Creating an app from the template#
The best way to create a new Safir-based application for Roundtable is with the fastapi_safir_app template.
The quickest way to do this is with the
@sqrbot-jr create project Slack command.
This page describes how to manually use the template to set up a new application.
The question for either creation method about deployment with Helm may require some further clarification.
By default, the generated app will include Kustomize deployment configuration in a
However, if you are planning on writing a Helm chart for it instead (normally in the charts repository), this configuration is not useful.
If you indicate the app will be deployed with Helm, the
manifests directory will be omitted so that it won’t clutter your app with unused files.
1. Install templatekit#
In a clean Python virtual environment, install templatekit:
python -m pip install templatekit
2. Start the project with the template#
Next, you’ll actually create the project files using the template.
git clone https://github.com/lsst/templates templatekit -r templates make fastapi_safir_app
Answer the prompts, and move into that directory in your shell.
The rest of this tutorial uses
safirdemo as the repository (and package) name:
3. Initialize the repository#
From the root of the project directory, initialize the Git repository:
git init . git add . git commit
4. Initialize the dependencies#
Create a new Python virtual environment for application development (don’t reuse the existing environment with templatekit). This is important so that your dependencies resolve reliably.
Now run the initialization command:
This command does several important things for you:
Compiles the direct dependencies listed in
requirements/*.ininto resolved dependencies in
Installs your project in a locally editable mode, along with the third-party dependencies listed in the
Installs pre-commit hooks
After the requirements are resolved, commit those files:
git add requirements/*.txt git commit
In the future you can update your project’s dependencies by re-running
make update and re-committing the requirements files.
To install the project for development without updating dependencies, run:
5. Format code with Black#
The Python code generated by the template is good, but there may be minor formatting issues related to line length and your application’s chosen name. You can format the code and by running tox:
tox -e lint git commit -a
6. Push to GitHub#
Now create your application’s repository on GitHub and push to it.
7. Configure Docker Hub credentials#
The first push to GitHub will fail. That’s because the Docker build step doesn’t credentials for Docker Hub.
To set those credentials, follow GitHub’s help page Creating and storing encrypted secrets. The variables are:
A Docker Hub username that has access to the lsstsqre organization on Docker Hub.
A Docker Hub Personal Access Token associated with
DOCKER_USERNAME. Create a dedicated token specifically for your project’s GitHub Actions workflow.
After setting these secrets, re-run the GitHub Action by re-running the workflow job from the GitHub Actions UI or by pushing a new commit to GitHub.
8. Try the local test commands#
The fastapi_safir_app template is set up to help you successfully test and maintain your bot. There are two ways for you to run tests.
First, you can run pytest directly from your local development environment:
An even better, and more robust approach is with tox:
Tox runs several test steps, each in their own virtual environment. To learn about these test steps:
For example, to only run mypy to check type annotations:
tox -e typing
Or to only lint the code (and reformat it):
tox -e lint
To run all the default test steps, but in parallel:
tox -p auto
9. Try the local development server#
In addition to running tests, tox is also configured with a command to spin up a development server:
tox -e run
In another shell, send an HTTP GET request to the development server:
curl http://localhost:8000/ | python -m json.tool
This development server auto-reloads, so any time you change the code, the server will restart for you.
Now that you have a working application repository, the next steps are to develop your application’s logic and interface, and then deploy it to Roundtable.
To learn learn more about developing Safir-based applications like yours, refer to the guides in this documentation and the FastAPI documentation.
To learn how to deploy your application to Roundtable, see the Roundtable documentation.