Adds a snapshot agent stub to the config structure.

Fixes #3678

agent/config/config.go

@@ -234,6 +234,12 @@ type Config struct {
 	VerifyServerHostname        *bool                    `json:"verify_server_hostname,omitempty" hcl:"verify_server_hostname" mapstructure:"verify_server_hostname"`
 	Watches                     []map[string]interface{} `json:"watches,omitempty" hcl:"watches" mapstructure:"watches"`
 
+	// This isn't used by Consul but we've documented a feature where users
+	// can deploy their snapshot agent configs alongside their Consul configs
+	// so we have a placeholder here so it can be parsed but this doesn't
+	// manifest itself in any way inside the runtime config.
+	SnapshotAgent map[string]interface{} `json:"snapshot_agent,omitempty" hcl:"snapshot_agent" mapstructure:"snapshot_agent"`
+
 	// non-user configurable values
 	ACLDisabledTTL             *string  `json:"acl_disabled_ttl,omitempty" hcl:"acl_disabled_ttl" mapstructure:"acl_disabled_ttl"`
 	AEInterval                 *string  `json:"ae_interval,omitempty" hcl:"ae_interval" mapstructure:"ae_interval"`

agent/config/runtime_test.go

@@ -1194,6 +1194,7 @@ func TestConfigFlagsAndEdgecases(t *testing.T) {
 		// ------------------------------------------------------------
 		// transformations
 		//
+
 		{
 			desc: "raft performance scaling",
 			args: []string{`-data-dir=` + dataDir},
@@ -1922,6 +1923,21 @@ func TestConfigFlagsAndEdgecases(t *testing.T) {
 				rt.DataDir = dataDir
 			},
 		},
+		{
+			desc: "ignore snapshot_agent sub-object",
+			args: []string{
+				`-data-dir=` + dataDir,
+			},
+			json: []string{
+				`{ "snapshot_agent": { "dont": "care" } }`,
+			},
+			hcl: []string{
+				`snapshot_agent = { dont = "care" }`,
+			},
+			patch: func(rt *RuntimeConfig) {
+				rt.DataDir = dataDir
+			},
+		},
 	}
 
 	testConfig(t, tests, dataDir)