updated docs for tornado stage 01

# Tornado Backend (Stage 01) - Else

# Tornado Backend (Stage 01) - Details

This document explains the architecture of the current stage of the Tornado-based blogging web application.

- **Scalable Deployment**:

  - Dockerized environment ensures consistency and ease of deployment.

## Visualization of This Stage

```mermaid

graph TD

    subgraph Application

        TornadoServer["Tornado Server"]

        Templates["HTML Templates (Jinja-like)"]

        StaticAssets["Static Assets (CSS/JS)"]

    end

    subgraph Database

        PostgreSQL["PostgreSQL Database"]

    end

    subgraph Docker

        BlogService["Blog Service (Python/Tornado)"]

        DatabaseService["Database Service (PostgreSQL)"]

    end

    User["User"] -->|HTTP Requests| TornadoServer

    TornadoServer -->|Renders| Templates

    TornadoServer -->|Serves| StaticAssets

    TornadoServer -->|Async Queries| PostgreSQL

    TornadoServer -->|Renders| Responses

    BlogService -->|Links To| DatabaseService

    TornadoServer -->|Port 8888| BlogService

    PostgreSQL -->|Port 5432| DatabaseService

```

---

This architecture provides a solid foundation for building a more complex web application. Future enhancements might include additional user roles, improved UI, or REST API support.

## Additional Notes

Enter the postgres database container using,

```bash

docker exec -it tornado-backend_postgres_1 psql -U blog -d blog

```

1) Check the entries of the authors table,

```bash

SELECT * from authors;

```

Which results in, e.g., 

```psql

blog=# SELECT * from authors;

 id |         email         |     name      |                       hashed_password                        

----+-----------------------+---------------+--------------------------------------------------------------

  1 | first-blogger@blog.de | First Blogger | $2b$12$G0JKWQT7Tx1DoVqjze2mruM.kxmhP0EeiltKesZT5ZpqWlNnu3dOe

(1 row)

```

2) Check the entries of the entries table,

```psql

SELECT * from entries;

```

Which results in, e.g., 

```psql

blog=# SELECT * from entries;

 id | author_id |            slug             |            title            |                    markdown                    |                         html     

                     |         published          |          updated           

----+-----------+-----------------------------+-----------------------------+------------------------------------------------+----------------------------------

---------------------+----------------------------+----------------------------

  1 |         1 | first-post-by-first-blogger | First post by first blogger | This is the first post by the first blogger... | <p>This is the first post by the 

first blogger...</p> | 2024-12-06 17:23:18.595355 | 2024-12-06 17:23:18.595355

(1 row)

```

 No newline at end of file

  command: --db_host=postgres

```

This configuration does not define any volume for the PostgreSQL service so if the container is removed or recreated the data will be lost. To make the data persistent use add a volume mapping to the postgres service in the docker compose file, e.g., 

```yml

    volumes:

      - postgres_data:/var/lib/postgresql/data

```

Note, the exposer of port 3306 is probably a mistake. The PostgrSQL default port is 5432 which is also used in `./tornado-backend/blog.py` to connect to the database.

Note also, the python image used installs tornado version 6.2, thus the `set_secure_cookie` and `get_secure_cookie` instead of `set_signed_cookie` and `get_signed_cookie` used in `./tornado-backend/blog.py`. The naming of these methods changed with tornado version 6.3. This is another mistake in the blog demo on GitHub. ([see](https://www.tornadoweb.org/en/stable/web.html#))

```mermaid

graph TD

    subgraph Blog Service

        TornadoServer["Tornado Server"]

    %% External user

    User["User (Web Browser)"]

    %% Docker network

    subgraph Docker_Network["Docker Network"]

      %% Blog Container

      subgraph BlogContainer["Blog Container"]

        TornadoServer["🐍 Tornado Web Server"]

        Templates["HTML Templates (Jinja-like)"]

        StaticAssets["Static Assets (CSS/JS)"]

      end

    subgraph Database Service 

        PostgreSQL["PostgreSQL Database"]

      %% Database Container

      subgraph DBContainer["PostgreSQL Container"]

        PostgreSQL["🐘 PostgreSQL Database"]

        Volume["📦 Data Volume (Not Persistent Storage Here!)"]

      end

    end

    User["User"] -->|HTTP Requests<br>Port 8888| TornadoServer

    %% Connections

    User -->|HTTP Requests<br>Port 8888| TornadoServer

    TornadoServer -->|Renders| Templates

    TornadoServer -->|Serves| StaticAssets

    TornadoServer -->|Async Queries<br>Port 5432| PostgreSQL

    PostgreSQL -->|Reads/Writes| Volume

```

Note, Tornado is used as web server and web framework e.g. with frontend and backend

Note, Tornado is used as web server and web framework e.g. as frontend and backend

### More Details

* More details on the general architecture of a tornado web app can be found [here](https://www.tornadoweb.org/en/stable/guide/structure.html)

More details on the general architecture of a tornado web app can be found [here](https://www.tornadoweb.org/en/stable/guide/structure.html)

cd tornado-backend/

```

## Step 2) Build multi-container app

## Step 2) Start multi-container app

```bash

docker-compose up --build

docker-compose up

```

## Step 3) Check container status and restart blog container

Check container status,

```bash

docker-compose ps

```

which results in, e.g.,

```bash

NAME                         IMAGE               COMMAND                  SERVICE             CREATED             STATUS              PORTS

tornado-backend-postgres-1   postgres:10.3       "docker-entrypoint.s…"   postgres            52 seconds ago      Up 52 seconds       5432/tcp, 0.0.0.0:32768->3306/tcp, :::32768->3306/tc

```

The blog container will most likely not start the first time. Restart the blog container,

The blog container will most likely not start at the first time. Restart the blog container,

```bash

docker-compose restart blog

[+] Restarting 1/1

 ✔ Container tornado-backend-blog-1  Started                                                                                           0.2s 

```

## Step 4) Use the blog web app

## Step 5) Enter the postgres container and check the entries

Enter the postgres database container using,

Enter the postgres database container using psql,

```bash

docker exec -it tornado-backend-postgres-1 psql -U blog -d blog

(1 row)

```

Check the entries of the entries table

Check the entries of the entries table,

```psql

SELECT * from entries;

(1 row)

```

Exit the psql terminal,

```psql

\q

```

## Step 6) Stop the container

```bash