faaso/docs/funkos.md

# Funkos What, Why, How

A funko is the equivalent of a AWS lambda. It's the unit
of deployment for FaaSO.

A funko is a folder containing a metadata `funko.yml` file
and source code in any language supported by a *runtime*

Think of a runtime as a template that gets merged with yout
funko and produces a full containerized application.

FaaSO can use your funko and its runtime to create a Docker image.

That docker image can be built in a server by the FaaSO proxy or it can be
built locally just like any docker image.

Then we can start it locally or, using the proxy, in the server.

```mermaid
flowchart TD
subgraph funko_hello
  A(fa:fa-code Metadata)
  B(fa:fa-code Code in language X)
end

R(runtime for X)

C(fa:fa-box Containerized Application Code)
D1(fa:fa-image Local Docker Image)
subgraph server
D2(fa:fa-image Remote Docker Image)
E(fa:fa-server FaaSO Proxy)
F(Container Instance Running In Server)
end
G(Container Instance Running Locally)

funko_hello --> C -- faaso build -l --> D1
C --> E -- faaso build --> D2
R --> C
D2 -- faaso up --> F
D1 -- faaso up -local --> G
```

How is that application reached? FaaSO will usually run the image
in a *opinionated* way. All funkos listen in port 3000 in their own
container instances, and they are all segregated into a network called
faaso-net.

The proxy is the only container exposed to the host network, everything
else needs to be accessed through it.

The faaso-proxy container will automatically proxy all requests so if you access the URL `http://faaso-proxy:8888/funko/hello/foo` that will be
proxied to `/foo` in the `hello` funko.

This is all done via naming conventions. You can create your own `faaso-whatever` container, add it to the `faaso-net` and faaso will
happily consider it a funko.

In the same way all funkos are simply docker containers running in that
network, with names following that convention. There is zero magic
involved.

```mermaid
flowchart TD
subgraph faaso-net
    faaso-proxy
    faaso-funko1
    faaso-funko2
    faaso-hello
end

client -- GET /funko/hello/foo --> faaso-proxy
client -- GET /funko/funko1/bar --> faaso-proxy

faaso-proxy -- GET /foo --> faaso-hello
faaso-proxy -- GET /bar --> faaso-funko1
```

The dynamic proxying is achieved by reading the current state of
Docker and just adapt to it using the naming conventions mentioned
above.