Move service hash logic to Service.Hash method

command/agent/consul/client.go

@@ -1023,20 +1023,7 @@ func makeAgentServiceID(role string, service *structs.Service) string {
 //
 //	Example Service ID: _nomad-task-TNM333JKJPM5AK4FAS3VXQLXFDWOF4VH
 func makeTaskServiceID(allocID, taskName string, service *structs.Service) string {
-	h := sha1.New()
-	io.WriteString(h, allocID)
-	io.WriteString(h, taskName)
-	io.WriteString(h, service.Name)
-	io.WriteString(h, service.PortLabel)
-	io.WriteString(h, service.AddressMode)
-	for _, tag := range service.Tags {
-		io.WriteString(h, tag)
-	}
-
-	// Base32 is used for encoding the hash as sha1 hashes can always be
-	// encoded without padding, only 4 bytes larger than base64, and saves
-	// 8 bytes vs hex.
-	return nomadTaskPrefix + base32.StdEncoding.EncodeToString(h.Sum(nil))
+	return nomadTaskPrefix + service.Hash(allocID, taskName)
 }
 
 // makeCheckID creates a unique ID for a check.

nomad/structs/structs.go

@@ -6,6 +6,7 @@ import (
 	"crypto/sha1"
 	"crypto/sha256"
 	"crypto/sha512"
+	"encoding/base32"
 	"encoding/hex"
 	"errors"
 	"fmt"
@@ -3140,6 +3141,26 @@ func (s *Service) ValidateName(name string) error {
 	return nil
 }
 
+// Hash returns a base32 encoded hash of a Service's contents excluding checks
+// as they're hashed independently.
+func (s *Service) Hash(allocID, taskName string) string {
+	h := sha1.New()
+	io.WriteString(h, allocID)
+	io.WriteString(h, taskName)
+	io.WriteString(h, s.Name)
+	io.WriteString(h, s.PortLabel)
+	io.WriteString(h, s.AddressMode)
+	for _, tag := range s.Tags {
+		io.WriteString(h, tag)
+	}
+
+	// Base32 is used for encoding the hash as sha1 hashes can always be
+	// encoded without padding, only 4 bytes larger than base64, and saves
+	// 8 bytes vs hex. Since these hashes are used in Consul URLs it's nice
+	// to have a reasonably compact URL-safe representation.
+	return base32.StdEncoding.EncodeToString(h.Sum(nil))
+}
+
 const (
 	// DefaultKillTimeout is the default timeout between signaling a task it
 	// will be killed and killing it.