Podman Error Arch WSL2: newuidmap: Could not set caps

When I’m not using my Linux workstation I run Arch using WSL2 on my Windows workstation. WSL2 has come a long way but this post isn’t about that.

I went to write a blog post and I needed a container engine to build the container this website runs in. My container engine of choice is Podman so I installed Podman in Arch like so.

sudo pacman -S podman

When I ran Podman I was greeted with this lovely newuidmap: Could not set caps error.

> podman run hello-world
WARN[0000] "/" is not a shared mount, this could cause issues or missing mounts with rootless containers
ERRO[0000] running `/usr/sbin/newuidmap 410 0 1000 1 1 100000 65536`: newuidmap: Could not set caps
Error: cannot set up namespace using "/usr/sbin/newuidmap": should have setuid or have filecaps setuid: exit status 1

I asked AI and searched the Internet and I found moby/moby#41812 which suggested to set CAP_SETUID and CAP_SETGID on /usr/bin/newuidmap and /usr/bin/newgidmap respectively.

sudo setcap cap_setuid+ep /usr/bin/newuidmap
sudo setcap cap_setgid+ep /usr/bin/newgidmap

Then I found containers/podman#12147 that suggested to reinstall the shadow package and restart the WSL2 virtual machine.

I reinstalled the shadow package.

sudo pacman -S shadow

Then restarted the WSL2 virtual machine.

wsl --terminate arch

Now Podman works!

> podman run hello-world
!... Hello Podman World ...!

         .--"--.
       / -     - \
      / (O)   (O) \
   ~~~| -=(,Y,)=- |
    .---. /`  \   |~~
 ~/  o  o \~~~~.----. ~~
  | =(X)= |~  / (O (O) \
   ~~~~~~~  ~| =(Y_)=-  |
  ~~~~    ~~~|   U      |~~

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