Continuously patch and deliver a Debian package

Question

We have an issue with a Debian package that would have to be addressed upstream. (So it's not Debian specific.) I've managed to patch the C source, build my custom package version, and fix the issue.

But how do I set up a continuous process to have my patch done automatically when there's a new version of the package, e.g., a security update? (I can't wait for an official "solution" as my users already throw eggs at me. ;D )

Is there a tool one can use? Or do I have to build such a thing myself?

We already have a custom APT repository, but it has only been used for internal software up to now.

I identify these steps I would have to make:

1. Recognize when there is a new version of the package in the official Debian repository. (Cronjob?)
2. Download the source package.
3. Apply my patch.
4. Alter the CONTROL file of the deb package to make my patched version "newer" than the original package (necessary? or just make my custom APT repository have a higher priority than the original Debian repository, so in case of equal version my custom package "wins"??)
5. Build the package.
6. scp it to the custom repository web server.
7. Send a notification email that I have to regenerate the indexes and sign them (GPG).

Concerning step (4): How do I increase any arbitrary upstream version string by a "micro" revision so that my version is newer than the original one? Just append ".1"?

Do you have such a process set up already, so I wouldn't have to reinvent the wheel?

Answer 1

As a starter/trigger:

#!/bin/sh

package=apt

apt-get update -yyq >/dev/null 2>&1

if ! apt-cache policy "$package" |
    awk '
        $1=="Installed:"{i=$2}
        $1=="Candidate:"{n=$2;last}
        END{if (i!=n) exit 0; else exit 1}'
then
    exit 0 # no new version, bail out early
fi



# here the rest of the script

# patch
# scp
# ...

This can be the beginning of a script to run as a cronjob.