Take a container left set aside as the next apply's, and bound an apply to 30 minutes (issue 1945)

cmd/mesh-host/apply_context_test.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"testing"
+	"time"
 )
 
 // An apply runs in a context the bus's loss cannot end: the link's context ends when the bus goes, and the bus may go
@@ -12,7 +13,8 @@ import (
 func TestAnApplyOutlivesTheLinksContext(t *testing.T) {
 	type key struct{}
 	link, cancel := context.WithCancel(context.WithValue(context.Background(), key{}, "v"))
-	ctx := applyContext(link)
+	ctx, done := applyContext(link)
+	defer done()
 	cancel()
 	if ctx.Err() != nil {
 		t.Fatalf("the apply's context ended with the link's: %v", ctx.Err())
@@ -21,3 +23,17 @@ func TestAnApplyOutlivesTheLinksContext(t *testing.T) {
 		t.Fatal("the apply's context lost the link's values")
 	}
 }
+
+// An apply is bounded all the same: a step that hangs (a docker call that never returns) cannot hold the node agent for
+// ever (the review of issue 1945).
+func TestAnApplyIsBounded(t *testing.T) {
+	ctx, done := applyContext(context.Background())
+	defer done()
+	at, ok := ctx.Deadline()
+	if !ok {
+		t.Fatal("an apply has no bound")
+	}
+	if left := time.Until(at); left > applyBound || left < applyBound-time.Minute {
+		t.Fatalf("the bound is %s away, want about %s", left, applyBound)
+	}
+}