unshare: write failed /proc/self/uid_map: Operation not permitted

[eniompw]

./bootstrap.sh ./alpine.tar example.json

reading config: example.json
arch: x86_64
repos: 2
- https://dl-cdn.alpinelinux.org/alpine/v3.21/main
- https://dl-cdn.alpinelinux.org/alpine/v3.21/community
packages: 5
- alpine-keys
- bash
- clang
- musl-dev
- openrc
output: /home/ubuntu/alpine-linux-self-setup/./alpine.tar
work dir: /tmp/tmp.jBw6zDNUnh
resolving apk-tools-static
listing: https://dl-cdn.alpinelinux.org/alpine/latest-stable/main/x86_64/
found: apk-tools-static-3.0.6-r0.apk
downloading apk-tools-static
from: https://dl-cdn.alpinelinux.org/alpine/latest-stable/main/x86_64/apk-tools-static-3.0.6-r0.apk
to: /tmp/tmp.jBw6zDNUnh/apk-tools.apk
size: 2217857 bytes
extracting sbin/apk.static from the apk
tar: Ignoring unknown extended header keyword 'APK-TOOLS.checksum.SHA1'
tar: Ignoring unknown extended header keyword 'APK-TOOLS.checksum.SHA1'
tar: Ignoring unknown extended header keyword 'APK-TOOLS.checksum.SHA1'
apk.static: /tmp/tmp.jBw6zDNUnh/sbin/apk.static (5458600 bytes)
preparing sysroot skeleton at /tmp/tmp.jBw6zDNUnh/sysroot
generating helper script: /tmp/tmp.jBw6zDNUnh/install-and-pack.sh
entering user namespace (unshare --user --map-root-user) to:

1. apk.static add (install 5 package(s) into /tmp/tmp.jBw6zDNUnh/sysroot)
2. tar (pack /tmp/tmp.jBw6zDNUnh/sysroot -> /home/ubuntu/alpine-linux-self-setup/./alpine.tar)
   unshare: write failed /proc/self/uid_map: Operation not permitted

[marcosnils]

you need to run the script with sudo since unshare requires elevated privileges.