setup: replace OS-provided conmon tool (fix podman issue)

"conmon" is a binary started withing podman containers.
The version provided with bullseye has a serious issue sometimes
causing the output of "podman [run|exec]" to be truncated.
containers/podman#9096

We replace this binary with a more up-to-date version statically
compiled using the nix method.
https://github.com/containers/conmon#nix
(note: nix compilation is very long.)

server/MANIFEST.in

@@ -2,4 +2,5 @@ include walt/server/processes/main/images/walt-*
 include walt/server/processes/main/network/walt-*.kpxe
 include walt/server/processes/main/vpn-proxy-setup.sh
 include walt/server/setup/*.service
+include walt/server/setup/conmon.gz
 include walt/server/processes/blocking/snmp/mibs/*.mib

server/walt/server/setup/ossetup.py

@@ -1,5 +1,6 @@
-import shlex, datetime, requests, subprocess, json, sys
+import shlex, datetime, requests, subprocess, json, sys, gzip
 from pathlib import Path
+from pkg_resources import resource_filename
 from walt.common.version import __version__ as WALT_VERSION
 from walt.server.setup.pip import install_pip, pip
 from walt.server.setup.apt import fix_dpkg_options, package_is_installed, get_debconf_selection, \
@@ -203,3 +204,29 @@ def install_os_on_image():
     fix_docker_keyring()
     fix_dpkg_options()
     fix_packets(upgrade_packets = True)     # have up-to-date packets on image
+
+def has_diversion(path):
+    diversion = subprocess.run(f'dpkg-divert --list {path}'.split(),
+                   stdout=subprocess.PIPE).stdout.strip()
+    return len(diversion) > 0
+
+def divert(path, diverted_path):
+    subprocess.run(f'dpkg-divert --divert {diverted_path} --rename {path}'.split(),
+                   check=True, stdout=subprocess.PIPE)
+
+# 'conmon' binary distributed in bullseye has a serious issue
+# causing possibly truncated stdout in podman [run|exec]).
+# we replace it with a more up-to-date binary statically compiled
+# using the nix-based method.
+def fix_conmon():
+    if not has_diversion('/usr/bin/conmon'):
+        print('Fixing issue with conmon tool... ', end=''); sys.stdout.flush()
+        divert('/usr/bin/conmon', '/usr/bin/conmon.distrib')
+        conmon_gz_path = resource_filename(__name__, 'conmon.gz')
+        conmon_gz_content = Path(conmon_gz_path).read_bytes()
+        conmon_content = gzip.decompress(conmon_gz_content)
+        conmon_fixed_path = Path('/usr/bin/conmon.fixed')
+        conmon_fixed_path.write_bytes(conmon_content)
+        conmon_fixed_path.chmod(0o755)
+        print('done')
+        Path('/usr/bin/conmon').symlink_to('/usr/bin/conmon.fixed')

server/walt/server/setup/setup.py

@@ -4,7 +4,7 @@
 from walt.common import systemd
 from walt.common.setup import WaltGenericSetup
 from walt.common.tools import verify_root_login_shell
-from walt.server.setup.ossetup import get_os_codename, upgrade_os, install_os, fix_os, install_os_on_image
+from walt.server.setup.ossetup import get_os_codename, upgrade_os, install_os, fix_os, fix_conmon, install_os_on_image
 from walt.server.setup.conf import fix_other_conf_files, setup_default_server_conf, ask_server_conf
 
 WALT_SERVICES = [
@@ -29,18 +29,18 @@
 
 OS_ACTIONS = {
     'image-install': {
-        'bullseye': ('install_os_on_image', 'disable_os_services', 'setup_walt_services',
+        'bullseye': ('install_os_on_image', 'fix_conmon', 'disable_os_services', 'setup_walt_services',
                      'fix_other_conf_files', 'setup_default_server_conf', 'update_completion'),
     },
     'install': {
-        'bullseye': ('install_os', 'disable_os_services', 'setup_walt_services',
+        'bullseye': ('install_os', 'fix_conmon', 'disable_os_services', 'setup_walt_services',
                      'fix_other_conf_files', 'ask_server_conf', 'systemd_reload',
                      'start_walt_services', 'update_completion', 'msg_ready'),
     },
     'upgrade': {
-        'buster': ('stop_services', 'upgrade_os', 'disable_os_services', 'setup_walt_services',
+        'buster': ('stop_services', 'upgrade_os', 'fix_conmon', 'disable_os_services', 'setup_walt_services',
                    'fix_other_conf_files', 'update_completion', 'msg_reboot'),
-        'bullseye': ('stop_services', 'fix_os', 'disable_os_services', 'setup_walt_services',
+        'bullseye': ('stop_services', 'fix_os', 'fix_conmon', 'disable_os_services', 'setup_walt_services',
                      'fix_other_conf_files', 'may_ask_server_conf', 'systemd_reload', 'start_walt_services',
                      'update_completion', 'msg_ready'),
     }
@@ -135,6 +135,9 @@ def install_os(self):
     def fix_os(self):
         fix_os()
 
+    def fix_conmon(self):
+        fix_conmon()
+
     def install_os_on_image(self):
         install_os_on_image()