m/n/time: add time service
This adds a bare-minimum time service based on chrony/NTP for keeping
the system clock and RTC on Metropolis nodes accurate.
It also introduces a UID/GID registry in the Metropolis node code
as this is the first unprivileged service to run on the node itself.
It does not yet use a secure time source, this is tracked as #73.
Change-Id: I873971e6d3825709bc8c696e227bece4cfbda93a
Reviewed-on: https://review.monogon.dev/c/monogon/+/319
Reviewed-by: Sergiusz Bazanski <serge@monogon.tech>
diff --git a/metropolis/node/core/time/time.go b/metropolis/node/core/time/time.go
new file mode 100644
index 0000000..6c2e906
--- /dev/null
+++ b/metropolis/node/core/time/time.go
@@ -0,0 +1,60 @@
+// Package time implements a supervisor runnable which is responsible for
+// keeping both the system clock and the RTC accurate.
+// Metropolis nodes need accurate time both for themselves (for log
+// timestamping, validating certain certificates, ...) as well as workloads
+// running on top of it expecting accurate time.
+// This initial implementation is very minimalistic, running just a stateless
+// NTP client per node for the whole lifecycle of it.
+// This implementation is simple, but is fairly unsafe as NTP by itself does
+// not offer any cryptography, so it's easy to tamper with the responses.
+// See #73 for further work in that direction.
+package time
+
+import (
+ "context"
+ "fmt"
+ "os/exec"
+ "strconv"
+ "strings"
+
+ "source.monogon.dev/metropolis/node"
+ "source.monogon.dev/metropolis/pkg/fileargs"
+ "source.monogon.dev/metropolis/pkg/supervisor"
+)
+
+// Service implements the time service. See package documentation for further
+// information.
+type Service struct{}
+
+func New() *Service {
+ return &Service{}
+}
+
+func (s *Service) Run(ctx context.Context) error {
+ // TODO(#72): Apply for a NTP pool vendor zone
+ config := strings.Join([]string{
+ "pool pool.ntp.org iburst",
+ "bindcmdaddress /",
+ "stratumweight 0.01",
+ "leapsecmode slew",
+ "maxslewrate 10000",
+ "makestep 2.0 3",
+ "rtconutc",
+ "rtcsync",
+ }, "\n")
+ args, err := fileargs.New()
+ if err != nil {
+ return fmt.Errorf("cannot create fileargs: %w", err)
+ }
+ defer args.Close()
+ cmd := exec.Command(
+ "/time/chrony",
+ "-d",
+ "-i", strconv.Itoa(node.TimeUid),
+ "-g", strconv.Itoa(node.TimeUid),
+ "-f", args.ArgPath("chrony.conf", []byte(config)),
+ )
+ cmd.Stdout = supervisor.RawLogger(ctx)
+ cmd.Stderr = supervisor.RawLogger(ctx)
+ return supervisor.RunCommand(ctx, cmd)
+}