An outline of package sign process in Copr

To sign packages we decided to use obs-signd 1. Unfortunately it doesn’t manage user keys in any way, but it’s possible to minimize Copr operations with gpg key-pairs.

Expected setup

host-sign: secure machine where key-pairs is stored in /usr/share/copr-keygen/gnupg/ it runs:

  • [A] perl signd from obs-signd
  • [B] copr-keygen service

host-build: backend where builds occurs and result rpms are signed by invocation of /bin/sign [C] from obs-signd

[C] is configured by /etc/sign.conf to access [A] at host-0

When user foo builds first package, service [B] will be invoked to generate new keys (they will be contained in the keyring in GPGHOMEDIR). Also it creates dummy file into PHRASESDIR, that file indicates that user foo exists for [A]. Finally [A] can sign packages for user foo without receiving keys through network.

copr-backend do everything related to sign through new module backend.sign which either runs [C] or calls [B].

Configuration notes

At host-build

sign should be executed from the root user
/etc/sign.conf:
  • server: host of machine with signd

ensure that configs/sudoers/copr_signer is copied into /etc/sudoers.d/

At host-sign

/etc/sign.conf:
  • allow: list of backend hosts
  • phrases: /var/lib/copr-keygen/phrases – location of PHRASESDIR
NB:
obs-signd always run as root and doesn’t accept alternative GPGHOMEDIR. To overcome this obstacle we added /usr/bin/gpg_copr Bash script wrapper which calls gpg2 with correct user and homedir