chore: add sqlx scaffolding

This adds installation of `sqlx-cli` to the README, which is now used in
`make prepare-db` to create and migrate the database. `make run` now
depends on `prepare-db`, so the project can still be launched with that
single command. The database isn't used yet.

Author: Chris Connelly

Makefile

@@ -1,10 +1,21 @@
-@PHONY: start-db stop-db run
+@PHONY: prepare-db start-db stop-db run
+
+export PGHOST ?= localhost
+export PGPORT ?= 5432
+export PGUSER ?= postgres
+export PGPASSWORD ?= password
+export PGDATABASE ?= sample
+export DATABASE_URL ?= postgres://$(PGUSER):$(PGPASSWORD)@$(PGHOST):$(PGPORT)/$(PGDATABASE)
+
+prepare-db: start-db
+	@sqlx database create
+	@sqlx migrate run
 
 start-db:
 	@scripts/start-db.sh
 
 stop-db:
 	@scripts/stop-db.sh
 
-run: start-db
+run: start-db prepare-db
 	@RUST_LOG=rust_graphql_sample=debug,tower_http=debug cargo run

README.md

@@ -5,8 +5,11 @@ A sample of GraphQL in Rust.
 ## Setup
 
 1. [Get Rust](https://rustup.rs/).
-2. `git clone https://github.com/connec/rust-graphql-sample`
-3. `make run`
+2. Install [`sqlx-cli`](https://github.com/launchbadge/sqlx/blob/master/sqlx-cli/README.md)
+   ```sh
+   cargo install sqlx-cli --no-default-features --features postgres
+   ```
+3. `git clone https://github.com/connec/rust-graphql-sample`
+4. `make run` – this will start a PostgreSQL container, prepare a sample database, and start the server.
 
 [GraphiQL](https://github.com/graphql/graphiql) is served from http://localhost:3000/, and the GraphQL API itself from http://localhost:3000/query.
-The `make` task is just setting a sensible default log filter and calling `cargo run`.

migrations/.gitkeep

@@ -5,11 +5,6 @@ set -euo pipefail
 container_name=sample-db
 container_image=postgres:14
 
-export PGHOST=localhost
-export PGPORT=5432
-export PGUSER=postgres
-export PGPASSWORD=password
-
 if ! [[ "$(docker ps --filter name="$container_name" --latest -q)" != '' ]]; then
   if
     ! output="$(