httpcaddyfile: Fix generated config related to ACME global options

If global DNS provider is configured, it does not need to be repeated in the JSON.

If acme_* options are used, base automation policies should populate their issuers accordingly.

Global issuer settings like acme_* options don't need to specify subjects in the automation policy since they should apply as a global default.

caddyconfig/httpcaddyfile/tlsapp.go

@@ -571,6 +571,10 @@ func fillInGlobalACMEDefaults(issuer certmagic.Issuer, options map[string]any) e
 				return fmt.Errorf("acme_dns specified without DNS provider config, but no provider specified with 'dns' global option")
 			}
 		}
+		acmeIssuer.Challenges = &caddytls.ChallengesConfig{
+			DNS: new(caddytls.DNSChallengeConfig),
+		}
+	} else if globalACMEDNS != nil {
 		acmeIssuer.Challenges = &caddytls.ChallengesConfig{
 			DNS: &caddytls.DNSChallengeConfig{
 				ProviderRaw: caddyconfig.JSONModuleObject(globalACMEDNS, "name", globalACMEDNS.(caddy.Module).CaddyModule().ID.Name(), nil),
@@ -622,12 +626,18 @@ func newBaseAutomationPolicy(
 	_, hasLocalCerts := options["local_certs"]
 	keyType, hasKeyType := options["key_type"]
 	ocspStapling, hasOCSPStapling := options["ocsp_stapling"]
-
 	hasGlobalAutomationOpts := hasIssuers || hasLocalCerts || hasKeyType || hasOCSPStapling
 
+	globalACMECA := options["acme_ca"]
+	globalACMECARoot := options["acme_ca_root"]
+	_, globalACMEDNS := options["acme_dns"] // can be set to nil (to use globally-defined "dns" value instead), but it is still set
+	globalACMEEAB := options["acme_eab"]
+	globalPreferredChains := options["preferred_chains"]
+	hasGlobalACMEDefaults := globalACMECA != nil || globalACMECARoot != nil || globalACMEDNS || globalACMEEAB != nil || globalPreferredChains != nil
+
 	// if there are no global options related to automation policies
 	// set, then we can just return right away
-	if !hasGlobalAutomationOpts {
+	if !hasGlobalAutomationOpts && !hasGlobalACMEDefaults {
 		if always {
 			return new(caddytls.AutomationPolicy), nil
 		}
@@ -649,6 +659,14 @@ func newBaseAutomationPolicy(
 		ap.Issuers = []certmagic.Issuer{new(caddytls.InternalIssuer)}
 	}
 
+	if hasGlobalACMEDefaults {
+		for i := range ap.Issuers {
+			if err := fillInGlobalACMEDefaults(ap.Issuers[i], options); err != nil {
+				return nil, fmt.Errorf("filling in global issuer defaults for issuer %d: %v", i, err)
+			}
+		}
+	}
+
 	if hasOCSPStapling {
 		ocspConfig := ocspStapling.(certmagic.OCSPConfig)
 		ap.DisableOCSPStapling = ocspConfig.DisableStapling

caddytest/integration/caddyfile_adapt/acme_dns_naked_use_dns_defaults.caddyfiletest

@@ -34,17 +34,10 @@ example.com {
 			"automation": {
 				"policies": [
 					{
-						"subjects": [
-							"example.com"
-						],
 						"issuers": [
 							{
 								"challenges": {
-									"dns": {
+									"dns": {}
-										"provider": {
-											"name": "mock"
-										}
-									}
 								},
 								"module": "acme"
 							}

caddytest/integration/caddyfile_adapt/global_options_preferred_chains.caddyfiletest

@@ -31,9 +31,6 @@ example.com
 			"automation": {
 				"policies": [
 					{
-						"subjects": [
-							"example.com"
-						],
 						"issuers": [
 							{
 								"module": "acme",