gateway.poc

Proof of concept of an asynchronous gateway with persistent state.

Building

Prerequisites

To compile the project the following is required:

• C++ compiler with C++20 support (tested with GCC and Clang)
• CMake >= 3.20.0

Also the set of third party libraries. This is the list of Ubuntu 22.04 packages:

• libboost-log-dev
• libboost-program-options-dev
• libhiredis-dev
• libpqxx-dev
• postgresql-server-dev-all

Other Linux distros may include the same libraries under different names.

Compiling

One simple command:

./build.h

will create a release build. To make a debug one:

./build.sh -m debug

To delete all build artifacts, including executable binaries:

./clean.sh

Linux tuning

If expected number of open connection exceeds open files limit, this limit needs to be updated. On Ubuntu 22.04 this can be done in the following steps:

• add 2 lines to the file /etc/security/limits.conf:

  * soft nofile 16384
  * hard nofile 524288
  

• add one line to the file /etc/pam.d/common-session:

  session requried pam_limits.so
  

• and the same line to the file /etc/pam.d/common-session-noninteractive:

  session requried pam_limits.so
  

Supported storages

At the moment 2 storages are supported: PostgreSQL and Redis.

PostgreSQL

The tested version is 14.5. Steps to install and set up:

• install PostgreSQL:

  sudo apt-get install postgresql

• create a user and set a password:

  sudo -u postgres createuser -eP <username>

• create a database:

  sudo -u postgres psql -c 'CREATE DATABASE <dbname>'

• create messages table:

  sudo -u postgres psql -d <dbname> -c 'CREATE TABLE messages (id BIGSERIAL PRIMARY KEY, ts TIMESTAMP NOT NULL DEFAULT NOW(), data BYTEA NOT NULL)'

• grant the user right to user the table:

  sudo -u postgres psql -d <dbname> -c 'GRANT SELECT, INSERT, DELETE ON TABLE messages TO "<username>"'
  sudo -u postgres psql -d <dbname> -c 'GRANT USAGE, SELECT ON SEQUENCE messages_id_seq TO "<username>"'

• add line to the file /etc/postgresql/14/main/postgresql.conf to accept connections on all network interfaces:

  listen_addresses = '*'
  

• add lines to the file /etc/postgresql/14/main/pg_hba.conf to accept connection from other hosts:

  host    all     all     0.0.0.0/0   scram-sha-256
  host    all     all     ::/0        scram-sha-256
  

• increase maximum number of simultaneous connections in /etc/postgresql/14/main/postgresql.conf:

  max_connections = 8192
  

Redis

The tested verion is 7.0. Steps to install and set up:

• add official Redis repository:

  curl -fsSL https://packages.redis.io/gpg | sudo gpg --dearmor -o /usr/share/keyrings/redis-archive-keyring.gpg
  echo "deb [signed-by=/usr/share/keyrings/redis-archive-keyring.gpg] https://packages.redis.io/deb $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/redis.list

• install Redis:

  sudo apt-get update
  sudo apt-get install redis

• add the following lines to the /etc/redis/redis.conf file:
  • to accept connections on all network interfaces:

    bind * -::*
    

  • to create a user with password:

    user <username> allcommands allkeys on ><passwrod>
    

  • to set up passwrod for the default user:

    requirepass 12345
    

  • to enable Append Only File for maximum durability:

    appendonly yes
    

  • to fsync on every write for maximum durability:

    appendfsync always