| 1 | package instanceexec |
| 2 | |
| 3 | import ( |
| 4 | "encoding/json" |
| 5 | "errors" |
| 6 | "flag" |
| 7 | "fmt" |
| 8 | "log" |
| 9 | "os" |
| 10 | "path/filepath" |
| 11 | "regexp" |
| 12 | "time" |
| 13 | |
| 14 | "github.com/carlosframework/platform/internal/cliflag" |
| 15 | "github.com/carlosframework/platform/internal/instancectl" |
| 16 | "github.com/carlosframework/platform/internal/instancefs" |
| 17 | "github.com/carlosframework/platform/internal/provision" |
| 18 | ) |
| 19 | |
| 20 | // invocationShape is systemd's 128-bit invocation id as 32 hex digits. The |
| 21 | // id becomes part of a file name, so anything else is refused before it can |
| 22 | // name a path. |
| 23 | var invocationShape = regexp.MustCompile(`^[0-9a-f]{32}$`) |
| 24 | |
| 25 | // RunExit is `carlos instance-exit <role> <iid>`, the ExecStopPost= of every |
| 26 | // template unit. It runs inside the namespace as carlos with systemd's |
| 27 | // $INVOCATION_ID, $SERVICE_RESULT, $EXIT_CODE and $EXIT_STATUS, and leaves |
| 28 | // the advisory exit record in the instance's own run directory (design |
| 29 | // §6.5). It never fails the unit: a stop that could not be recorded is |
| 30 | // still a stop, and the agent proves termination from unit state and the |
| 31 | // cgroup, not from this file. |
| 32 | func RunExit(args []string) { |
| 33 | fs := flag.NewFlagSet("instance-exit", flag.ExitOnError) |
| 34 | runDir := fs.String("run-dir", provision.SocketDir, "run directory holding instances/<id>") |
| 35 | fs.Usage = cliflag.Usage(fs, "usage: carlos instance-exit <run|seed|sidecar|cmd> <instance-id>") |
| 36 | _ = fs.Parse(args) |
| 37 | if fs.NArg() != 2 { |
| 38 | fs.Usage() |
| 39 | os.Exit(2) |
| 40 | } |
| 41 | role, ok := instancectl.ParseRole(fs.Arg(0)) |
| 42 | if !ok { |
| 43 | log.Printf("instance-exit: role %q is not run, seed, sidecar or cmd", fs.Arg(0)) |
| 44 | return |
| 45 | } |
| 46 | if err := writeExitRecord(*runDir, role, fs.Arg(1), os.Getenv, time.Now()); err != nil { |
| 47 | log.Printf("instance-exit: %v", err) |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | // writeExitRecord writes exit.<role>.<invocation>.json with O_EXCL into |
| 52 | // <runDir>/instances/<iid>. A missing invocation id is a no-op (the |
| 53 | // variables are systemd's to provide); a malformed one is an error. |
| 54 | func writeExitRecord(runDir string, role instancectl.Role, inst string, env func(string) string, now time.Time) error { |
| 55 | inv := env("INVOCATION_ID") |
| 56 | if inv == "" { |
| 57 | return nil |
| 58 | } |
| 59 | if !invocationShape.MatchString(inv) { |
| 60 | return fmt.Errorf("INVOCATION_ID %q is not 32 hex digits", inv) |
| 61 | } |
| 62 | iid, name, err := recordTarget(role, inst, inv) |
| 63 | if err != nil { |
| 64 | return err |
| 65 | } |
| 66 | rec := instancectl.ExitRecord{ |
| 67 | Invocation: inv, |
| 68 | Result: env("SERVICE_RESULT"), |
| 69 | Code: env("EXIT_CODE"), |
| 70 | Status: env("EXIT_STATUS"), |
| 71 | At: now.UTC(), |
| 72 | } |
| 73 | raw, err := json.MarshalIndent(rec, "", " ") |
| 74 | if err != nil { |
| 75 | return err |
| 76 | } |
| 77 | raw = append(raw, '\n') |
| 78 | dir := filepath.Join(runDir, "instances", iid) |
| 79 | // 0600: this record carries SERVICE_RESULT/EXIT_CODE/EXIT_STATUS from |
| 80 | // systemd, which is diagnostic detail about the instance's own process, |
| 81 | // not something every reader of the instance directory needs (final |
| 82 | // review, plan 2, item 6). |
| 83 | f, err := instancefs.OpenBeneath(dir, name, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o600) |
| 84 | if err != nil { |
| 85 | if errors.Is(err, os.ErrExist) { |
| 86 | return fmt.Errorf("record for invocation %s already exists", inv) |
| 87 | } |
| 88 | return err |
| 89 | } |
| 90 | if _, err := f.Write(raw); err != nil { |
| 91 | f.Close() |
| 92 | return err |
| 93 | } |
| 94 | return f.Close() |
| 95 | } |
| 96 | |
amadan