Rust Async-GraphQL Example: Caster API

This is an example app for the upcoming Rust video series by Brandon Konkle. It implements a basic API to support a number of hypothetical frontends for the imaginary "Caster" app, a tool to help podcasters, broadcasters, and streamers coordinate show content with their co-hosts and guests. Limited to just the API to support the front end.

Local Development

Install Rust with rustup.

Clippy

For helpful linting rools, install Clippy with rustup:

rustup component add clippy

Run it with cargo:

cargo clippy --fix

Configure the rust-analyzer VS Code plugin to use it (in settings.json):

{
    "rust-analyzer.checkOnSave.command": "clippy"
}

Cargo Make

To build scripts from the Makefile.toml, install Cargo Make:

cargo install cargo-make

Configuration

Configuration is unfortunately stored in two places, with the primary location being the config folder. This folder contains hierarchical config files that are read by Figment.

To set up your local environment, create a local.toml file and a test.toml file, using local.toml.example and test.toml.example as a guide.

The local.toml config is loaded by default in every run mode. In addition, an attempt to load a config file with the name of the run mode is also made - for example, test.toml when the run_mode is "test".

This config is read in as part of a lazy_static instance that is first initialized when the main.rs module from the caster_api app calls caster_utils::config::get_config().

For CLI tools, however, we have to provide a small .env file with a subset of our config values so that tools like docker-compose and sqlx-cli can read them. Use the .env.example as a guide.

Running Docker

To run the docker-compose formation for the API app:

cargo make docker-api up -d

To shut it down:

cargo make docker-api down

SQLx CLI

Install the SQLx CLI for running migrations:

cargo install sqlx-cli --no-default-features --features rustls,postgres

Create a database based on the DATABASE_URL in the .env, if you haven't already:

cargo make db-create

Run migrations:

cargo make db-migrate

If you want to wipe your database and start over:

cargo make db-reset

Running the Local Server

Use cargo to run the server locally:

cargo run

Update Dependencies

First, install the outdated command for cargo:

cargo install --locked cargo-outdated

Then, update and check for any major dependency changes:

cargo update
cargo outdated

Running Integration Tests

To integration test, you need to have the Docker Compose stack with Postgres and Redis running locally, or within your CI pipeline.

NOTE: This is destructive, and will wipe out data within your local database. See below for how to use an alternate test database locally.

To run the integration tests:

cargo make integration

Using an Alternate Test Database

Running integration tests is destructive. If you want to preserve your local data, use an alternate database for local integration testing. Create a config/test.toml file and customize the DATABASE_URL:

[database]
name = "caster_rust_test"
url = "postgresql://caster:caster@localhost:1701/caster_rust_test"

Since the RUN_MODE environment variable is set by the tasks.integration make task to "test", this file will automatically be picked up by the config reader.

NOTE: To manage this test database with the SQLx CLI, you'll need to temporarily edit your .env file to match the values above, and then run the command to reset the test database:

cargo make db-reset

You can restore the original values in your .env afterwards.

Deployment

Building Docker Containers Locally

To build locally, use Buildkit:

DOCKER_BUILDKIT=1 docker build -t caster-api -f apps/api/Dockerfile .

To clear the build cache:

docker builder prune --filter type=exec.cachemount

To inspect the local filesystem:

docker run --rm -it --entrypoint=/bin/bash caster-api

To inspect the full build context:

docker image build --no-cache -t build-context -f - . <<EOF
FROM busybox
WORKDIR /build-context
COPY . .
CMD find .
EOF

docker container run --rm build-context

And to clean up the build context test image:

docker image rm build-context