Revert "Merge pull request 'Revert L3: its node-engine removed every held module on novox, the bus server among them (issue 774)' (#174) from revert/774-l3 into main"

This reverts commit 1ec73915b8, reversing
changes made to 0a4c35f731.

internal/selfcompose/selfcompose_test.go

@@ -3,6 +3,7 @@ package selfcompose
 import (
 	"context"
 	"crypto/sha256"
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
@@ -1221,6 +1222,32 @@ func TestTheNodeComposesItsWantsFromTheBus(t *testing.T) {
 		}
 	}
 	b.mu.Unlock()
+
+	// L3 s7 (ADR 0550 §2): the node asks the vault for its own certificate only when a module placed here asks for one
+	// and its record holds none from an authority it trusts; once per serving key.
+	certBus := newFakeBus()
+	certAsks := 0
+	certEnv := certBus.env()
+	certEnv.Certify = func(context.Context) error { certAsks++; return nil }
+	certEnv.VaultAuthority = func() string { return "" }
+	cc := New(certEnv)
+	withCert := `{"module":"web","version":"1","certificate":{"into":"/etc/web/tls.crt"}}`
+	cdigest := delivery.ManifestDigest([]byte(withCert))
+	cc.manifests[digest] = []byte(lemurs)
+	cc.manifests[cdigest] = []byte(withCert)
+	cc.modules = map[string]delivery.Module{"lemurs": {Manifest: digest}, "web": {Manifest: cdigest}}
+	cc.records["n1"] = delivery.NodeRecord{Node: "n1", ServingKey: base64.StdEncoding.EncodeToString(make([]byte, 32))}
+	onlyLemurs := delivery.Placement{Node: "n1", Modules: []delivery.PlacedModule{{Module: "lemurs"}}}
+	cc.certifyIfWanted(context.Background(), reader{c: cc}, onlyLemurs)
+	if certAsks != 0 {
+		t.Errorf("no module asks for a certificate, and the vault was asked %d times", certAsks)
+	}
+	withWeb := delivery.Placement{Node: "n1", Modules: []delivery.PlacedModule{{Module: "lemurs"}, {Module: "web"}}}
+	cc.certifyIfWanted(context.Background(), reader{c: cc}, withWeb)
+	cc.certifyIfWanted(context.Background(), reader{c: cc}, withWeb)
+	if certAsks != 1 {
+		t.Errorf("a module asks for a certificate: the vault was asked %d times, want once", certAsks)
+	}
 }
 
 // patternBus is a bus whose every watch gets the updates of its bucket matching its pattern, as the bus's own watches