Ensure that config entry writes are forwarded to the primary DC (#6339)

agent/consul/config_endpoint.go

@@ -19,6 +19,10 @@ type ConfigEntry struct {
 
 // Apply does an upsert of the given config entry.
 func (c *ConfigEntry) Apply(args *structs.ConfigEntryRequest, reply *bool) error {
+	// Ensure that all config entry writes go to the primary datacenter. These will then
+	// be replicated to all the other datacenters.
+	args.Datacenter = c.srv.config.PrimaryDatacenter
+
 	if done, err := c.srv.forward("ConfigEntry.Apply", args, args, reply); done {
 		return err
 	}
@@ -181,6 +185,10 @@ func (c *ConfigEntry) ListAll(args *structs.DCSpecificRequest, reply *structs.In
 
 // Delete deletes a config entry.
 func (c *ConfigEntry) Delete(args *structs.ConfigEntryRequest, reply *struct{}) error {
+	// Ensure that all config entry writes go to the primary datacenter. These will then
+	// be replicated to all the other datacenters.
+	args.Datacenter = c.srv.config.PrimaryDatacenter
+
 	if done, err := c.srv.forward("ConfigEntry.Delete", args, args, reply); done {
 		return err
 	}

agent/consul/config_endpoint_test.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/hashicorp/consul/acl"
 	"github.com/hashicorp/consul/agent/structs"
+	"github.com/hashicorp/consul/sdk/testutil/retry"
 	"github.com/hashicorp/consul/testrpc"
 	msgpackrpc "github.com/hashicorp/net-rpc-msgpackrpc"
 	"github.com/stretchr/testify/require"
@@ -15,34 +16,59 @@ import (
 func TestConfigEntry_Apply(t *testing.T) {
 	t.Parallel()
 
-	require := require.New(t)
-
 	dir1, s1 := testServer(t)
 	defer os.RemoveAll(dir1)
 	defer s1.Shutdown()
 	codec := rpcClient(t, s1)
 	defer codec.Close()
 
+	testrpc.WaitForLeader(t, s1.RPC, "dc1")
+
+	dir2, s2 := testServerWithConfig(t, func(c *Config) {
+		c.Datacenter = "dc2"
+		c.PrimaryDatacenter = "dc1"
+	})
+	defer os.RemoveAll(dir2)
+	defer s2.Shutdown()
+	codec2 := rpcClient(t, s2)
+	defer codec2.Close()
+
+	testrpc.WaitForLeader(t, s2.RPC, "dc2")
+	joinWAN(t, s2, s1)
+	// wait for cross-dc queries to work
+	testrpc.WaitForLeader(t, s2.RPC, "dc1")
+
 	updated := &structs.ServiceConfigEntry{
 		Name: "foo",
 	}
-
+	// originally target this as going to dc2
 	args := structs.ConfigEntryRequest{
-		Datacenter: "dc1",
+		Datacenter: "dc2",
 		Entry:      updated,
 	}
 	out := false
-	require.NoError(msgpackrpc.CallWithCodec(codec, "ConfigEntry.Apply", &args, &out))
+	require.NoError(t, msgpackrpc.CallWithCodec(codec2, "ConfigEntry.Apply", &args, &out))
-	require.True(out)
+	require.True(t, out)
 
+	// the previous RPC should not return until the primary has been updated but will return
+	// before the secondary has the data.
 	state := s1.fsm.State()
 	_, entry, err := state.ConfigEntry(nil, structs.ServiceDefaults, "foo")
-	require.NoError(err)
+	require.NoError(t, err)
 
 	serviceConf, ok := entry.(*structs.ServiceConfigEntry)
-	require.True(ok)
+	require.True(t, ok)
-	require.Equal("foo", serviceConf.Name)
+	require.Equal(t, "foo", serviceConf.Name)
-	require.Equal(structs.ServiceDefaults, serviceConf.Kind)
+	require.Equal(t, structs.ServiceDefaults, serviceConf.Kind)
+
+	retry.Run(t, func(r *retry.R) {
+		// wait for replication to happen
+		state := s2.fsm.State()
+		_, entry, err := state.ConfigEntry(nil, structs.ServiceDefaults, "foo")
+		require.NoError(r, err)
+		require.NotNil(r, entry)
+		// this test is not testing that the config entries that are replicated are correct as thats done elsewhere.
+	})
 
 	updated = &structs.ServiceConfigEntry{
 		Name: "foo",
@@ -57,23 +83,23 @@ func TestConfigEntry_Apply(t *testing.T) {
 		Entry:      updated,
 	}
 
-	require.NoError(msgpackrpc.CallWithCodec(codec, "ConfigEntry.Apply", &args, &out))
+	require.NoError(t, msgpackrpc.CallWithCodec(codec, "ConfigEntry.Apply", &args, &out))
-	require.False(out)
+	require.False(t, out)
 
 	args.Entry.GetRaftIndex().ModifyIndex = serviceConf.ModifyIndex
-	require.NoError(msgpackrpc.CallWithCodec(codec, "ConfigEntry.Apply", &args, &out))
+	require.NoError(t, msgpackrpc.CallWithCodec(codec, "ConfigEntry.Apply", &args, &out))
-	require.True(out)
+	require.True(t, out)
 
 	state = s1.fsm.State()
 	_, entry, err = state.ConfigEntry(nil, structs.ServiceDefaults, "foo")
-	require.NoError(err)
+	require.NoError(t, err)
 
 	serviceConf, ok = entry.(*structs.ServiceConfigEntry)
-	require.True(ok)
+	require.True(t, ok)
-
+	require.Equal(t, structs.ServiceDefaults, serviceConf.Kind)
-	updated.Kind = structs.ServiceDefaults    // the server adds this
+	require.Equal(t, "foo", serviceConf.Name)
-	updated.RaftIndex = serviceConf.RaftIndex // these will always be different
+	require.Equal(t, "", serviceConf.Protocol)
-	require.Equal(updated, serviceConf)
+	require.Equal(t, structs.ServiceDefaults, serviceConf.Kind)
 }
 
 func TestConfigEntry_ProxyDefaultsMeshGateway(t *testing.T) {
@@ -546,42 +572,71 @@ operator = "read"
 func TestConfigEntry_Delete(t *testing.T) {
 	t.Parallel()
 
-	require := require.New(t)
-
 	dir1, s1 := testServer(t)
 	defer os.RemoveAll(dir1)
 	defer s1.Shutdown()
 	codec := rpcClient(t, s1)
 	defer codec.Close()
 
+	testrpc.WaitForLeader(t, s1.RPC, "dc1")
+
+	dir2, s2 := testServerWithConfig(t, func(c *Config) {
+		c.Datacenter = "dc2"
+		c.PrimaryDatacenter = "dc1"
+	})
+	defer os.RemoveAll(dir2)
+	defer s2.Shutdown()
+	codec2 := rpcClient(t, s2)
+	defer codec2.Close()
+
+	testrpc.WaitForLeader(t, s2.RPC, "dc2")
+	joinWAN(t, s2, s1)
+	// wait for cross-dc queries to work
+	testrpc.WaitForLeader(t, s2.RPC, "dc1")
+
 	// Create a dummy service in the state store to look up.
 	entry := &structs.ServiceConfigEntry{
 		Kind: structs.ServiceDefaults,
 		Name: "foo",
 	}
 	state := s1.fsm.State()
-	require.NoError(state.EnsureConfigEntry(1, entry))
+	require.NoError(t, state.EnsureConfigEntry(1, entry))
 
 	// Verify it's there.
 	_, existing, err := state.ConfigEntry(nil, structs.ServiceDefaults, "foo")
-	require.NoError(err)
+	require.NoError(t, err)
 
 	serviceConf, ok := existing.(*structs.ServiceConfigEntry)
-	require.True(ok)
+	require.True(t, ok)
-	require.Equal("foo", serviceConf.Name)
+	require.Equal(t, "foo", serviceConf.Name)
-	require.Equal(structs.ServiceDefaults, serviceConf.Kind)
+	require.Equal(t, structs.ServiceDefaults, serviceConf.Kind)
 
+	retry.Run(t, func(r *retry.R) {
+		// wait for it to be replicated into the secondary dc
+		_, existing, err := s2.fsm.State().ConfigEntry(nil, structs.ServiceDefaults, "foo")
+		require.NoError(r, err)
+		require.NotNil(r, existing)
+	})
+
+	// send the delete request to dc2 - it should get forwarded to dc1.
 	args := structs.ConfigEntryRequest{
-		Datacenter: "dc1",
+		Datacenter: "dc2",
 	}
 	args.Entry = entry
 	var out struct{}
-	require.NoError(msgpackrpc.CallWithCodec(codec, "ConfigEntry.Delete", &args, &out))
+	require.NoError(t, msgpackrpc.CallWithCodec(codec2, "ConfigEntry.Delete", &args, &out))
 
 	// Verify the entry was deleted.
-	_, existing, err = state.ConfigEntry(nil, structs.ServiceDefaults, "foo")
+	_, existing, err = s1.fsm.State().ConfigEntry(nil, structs.ServiceDefaults, "foo")
-	require.NoError(err)
+	require.NoError(t, err)
-	require.Nil(existing)
+	require.Nil(t, existing)
+
+	// verify it gets deleted from the secondary too
+	retry.Run(t, func(r *retry.R) {
+		_, existing, err := s2.fsm.State().ConfigEntry(nil, structs.ServiceDefaults, "foo")
+		require.NoError(r, err)
+		require.Nil(r, existing)
+	})
 }
 
 func TestConfigEntry_Delete_ACLDeny(t *testing.T) {