httpcaddyfile, caddytls: Multiple edge case fixes; add tests

- Create two default automation policies; if the TLS app is used in
  isolation with the 'automate' certificate loader, it will now use
  an internal issuer for internal-only names, and an ACME issuer for
  all other names by default.
- If the HTTP Caddyfile adds an 'automate' loader, it now also adds an
  automation policy for any names in that loader that do not qualify
  for public certificates so that they will be issued internally. (It
  might be nice if this wasn't necessary, but the alternative is to
  either make auto-HTTPS logic way more complex by scanning the names in
  the 'automate' loader, or to have an automation policy without an
  issuer switch between default issuer based on the name being issued
  a certificate - I think I like the latter option better, right now we
  do something kind of like that but at a level above each individual
  automation policies, we do that switch only when no automation
  policies match, rather than when a policy without an issuer does
  match.)
- Set the default LoggerName rather than a LoggerNames with an empty
  host value, which is now taken literally rather than as a catch-all.
- hostsFromKeys, the function that gets a list of hosts from server
  block keys, no longer returns an empty string in its resulting slice,
  ever.

2 files changed, 22 insertions, 6 deletions

diff --git a/modules/caddytls/automation.go b/modules/caddytls/automation.go
index 22cf20b..87e6b28 100644
--- a/modules/caddytls/automation.go
+++ b/modules/caddytls/automation.go
@@ -53,7 +53,8 @@ type AutomationConfig struct {
 	// a low value.
 	RenewCheckInterval caddy.Duration `json:"renew_interval,omitempty"`
 
-	defaultAutomationPolicy *AutomationPolicy
+	defaultPublicAutomationPolicy   *AutomationPolicy
+	defaultInternalAutomationPolicy *AutomationPolicy
 }
 
 // AutomationPolicy designates the policy for automating the
@@ -67,7 +68,8 @@ type AutomationPolicy struct {
 	// Which subjects (hostnames or IP addresses) this policy applies to.
 	Subjects []string `json:"subjects,omitempty"`
 
-	// The module that will issue certificates. Default: acme
+	// The module that will issue certificates. Default: internal if all
+	// subjects do not qualify for public certificates; othewise acme.
 	IssuerRaw json.RawMessage `json:"issuer,omitempty" caddy:"namespace=tls.issuance inline_key=module"`
 
 	// If true, certificates will be requested with MustStaple. Not all
diff --git a/modules/caddytls/tls.go b/modules/caddytls/tls.go
index 54f0e23..1255d3d 100644
--- a/modules/caddytls/tls.go
+++ b/modules/caddytls/tls.go
@@ -93,10 +93,17 @@ func (t *TLS) Provision(ctx caddy.Context) error {
 	if t.Automation == nil {
 		t.Automation = new(AutomationConfig)
 	}
-	t.Automation.defaultAutomationPolicy = new(AutomationPolicy)
-	err := t.Automation.defaultAutomationPolicy.Provision(t)
+	t.Automation.defaultPublicAutomationPolicy = new(AutomationPolicy)
+	err := t.Automation.defaultPublicAutomationPolicy.Provision(t)
 	if err != nil {
-		return fmt.Errorf("provisioning default automation policy: %v", err)
+		return fmt.Errorf("provisioning default public automation policy: %v", err)
+	}
+	t.Automation.defaultInternalAutomationPolicy = &AutomationPolicy{
+		IssuerRaw: json.RawMessage(`{"module":"internal"}`),
+	}
+	err = t.Automation.defaultInternalAutomationPolicy.Provision(t)
+	if err != nil {
+		return fmt.Errorf("provisioning default internal automation policy: %v", err)
 	}
 	for i, ap := range t.Automation.Policies {
 		err := ap.Provision(t)
@@ -318,6 +325,10 @@ func (t *TLS) getConfigForName(name string) *certmagic.Config {
 	return ap.magic
 }
 
+// getAutomationPolicyForName returns the first matching automation policy
+// for the given subject name. If no matching policy can be found, the
+// default policy is used, depending on whether the name qualifies for a
+// public certificate or not.
 func (t *TLS) getAutomationPolicyForName(name string) *AutomationPolicy {
 	for _, ap := range t.Automation.Policies {
 		if len(ap.Subjects) == 0 {
@@ -329,7 +340,10 @@ func (t *TLS) getAutomationPolicyForName(name string) *AutomationPolicy {
 			}
 		}
 	}
-	return t.Automation.defaultAutomationPolicy
+	if certmagic.SubjectQualifiesForPublicCert(name) {
+		return t.Automation.defaultPublicAutomationPolicy
+	}
+	return t.Automation.defaultInternalAutomationPolicy
 }
 
 // AllMatchingCertificates returns the list of all certificates in