Revert "switch node names to machine ID (#251)" (#258)

This reverts commit a39f76f.

Author: benwaffle

bin/restart-repmgrd

@@ -1,10 +1,3 @@
 #!/bin/bash
 
-if [ -f /tmp/repmgrd.pid ]; then
-    PID=$(cat /tmp/repmgrd.pid)
-
-    # Check if the process is running
-    if ps -p $PID > /dev/null 2>&1; then
-        kill $PID
-    fi
-fi
+kill `cat /tmp/repmgrd.pid`

cmd/pg_unregister/main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"context"
 	"encoding/base64"
-	"errors"
 	"fmt"
 	"log"
 	"os"
@@ -45,15 +44,7 @@ func processUnregistration(ctx context.Context) error {
 	defer func() { _ = conn.Close(ctx) }()
 
 	member, err := node.RepMgr.MemberByHostname(ctx, conn, string(hostnameBytes))
-	if errors.Is(err, pgx.ErrNoRows) {
-		// for historical reasons, old versions of flyctl passes in the 6pn as the hostname
-		// most likely this won't work because the hostname does not resolve if the machine is stopped,
-		// but we try anyway
-		member, err = node.RepMgr.MemberBy6PN(ctx, conn, string(hostnameBytes))
-		if err != nil {
-			return fmt.Errorf("failed to resolve member by hostname and 6pn: %s", err)
-		}
-	} else if err != nil {
+	if err != nil {
 		return fmt.Errorf("failed to resolve member: %s", err)
 	}
 

go.mod

@@ -8,10 +8,8 @@ require (
 	github.com/hashicorp/consul/api v1.18.0
 	github.com/jackc/pgconn v1.14.3
 	github.com/jackc/pgx/v5 v5.5.4
-	github.com/olekukonko/tablewriter v0.0.5
 	github.com/pkg/errors v0.9.1
 	github.com/pkg/term v1.1.0
-	github.com/spf13/cobra v1.8.1
 	github.com/superfly/fly-checks v0.0.0-20230510154016-d189351293f2
 	golang.org/x/exp v0.0.0-20230105202349-8879d0199aa3
 	golang.org/x/sync v0.1.0
@@ -38,6 +36,8 @@ require (
 	github.com/mattn/go-runewidth v0.0.9 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/mitchellh/mapstructure v1.4.1 // indirect
+	github.com/olekukonko/tablewriter v0.0.5 // indirect
+	github.com/spf13/cobra v1.8.1 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/stretchr/objx v0.5.0 // indirect
 	golang.org/x/crypto v0.20.0 // indirect

internal/flypg/node.go

@@ -16,12 +16,10 @@ import (
 	"github.com/fly-apps/postgres-flex/internal/privnet"
 	"github.com/fly-apps/postgres-flex/internal/utils"
 	"github.com/jackc/pgx/v5"
-	"golang.org/x/exp/slices"
 )
 
 type Node struct {
 	AppName       string
-	MachineID     string
 	PrivateIP     string
 	PrimaryRegion string
 	DataDir       string
@@ -54,8 +52,6 @@ func NewNode() (*Node, error) {
 
 	node.PrivateIP = ipv6.String()
 
-	node.MachineID = os.Getenv("FLY_MACHINE_ID")
-
 	node.PrimaryRegion = os.Getenv("PRIMARY_REGION")
 	if node.PrimaryRegion == "" {
 		return nil, fmt.Errorf("PRIMARY_REGION environment variable must be set")
@@ -93,7 +89,6 @@ func NewNode() (*Node, error) {
 		PasswordConfigPath: "/data/.pgpass",
 		DataDir:            node.DataDir,
 		PrivateIP:          node.PrivateIP,
-		MachineID:          node.MachineID,
 		Port:               5433,
 		DatabaseName:       "repmgr",
 		Credentials:        node.ReplCredentials,
@@ -270,7 +265,7 @@ func (n *Node) PostInit(ctx context.Context) error {
 			return fmt.Errorf("failed to resolve member role: %s", err)
 		}
 
-		// Restart repmgrd in the event the machine ID changes for an already registered node.
+		// Restart repmgrd in the event the IP changes for an already registered node.
 		// This can happen if the underlying volume is moved to a different node.
 		daemonRestartRequired := n.RepMgr.daemonRestartRequired(member)
 
@@ -284,8 +279,6 @@ func (n *Node) PostInit(ctx context.Context) error {
 				if err := Quarantine(ctx, n, primary); err != nil {
 					return fmt.Errorf("failed to quarantine failed primary: %s", err)
 				}
-
-				panic(err)
 			} else if errors.Is(err, ErrZombieDiscovered) {
 				log.Printf("[ERROR] The majority of registered members agree that '%s' is the real primary.\n", primary)
 				// Turn member read-only
@@ -299,10 +292,10 @@ func (n *Node) PostInit(ctx context.Context) error {
 			}
 
 			// This should never happen
-			if primary != n.RepMgr.machineIdToDNS(n.MachineID) {
+			if primary != n.PrivateIP {
 				return fmt.Errorf("resolved primary '%s' does not match ourself '%s'. this should not happen",
 					primary,
-					n.RepMgr.machineIdToDNS(n.MachineID),
+					n.PrivateIP,
 				)
 			}
 
@@ -318,11 +311,6 @@ func (n *Node) PostInit(ctx context.Context) error {
 				}
 			}
 		case StandbyRoleName:
-			if err := n.migrateNodeNameIfNeeded(ctx, repConn); err != nil {
-				log.Printf("[ERROR] failed to migrate node name: %s", err)
-				// We try to bring the standby up anyway
-			}
-
 			// Register existing standby to apply any configuration changes.
 			if err := n.RepMgr.registerStandby(daemonRestartRequired); err != nil {
 				return fmt.Errorf("failed to register existing standby: %s", err)
@@ -539,50 +527,3 @@ func (n *Node) handleRemoteRestore(ctx context.Context, store *state.Store) erro
 
 	return nil
 }
-
-// migrate node name from 6pn to machine ID if needed
-func (n *Node) migrateNodeNameIfNeeded(ctx context.Context, repConn *pgx.Conn) error {
-	primary, err := n.RepMgr.PrimaryMember(ctx, repConn)
-	if err != nil {
-		return fmt.Errorf("failed to resolve primary member when updating standby: %s", err)
-	}
-
-	primaryConn, err := n.RepMgr.NewRemoteConnection(ctx, primary.Hostname)
-	if err != nil {
-		return fmt.Errorf("failed to establish connection to primary: %s", err)
-	}
-	defer func() { _ = primaryConn.Close(ctx) }()
-
-	rows, err := primaryConn.Query(ctx, "select application_name from pg_stat_replication")
-	if err != nil {
-		return fmt.Errorf("failed to query pg_stat_replication: %s", err)
-	}
-	defer rows.Close()
-
-	var applicationNames []string
-	for rows.Next() {
-		var applicationName string
-		if err := rows.Scan(&applicationName); err != nil {
-			return fmt.Errorf("failed to scan application_name: %s", err)
-		}
-		applicationNames = append(applicationNames, applicationName)
-	}
-	if err := rows.Err(); err != nil {
-		return fmt.Errorf("failed to iterate over rows: %s", err)
-	}
-
-	// if we find our 6pn as application_name, we need to regenerate postgresql.auto.conf and reload postgresql
-	if slices.Contains(applicationNames, n.PrivateIP) {
-		log.Printf("pg_stat_replication on the primary has our ipv6 address as application_name, converting to machine ID...")
-
-		if err := n.RepMgr.regenReplicationConf(ctx); err != nil {
-			return fmt.Errorf("failed to clone standby: %s", err)
-		}
-
-		if err := admin.ReloadPostgresConfig(ctx, repConn); err != nil {
-			return fmt.Errorf("failed to reload postgresql: %s", err)
-		}
-	}
-
-	return nil
-}

internal/flypg/readonly.go

@@ -70,7 +70,7 @@ func BroadcastReadonlyChange(ctx context.Context, n *Node, enabled bool) error {
 
 	for _, member := range members {
 		if member.Role == PrimaryRoleName {
-			endpoint := fmt.Sprintf("http://%s:5500/%s", member.Hostname, target)
+			endpoint := fmt.Sprintf("http://[%s]:5500/%s", member.Hostname, target)
 			resp, err := http.Get(endpoint)
 			if err != nil {
 				log.Printf("[WARN] Failed to broadcast readonly state change to member %s: %s", member.Hostname, err)
@@ -85,7 +85,7 @@ func BroadcastReadonlyChange(ctx context.Context, n *Node, enabled bool) error {
 	}
 
 	for _, member := range members {
-		endpoint := fmt.Sprintf("http://%s:5500/%s", member.Hostname, RestartHaproxyEndpoint)
+		endpoint := fmt.Sprintf("http://[%s]:5500/%s", member.Hostname, RestartHaproxyEndpoint)
 		resp, err := http.Get(endpoint)
 		if err != nil {
 			log.Printf("[WARN] Failed to restart haproxy on member %s: %s", member.Hostname, err)

internal/flypg/repmgr.go

@@ -34,7 +34,6 @@ type RepMgr struct {
 	PrimaryRegion      string
 	Region             string
 	PrivateIP          string
-	MachineID          string
 	DataDir            string
 	DatabaseName       string
 	Credentials        admin.Credential
@@ -162,12 +161,10 @@ func (r *RepMgr) setDefaults() error {
 		return err
 	}
 
-	hostname := r.machineIdToDNS(r.MachineID)
-
 	conf := ConfigMap{
 		"node_id":                      nodeID,
-		"node_name":                    fmt.Sprintf("'%s'", hostname),
-		"conninfo":                     fmt.Sprintf("'host=%s port=%d user=%s dbname=%s connect_timeout=5'", hostname, r.Port, r.Credentials.Username, r.DatabaseName),
+		"node_name":                    fmt.Sprintf("'%s'", r.PrivateIP),
+		"conninfo":                     fmt.Sprintf("'host=%s port=%d user=%s dbname=%s connect_timeout=5'", r.PrivateIP, r.Port, r.Credentials.Username, r.DatabaseName),
 		"data_directory":               fmt.Sprintf("'%s'", r.DataDir),
 		"failover":                     "'automatic'",
 		"use_replication_slots":        "yes",
@@ -279,7 +276,7 @@ func (*RepMgr) restartDaemon() error {
 }
 
 func (r *RepMgr) daemonRestartRequired(m *Member) bool {
-	return m.Hostname != r.MachineID
+	return m.Hostname != r.PrivateIP
 }
 
 func (r *RepMgr) unregisterWitness(id int) error {
@@ -304,14 +301,14 @@ func (r *RepMgr) rejoinCluster(hostname string) error {
 	return err
 }
 
-func (r *RepMgr) clonePrimary(hostname string) error {
+func (r *RepMgr) clonePrimary(ipStr string) error {
 	cmdStr := fmt.Sprintf("mkdir -p %s", r.DataDir)
 	if _, err := utils.RunCommand(cmdStr, "postgres"); err != nil {
 		return fmt.Errorf("failed to create pg directory: %s", err)
 	}
 
 	cmdStr = fmt.Sprintf("repmgr -h %s -p %d -d %s -U %s -f %s standby clone -c -F",
-		hostname,
+		ipStr,
 		r.Port,
 		r.DatabaseName,
 		r.Credentials.Username,
@@ -325,21 +322,6 @@ func (r *RepMgr) clonePrimary(hostname string) error {
 	return nil
 }
 
-func (r *RepMgr) regenReplicationConf(ctx context.Context) error {
-	// TODO: do we need -c?
-	if _, err := utils.RunCmd(ctx, "postgres",
-		"repmgr", "--replication-conf-only",
-		"-h", "",
-		"-p", fmt.Sprint(r.Port),
-		"-d", r.DatabaseName,
-		"-U", r.Credentials.Username,
-		"-f", r.ConfigPath,
-		"standby", "clone", "-F"); err != nil {
-		return fmt.Errorf("failed to regenerate replication conf: %s", err)
-	}
-	return nil
-}
-
 type Member struct {
 	ID       int
 	Hostname string
@@ -449,56 +431,26 @@ func (*RepMgr) MemberByHostname(ctx context.Context, pg *pgx.Conn, hostname stri
 	return &member, nil
 }
 
-// MemberBy6PN returns a member by its 6PN address.
-func (r *RepMgr) MemberBy6PN(ctx context.Context, pg *pgx.Conn, ip string) (*Member, error) {
-	members, err := r.Members(ctx, pg)
-	if err != nil {
-		return nil, err
-	}
-
-	resolver := privnet.GetResolver()
-	var lastErr error
-	for _, member := range members {
-		ips, err := resolver.LookupIPAddr(ctx, member.Hostname)
-		if err != nil {
-			lastErr = err
-			continue
-		}
-
-		for _, addr := range ips {
-			if addr.IP.String() == ip {
-				return &member, nil
-			}
-		}
-	}
-
-	if lastErr != nil {
-		return nil, fmt.Errorf("no matches found for %s, and error encountered: %s", ip, lastErr)
-	}
-
-	return nil, nil
-}
-
 func (r *RepMgr) ResolveMemberOverDNS(ctx context.Context) (*Member, error) {
-	machineIds, err := r.InRegionPeerMachines(ctx)
+	ips, err := r.InRegionPeerIPs(ctx)
 	if err != nil {
 		return nil, err
 	}
 
 	var target *Member
 
-	for _, machineId := range machineIds {
-		if machineId == r.MachineID {
+	for _, ip := range ips {
+		if ip.String() == r.PrivateIP {
 			continue
 		}
 
-		conn, err := r.NewRemoteConnection(ctx, r.machineIdToDNS(machineId))
+		conn, err := r.NewRemoteConnection(ctx, ip.String())
 		if err != nil {
 			continue
 		}
 		defer func() { _ = conn.Close(ctx) }()
 
-		member, err := r.MemberByHostname(ctx, conn, r.machineIdToDNS(machineId))
+		member, err := r.MemberByHostname(ctx, conn, ip.String())
 		if err != nil {
 			continue
 		}
@@ -525,21 +477,6 @@ func (r *RepMgr) InRegionPeerIPs(ctx context.Context) ([]net.IPAddr, error) {
 	return privnet.AllPeers(ctx, targets)
 }
 
-func (r *RepMgr) InRegionPeerMachines(ctx context.Context) ([]string, error) {
-	machines, err := privnet.AllMachines(ctx, r.AppName)
-	if err != nil {
-		return nil, err
-	}
-
-	var machineIDs []string
-	for _, machine := range machines {
-		if machine.Region == r.PrimaryRegion {
-			machineIDs = append(machineIDs, machine.Id)
-		}
-	}
-	return machineIDs, nil
-}
-
 func (r *RepMgr) HostInRegion(ctx context.Context, hostname string) (bool, error) {
 	ips, err := r.InRegionPeerIPs(ctx)
 	if err != nil {
@@ -577,11 +514,3 @@ func (r *RepMgr) UnregisterMember(member Member) error {
 func (r *RepMgr) eligiblePrimary() bool {
 	return r.Region == r.PrimaryRegion
 }
-
-func (r *RepMgr) machineIdToDNS(nodeName string) string {
-	if len(nodeName) != 14 {
-		panic("invalid machine id")
-	}
-
-	return fmt.Sprintf("%s.vm.%s.internal", nodeName, r.AppName)
-}

internal/flypg/repmgr_test.go

@@ -33,7 +33,6 @@ func TestRepmgrInitialization(t *testing.T) {
 		UserConfigPath:     repgmrUserConfigFilePath,
 		PasswordConfigPath: repgmrPasswordConfigFilePath,
 		DataDir:            repmgrTestDirectory,
-		MachineID:          "abcdefg1234567",
 		PrivateIP:          "127.0.0.1",
 		Credentials: admin.Credential{
 			Username: "user",
@@ -92,8 +91,8 @@ func TestRepmgrInitialization(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		if config["node_name"] != "'abcdefg1234567.vm.test-app.internal'" {
-			t.Fatalf("expected node_name to be 'abcdefg1234567.vm.test-app.internal', got %v", config["node_name"])
+		if config["node_name"] != "'127.0.0.1'" {
+			t.Fatalf("expected node_name to be '127.0.0.1', got %v", config["node_name"])
 		}
 
 		if config["location"] != "'dev'" {
@@ -123,7 +122,6 @@ func TestRepmgrNodeIDGeneration(t *testing.T) {
 
 		DataDir:      repmgrTestDirectory,
 		PrivateIP:    "127.0.0.1",
-		MachineID:    "abcdefg1234567",
 		Port:         5433,
 		DatabaseName: "repmgr",
 		Credentials: admin.Credential{