clairctl: admin subcommand

This change adds the skeleton of an `admin` subcommand that we can
expand for various administrator tasks.

The proximate need is to be able to run an index creation that may take
days on a sufficiently large database.

Signed-off-by: Hank Donnay <hdonnay@redhat.com>

cmd/clairctl/admin.go

@@ -0,0 +1,135 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"regexp"
+
+	"github.com/jackc/pgx/v4"
+	"github.com/jackc/pgx/v4/pgxpool"
+	"github.com/quay/zlog"
+	"github.com/urfave/cli/v2"
+)
+
+// AdminCmd is the "admin" subcommand.
+var AdminCmd = &cli.Command{
+	Name:        "admin",
+	Description: "Various administrator tasks. May require additional privileges, cause data loss, or frighten small children.",
+	Usage:       "run administrator task",
+	Flags:       []cli.Flag{},
+	Category:    "Advanced",
+	Subcommands: []*cli.Command{
+		{
+			Name:        "pre",
+			Description: "Tasks that can be run in preparation for a Clair version",
+			Usage:       "run pre-upgrade task",
+			ArgsUsage:   "\b",
+			Subcommands: []*cli.Command{
+				{
+					Name:    "v4.7.0",
+					Aliases: []string{"4.7.0"},
+					Description: "This task does a `CONCURRENT` create of the `idx_manifest_index_manifest_id` index in the `indexer` database.\n" +
+						"This may take a long time if the indexer database has gotten large.\n\n" +
+						"The command will attempt to resume work if it is interrupted.",
+					Usage:  "create `idx_manifest_index_manifest_id` index in the `indexer` database",
+					Action: adminPre470,
+				},
+			},
+			Before: otherVersion,
+		},
+		{
+			Name:        "post",
+			Description: "Tasks that can be run after a Clair version is deployed",
+			Usage:       "run post-upgrade task",
+			ArgsUsage:   "\b",
+			Before:      otherVersion,
+		},
+		{
+			Name:        "oneoff",
+			Description: "Tasks that may be useful on occasion",
+			Usage:       "run one-off task",
+			ArgsUsage:   "\b",
+		},
+	},
+}
+
+// If the argument that would be interpreted as a subcommand is just a version
+// we don't know about, exit 0.
+func otherVersion(c *cli.Context) error {
+	args := c.Args()
+	if args.Len() != 1 {
+		return nil
+	}
+	n := args.First()
+	for _, cmd := range c.Command.VisibleCommands() {
+		if cmd.HasName(n) {
+			return nil
+		}
+	}
+	if verRegexp.MatchString(n) {
+		os.Exit(0)
+	}
+	return nil
+}
+
+// This is the semver regexp.
+var verRegexp = regexp.MustCompile(`^v?(?P<major>0|[1-9]\d*)\.(?P<minor>0|[1-9]\d*)\.(?P<patch>0|[1-9]\d*)(?:-(?P<prerelease>(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+(?P<buildmetadata>[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$`)
+
+// Attempt to build the giant index that the migrations in 4.7.0 check for.
+func adminPre470(c *cli.Context) error {
+	ctx := c.Context
+	fi, err := os.Stat(c.Path("config"))
+	switch {
+	case !errors.Is(err, nil):
+		return fmt.Errorf("bad config: %w", err)
+	case fi.IsDir():
+		return fmt.Errorf("bad config: is a directory")
+	}
+	cfg, err := loadConfig(c.Path("config"))
+	if err != nil {
+		return fmt.Errorf("error loading config: %w", err)
+	}
+	dsn := cfg.Indexer.ConnString
+	zlog.Info(ctx).
+		Str("dsn", dsn).
+		Msg("using discovered connnection string")
+
+	pgcfg, err := pgxpool.ParseConfig(dsn)
+	if err != nil {
+		return fmt.Errorf("error parsing dsn: %w", err)
+	}
+	zlog.Debug(ctx).
+		Msg("resizing pool to 2 connections")
+	pgcfg.MaxConns = 2
+	pool, err := pgxpool.ConnectConfig(ctx, pgcfg)
+	if err != nil {
+		return fmt.Errorf("error creating pool: %w", err)
+	}
+	defer pool.Close()
+	if err := pool.Ping(ctx); err != nil {
+		return fmt.Errorf("error connecting to database: %w", err)
+	}
+
+	return pool.AcquireFunc(ctx, func(conn *pgxpool.Conn) error {
+		const checkindex = `SELECT pg_index.indisvalid FROM pg_class, pg_index WHERE pg_index.indexrelid = pg_class.oid AND pg_class.relname = 'idx_manifest_index_manifest_id';`
+		const mkindex = `CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_manifest_index_manifest_id ON manifest_index(manifest_id);`
+		const reindex = `REINDEX INDEX CONCURRENTLY idx_manifest_index_manifest_id;`
+		var ok *bool
+		if err := conn.QueryRow(ctx, checkindex).Scan(ok); err != nil {
+			if !errors.Is(err, pgx.ErrNoRows) {
+				zlog.Info(ctx).
+					AnErr("index_check", err).
+					Msg("error checking index existence")
+			}
+		}
+		var query = mkindex
+		if ok != nil && !*ok { // If it exists but isn't valid:
+			query = reindex
+		}
+		if _, err := conn.Exec(ctx, query); err != nil {
+			return fmt.Errorf("error (re)indexing database: %w", err)
+		}
+		return nil
+	})
+}

cmd/clairctl/main.go

@@ -57,6 +57,7 @@ func main() {
 			ImportCmd,
 			DeleteCmd,
 			CheckConfigCmd,
+			AdminCmd,
 		},
 		Flags: []cli.Flag{
 			&cli.BoolFlag{