containers

Container notes

You can change podman to docker and viceversa, it should just work

Deleting all containers or images

podman rm -a
podman rmi -a

Building images

podman build -t name:version .

Watching logs

podman logs --tail 50 --follow --timestamps name-of-the-container

Fast disposable container

In some cases I need to test some command in a distro, the fastest way of doing this is through a podman container, you can change fedora for the distro of your choice.

podman run -it --rm fedora bash

Creating systemd services with podman

Documentation

For running this as a user you need 'sudo loginctl enable-linger username'

1. Generating the files
2. Enable the service
3. Check if it is enabled

podman generate systemd --files --name --restart-policy=always <name_of_pod_or_container>
systemctl --user enable --now <name_of_pod.service>
mv <name_of_pod.service>  ~/.config/systemd/user/
# if root : mv <name_of_pod.service>  /etc/systemd/system/
systemctl --user is-enabled <name_of_pod.service>

Building image in podman with docker format

podman build -t name:version --format docker .

Using a system with selinux and podman

When mounting volumes use :z if multiple containers need access to the volume or :Z if only that contianer needs access.

Example:

podman run -it --rm -v ./thing/:/thing:z alpine sh

or in a docker-compose.yml:

- ./postgresdata:/var/lib/postgresql/data:z

Extrating binaries from container

This is useful for example for a raspberry, when you want to run software without containers but there is no oficial binaries for aarch64 released only precompiled container, you can extract the binary from a oficial container image.

Read the Containerfile first to know what are the dependencies

Extracting binaries for vaultwarden

1. Pull the image for the architecture you want, be careful with tags
2. Create but not start a container based on the image
3. Copy the needed binaries
4. Delete container and image

podman pull --platform linux/arm64 vaultwarden/server
podman create --name vw vaultwarden/server
podman cp vw:/vaultwarden .
podman cp vw:/web-vault .
podman rm vw
podman rmi vaultwarden/server:latest

Ping from rootless container

In case you want to be able to use ping inside rootless containers, you can run:

echo -e 'net.ipv4.ping_group_range=0 165535' | sudo tee /etc/sysctl.d/podman-ping.conf

Enable docker registrie on podman

In some distributions podman package it is not included the docker registrie so if you want to use it, you must specify it in the configuration.

mkdir -p $HOME/.config/containers/
echo -e "[registries.search]\nregistries = ['docker.io']" | tee $HOME/.config/containers/registries.conf

Enable podman socket

For a rootless user:

systemctl --user enable --now podman.socket
export DOCKER_HOST=///run/user/$UID/podman/podman.sock

Problems with SELINUX

I had a problem when using the linuxserver's swag image where the image could not make the needed chown. To solve it, I added this to the podman command.

--security-opt label=disable