual docker compose use podman by running a user podman docker socket and setting that as an environment variable (export DOCKER_HOST=unix:///run/user/$UID/podman/podman.sock)

    brandonrozek.com/…/rootless-docker-compose-podman…

    possiblylinux127,

    Podman isn’t a replacement for docker. Its very similar syntax wise but its not a replacement.

    The only thing I use podman for is Jellyfin and distrobox

    Molecular0079,

    Have you tried it with podman-docker? I’ve basically switched my entire self-hosting stack onto podman without much issue using that compatibility layer.

    chameleon,
    @chameleon@kbin.social avatar

    For the port thing, you can set the net.ipv4.ip_unprivileged_port_start sysctl to a lower value like 80 (may need to go lower if you also do email). It also applies to IPv6.

    The default of 1024 is for security, but the actual security granted by it is not really that relevant nowadays. It stems from a time where ports < 1024 were used by machines to trust other machines using stuff like rsh & telnet, and before we considered man-in-the-middle attacks to be practical and relevant. Around the start of this millennium, we learned better. Nowadays we use SSH and everything is encrypted & authenticated.

    The only particularly relevant risk is that if you lower it enough to also include SSH's default port 22, some rogue process at startup might make a fake SSH server. That would come along with the scary version of the "host key changed" banner so the risk is not that high. Not very relevant if you're following proper SSH security practices.

    shasta,

    The only reasons I ever use podman is that is efficient with resources, and at work we can’t use Docker due to licensing purposes.

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