architecture.md

Simple Standalone Architecture

Components

The Simple Server setup managed by this tooling has the following components.

Component	Purpose	Technologies
Primary relational database	Primary application database	PostgreSQL
Secondary relational database	Follower application database	PostgreSQL
Primary non-relational datastore	Datastore for application caching and background jobs	Redis
Secondary non-relational datastore	Follower for primary non-relational datastore	Redis
Web servers	Dashboard web application and APIs	Ruby on Rails Passenger Metabase
Background processing servers	Perform enqueued tasks asynchronously	Sidekiq
Load balancer	Route incoming web requests across web servers	HAProxy
System health monitoring	Monitor the system health of all Simple servers	Prometheus Grafana
Storage	Large storage location for logs and database backups	rsync

Topography

These components are arranged in the following topography.

                                                         ┌────────────────┐
                                                         │    replica     │
                                                         │ non-relational │
                                                         │     store      │
                                                         └────────────────┘
                                                                 │
                                                                 │
                                    ┌─────────┐                  │                     ┌────────────┐
                  ┌──────────┐     ┌─────────┐│          ┌────────────────┐           ┌────────────┐│
    incoming      │   load   │     │   web   ││          │    primary     │           │ background ││
    requests  ─── │ balancer │ ─── │ servers ││ ─┬────── │ non-relational │ ──────┬── │ processors ││
                  │          │     │         │┘  │       │     store      │       │   │            │┘
       │          └──────────┘     └─────────┘   │       └────────────────┘       │   └────────────┘
       │                                         │                                │
       │                                │        │       ┌────────────────┐       │
┌────────────┐                          │        │       │    primary     │       │
│   system   │                          │        │       │   relational   │       │
│ monitoring │                          │        └────── │     store      │ ──────┘
│            │                          │                └────────────────┘
└────────────┘                          │                        │
                                     ┌──────┐                    │
                                     │ logs │                    │
                                     └──────┘            ┌────────────────┐
                                                         │    replica     │
                                                         │   relational   │
                                                         │     store      │
                                                         └────────────────┘