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Prevent overwriting existing host_uuid file
In some circumstances, multiple Teleport processes may be trying to write the host_uuid file in the same data directory simultaneously. The last of the writers would win, and any process using a host UUID that did not match what ended up on disk could get into a perpertual state of being unable to connect to the cluster. To avoid the raciness, the host_uuid file writing process is no longer a blind upsert. Instead, special care is taken to ensure that there can only be a single writer, and that any subsequent updates to the file are aborted and the first value written is used instead.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,61 @@ | ||
| // Teleport | ||
| // Copyright (C) 2024 Gravitational, Inc. | ||
| // | ||
| // This program is free software: you can redistribute it and/or modify | ||
| // it under the terms of the GNU Affero General Public License as published by | ||
| // the Free Software Foundation, either version 3 of the License, or | ||
| // (at your option) any later version. | ||
| // | ||
| // This program is distributed in the hope that it will be useful, | ||
| // but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| // GNU Affero General Public License for more details. | ||
| // | ||
| // You should have received a copy of the GNU Affero General Public License | ||
| // along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
|
|
||
| package hostid | ||
|
|
||
| import ( | ||
| "errors" | ||
| "io/fs" | ||
| "path/filepath" | ||
| "strings" | ||
|
|
||
| "github.com/gravitational/trace" | ||
|
|
||
| "github.com/gravitational/teleport/lib/utils" | ||
| ) | ||
|
|
||
| const ( | ||
| // FileName is the file name where the host UUID file is stored | ||
| FileName = "host_uuid" | ||
| ) | ||
|
|
||
| // GetPath returns the path to the host UUID file given the data directory. | ||
| func GetPath(dataDir string) string { | ||
| return filepath.Join(dataDir, FileName) | ||
| } | ||
|
|
||
| // ExistsLocally checks if dataDir/host_uuid file exists in local storage. | ||
| func ExistsLocally(dataDir string) bool { | ||
| _, err := ReadFile(dataDir) | ||
| return err == nil | ||
| } | ||
|
|
||
| // ReadFile reads host UUID from the file in the data dir | ||
| func ReadFile(dataDir string) (string, error) { | ||
| out, err := utils.ReadPath(GetPath(dataDir)) | ||
| if err != nil { | ||
| if errors.Is(err, fs.ErrPermission) { | ||
| //do not convert to system error as this loses the ability to compare that it is a permission error | ||
| return "", trace.Wrap(err) | ||
| } | ||
| return "", trace.ConvertSystemError(err) | ||
| } | ||
| id := strings.TrimSpace(string(out)) | ||
| if id == "" { | ||
| return "", trace.NotFound("host uuid is empty") | ||
| } | ||
| return id, nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,113 @@ | ||
| //go:build !windows | ||
|
|
||
| // Teleport | ||
| // Copyright (C) 2024 Gravitational, Inc. | ||
| // | ||
| // This program is free software: you can redistribute it and/or modify | ||
| // it under the terms of the GNU Affero General Public License as published by | ||
| // the Free Software Foundation, either version 3 of the License, or | ||
| // (at your option) any later version. | ||
| // | ||
| // This program is distributed in the hope that it will be useful, | ||
| // but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| // GNU Affero General Public License for more details. | ||
| // | ||
| // You should have received a copy of the GNU Affero General Public License | ||
| // along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
|
|
||
| package hostid_test | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "os" | ||
| "path/filepath" | ||
| "slices" | ||
| "strings" | ||
| "testing" | ||
|
|
||
| "github.com/google/uuid" | ||
| "github.com/stretchr/testify/require" | ||
| "golang.org/x/sync/errgroup" | ||
|
|
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| "github.com/gravitational/teleport/lib/utils" | ||
| "github.com/gravitational/teleport/lib/utils/hostid" | ||
| ) | ||
|
|
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| func TestMain(m *testing.M) { | ||
| utils.InitLoggerForTests() | ||
| os.Exit(m.Run()) | ||
| } | ||
|
|
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| func TestReadOrCreate(t *testing.T) { | ||
| t.Parallel() | ||
|
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| dir := t.TempDir() | ||
|
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| var wg errgroup.Group | ||
| concurrency := 10 | ||
| ids := make([]string, concurrency) | ||
| barrier := make(chan struct{}) | ||
|
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| for i := 0; i < concurrency; i++ { | ||
| wg.Go(func() error { | ||
| <-barrier | ||
| id, err := hostid.ReadOrCreateFile(dir) | ||
| ids[i] = id | ||
| return err | ||
| }) | ||
| } | ||
|
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| close(barrier) | ||
|
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| require.NoError(t, wg.Wait()) | ||
| require.Equal(t, slices.Repeat([]string{ids[0]}, concurrency), ids) | ||
| } | ||
|
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| func TestIdempotence(t *testing.T) { | ||
| t.Parallel() | ||
|
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| // call twice, get same result | ||
| dir := t.TempDir() | ||
| id, err := hostid.ReadOrCreateFile(dir) | ||
| require.Len(t, id, 36) | ||
| require.NoError(t, err) | ||
| uuidCopy, err := hostid.ReadOrCreateFile(dir) | ||
| require.NoError(t, err) | ||
| require.Equal(t, id, uuidCopy) | ||
| } | ||
|
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| func TestBadLocation(t *testing.T) { | ||
| t.Parallel() | ||
|
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| // call with a read-only dir, make sure to get an error | ||
| id, err := hostid.ReadOrCreateFile("/bad-location") | ||
| require.Empty(t, id) | ||
| require.Error(t, err) | ||
| require.Regexp(t, "^.*no such file or directory.*$", err.Error()) | ||
| } | ||
|
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| func TestIgnoreWhitespace(t *testing.T) { | ||
| t.Parallel() | ||
|
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| // newlines are getting ignored | ||
| dir := t.TempDir() | ||
| id := fmt.Sprintf("%s\n", uuid.NewString()) | ||
| err := os.WriteFile(filepath.Join(dir, hostid.FileName), []byte(id), 0666) | ||
| require.NoError(t, err) | ||
| out, err := hostid.ReadFile(dir) | ||
| require.NoError(t, err) | ||
| require.Equal(t, strings.TrimSpace(id), out) | ||
| } | ||
|
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| func TestRegenerateEmpty(t *testing.T) { | ||
| t.Parallel() | ||
|
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| // empty UUID in file is regenerated | ||
| dir := t.TempDir() | ||
| err := os.WriteFile(filepath.Join(dir, hostid.FileName), nil, 0666) | ||
| require.NoError(t, err) | ||
| out, err := hostid.ReadOrCreateFile(dir) | ||
| require.NoError(t, err) | ||
| require.Len(t, out, 36) | ||
| } |
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