#
Your First Docker Space: Text Generation with T5

In the following sections, you’ll learn the basics of creating a Docker Space, configuring it, and deploying your code to it. We’ll create a Text Generation Space with Docker that’ll be used to demo the google/flan-t5-small model, which can generate text given some input text, using FastAPI as the server.

You can find a completed version of this hosted here.

##
Create a new Docker Space

We’ll start by creating a brand new Space and choosing Docker as our SDK.

Hugging Face Spaces are Git repositories, meaning that you can work on your Space incrementally (and collaboratively) by pushing commits. Take a look at the Getting Started with Repositories guide to learn about how you can create and edit files before continuing. If you prefer to work with a UI, you can also do the work directly in the browser.

Selecting Docker as the SDK when creating a new Space will initialize your Docker Space by setting the `sdk` property to `docker` in your `README.md` file’s YAML block.

    sdk: docker

You have the option to change the default application port of your Space by setting the `app_port` property in your `README.md` file’s YAML block. The default port is `7860`.

    app_port: 7860

##
Add the dependencies

For the Text Generation Space, we’ll be building a FastAPI app that showcases a text generation model called Flan T5. For the model inference, we’ll be using a 🤗 Transformers pipeline to use the model. We need to start by installing a few dependencies. This can be done by creating a requirements.txt file in our repository, and adding the following dependencies to it:

    fastapi==0.74.*
    requests==2.27.*
    sentencepiece==0.1.*
    torch==1.11.*
    transformers==4.*
    uvicorn[standard]==0.17.*

These dependencies will be installed in the Dockerfile we’ll create later.

##
Create the app

Let’s kick off the process with a dummy FastAPI app to see that we can get an endpoint working. The first step is to create an app file, in this case, we’ll call it `main.py`.

    from fastapi import FastAPI

    app = FastAPI()

    @app.get("/")
    def read_root():
        return {"Hello": "World!"}

##
Create the Dockerfile

The main step for a Docker Space is creating a Dockerfile. You can read more about Dockerfiles here. Although we’re using FastAPI in this tutorial, Dockerfiles give great flexibility to users allowing you to build a new generation of ML demos. Let’s write the Dockerfile for our application

    FROM python:3.9

    WORKDIR /code

    COPY ./requirements.txt /code/requirements.txt

    RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt

    COPY . .

    CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "7860"]

When the changes are saved, the Space will rebuild and your demo should be up after a couple of seconds! Here is an example result at this point.

###
Testing locally

Tip for power users (you can skip): If you’re developing locally, this is a good moment in which you can do `docker build` and `docker run` to debug locally, but it’s even easier to push the changes to the Hub and see how it looks like!

    docker build -t fastapi .
    docker run  -it -p 7860:7860 fastapi

If you have Secrets you can use `docker buildx` and pass the secrets as build arguments

    export SECRET_EXAMPLE="my_secret_value"
    docker buildx build --secret id=SECRET_EXAMPLE,env=SECRET_EXAMPLE -t fastapi .

and run with `docker run` passing the secrets as environment variables

    export SECRET_EXAMPLE="my_secret_value"
    docker run -it -p 7860:7860 -e SECRET_EXAMPLE=$SECRET_EXAMPLE fastapi

##
Adding some ML to our app

As mentioned before, the idea is to use a Flan T5 model for text generation. We’ll want to add some HTML and CSS for an input field, so let’s create a directory called static with `index.html`, `style.css`, and `script.js` files. At this moment, your file structure should look like this:

    /static
    /static/index.html
    /static/script.js
    /static/style.css
    Dockerfile
    main.py
    README.md
    requirements.txt

Let’s go through all the steps to make this working. We’ll skip some of the details of the CSS and HTML. You can find the whole code in the Files and versions tab of the DockerTemplates/fastapi_t5 Space.

1. Write the FastAPI endpoint to do inference

We’ll use the `pipeline` from `transformers` to load the google/flan-t5-small model. We’ll set an endpoint called `infer_t5` that receives and input and outputs the result of the inference call

    from transformers import pipeline

    pipe_flan = pipeline("text2text-generation", model="google/flan-t5-small")

    @app.get("/infer_t5")
    def t5(input):
        output = pipe_flan(input)
        return {"output": output[0]["generated_text"]}

2. Write the `index.html` to have a simple form containing the code of the page.

    <main>
      <section id="text-gen">
        <h2>Text generation using Flan T5</h2>
        <p>
          Model:
          <a
            href="https://huggingface.co/google/flan-t5-small"
            rel="noreferrer"
            target="_blank"
            >google/flan-t5-small
          </a>
        </p>
        <form class="text-gen-form">
          <label for="text-gen-input">Text prompt</label>
          <input
            id="text-gen-input"
            type="text"
            value="German: There are many ducks"
          />
          <button id="text-gen-submit">Submit</button>
          <p class="text-gen-output"></p>
        </form>
      </section>
    </main>

3. In the `app.py` file, mount the static files and show the html file in the root route

    app.mount("/", StaticFiles(directory="static", html=True), name="static")

    @app.get("/")
    def index() -> FileResponse:
        return FileResponse(path="/app/static/index.html", media_type="text/html")

4. In the `script.js` file, make it handle the request

    const textGenForm = document.querySelector(".text-gen-form");

    const translateText = async (text) => {
      const inferResponse = await fetch(`infer_t5?input=${text}`);
      const inferJson = await inferResponse.json();

      return inferJson.output;
    };

    textGenForm.addEventListener("submit", async (event) => {
      event.preventDefault();

      const textGenInput = document.getElementById("text-gen-input");
      const textGenParagraph = document.querySelector(".text-gen-output");

      textGenParagraph.textContent = await translateText(textGenInput.value);
    });

5. Grant permissions to the right directories

As discussed in the Permissions Section, the container runs with user ID 1000. That means that the Space might face permission issues. For example, `transformers` downloads and caches the models in the path under the `HUGGINGFACE_HUB_CACHE` path. The easiest way to solve this is to create a user with righ permissions and use it to run the container application. We can do this by adding the following lines to the `Dockerfile`.

    # Set up a new user named "user" with user ID 1000
    RUN useradd -m -u 1000 user

    # Switch to the "user" user
    USER user

    # Set home to the user's home directory
    ENV HOME=/home/user \
    	PATH=/home/user/.local/bin:$PATH

    # Set the working directory to the user's home directory
    WORKDIR $HOME/app

    # Copy the current directory contents into the container at $HOME/app setting the owner to the user
    COPY --chown=user . $HOME/app

The final `Dockerfile` should look like this:

    FROM python:3.9

    WORKDIR /code

    COPY ./requirements.txt /code/requirements.txt

    RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt

    RUN useradd -m -u 1000 user

    USER user

    ENV HOME=/home/user \
    	PATH=/home/user/.local/bin:$PATH

    WORKDIR $HOME/app

    COPY --chown=user . $HOME/app

    CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "7860"]

Success! Your app should be working now! Check out DockerTemplates/fastapi_t5 to see the final result.

What a journey! Please remember that Docker Spaces give you lots of freedom, so you’re not limited to use FastAPI. From a Go Endpoint to a Shiny App, the limit is the moon! Check out some official examples. You can also upgrade your Space to a GPU if needed 😃

##
Debugging

You can debug your Space by checking the Build and Container logs. Click on the Open Logs button to open the modal.

If everything went well, you will see `Pushing Image` and `Scheduling Space` on the Build tab

On the Container tab, you will see the application status, in this case, `Uvicorn running on http://0.0.0.0:7860`

##
Read More

- Docker Spaces
- List of Docker Spaces examples