rancher
Podman support
Podman is a rootless and lighter alternative to Docker which is compatible with the OCI standard. The command syntax is the same as Docker. The ability to build elemental-toolkit with Podman would be greatly appreciated.
Currently make build depends on Docker which results in:
# make build
(...)
INFO 📦 system/cos-features-0.5-17 Using image: quay.io/costoolkit/build-teal-cache:2d5da2ad8e7abf9ab55b5a8336e1126ba2cf32973ccfc598dbfebf84de66dbd0
INFO 📦 system/cos-features-0.5-17 🐋 Generating 'builder' image from quay.io/costoolkit/build-teal-cache:2d5da2ad8e7abf9ab55b5a8336e1126ba2cf32973ccfc598dbfebf84de66dbd0 as quay.io/costoolkit/build-teal-cache:builder-4392e325315c39c9887e7b38f5289171 with prelude steps
WARNING Failed to download 'quay.io/costoolkit/build-teal-cache:builder-4392e325315c39c9887e7b38f5289171'. Will keep going and build the image unless you use --fatal
WARNING Failed pulling image: : exec: "docker": executable file not found in $PATH
Thanks for the idea @kkaempf This turned out to be more complex than I anticipated, nonetheless here's the solutions that I came up with 🙂
v0.10.7
Using alias in bash doesn't work with Makefile / make command as it spawns a new non-interactive subshell which uses /bin/sh (on my system this resolves to /usr/bin/bash):
$ echo "alias docker=podman" >> ~/.bashrc && source ~/.bashrc
$ docker version
Client: Podman Engine
Version: 4.5.1
(...)
$ make build
(...)
WARNING Failed to download 'quay.io/costoolkit/build-teal-cache:builder-4392e325315c39c9887e7b38f5289171'. Will keep going and build the image unless you use --fatal
WARNING Failed pulling image: : exec: "docker": executable file not found in $PATH
This makes the alias unavailable as per the documentation:
When Bash is invoked as an interactive login shell, or as a non-interactive shell with the --login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The --noprofile option may be used when the shell is started to inhibit this behavior.
However, it's possible to workaround this with:
$ make SHELL="/bin/bash -i" build
But this might lead to unexpected behavior depending on the user's environment variables and aliases
Another alternative is setting non-interactive variables in /etc/bashrc or /etc/environment but I'm not a fan of that either which lead me further down the rabbit hole:
Aliases are not expanded when the shell is not interactive, unless the expand_aliases shell option is set using shopt […].
The rules concerning the definition and use of aliases are somewhat confusing. Bash always reads at least one complete line of input before executing any of the commands on that line. Aliases are expanded when a command is read, not when it is executed. Therefore, an alias definition appearing on the same line as another command does not take effect until the next line of input is read. […] To be safe, always put alias definitions on a separate line, and do not use alias in compound commands.
For almost every purpose, aliases are superseded by shell functions.
Unfortunately aliases are tricky with subshells and the best practice is to use functions:
$ docker () { podman $@; }
$ export -f docker
$ make SHELL="/bin/bash -O expand_aliases" build
Ultimately I wanted less commands and ended up doing:
$ ln -s $(which podman) /usr/bin/docker
main / upcoming release
Fortunately, DOCKER argument is already properly implemented in Makefile (which is the best practice). I was able to do it this way:
sudo -i
pacman -S crun podman git go
git clone --depth 1 --single-branch --branch main https://github.com/rancher/elemental-toolkit.git && cd elemental-toolkit
echo 'unqualified-search-registries = ["docker.io"]' >> /etc/containers/registries.conf
DOCKER=podman make build