chore: Initial database scaffolding (#2)

* chore: Initial database scaffolding

This implements migrations and code generation for interfacing with a PostgreSQL database.

A dependency is added for the "postgres" binary on the host, but that seems like an acceptable requirement considering it's our primary database.

An in-memory database object can be created for simple cross-OS and fast testing.

* Run tests in CI

* Use Docker instead of binaries on the host

* Skip database tests on non-Linux operating systems

* chore: Add golangci-lint and codecov

* Use consistent file names

database/postgres/postgres.go

@@ -0,0 +1,59 @@
+package postgres
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+	"time"
+
+	"github.com/ory/dockertest/v3"
+	"github.com/ory/dockertest/v3/docker"
+	"golang.org/x/xerrors"
+)
+
+// Open creates a new PostgreSQL server using a Docker container.
+func Open() (string, func(), error) {
+	pool, err := dockertest.NewPool("")
+	if err != nil {
+		return "", nil, xerrors.Errorf("create pool: %w", err)
+	}
+	resource, err := pool.RunWithOptions(&dockertest.RunOptions{
+		Repository: "postgres",
+		Tag:        "11",
+		Env: []string{
+			"POSTGRES_PASSWORD=postgres",
+			"POSTGRES_USER=postgres",
+			"POSTGRES_DB=postgres",
+			"listen_addresses = '*'",
+		},
+	}, func(config *docker.HostConfig) {
+		// set AutoRemove to true so that stopped container goes away by itself
+		config.AutoRemove = true
+		config.RestartPolicy = docker.RestartPolicy{Name: "no"}
+	})
+	if err != nil {
+		log.Fatalf("Could not start resource: %s", err)
+	}
+	hostAndPort := resource.GetHostPort("5432/tcp")
+	dbURL := fmt.Sprintf("postgres://postgres:postgres@%s/postgres?sslmode=disable", hostAndPort)
+
+	// Docker should hard-kill the container after 120 seconds.
+	resource.Expire(120)
+
+	pool.MaxWait = 120 * time.Second
+	err = pool.Retry(func() error {
+		db, err := sql.Open("postgres", dbURL)
+		if err != nil {
+			return err
+		}
+		err = db.Ping()
+		_ = db.Close()
+		return err
+	})
+	if err != nil {
+		return "", nil, err
+	}
+	return dbURL, func() {
+		_ = pool.Purge(resource)
+	}, nil
+}

database/postgres/postgres_test.go

@@ -0,0 +1,32 @@
+//go:build linux
+
+package postgres_test
+
+import (
+	"database/sql"
+	"testing"
+
+	"github.com/coder/coder/database/postgres"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/goleak"
+
+	_ "github.com/lib/pq"
+)
+
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}
+
+func TestPostgres(t *testing.T) {
+	t.Parallel()
+
+	connect, close, err := postgres.Open()
+	require.NoError(t, err)
+	defer close()
+	db, err := sql.Open("postgres", connect)
+	require.NoError(t, err)
+	err = db.Ping()
+	require.NoError(t, err)
+	err = db.Close()
+	require.NoError(t, err)
+}