Ticketing (think concert tickets)

📚 This repository is a learning resource for building a full-stack application with Nx, NestJS, Angular, and Ory.

It shows:

how to organize internal dependencies
tricks to use Fastify with NestJS
tricks to consume and produce ES6 modules with NestJS, Jest and Nx
how to integrate Ory in NestJS and Angular apps for authentication and authorization flows
how to set up Ory in local and remote working environments
how to use RabbitMQ with NestJS
how to define/validate environment variables
how to containerize Nx apps with Docker
how to integrate Nx into a Kubernetes workflow
how to dynamically rebuild Docker images based on the Nx project graph

And there is even a list of challenges! 🏁

[!NOTE] This project is inspired by Stephen Grider's Microservices with Node JS and React course on Udemy, starting in chapter 5. You can find the source code for the course here.

User story

journey
  title Exchanging tickets online
  section Register
    Create a user: 3: Seller, Buyer
    Signin : 3: Seller
  section Search tickets
    Find by name: 5: Buyer, Seller
  section Create ticket offer
    Write description: 3: Seller
    Define price: 3: Seller
  section Buy ticket
    Reserve tickets: 5: Buyer
    Place order: 3: Buyer
    Pay ticket: 3: Buyer
  section Check orders
    See orders list: 5: Seller, Buyer

Architecture

---
title: Ticketing architecture
---
flowchart LR
%% defining styles
    classDef app fill:#f7e081,stroke:#333,stroke-width:1px

%% defining entities
    FE[Angular app]
    LB[Nginx proxy]
    A[Auth API]
    A-M[(Mongo)]
    T[Tickets API]
    T-M[(Mongo)]
    O[Orders API]
    O-M[(Mongo)]
    P[Payments API]
    P-M[(Mongo)]
    St[Stripe]
    E[Expiration API]
    E-R[(Redis)]
    RMQ[RabbitMQ]
    Kr[Kratos]
    Ke[Keto]
    Hy[Hydra]

%% assigning styles to entities
    %%AS,OS,ES,TS,PS:::service
    %%class A,T,O,E,P,FE app;

%% flow
    FE -->|HTTP| LB
    FE -->|HTTP| St <-->|HTTP| PS
    FE -->|HTTP| ORY <-->|HTTP| AS
    LB --->|HTTP| AS & TS & OS & PS
    RMQ <-.->|AMQP| TS & OS & ES & PS
    TS & OS & PS -->|HTTP| ORY
    subgraph AS [Auth service]
    direction LR
    A --> A-M
    end
    subgraph ORY [Ory Network]
    direction LR
    Kr
    Ke
    Hy
    end
    subgraph TS [Tickets service]
    direction LR
    T --> T-M
    end
    subgraph OS [Orders service]
    direction LR
    O --> O-M
    end
    subgraph ES [Expiration service]
    direction LR
    E <--> E-R
    end
    subgraph PS [Payments service]
    direction LR
    P --> P-M
    end

Entities

---
title: Ticketing entities
---
erDiagram
    User ||--o{ Ticket : owns
    User ||--o{ Order : owns
    User ||--o{ Payment : owns
    Ticket ||--o| Order : "bound to"
    Order ||--o| Payment : "bound to"

    User {
        int id PK
        string email "unique"
    }
    Ticket {
        string id PK
        string title
        float price
        int version
        string userId FK
        string orderId FK "Optional"
    }
    Order {
        string id PK
        string status
        int version
        string ticketId FK
        string userId FK
    }
    Payment {
        string id PK
        string orderId FK
        string stripeId "Charge ID from Stripe"
        int version
    }

Permissions

Permissions are granted or denied using Ory Permissions (Keto) policies.

---
title: Entities namespaces and relationships
---
classDiagram

    NamespaceRelations *-- Namespace
    NamespacePermissions *-- Namespace
    Namespace <|-- User
    Namespace <|-- Group
    Namespace <|-- Ticket
    Namespace <|-- Order
    Namespace <|-- Payment
    Group o-- User : "members"
    Ticket o-- User : "owners"
    Order o-- User : "owners"
    Order *-- Ticket : "parents"
    Payment o-- User : "owners"
    Payment *-- Order : "parents"

    class Context {
      <<Interface>>
      subject: never;
    }

    class NamespaceRelations {
        <<Interface>>
        +[relation: string]: INamespace[]
    }

    class NamespacePermissions {
        <<Interface>>
        +[method: string]: (ctx: Context) => boolean
    }

    class Namespace {
        <<Interface>>
        -related?: NamespaceRelations
        -permits?: NamespacePermissions
    }

    class User {
    }

    note for Group "<i>Users</i> can be <b>members</b> of a <i>Group</i>"
    class Group {
        +related.members: User[]
    }

    note for Ticket "<i>Users</i> (in owners) are allowed to <b>edit</b>. \nHowever <i>Ticket</i> <b>owners</b> cannot <b>order</b> a Ticket. \nImplicitly, anyone can <b>view</b> Tickets"
    class Ticket {
        +related.owners: User[]
        +permits.edit(ctx: Context): boolean
        +permits.order(ctx: Context): boolean
    }

    note for Order "<i>Order</i> is bound to a <i>Ticket</i>. \n<i>Users</i> (in <b>owners</b>) are allowed to <b>view and edit</b>. \n <i>Order's Ticket</i> <b>owners</b> are allowed to <b>view</b>."
    class Order {
        +related.owners: User[]
        +related.parents: Tickets[]
        +permits.edit(ctx: Context): boolean
        +permits.view(ctx: Context): boolean
    }

    note for Payment "<i>Payment</i> is bound to a Ticket's <i>Order</i>. \n<i>Users</i> (in <b>owners</b>) are allowed to <b>view and edit</b>. \n<i>Payment</i> can be <b>viewed</b> by <i>Order's Ticket</i> <b>owners</b>."
    class Payment {
        +related.owners: User[]
        +related.parents: Order[]
        +permits.edit(ctx: Context): boolean
        +permits.view(ctx: Context): boolean
    }

Events

sequenceDiagram
  participant Tickets service
  participant Orders service
  participant Payments service
  participant Expiration service
  participant RMQ

  loop ticket:created
    %% event emitted by tickets service
    Tickets service->>+RMQ: Publish new ticket
    RMQ-->>-Orders service: Dispatch new ticket
    Note left of Orders service: Orders service needs to know <br> about tickets that can be reserved.
  end

  loop ticket:updated
    %% event emitted by tickets service
    Tickets service->>+RMQ: Publish updated ticket
    RMQ-->>-Orders service: Dispatch updated ticket
    Note left of Orders service: Orders service needs to know <br> if tickets price have changed and <br>if they are successfully reserved
  end

  loop order:created
    %% event emitted by orders service
    Orders service->>+RMQ: Publish new order
    par RMQ to Tickets service
      RMQ->>Tickets service: Dispatch new order
      Note left of Tickets service: Tickets service needs to know<br>if a ticket has been reserved<br>to prevent its edition.
      and RMQ to Payments service
      RMQ->>Payments service: Dispatch new order
      Note left of Payments service: Payments service needs to know<br>there is a new order that a user<br>might submit a payment for.
      and RMQ to Expiration service
      RMQ->>Expiration service: Dispatch new order
      Note left of Expiration service: Expiration service needs to start<br>a timer to eventually time out<br>this order.
    end
  end

  loop order:cancelled
    %% event emitted by orders service
    Orders service->>+RMQ: Publish cancelled order
    par RMQ to Tickets service
      RMQ->>Tickets service: Dispatch cancelled order
      Note left of Tickets service: Tickets service should unreserve ticket<br>if the corresponding order has been<br>cancelled so this ticket can be <br>edited again
      and RMQ to Payments service
      RMQ->>Payments service: Dispatch cancelled order
      Note left of Payments service: Payments service should know that<br>any incoming payments for this order<br>should be rejected
    end
  end

  loop expiration:complete
    %% event emitted by expiration service
    Expiration service->>+RMQ: Publish complete expiration
    par RMQ to Orders service
      RMQ->>Orders service: Dispatch expired order
      Note left of Orders service: Orders service needs to know that an order<br>has gone over the 15 minutes time limit.<br>It is up to the order service to decide<br> wether or not to cancel the order.
    end
  end

  loop payment:created
    %% event emitted by payments service
    Payments service->>+RMQ: Publish payment created
    par RMQ to Orders service
      RMQ->>Orders service: Dispatch payment created
      Note left of Orders service: Orders service needs to know that an order<br>has been paid for.
    end
  end

Environment variables

I am using dotenv-vault to manage environment variables. You can fork the project and use the following links to create your Dotenv project by forking the corresponding Dotenv project.

project	fork
docker
auth
expiration
moderation
orders
payments
tickets

Useful commands

... to run after configuring the required environment variables

# build custom Nginx Proxy
yarn docker:proxy:build

# build custom RabbitMQ node
yarn docker:rmq:build

# start the Storage and Broker dependencies (mongo, redis, rabbitmq)
yarn docker:deps:up

# start Nginx Proxy (for backend services and frontend app)
yarn docker:proxy:up

# Generate Ory network configuration from .env
yarn ory:generate:kratos
yarn ory:generate:keto

# start Ory network (Kratos and Keto with database migrations)
yarn docker:ory:up

# start backend services
yarn start:backend

# start (Angular) frontend app
yarn start:frontend:local

getlarge / ticketing

readme