feat: add postgres setup

devices/acer.md

@@ -11,3 +11,4 @@
 * [SSH Server](../doc/ssh-server.md)
 * [SSH Public Key Authentication](../doc/ssh-pub-key-auth.md)
 * [Cups](../doc/cups.md)
+* [Postges](../doc/postgres.md)

doc/postgres.md

@@ -0,0 +1,112 @@
+# Setup Postgres
+
+* get the latest version of installed packages and refresh the repo cache
+```
+sudo apt update
+```
+
+* install postgres directly from the official repository
+```
+sudo apt-get install postgresql  --no-install-recommends
+```
+
+* validate the existens of the postgres admin user
+```
+cat /etc/passwd|grep postgres
+cat /etc/group|grep postgres
+```
+
+* set key for user postgres
+```
+sudo -u postgres psql postgres
+postgres=# \password postgres
+```
+
+* create a new database user
+```
+sudo -u postgres createuser --interactive --password <user name>
+```
+
+* create a new database with createdb command, which is going to be owned by user <user name>
+```
+sudo -u postgres createdb <database name> -O <user name>
+```
+
+* edit the pg_hba.conf file
+```
+sudo cp /etc/postgresql/13/main/pg_hba.conf /etc/postgresql/13/main/pg_hba.conf-backup
+sudo vi /etc/postgresql/13/main/pg_hba.conf
+```
+
+* in order to be able to run a Spring Boot application with a local PostgreSQL installation, change the authentication method for the Unix domain socket and local connections to trust like this
+```
+# "local" is for Unix domain socket connections only
+local   all             all                                     trust
+# IPv4 local connections:
+host    all             all             127.0.0.1/32            trust
+```
+
+* restart PostgreSQL to enable the changes
+```
+sudo systemctl restart postgresql
+systemctl status postgresql
+```
+
+* use the psql tool to connect to the database
+```
+psql -U <user name> -d <database name> -W
+```
+
+* configure ports and update firewall using the [firewall setup](firewall.md)
+```
+sudo ufw allow 5432
+sudo ufw enable
+sudo ufw status numbered
+```
+
+# Allow Remote Connections
+
+* create config backup
+```
+sudo cp /etc/postgresql/13/main/postgresql.conf /etc/postgresql/13/main/postgresql.conf-backup
+```
+
+* open config file
+```
+sudo vi /etc/postgresql/13/main/postgresql.conf
+```
+
+* edit config file like this
+```
+#listen_addresses = 'localhost'
+listen_addresses = '*'
+```
+
+* open config file
+```
+sudo vi /etc/postgresql/13/main/pg_hba.conf
+```
+
+* edit config file like this
+```
+# TYPE  DATABASE	USER	ADDRESS   	METHOD
+host    all     	all     0.0.0.0/0       md5
+host    all             all     :/0             md5
+```
+
+* restart PostgreSQL to enable the changes
+```
+sudo systemctl restart postgresql
+systemctl status postgresql
+```
+
+# Disable Start Up At System Boot
+
+* If you install the PostgreSQL database from packages, it is automatically added to the start up scripts of the operating system. If you are only learning to work with the database, it is unnecessary to start the database each time you boot the system. Remove system startup link for the PostgreSQL database
+```
+sudo update-rc.d -f postgresql remove
+```
+
+# Links
+
+* [PostgreSQL Java](https://zetcode.com/java/postgresql/)