Do a large chunk of the move to go

This commit moves a huge chunk of the code to go. The TODO.md document
indicates what is left to be done.

env/stack_resolver.go

@@ -0,0 +1,39 @@
+package env
+
+import (
+	"path/filepath"
+	"strings"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/stack"
+)
+
+const ResolverPrefixFile = "prefix.cfg"
+
+func (dis *Distillery) ResolverStack() stack.Installable {
+	stack := dis.asCoreStack(stack.Installable{
+		Stack: stack.Stack{
+			Name: "resolver",
+		},
+
+		EnvFileContext: map[string]string{
+			"VIRTUAL_HOST":      dis.DefaultVirtualHost(),
+			"LETSENCRYPT_HOST":  dis.DefaultLetsencryptHost(),
+			"LETSENCRYPT_EMAIL": dis.Config.CertbotEmail,
+			"PREFIX_FILE":       "", // set below!
+			"DEFAULT_DOMAIN":    dis.Config.DefaultDomain,
+			"LEGACY_DOMAIN":     strings.Join(dis.Config.SelfExtraDomains, ","),
+		},
+
+		TouchFiles: []string{ResolverPrefixFile},
+	})
+	stack.EnvFileContext["PREFIX_FILE"] = filepath.Join(stack.Dir, ResolverPrefixFile)
+	return stack
+}
+
+func (dis *Distillery) ResolverStackPath() string {
+	return dis.ResolverStack().Dir
+}
+
+func (dis Distillery) ResolverPrefixConfig() string {
+	return filepath.Join(dis.ResolverStackPath(), ResolverPrefixFile)
+}