powa-collector for Debian
=========================

powa-collector is configured to run as the `powa` system user. The instructions
below create a `powa` PostgreSQL user and a `powa` database for the PoWA
repository on the collector node. On the remote nodes, a `powa` PostgreSQL user
is created, and the powa extension is installed in the `postgres` database.

Setup steps on the collector node
---------------------------------

Install packages:

  apt install postgresql-powa # postgresql-14-powa to be explicit about PG version
  apt install powa-collector
  apt install powa-web

Enable pg_stat_statements (omit for remote-only monitoring):

  pg_conftool set shared_preload_libraries pg_stat_statements
  systemctl restart postgresql

Create repository database and user:

sudo -u postgres psql <<EOF
  create user powa;
  grant pg_read_all_stats to powa;
  create database powa owner powa;
  \c powa
  create extension powa cascade;
  grant select, insert, update, delete on all tables in schema public to powa;
  grant usage on all sequences in schema public to powa;
EOF

Setup steps on remote nodes
---------------------------

Install packages:

  apt install postgresql-powa # postgresql-14-powa to be explicit about PG version

Enable pg_stat_statements:

  pg_conftool set shared_preload_libraries pg_stat_statements
  systemctl restart postgresql

Create monitoring extension in postgres database:

sudo -u postgres psql <<EOF
  create user powa password '<powapass>';
  grant pg_read_all_stats to powa;
  create extension powa cascade;
EOF

Refer to the PostgreSQL documentation for configuring the server to allow
remote connections (pg_hba.conf, listen_addresses).

Register node in repository database:

sudo -u postgres psql -d powa -c \
  "select powa_register_server(hostname := '<remotehost>', password := '<powapass>', dbname := 'postgres')"