| 1 | package activator |
| 2 | |
| 3 | import ( |
| 4 | "errors" |
| 5 | "fmt" |
| 6 | "os" |
| 7 | "path/filepath" |
| 8 | "strings" |
| 9 | |
| 10 | "github.com/carlosframework/platform/internal/instancefs" |
| 11 | "github.com/carlosframework/platform/internal/instancekey" |
| 12 | "github.com/carlosframework/platform/internal/registry" |
| 13 | ) |
| 14 | |
| 15 | // An import and the instance key (instancekey.go; merge review S1). |
| 16 | // |
| 17 | // The platform mints CARLOS_INSTANCE_KEY into the instance's own |
| 18 | // <host>.env at its first launch, create-only, and a key there outranks one |
| 19 | // the app's configuration sets (instancekey.Effective). An import's first |
| 20 | // launch is its verify request, so an import that is then aborted has left |
| 21 | // a key behind. Left in place it would outlive the rollback: a second |
| 22 | // import of the same host, whose owner configured the old process's key |
| 23 | // before verifying, would still be handed the first import's key, and the |
| 24 | // values the old process sealed would not open. |
| 25 | // |
| 26 | // So the swap records what the own env file held before the import |
| 27 | // (SeedEnvBefore, kept in the import journal), and the fenced rollback |
| 28 | // retires what the import created and nothing else (RetireSeedKey). |
| 29 | // |
| 30 | // Removing a minted key is within the key's rules. Create-only means a key |
| 31 | // is never replaced under data sealed with it. Here the data goes too: the |
| 32 | // rollback removes the import's database and deletes its replica, under the |
| 33 | // same fence. <host>.env is an installation artifact, retired with its |
| 34 | // installation, as a move retires it on the box it leaves. |
| 35 | |
| 36 | // seedEnvDir is the directory holding the own env file of the nested row |
| 37 | // whose database is dbPath, and the file's name. |
| 38 | func seedEnvDir(dbPath, host string) (dir, name string, err error) { |
| 39 | dir, _, err = splitDBPath(dbPath) |
| 40 | if err != nil { |
| 41 | return "", "", err |
| 42 | } |
| 43 | if host == "" || host != filepath.Base(host) { |
| 44 | return "", "", fmt.Errorf("activator: %q is not a host name", host) |
| 45 | } |
| 46 | return dir, host + ".env", nil |
| 47 | } |
| 48 | |
| 49 | // SeedEnvBefore reports what the own env file of the nested row at dbPath |
| 50 | // holds now, as one of registry's EnvBefore values: no file, a file with no |
| 51 | // instance key, or a file that carries one. The swap calls it before the |
| 52 | // import's row exists, so before anything can launch the import. The file |
| 53 | // is read through instancefs, as every nested read of it is. A file that |
| 54 | // cannot be read (a link, a FIFO, over the limit) is an error: the caller |
| 55 | // cannot tell, and does not swap. |
| 56 | func SeedEnvBefore(dbPath, host string) (string, error) { |
| 57 | dir, name, err := seedEnvDir(dbPath, host) |
| 58 | if err != nil { |
| 59 | return "", err |
| 60 | } |
| 61 | adminTokenMu.Lock() |
| 62 | defer adminTokenMu.Unlock() |
| 63 | raw, exists, err := readSeedEnv(dir, name) |
| 64 | switch { |
| 65 | case err != nil: |
| 66 | return "", err |
| 67 | case !exists: |
| 68 | return registry.EnvBeforeAbsent, nil |
| 69 | case parseEnvBytes(raw)[InstanceKeyVar] != "": |
| 70 | return registry.EnvBeforeKey, nil |
| 71 | } |
| 72 | return registry.EnvBeforeNoKey, nil |
| 73 | } |
| 74 | |
| 75 | // readSeedEnv reads dir/name beneath dir. An instance directory that is not |
| 76 | // there holds no file. |
| 77 | func readSeedEnv(dir, name string) (raw []byte, exists bool, err error) { |
| 78 | if _, err := os.Lstat(dir); errors.Is(err, os.ErrNotExist) { |
| 79 | return nil, false, nil |
| 80 | } |
| 81 | raw, err = instancefs.ReadBeneathLimit(dir, name, ownEnvReadLimit) |
| 82 | if errors.Is(err, os.ErrNotExist) { |
| 83 | return nil, false, nil |
| 84 | } |
| 85 | if err != nil { |
| 86 | return nil, false, fmt.Errorf("read %s: %w", filepath.Join(dir, name), err) |
| 87 | } |
| 88 | return raw, true, nil |
| 89 | } |
| 90 | |
| 91 | // RetireSeedKey retires the instance key an import created, for the nested |
| 92 | // row at dbPath, by what the swap recorded (before): |
| 93 | // |
| 94 | // - EnvBeforeAbsent: there was no env file, so the one there now is the |
| 95 | // import's whole. It is removed, and with it the adoption record beside |
| 96 | // it, which belongs to the same installation. |
| 97 | // - EnvBeforeNoKey: the file was there with no key. Its CARLOS_INSTANCE_KEY |
| 98 | // lines are the import's and are removed; every other line stays, byte |
| 99 | // for byte. |
| 100 | // - EnvBeforeKey: the key was there before the import. Nothing is touched. |
| 101 | // - "": the journal row predates the record. Nothing is known, and nothing |
| 102 | // is touched. |
| 103 | // |
| 104 | // The caller holds the host fenced and stopped (the import rollback's step |
| 105 | // 3), so no launch reads the file meanwhile; adminTokenMu keeps the |
| 106 | // startup backfill's append out. It is idempotent: a second run finds |
| 107 | // nothing of the import's left. |
| 108 | func RetireSeedKey(dbPath, host, before string) error { |
| 109 | switch before { |
| 110 | case registry.EnvBeforeAbsent, registry.EnvBeforeNoKey: |
| 111 | case registry.EnvBeforeKey, "": |
| 112 | return nil |
| 113 | default: |
| 114 | return fmt.Errorf("activator: %s: %q is not a recorded env state", host, before) |
| 115 | } |
| 116 | dir, name, err := seedEnvDir(dbPath, host) |
| 117 | if err != nil { |
| 118 | return err |
| 119 | } |
| 120 | adminTokenMu.Lock() |
| 121 | defer adminTokenMu.Unlock() |
| 122 | if _, err := os.Lstat(dir); errors.Is(err, os.ErrNotExist) { |
| 123 | return nil |
| 124 | } |
| 125 | if before == registry.EnvBeforeAbsent { |
| 126 | for _, n := range []string{name, host + instancekey.AdoptionSuffix} { |
| 127 | if err := instancefs.RemoveAllBeneath(dir, n); err != nil { |
| 128 | return fmt.Errorf("retire %s: %w", filepath.Join(dir, n), err) |
| 129 | } |
| 130 | } |
| 131 | return syncDir(dir) |
| 132 | } |
| 133 | raw, exists, err := readSeedEnv(dir, name) |
| 134 | if err != nil || !exists { |
| 135 | return err |
| 136 | } |
| 137 | kept, removed := withoutInstanceKey(raw) |
| 138 | if !removed { |
| 139 | return nil |
| 140 | } |
| 141 | if err := instancefs.WriteAtomic(dir, name, kept, 0o600); err != nil { |
| 142 | return fmt.Errorf("retire the instance key in %s: %w", filepath.Join(dir, name), err) |
| 143 | } |
| 144 | return syncDir(dir) |
| 145 | } |
| 146 | |
| 147 | // withoutInstanceKey is raw with every line that sets CARLOS_INSTANCE_KEY |
| 148 | // removed, by instancekey.ParseEnv's reading of a line; the other lines are |
| 149 | // kept exactly. removed is whether any line went. |
| 150 | func withoutInstanceKey(raw []byte) (kept []byte, removed bool) { |
| 151 | lines := strings.Split(string(raw), "\n") |
| 152 | out := lines[:0] |
| 153 | for _, line := range lines { |
| 154 | t := strings.TrimSpace(line) |
| 155 | if t != "" && !strings.HasPrefix(t, "#") { |
| 156 | if k, _, ok := strings.Cut(t, "="); ok && strings.TrimSpace(k) == InstanceKeyVar { |
| 157 | removed = true |
| 158 | continue |
| 159 | } |
| 160 | } |
| 161 | out = append(out, line) |
| 162 | } |
| 163 | return []byte(strings.Join(out, "\n")), removed |
| 164 | } |
| 165 | |
amadan