Requirements

Functional Requirements:

• Log workouts
• View history & basic stats.
• Sync across devices.
• assume cardio type workouts not lifting or jiujutsu

Non-Functional Requirements:

• high availability
• scalability
• reliability
• no duplicates of workouts

Capacity Estimation

API Design

Write path: Logging workouts

/log API takes a workout description and persists it to the database - returns workout ID

/history shows workouts for a user, optional time frame parameters, workout type parameters

/stats shows statistics for workouts (how frequently you've worked out in the last 30 days, average workout duration, etc)

High-Level Design

API Gateway for userauthentication, in front of k8s microservices

Workout service - this service ingests workout descriptions from authenticated users and persists them to a SQL database.

Stats service - background chron processor which periodically computes statistics for workouts

History service - hosts API for history API showing a users historical workouts over the last 30days

Database Design

Workout Type ( name -> PK)

Workouts ( id -> PK , user -> FK, workout_type-> FK, duration INTERVAL, distance int, time timestamp)

Stats(id->PK, user->FK, stats jsonb, time timestamp, type varchar)

Detailed Component Design

Workout service -> synchronous API which ingests details about a workout for an authenticated user. Workout type (run/swim/jumprope/walk etc) , distance, and duration etc .

Generates a UUID, for workout ID , persists to database as a synchrnous HTTP API

Stats service -> Periodically generates summary statistics for a user. On some period like 24 hours, check if a user does not have statistics generated in the last 24 hours, and generate new statistics looking back 24, 7, and 30 days which are persisted to the database.