Decrease maximum limit for number of possible open files

When installing python packages via apt, a pycompile process would get
stuck in a seemingly infinite loop.

Debian (Ubuntu), seems to run a post install script after every (?) python
package installed via apt. That script calls pycompile [0], which in
turn makes a call to Popen() with close_fds=True [1]. In (C)Python
2.7, at least, subprocess (Popen()) would then try to close all possibly
open files [2].

I'm guessing (and strace'ing the stuck process seems to agree) that it
gets stuck trying to close "file descriptors" that are not actually
linked to any file. I guess for a low OPEN_MAX this would be ok. But in
my machine I have these limits:
 $ docker run debian:buster getconf OPEN_MAX
 1073741816

Although locally (not in a docker container) I have this:
 $ getconf OPEN_MAX
 1024
which I guess comes from a default config for systemd? (Archlinux)
/etc/systemd/system.conf: #DefaultLimitNOFILE=1024:524288

Not sure if this has to do with a later version of docker, or a
combination of new docker version and new kernel? More investigation is
required here to know how OPEN_MAX gets its value in a docker container
(and during build).

For now, this is a way of fixing the problem for _running_ containers.
During build however, I don't think this will work. For that you might
want to change your systemd unit for docker to something like:

 LimitNOFILE=1048576

Instead of "infinity", which is what moby (docker) now ships with [3].

There's a chance this is what was causing [4] as well? Unsure.

[0]: https://salsa.debian.org/cpython-team/python-defaults/-/blob/2.7.18-2/pycompile
[1]: https://salsa.debian.org/cpython-team/python-defaults/-/blob/2.7.18-2/pycompile#L134-135
[2]: https://github.com/python/cpython/blob/v2.7.16/Lib/subprocess.py#L873-L874
[3]: moby/moby@80039b4
[4]: moby/buildkit#1785

[DHDO-789]

docker-compose-irods.yml

@@ -50,6 +50,10 @@ services:
       - net.ipv4.tcp_keepalive_intvl=75
       - net.ipv4.tcp_keepalive_probes=9
       - net.ipv4.tcp_keepalive_time=600
+    ulimits:
+      nofile:
+        soft: 1048576
+        hard: 1048576
     depends_on:
        - irods-db
     hostname: icat.dh.local
@@ -132,6 +136,10 @@ services:
       - net.ipv4.tcp_keepalive_intvl=75
       - net.ipv4.tcp_keepalive_probes=9
       - net.ipv4.tcp_keepalive_time=600
+    ulimits:
+      nofile:
+        soft: 1048576
+        hard: 1048576
     hostname: ires-hnas-um.dh.local
     env_file:
       - .env
@@ -214,6 +222,10 @@ services:
       - net.ipv4.tcp_keepalive_intvl=75
       - net.ipv4.tcp_keepalive_probes=9
       - net.ipv4.tcp_keepalive_time=600
+    ulimits:
+      nofile:
+        soft: 1048576
+        hard: 1048576
     hostname: ires-hnas-azm.dh.local
     env_file:
       - .env