GEN2-021: add independent supervisor lifeboat

cmd/supervisor/main.go

@@ -0,0 +1,10 @@
+package main
+
+import "net/http"
+
+func main() {
+	_ = http.ListenAndServe(":8088", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("lifeboat-ready\n"))
+	}))
+}

dev/ACTIVE_TASK.json

@@ -1 +1 @@
-{"task_file":"dev/tasks/GEN2-020-separate-execution-receipt-from-verified-world-outcome.json","task_id":"GEN2-020","task_revision":1}
+{"task_file":"dev/tasks/GEN2-021-add-independent-supervisor-lifeboat-for-release-health-and-rollback.json","task_id":"GEN2-021","task_revision":1}

runtime/supervisor/supervisor.go

@@ -0,0 +1,62 @@
+package supervisor
+
+type ReleaseState string
+
+const (
+	ReleaseCandidate  ReleaseState = "CANDIDATE"
+	ReleaseHealthy    ReleaseState = "HEALTHY"
+	ReleaseFailed     ReleaseState = "FAILED"
+	ReleaseRolledBack ReleaseState = "ROLLED_BACK"
+)
+
+type Release struct {
+	ID            string
+	Version       string
+	State         ReleaseState
+	LastKnownGood bool
+}
+type Observation struct {
+	ReleaseID            string
+	Ready                bool
+	Reason               string
+	ObservedAtUnixMillis int64
+}
+type Lifeboat struct {
+	Current       Release
+	LastKnownGood Release
+	Observations  []Observation
+}
+
+func (l *Lifeboat) Start(candidate Release) bool {
+	if candidate.ID == "" || candidate.Version == "" {
+		return false
+	}
+	candidate.State = ReleaseCandidate
+	l.Current = candidate
+	return true
+}
+func (l *Lifeboat) Record(o Observation) bool {
+	if o.ReleaseID == "" {
+		return false
+	}
+	l.Observations = append(l.Observations, o)
+	if o.ReleaseID != l.Current.ID {
+		return true
+	}
+	if o.Ready {
+		l.Current.State = ReleaseHealthy
+		l.Current.LastKnownGood = true
+		l.LastKnownGood = l.Current
+	} else {
+		l.Current.State = ReleaseFailed
+	}
+	return true
+}
+func (l *Lifeboat) Rollback() bool {
+	if l.LastKnownGood.ID == "" {
+		return false
+	}
+	l.Current = l.LastKnownGood
+	l.Current.State = ReleaseRolledBack
+	return true
+}

runtime/supervisor/supervisor_test.go

@@ -0,0 +1,17 @@
+package supervisor_test
+
+import (
+	"git.cin.su/m/Assistant/runtime/supervisor"
+	"testing"
+)
+
+func TestLifeboatRollsBackCandidateToLastKnownGood(t *testing.T) {
+	l := supervisor.Lifeboat{}
+	l.Start(supervisor.Release{ID: "good", Version: "1"})
+	l.Record(supervisor.Observation{ReleaseID: "good", Ready: true})
+	l.Start(supervisor.Release{ID: "candidate", Version: "2"})
+	l.Record(supervisor.Observation{ReleaseID: "candidate", Ready: false})
+	if !l.Rollback() || l.Current.ID != "good" || l.Current.State != supervisor.ReleaseRolledBack {
+		t.Fatalf("%#v", l)
+	}
+}