themis

Discord App to allow EU4 players to take claims on regions and provinces.

Setup

Requirements

To develop:

• Go version 1.19 or higher installed locally
• sqlite3 installed locally (already ships by default on most OSes)

To deploy:

• Register for a free account on Fly
• An AWS account

Steps

To work with the core modules that simply interact with the database, or make sure that everything compiles correctly, you can run the following commands:

go test ./...
go build -o ./bin/ ./cmd/...

Operations

This application is deployed via Fly on a single virtual machine instance. It uses an embed SQLite database as its database engine, and uses Litestream to replicate the database to an S3 bucket.

Application Configuration

The deployment configurations can be found in the fly.toml file and you can find more information on the configuration options in the official Fly documentation.

The virtual image is based off of the Dockerfile which is a multi-stage build that builds the main application binary, downloads Litestream and packages everything on top of an Ubuntu 22.04 base.

Entrypoint

The application is started using a custom entrypoint shell script that is in charge of first restoring the database file through Litestream and then starting the main application as a child process of Litestream's replication process.

It's a very simple script but is necessary since the application doesn't have a persistent volume to rely on and must rehydrate its database file after every deployment.

Environment Variables

Env Var	Defined At
DISCORD_TOKEN	fly secret
DISCORD_APP_ID	fly.toml
DISCORD_GUILD_ID	fly.toml
AWS_ACCESS_KEY_ID	fly secret
AWS_SECRET_ACCESS_KEY	fly secret

Local Development

Application Entrypoint

• ./cmd/themis-server This is the main application entrypoint
• ./cmd/themis-repl coming soon

Core Functions

The core database functions can be developed and tested locally easily, just run go test ./... to test your changes locally.

You can also load a test database easily by using the init.sql script. You can use the cli sqlite3 client or connect using whatever SQL editor you prefer that can open sqlite3 connections.

sqlite3 local.db < migrations/init.sql
sqlite3 local.db
# interactive SQLite session

Discord Integration

This is a work in progress, but I am currently using a dedicated Discord server with this application already signed into it. You can contact me directly to be invited into that server. From there you only need to set the following environment variables before launching the ./cmd/themis-server entrypoint:

export DISCORD_APP_ID="1014881815921705030"
export DISCORD_GUILD_ID="[test server id goes here]"

Litestream replication

Litestream is not a necessary component to run the ./cmd/themis-server entrypoint and can be safely ignored when developing locally. Still, if you wish to try it out, you can find the Litestream commands used in production in the start.sh script. As per the Litestream docs, it should work fine with Minio but I have not tested it yet nor are there any scripts provided to run it (yet).

SQLite

Importing From CSV

This is a neat feature built-in to SQLite. Using the source file at data/eu4-provinces.csv you can import the data directly into a SQLite database using the following command:

$ sqlite3
# ...
sqlite> .mode csv
sqlite> .import data/eu4-provinces.csv provinces
sqlite> .schema provinces
CREATE TABLE provinces(
  "ID" TEXT,
  "Name" TEXT,
  "Development" TEXT,
  "BT" TEXT,
  "BP" TEXT,
  "BM" TEXT,
  "Trade good" TEXT,
  "Trade node" TEXT,
  "Modifiers" TEXT,
  "Type" TEXT,
  "Continent" TEXT,
  "Superregion" TEXT,
  "Region" TEXT,
  "Area" TEXT
);
sqlite> select count(1) from provinces;
3925

Creating an SQL Dump From Imported Data

The init script at migrations/init.sql was initially created after importing the CSV data and running the following commands:

# In the same SQlite session as last section
sqlite> .output dump.sql
sqlite> .dump

Note: The column names were edited manually to remove capital letters and spaces to make it easier to work with.

Claims Schema

CREATE TABLE claim_types (
    claim_type TEXT PRIMARY KEY
);

CREATE TABLE claims (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    player TEXT,
    claim_type TEXT,
    val TEXT,
    FOREIGN KEY(claim_type) REFERENCES claim_types(claim_type)
);