feat(scripts): add script to check schema between migrations (#13037)

- migrations: allow passing in a custom migrate.FS
- gen/dump: extract some functions to dbtestutil
- scripts: write script to test migrations

scripts/migrate-test/main.go

@@ -0,0 +1,147 @@
+package main
+
+import (
+	"archive/zip"
+	"bytes"
+	"database/sql"
+	"flag"
+	"fmt"
+	"io/fs"
+	"os"
+	"os/exec"
+	"regexp"
+
+	"github.com/google/go-cmp/cmp"
+	"golang.org/x/xerrors"
+
+	"github.com/coder/coder/v2/coderd/database/dbtestutil"
+	"github.com/coder/coder/v2/coderd/database/migrations"
+)
+
+// This script validates the migration path between two versions.
+// It performs the following actions:
+// Given OLD_VERSION and NEW_VERSION:
+//  1. Checks out $OLD_VERSION and inits schema at that version.
+//  2. Checks out $NEW_VERSION and runs migrations.
+//  3. Compares database schema post-migrate to that in VCS.
+//     If any diffs are found, exits with an error.
+func main() {
+	var (
+		migrateFromVersion string
+		migrateToVersion   string
+		postgresURL        string
+		skipCleanup        bool
+	)
+
+	flag.StringVar(&migrateFromVersion, "from", "", "Migrate from this version")
+	flag.StringVar(&migrateToVersion, "to", "", "Migrate to this version")
+	flag.StringVar(&postgresURL, "postgres-url", "postgresql://postgres:postgres@localhost:5432/postgres?sslmode=disable", "Postgres URL to migrate")
+	flag.BoolVar(&skipCleanup, "skip-cleanup", false, "Do not clean up on exit.")
+	flag.Parse()
+
+	if migrateFromVersion == "" || migrateToVersion == "" {
+		_, _ = fmt.Fprintln(os.Stderr, "must specify --from=<old version> and --to=<new version>")
+		os.Exit(1)
+	}
+
+	_, _ = fmt.Fprintf(os.Stderr, "Read schema at version %q\n", migrateToVersion)
+	expectedSchemaAfter, err := gitShow("coderd/database/dump.sql", migrateToVersion)
+	if err != nil {
+		panic(err)
+	}
+
+	_, _ = fmt.Fprintf(os.Stderr, "Read migrations for %q\n", migrateFromVersion)
+	migrateFromFS, err := makeMigrateFS(migrateFromVersion)
+	if err != nil {
+		panic(err)
+	}
+	_, _ = fmt.Fprintf(os.Stderr, "Read migrations for %q\n", migrateToVersion)
+	migrateToFS, err := makeMigrateFS(migrateToVersion)
+	if err != nil {
+		panic(err)
+	}
+
+	_, _ = fmt.Fprintf(os.Stderr, "Connect to postgres\n")
+	conn, err := sql.Open("postgres", postgresURL)
+	if err != nil {
+		panic(err)
+	}
+	defer conn.Close()
+
+	ver, err := checkMigrateVersion(conn)
+	if err != nil {
+		panic(err)
+	}
+	if ver < 0 {
+		_, _ = fmt.Fprintf(os.Stderr, "No previous migration detected.\n")
+	} else {
+		_, _ = fmt.Fprintf(os.Stderr, "Detected migration version %d\n", ver)
+	}
+
+	_, _ = fmt.Fprintf(os.Stderr, "Init database at version %q\n", migrateFromVersion)
+	if err := migrations.UpWithFS(conn, migrateFromFS); err != nil {
+		panic(err)
+	}
+
+	_, _ = fmt.Fprintf(os.Stderr, "Migrate to version %q\n", migrateToVersion)
+	if err := migrations.UpWithFS(conn, migrateToFS); err != nil {
+		panic(err)
+	}
+
+	_, _ = fmt.Fprintf(os.Stderr, "Dump schema at version %q\n", migrateToVersion)
+	dumpBytesAfter, err := dbtestutil.PGDumpSchemaOnly(postgresURL)
+	if err != nil {
+		panic(err)
+	}
+
+	if diff := cmp.Diff(string(dumpBytesAfter), string(stripGenPreamble(expectedSchemaAfter))); diff != "" {
+		_, _ = fmt.Fprintf(os.Stderr, "Schema differs from expected after migration: %s\n", diff)
+		os.Exit(1)
+	}
+	_, _ = fmt.Fprintf(os.Stderr, "OK\n")
+}
+
+func makeMigrateFS(version string) (fs.FS, error) {
+	// Export the migrations from the requested version to a zip archive
+	out, err := exec.Command("git", "archive", "--format=zip", version, "coderd/database/migrations").CombinedOutput()
+	if err != nil {
+		return nil, xerrors.Errorf("git archive: %s\n", out)
+	}
+	// Make a zip.Reader on top of it. This implements fs.fs!
+	zr, err := zip.NewReader(bytes.NewReader(out), int64(len(out)))
+	if err != nil {
+		return nil, xerrors.Errorf("create zip reader: %w", err)
+	}
+	// Sub-FS to it's rooted at migrations dir.
+	subbed, err := fs.Sub(zr, "coderd/database/migrations")
+	if err != nil {
+		return nil, xerrors.Errorf("sub fs: %w", err)
+	}
+	return subbed, nil
+}
+
+func gitShow(path, version string) ([]byte, error) {
+	out, err := exec.Command("git", "show", version+":"+path).CombinedOutput() //nolint:gosec
+	if err != nil {
+		return nil, xerrors.Errorf("git show: %s\n", out)
+	}
+	return out, nil
+}
+
+func stripGenPreamble(bs []byte) []byte {
+	return regexp.MustCompile(`(?im)^(-- Code generated.*DO NOT EDIT.)$`).ReplaceAll(bs, []byte{})
+}
+
+func checkMigrateVersion(conn *sql.DB) (int, error) {
+	var version int
+	rows, err := conn.Query(`SELECT version FROM schema_migrations LIMIT 1;`)
+	if err != nil {
+		return -1, nil // not migrated
+	}
+	for rows.Next() {
+		if err := rows.Scan(&version); err != nil {
+			return 0, xerrors.Errorf("scan version: %w", err)
+		}
+	}
+	return version, nil
+}