Configure postgresql after installation with snap

I just installed Ubuntu Server 22.04.1 on a Raspberry Pi 4 in order to use it as a postgreslql server. Unfortunately, for compatibility reasons, I can't use a current postgresql version, but needed to install a 10.x version. The only way to get such an old version installed was by using the postgresql10 snap package.

So far it works. I can start it and create databases and tables with psql.

But now I need to do 2 more things:

1. Run postgresql when system is booted
2. Make it accessable over the (local) network

I searched a lot about how to do that, but I can't figure out how to do it in my case. All examples I can find are targeted to apt installations.

What I tried so far:

1. How I installed:

sudo snap install core
sudo snap install postgresql10
adduser postgres
sudo su postgres
postgresql10.initialize newlocale en_US UTF-8
postgresql10.initialize initdb en_US UTF-8
postgresql10.pgctl -D /home/postgres/snap/postgresql10/common/data start

After that, postgresql is running and ps lists a couple of postgresql processes. snap info lists the following commands, which are working:

postgres@Pi4DBServer:/etc$ snap info postgresql10
name:      postgresql10
summary:   PostgreSQL is a powerful, open source object-relational database system.
publisher: Command Prompt, Inc. (cmd✓)
store-url: https://snapcraft.io/postgresql10
license:   unset
description: |
  PostgreSQL is a powerful, open source object-relational database system. It has more than 15 years
  of active development and a proven architecture that has earned it a strong reputation for
  reliability, data integrity, and correctness.
commands:
  - postgresql10.clusterdb
  - postgresql10.createdb
  - postgresql10.createuser
  - postgresql10.dropdb
  - postgresql10.dropuser
  - postgresql10.ecpg
  - postgresql10.initdb
  - postgresql10.initialize
  - postgresql10.oid2name
  - postgresql10.pgarchivecleanup
  - postgresql10.pgbasebackup
  - postgresql10.pgbench
  - postgresql10.pgconfig
  - postgresql10.pgcontroldata
  - postgresql10.pgctl
  - postgresql10.pgdump
  - postgresql10.pgdumpall
  - postgresql10.pgisready
  - postgresql10.pgreceivewal
  - postgresql10.pgrecvlogical
  - postgresql10.pgresetwal
  - postgresql10.pgrestore
  - postgresql10.pgrewind
  - postgresql10.pgtestfsync
  - postgresql10.pgtesttiming
  - postgresql10.pgupgrade
  - postgresql10.pgwaldump
  - postgresql10.postgres
  - postgresql10.postmaster
  - postgresql10.psql
  - postgresql10.reindexdb
  - postgresql10.vacuumdb
  - postgresql10.vacuumlo
snap-id:      W7TagWOq55vJphD3Ek4ZUtQytGRMeQqK
tracking:     latest/stable
refresh-date: today at 13:53 CEST
channels:
  latest/stable:    10.4 2018-05-11 (46) 38MB -
  latest/candidate: ↑
  latest/beta:      ↑
  latest/edge:      ↑
installed:          10.4            (46) 38MB -

But after rebooting the system I have to manually start it again. And if I try to connect to the database from another machine with pgAdmin I get an "connection to server failed" error.

2. What I tried to make it run after system boot

Put it into /etc/rc.local like this:

#!/bin/bash

su postgres -c "postgresql10.pgctl -D /home/postgres/snap/postgresql10/common/data start"

exit 0

And called chmod a+x on it. -> Nothing happend

Then tried using systemctl:

When just trying to call sudo systemctl start/enable postgresql.service it gives an error that Unit postgresql.service has not been found.

So I created a file "postgresql10.service" in "/etc/systemd/system" with the following content:

[Unit]
Description="Postgresql 10 Startup"

[Service]
ExecStart=su postgres -c "postgresql10.pgctl -D /home/postgres/snap/postgresql10/common/data start"
Type=simple

[Install]
WantedBy=multi-user.target

Then called sudo systemctl enable postgresql10.service. Finishes without console output (Which I consider to be successful), but after reboot no postgreslql processes are running.

Also called sudo systemd-analyze verify postgresql10.service and sudo systemctl daemon-reload after enabling. Both finish without output, but seem to have no effect.

When I call sudo systemctl start postgresql10.service it starts some postgresql processes, but trying to use postgresql10.psql says "could not connect to server: No such file or directory ..."

3. Making it accessable over the network

I followed the step described here: https://tecadmin.net/postgresql-allow-remote-connections/

Added this line to postgresql.conf:

listen_addresses = '*'

And those 2 to pg_hba.conf:

host   all      all   0.0.0.0/0   md5
host   all      all   :/0         md5

But when stopped and started again, postgresql refuses to start with the following message:

pi@Pi4DBServer:~$ sudo su postgres -c "postgresql10.pgctl -D /home/postgres/snap/postgresql10/common/data start"
waiting for server to start....2022-10-27 16:06:05.080 CEST [1220] LOG:  listening on IPv4 address "0.0.0.0", port 5432
2022-10-27 16:06:05.080 CEST [1220] LOG:  listening on IPv6 address "::", port 5432
2022-10-27 16:06:05.089 CEST [1220] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5432"
2022-10-27 16:06:05.156 CEST [1220] LOG:  specifying both host name and CIDR mask is invalid: ":/0"
2022-10-27 16:06:05.156 CEST [1220] CONTEXT:  line 95 of configuration file "/home/postgres/snap/postgresql10/common/data/pg_hba.conf"
2022-10-27 16:06:05.156 CEST [1220] FATAL:  could not load pg_hba.conf
2022-10-27 16:06:05.162 CEST [1220] LOG:  database system is shut down
 stopped waiting
pg_ctl: could not start server
Examine the log output.

Now I removed the second line (The one with ":/0") from "pg_hba.conf" and it was able to start, but when I try connecting with pgAdmin I get an error saying "FATAL: No pg_hba.conf entry for host"

So now I'm stuck, I have no clue what to try next on both issues... Or if there is another possibility to get an 10.x Server running on Raspberry Pi (Which is actually all I wanted to do)

Please help