Rusty Mailer is a practice project using Rust, it's a simple email newsletter delivery service where users can publish newsletter issues to their subscribers. It features some degree of fault-tolerance and well-tested codebase. Built using Rust and Actix Web, it was a project from the book Zero to Production in Rust.
To achieve fault-tolerance, email newsletter deliveries are done asynchronously by queueing the delivery in the database, then background workers will dequeue it periodically.
The following is the diagram:
sequenceDiagram
participant User
participant Rusty Mailer
participant Database
participant Background Worker 1
participant Background Worker 2
participant Postmark
User->>+Rusty Mailer: Publish new newsletter issue
Rusty Mailer-)Database: Queue the newsletter deliveries
Rusty Mailer->>-User: "Success, newsletters will go out shortly"
loop Email Newsletter Delivery
par
Background Worker 1->>Database: Dequeue
Background Worker 1->>Postmark: Send email newsletter
and
Background Worker 2->>Database: Dequeue
Background Worker 2->>Postmark: Send email newsletter
end
end
PostgreSQL table is utilized as the queue, background workers will pick 1 row to process everytime it does dequeue operation and then delete the row immediately after it succeeded processing. PostgreSQL's row-level locking is utilized to prevent multiple background workers from processing the same row, thus preventing duplicate email delivery.
The following diagram illustrates what would happen when there are 2 rows (row A and row B) in the table and two workers do dequeue operation concurrently:
sequenceDiagram
participant Worker 1
participant Worker 2
participant Database
par Worker 1 tries to process row A
rect rgb(180, 150, 50)
alt Row A is not locked
Worker 1->>Database: Processes row A
else Row A is locked
Worker 1->>Database: Processes row B
end
end
and Worker 2 tries to process row A
rect rgb(50, 50, 50)
alt Row A is not locked
Worker 2->>Database: Processes row A
else Row A is locked
Worker 2->>Database: Processes row B
end
end
end
- Docker;
- Rust;
- SQLX-cli, install using
cargo install sqlx-cli; - PostgreSQL.
- Clone the repo and
cdinto the directory; - Run the following command:
scripts/init_db.sh && scripts/init_redis.sh- Run
cargo run - The web can be accessed at localhost:8081;
- Go to
localhost:8081/loginto login, use "admin" for username, and "everythinghastostartsomewhere" for the password.
- Deploy to a cloud provider
- Create automated deployment pipeline
- API docs (Swagger)
- Revamp UI
See the open issues for a full list of proposed features (and known issues).
Distributed under the MIT License. See LICENSE for more information.
Much thanks to these people/organizations/resources that made this project possible to be as it is now!