auto-apt-proxy

[charlescurley]

auto-apt-proxy is a utility to detect apt proxies, such as apt-cacher-ng. Alas, it does not detect apt-cacher-ultra. I may look into that some time in October.

[charlescurley]

Here are your options:

Modify auto-apt-proxy

Add a subroutine to detect apt-cacher-ultra (ACU). This creates a new subroutine, detect_apt_cacher_ultra, which does what it says on the tin: checks for ACU and returns appropriately. it is a nearly identical copy of the existing subroutine detect_apt_cacher_ng. The rest of the patch adds the new subroutine and makes nearby lines prettier.

charles@peregrine:~$ diff /usr/bin/auto-apt-proxy*
160,170d159
< detect_apt_cacher_ultra() {
<   local ip="$1"
<   local proxy="$(proxy_url "$ip" 3142)"
<   log_debug "looking for apt-cacher-ultra at ${proxy}"
<   if hit -o "Acquire::http::Proxy::${ip}=DIRECT" "$proxy" | grep -q -i 'HTTP.*400'; then
<     set_proxy "$proxy"
<     return 0
<   fi
<   return 1
< }
< 
360,364c349,352
<       detect_apt_cacher_ultra "$ip" && return 0
<       detect_apt_cacher_ng "$ip"    && return 0
<       detect_approx "$ip"           && return 0
<       detect_apt_cacher "$ip"       && return 0
<       detect_squid_deb_proxy "$ip"  && return 0
---
>       detect_apt_cacher_ng "$ip"   && return 0
>       detect_approx "$ip"          && return 0
>       detect_apt_cacher "$ip"      && return 0
>       detect_squid_deb_proxy "$ip" && return 0
377,381c365,368
<       detect_apt_cacher_ultra "$ip" && return 0
<       detect_apt_cacher_ng "$ip"    && return 0
<       detect_approx "$ip"           && return 0
<       detect_apt_cacher "$ip"       && return 0
<       detect_squid_deb_proxy "$ip"  && return 0
---
>       detect_apt_cacher_ng "$ip"   && return 0
>       detect_approx "$ip"          && return 0
>       detect_apt_cacher "$ip"      && return 0
>       detect_squid_deb_proxy "$ip" && return 0
charles@peregrine:~$ 

Modify apt-cacher-ultra

The only difference between ACU and ACNG is the HTTP error code auto-apt-proxy looks for, 400 and 406, respectively. With this change, auto-apt-proxy would mis-identify ACU as ACNG, but it would detect it. I have not tried this, so I have no idea how much is involved.

Something Completely Different

Your ideas here.

Discussion

I have not tried the second suggestion. It has the advantage of not requiring anyone to get the auto-apt-proxy maintainers to accept this patch. On the other tentacle, it would be nice to have ACU properly identified.

[grifferz]

I do not use auto-apt-proxy but I've had a look at it and from what I can see it gathers possible proxy IPs from:

• localhost
• directly configured network interfaces
• DNS entry for apt-proxy
• (IP address of) hostname of the real host, if this is a container

For each of those IPs it then runs detection functions against them for every kind of apt proxy that it knows about. So the issue here is that as you say it tries to detect ACNG, gets an HTTP code that doesn't correspond and moves on to the next type of check.

I think this is a clear deficiency in auto-apt-proxy to be honest. If there is a DNS entry for apt-proxy then I think it should just be used, without trying to detect what kind of proxy it is. They are all just used as HTTP proxies; I think it is the cacher's job to function like an HTTP proxy not to mimic other kinds of cacher. The detection only seems warranted when blindly trying ports on local IP addresses.

That said, it seems like a simple change for ACU and if the maintainers agree then that's going to reach a release long before a change in auto-apt-proxy.

Finally, it looks like auto-apt-proxy also supports getting a proxy URL from DNS SRVC entry or from Avahi, and does not run detection on these. So if you do have a single domain that all these machines are in, perhaps you can add a SRV record and then auto-apt-proxy will use it without trying to verify that it's ACNG?

[charlescurley]

The patch above works with auto-apt-proxy version 16.8, as on trixie. The current version of auto-apt-proxy is 1.8. That is also the version on forky. Invoke the patch
auto-apt-proxy.acu.patch like so:

patch -b /usr/bin/auto-apt-proxy auto-apt-proxy.acu.patch

[charlescurley]

Bug filed.