Merge pull request #11697 from hashicorp/f-raft-state-err

cli: return error from raft commands if db is open

helper/raftutil/state.go

@@ -2,20 +2,38 @@ package raftutil
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
+	"time"
 
+	"github.com/boltdb/bolt"
 	"github.com/hashicorp/go-msgpack/codec"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/raft"
 	raftboltdb "github.com/hashicorp/raft-boltdb"
 )
 
+var (
+	errAlreadyOpen = errors.New("unable to open raft logs that are in use")
+)
+
 // RaftStateInfo returns info about the nomad state, as found in the passed data-dir directory
 func RaftStateInfo(p string) (store *raftboltdb.BoltStore, firstIdx uint64, lastIdx uint64, err error) {
-	s, err := raftboltdb.NewBoltStore(p)
+	opts := raftboltdb.Options{
+		Path: p,
+		BoltOptions: &bolt.Options{
+			ReadOnly: true,
+			Timeout:  1 * time.Second,
+		},
+	}
+	s, err := raftboltdb.New(opts)
 	if err != nil {
+		if strings.HasSuffix(err.Error(), "timeout") {
+			return nil, 0, 0, errAlreadyOpen
+		}
 		return nil, 0, 0, fmt.Errorf("failed to open raft logs: %v", err)
 	}
 

helper/raftutil/state_test.go

@@ -0,0 +1,52 @@
+package raftutil
+
+import (
+	"path/filepath"
+	"testing"
+
+	raftboltdb "github.com/hashicorp/raft-boltdb"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// TestRaftStateInfo_InUse asserts that commands that inspect raft
+// state such as "nomad operator raft info" and "nomad operator raft
+// logs" fail with a helpful error message when called on an inuse
+// database.
+func TestRaftStateInfo_InUse(t *testing.T) {
+	t.Parallel() // since there's a 1s timeout.
+
+	// First create an empty raft db
+	dir := filepath.Join(t.TempDir(), "raft.db")
+
+	fakedb, err := raftboltdb.NewBoltStore(dir)
+	require.NoError(t, err)
+
+	// Next try to read the db without closing it
+	s, _, _, err := RaftStateInfo(dir)
+	assert.Nil(t, s)
+	require.EqualError(t, err, errAlreadyOpen.Error())
+
+	// LogEntries should produce the same error
+	_, _, err = LogEntries(dir)
+	require.EqualError(t, err, "failed to open raft logs: "+errAlreadyOpen.Error())
+
+	// Commands should work once the db is closed
+	require.NoError(t, fakedb.Close())
+
+	s, _, _, err = RaftStateInfo(dir)
+	assert.NotNil(t, s)
+	require.NoError(t, err)
+	require.NoError(t, s.Close())
+
+	logCh, errCh, err := LogEntries(dir)
+	require.NoError(t, err)
+
+	// Consume entries to cleanly close db
+	for closed := false; closed; {
+		select {
+		case _, closed = <-logCh:
+		case <-errCh:
+		}
+	}
+}