Add agent for certificate syncing

agent/agent.go

@@ -0,0 +1,182 @@
+package agent
+
+import (
+	"context"
+	"database/sql"
+	_ "embed"
+	"fmt"
+	"github.com/1f349/orchid/database"
+	"github.com/1f349/orchid/utils"
+	"github.com/bramvdbogaerde/go-scp"
+	"golang.org/x/crypto/ssh"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+//go:embed agent_readme.md
+var agentReadme []byte
+
+type agentQueries interface {
+	FindAgentToSync(ctx context.Context) ([]database.FindAgentToSyncRow, error)
+	UpdateAgentLastSync(ctx context.Context, row database.UpdateAgentLastSyncParams) error
+	UpdateAgentCertNotAfter(ctx context.Context, arg database.UpdateAgentCertNotAfterParams) error
+}
+
+func NewAgent(wg *sync.WaitGroup, db agentQueries, sshKey ssh.Signer, certDir string, keyDir string) (*Agent, error) {
+	a := &Agent{
+		db:       db,
+		ticker:   time.NewTicker(time.Minute * 10),
+		done:     make(chan struct{}),
+		syncLock: new(sync.Mutex),
+		sshKey:   sshKey,
+		certDir:  certDir,
+		keyDir:   keyDir,
+	}
+
+	wg.Add(1)
+	go a.syncRoutine(wg)
+	return a, nil
+}
+
+type Agent struct {
+	db       agentQueries
+	ticker   *time.Ticker
+	done     chan struct{}
+	syncLock *sync.Mutex
+	sshKey   ssh.Signer
+	certDir  string
+	keyDir   string
+}
+
+func (a *Agent) Shutdown() {
+	Logger.Info("Shutting down agent syncing service")
+	close(a.done)
+}
+
+func (a *Agent) syncRoutine(wg *sync.WaitGroup) {
+	Logger.Debug("Starting syncRoutine")
+
+	// Upon leaving the function stop the ticker and clear the WaitGroup.
+	defer func() {
+		a.ticker.Stop()
+		Logger.Info("Stopped agent syncing service")
+		wg.Done()
+	}()
+
+	for {
+		select {
+		case <-a.done:
+			// Exit if done has closed
+			return
+		case <-a.ticker.C:
+			Logger.Debug("Ticking agent syncing")
+
+			go a.syncCheck()
+		}
+	}
+}
+
+func (a *Agent) syncCheck() {
+	// if the lock is unavailable then ignore this cycle
+	if !a.syncLock.TryLock() {
+		return
+	}
+	defer a.syncLock.Unlock()
+
+	now := time.Now().UTC()
+
+	actions, err := a.db.FindAgentToSync(context.Background())
+	if err != nil {
+		panic(err)
+	}
+
+	agentErrs := make(map[int64][]error)
+
+	for _, action := range actions {
+		err = a.syncSingleAgentCertPair(now, action)
+		if err != nil {
+			agentErrs[action.AgentID] = append(agentErrs[action.AgentID], err)
+		}
+	}
+
+	for agentId, errs := range agentErrs {
+		Logger.Warn("Agent sync failed", "agent", agentId, "errs", errs)
+	}
+
+	// TODO: idk what to do now
+}
+
+func (a *Agent) syncSingleAgentCertPair(startTime time.Time, row database.FindAgentToSyncRow) error {
+	certName := utils.GetCertFileName(row.CertID)
+	keyName := utils.GetKeyFileName(row.CertID)
+
+	certPath := filepath.Join(a.certDir, certName)
+	keyPath := filepath.Join(a.keyDir, keyName)
+
+	// open cert and key files
+	openCert, err := os.Open(certPath)
+	if err != nil {
+		return fmt.Errorf("open cert file: %w", err)
+	}
+	defer openCert.Close()
+	openKey, err := os.Open(keyPath)
+
+	if err != nil {
+		return fmt.Errorf("open key file: %w", err)
+	}
+	defer openKey.Close()
+
+	hostPubKey, _, _, _, err := ssh.ParseAuthorizedKey([]byte(row.Fingerprint))
+	if err != nil {
+		return fmt.Errorf("failed to parse fingerprint: %w", err)
+	}
+
+	client, err := ssh.Dial("tcp", row.Address, &ssh.ClientConfig{
+		User: row.User,
+		Auth: []ssh.AuthMethod{
+			ssh.PublicKeys(a.sshKey),
+		},
+		HostKeyCallback: ssh.FixedHostKey(hostPubKey),
+		Timeout:         time.Second * 30,
+	})
+	if err != nil {
+		return fmt.Errorf("ssh dial: %w", err)
+	}
+
+	scpClient, err := scp.NewClientBySSH(client)
+	if err != nil {
+		return fmt.Errorf("scp client: %w", err)
+	}
+
+	// copy cert and key to agent
+	err = scpClient.CopyFromFile(context.Background(), *openCert, filepath.Join(row.Dir, "certificates", certName), "0600")
+	if err != nil {
+		return fmt.Errorf("copy cert file: %w", err)
+	}
+	err = scpClient.CopyFromFile(context.Background(), *openKey, filepath.Join(row.Dir, "keys", keyName), "0600")
+	if err != nil {
+		return fmt.Errorf("copy cert file: %w", err)
+	}
+
+	// update last sync to the time when the database request happened
+	err = a.db.UpdateAgentLastSync(context.Background(), database.UpdateAgentLastSyncParams{
+		LastSync: sql.NullTime{Time: startTime, Valid: true},
+		ID:       row.AgentID,
+	})
+	if err != nil {
+		return fmt.Errorf("error updating agent last sync: %v", err)
+	}
+
+	err = a.db.UpdateAgentCertNotAfter(context.Background(), database.UpdateAgentCertNotAfterParams{
+		NotAfter: row.CertNotAfter,
+		AgentID:  row.AgentID,
+		CertID:   row.CertID,
+	})
+	if err != nil {
+		return fmt.Errorf("error updating agent last sync: %v", err)
+	}
+
+	return nil
+}

agent/agent_readme.md

@@ -0,0 +1,5 @@
+# Orchid Agent
+
+This directory is controlled by Orchid agent configuration.
+
+Certificates in this directory will be automatically updated when required.

agent/agent_test.go

@@ -0,0 +1,378 @@
+package agent
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"crypto/x509/pkix"
+	"database/sql"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"github.com/1f349/orchid/database"
+	"github.com/1f349/orchid/logger"
+	"github.com/charmbracelet/log"
+	"github.com/mrmelon54/certgen"
+	"github.com/stretchr/testify/assert"
+	"golang.org/x/crypto/ed25519"
+	"golang.org/x/crypto/ssh"
+	"io"
+	"math/big"
+	"net"
+	"net/netip"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+)
+
+func TestAgentSyncing(t *testing.T) {
+	logger.Logger.SetLevel(log.DebugLevel)
+
+	if testing.Short() {
+		t.Skip("Skipping agent syncing tests in short mode")
+	}
+
+	t.Run("agent syncing test", func(t *testing.T) {
+		certDir, err := os.MkdirTemp("", "orchid-certs")
+		assert.NoError(t, err)
+		keyDir, err := os.MkdirTemp("", "orchid-keys")
+		assert.NoError(t, err)
+
+		defer func() {
+			assert.NoError(t, os.RemoveAll(certDir))
+			assert.NoError(t, os.RemoveAll(keyDir))
+		}()
+
+		_, privKey, err := ed25519.GenerateKey(nil)
+		if err != nil {
+			panic(err)
+		}
+		sshPrivKey, err := ssh.NewSignerFromKey(privKey)
+		if err != nil {
+			panic(err)
+		}
+
+		agent := &Agent{
+			db:       &fakeAgentDb{},
+			ticker:   nil,
+			done:     nil,
+			syncLock: nil,
+			sshKey:   sshPrivKey,
+			certDir:  certDir,
+			keyDir:   keyDir,
+		}
+
+		now := time.Now().UTC()
+
+		t.Run("missing cert file", func(t *testing.T) {
+			err = agent.syncSingleAgentCertPair(now, database.FindAgentToSyncRow{
+				AgentID:      1337,
+				Address:      "",
+				User:         "test",
+				Dir:          "~/hello/world",
+				Fingerprint:  "",
+				CertID:       420,
+				CertNotAfter: sql.NullTime{Time: now, Valid: true},
+			})
+			assert.Contains(t, err.Error(), "open cert file:")
+			assert.Contains(t, err.Error(), "no such file or directory")
+		})
+
+		// generate example certificate
+		tlsCert, err := certgen.MakeServerTls(nil, 2048, pkix.Name{
+			Country:       []string{"GB"},
+			Province:      []string{"London"},
+			StreetAddress: []string{"221B Baker Street"},
+			PostalCode:    []string{"NW1 6XE"},
+			SerialNumber:  "test123456",
+			CommonName:    "orchid-agent-test.local",
+		}, big.NewInt(1234567899), func(now time.Time) time.Time {
+			return now.Add(1 * time.Hour)
+		}, []string{"orchid-agent-test.local"}, []net.IP{
+			net.IPv6loopback,
+			net.IPv4(127, 0, 0, 1),
+		})
+		assert.NoError(t, err)
+
+		err = os.WriteFile(filepath.Join(certDir, "420.cert.pem"), tlsCert.GetCertPem(), 0600)
+		assert.NoError(t, err)
+
+		t.Run("missing key file", func(t *testing.T) {
+			err = agent.syncSingleAgentCertPair(now, database.FindAgentToSyncRow{
+				AgentID:      1337,
+				Address:      "",
+				User:         "test",
+				Dir:          "~/hello/world",
+				Fingerprint:  "",
+				CertID:       420,
+				CertNotAfter: sql.NullTime{Time: now, Valid: true},
+			})
+			assert.Contains(t, err.Error(), "open key file:")
+			assert.Contains(t, err.Error(), "no such file or directory")
+		})
+
+		err = os.WriteFile(filepath.Join(keyDir, "420.key.pem"), tlsCert.GetKeyPem(), 0600)
+		assert.NoError(t, err)
+
+		t.Run("successful sync", func(t *testing.T) {
+			var wg sync.WaitGroup
+			server := setupFakeSSH(&wg, func(remoteAddrPort netip.AddrPort, remotePubKey ssh.PublicKey) {
+				println("Attempt agent syncing")
+
+				err = agent.syncSingleAgentCertPair(now, database.FindAgentToSyncRow{
+					AgentID:      1337,
+					Address:      remoteAddrPort.String(),
+					User:         "test",
+					Dir:          "~/hello/world",
+					Fingerprint:  string(ssh.MarshalAuthorizedKey(remotePubKey)),
+					CertID:       420,
+					CertNotAfter: sql.NullTime{Time: now, Valid: true},
+				})
+				assert.NoError(t, err)
+			})
+			server.Close()
+
+			println("Waiting for ssh server to exit")
+
+			server.Wait()
+		})
+	})
+}
+
+func setupFakeSSH(wg *sync.WaitGroup, call func(addrPort netip.AddrPort, pubKey ssh.PublicKey)) *ssh.ServerConn {
+	pubKey, privKey, err := ed25519.GenerateKey(nil)
+	if err != nil {
+		panic(err)
+	}
+	sshPubKey, err := ssh.NewPublicKey(pubKey)
+	if err != nil {
+		panic(err)
+	}
+	sshSigner, err := ssh.NewSignerFromKey(privKey)
+	if err != nil {
+		panic(err)
+	}
+
+	tcp, err := net.ListenTCP("tcp", net.TCPAddrFromAddrPort(netip.AddrPortFrom(netip.IPv6Loopback(), 0)))
+	if err != nil {
+		panic(err)
+	}
+
+	addrPort := tcp.Addr().(*net.TCPAddr).AddrPort()
+
+	var wg2 sync.WaitGroup
+	wg2.Add(1)
+	go func() {
+		defer wg2.Done()
+		call(addrPort, sshPubKey)
+	}()
+
+	tcpConn, err := tcp.AcceptTCP()
+	if err != nil {
+		panic(err)
+	}
+
+	serverConfig := &ssh.ServerConfig{
+		PublicKeyCallback: func(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
+			if conn.User() != "test" {
+				return nil, fmt.Errorf("invalid user")
+			}
+			if !conn.RemoteAddr().(*net.TCPAddr).AddrPort().Addr().IsLoopback() {
+				return nil, fmt.Errorf("invalid remote address")
+			}
+			return &ssh.Permissions{}, nil
+		},
+		ServerVersion: "SSH-2.0-OrchidTester",
+	}
+	serverConfig.AddHostKey(sshSigner)
+
+	sshConn, chans, reqs, err := ssh.NewServerConn(tcpConn, serverConfig)
+	if err != nil {
+		return nil
+	}
+
+	// The incoming Request channel must be serviced.
+	wg.Add(1)
+	go func() {
+		ssh.DiscardRequests(reqs)
+		wg.Done()
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		// Service the incoming channel.
+		for newChannel := range chans {
+			// Channels have a type, depending on the application level
+			// protocol intended. In the case of a shell, the type is
+			// "session" and ServerShell may be used to present a simple
+			// terminal interface.
+			if newChannel.ChannelType() != "session" {
+				newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
+				continue
+			}
+			channel, requests, err := newChannel.Accept()
+			if err != nil {
+				panic(err)
+			}
+
+			var fullFilePath string
+
+			// Sessions have out-of-band requests such as "shell",
+			// "pty-req" and "env".  Here we handle only the
+			// "shell" request.
+			wg.Add(1)
+			go func(in <-chan *ssh.Request) {
+				for req := range in {
+					req.Reply(req.Type == "exec", nil)
+					if req.Type == "exec" {
+						length := binary.BigEndian.Uint32(req.Payload[:4])
+						if len(req.Payload) != int(length)+4 {
+							panic(fmt.Errorf("invalid exec payload (expected %d but got %d)", length, len(req.Payload)))
+						}
+						cmd := string(req.Payload[4:])
+						const scpStartStr = "scp -qt \""
+						if !strings.HasPrefix(cmd, scpStartStr) {
+							panic("invalid start")
+						}
+						if !strings.HasSuffix(cmd, "\"") {
+							panic("invalid end")
+						}
+						filePath := cmd[len(scpStartStr) : len(cmd)-1]
+						fmt.Println("Writing file:", filePath)
+						fullFilePath = filePath
+					}
+				}
+				wg.Done()
+			}(requests)
+
+			wg.Add(1)
+			go func() {
+				defer func() {
+					channel.Close()
+					wg.Done()
+				}()
+
+				var b [1024]byte
+				read := must(channel.Read(b[:]))
+				if read < 1 {
+					panic("invalid read")
+				}
+
+				fmt.Println(string(b[:read]))
+
+				r := bufio.NewReader(bytes.NewReader(b[:read]))
+				if readByte(r) != 'C' {
+					panic("invalid scp command")
+				}
+
+				fileMode := readN(r, 4)
+				if string(fileMode) != "0600" {
+					panic("unexpected file mode")
+				}
+
+				if readByte(r) != ' ' {
+					panic("missing space")
+				}
+
+				fileSizeStr := must(r.ReadString(' '))
+				fileSize := must(strconv.Atoi(fileSizeStr[:len(fileSizeStr)-1]))
+
+				fileName := strings.TrimSpace(string(must(io.ReadAll(r))))
+				if fileName != filepath.Base(fullFilePath) {
+					panic(fmt.Errorf("invalid file name (expected \"%s\" from full path \"%s\" but got \"%s\")", filepath.Base(fullFilePath), fullFilePath, fileName))
+				}
+
+				if fileName != "420.cert.pem" && fileName != "420.key.pem" {
+					panic("invalid file name")
+				}
+
+				channel.Write([]byte{0})
+
+				buf := new(bytes.Buffer)
+				_, err := io.CopyN(buf, channel, int64(fileSize))
+				if err != nil {
+					panic("Failed to copy channel")
+				}
+				fmt.Println("Copied file with size:", buf.Len())
+				fmt.Println(buf.String())
+
+				if readLastByte(r) != 0x00 {
+					panic("expected ending null byte")
+				}
+
+				channel.Write([]byte{0})
+
+				channel.SendRequest("exit-status", false, binary.BigEndian.AppendUint32(nil, 0))
+			}()
+		}
+	}()
+
+	wg2.Wait()
+
+	return sshConn
+}
+
+type fakeAgentDb struct{}
+
+func (f *fakeAgentDb) FindAgentToSync(ctx context.Context) ([]database.FindAgentToSyncRow, error) {
+	panic("implement me")
+}
+
+func (f *fakeAgentDb) UpdateAgentLastSync(ctx context.Context, arg database.UpdateAgentLastSyncParams) error {
+	if arg.ID != 1337 {
+		return fmt.Errorf("invalid agent id")
+	}
+	if !arg.LastSync.Valid {
+		return fmt.Errorf("invalid last sync")
+	}
+	return nil
+}
+
+func (f *fakeAgentDb) UpdateAgentCertNotAfter(ctx context.Context, arg database.UpdateAgentCertNotAfterParams) error {
+	if arg.AgentID != 1337 {
+		return fmt.Errorf("invalid agent id")
+	}
+	if arg.CertID != 420 {
+		return fmt.Errorf("invalid cert id")
+	}
+	if !arg.NotAfter.Valid {
+		return fmt.Errorf("invalid not after")
+	}
+	return nil
+}
+
+func must[T any](t T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return t
+}
+
+func readN(r io.Reader, n int) []byte {
+	b := make([]byte, n)
+	_, err := io.ReadFull(r, b)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}
+
+func readByte(r io.Reader) byte {
+	b := readN(r, 1)
+	return b[0]
+}
+
+func readLastByte(r io.Reader) byte {
+	var b [1]byte
+	_, err := io.ReadFull(r, b[:])
+	if !errors.Is(err, io.EOF) {
+		panic("expected EOF")
+	}
+	return b[0]
+}

agent/logger.go

@@ -0,0 +1,5 @@
+package agent
+
+import "github.com/1f349/orchid/logger"
+
+var Logger = logger.Logger.WithPrefix("Orchid Agent")

cmd/orchid/agent.go

@@ -0,0 +1,65 @@
+package main
+
+import (
+	"encoding/pem"
+	"github.com/1f349/orchid/logger"
+	"golang.org/x/crypto/ed25519"
+	"golang.org/x/crypto/ssh"
+	"os"
+	"path/filepath"
+)
+
+// loadAgentPrivateKey simply attempts to load the agent ssh private key and if
+// it is missing generates a new key
+func loadAgentPrivateKey(wd string) ssh.Signer {
+	// load or create a key for orchid agent
+	agentPrivKeyPath := filepath.Join(wd, "agent_id_ed25519")
+	agentPubKeyPath := filepath.Join(wd, "agent_id_ed25519.pub")
+	agentPrivKeyBytes, err := os.ReadFile(agentPrivKeyPath)
+	switch {
+	case err == nil:
+		break
+	case os.IsNotExist(err):
+		pubKey, privKey, err := ed25519.GenerateKey(nil)
+		if err != nil {
+			logger.Logger.Fatal("Failed to generate agent private key", "err", err)
+		}
+		marshalPrivKey, err := ssh.MarshalPrivateKey(privKey, "orchid-agent")
+		if err != nil {
+			logger.Logger.Fatal("Failed to encode private key", "err", err)
+		}
+		agentPrivKeyBytes = pem.EncodeToMemory(marshalPrivKey)
+
+		// public key
+		sshPubKey, err := ssh.NewPublicKey(pubKey)
+		if err != nil {
+			logger.Logger.Fatal("Failed to encode public key", "err", err)
+		}
+		marshalPubKey := ssh.MarshalAuthorizedKey(sshPubKey)
+		if err != nil {
+			logger.Logger.Fatal("Failed to encode public key", "err", err)
+		}
+
+		// write to files
+		err = os.WriteFile(agentPrivKeyPath, agentPrivKeyBytes, 0600)
+		if err != nil {
+			logger.Logger.Fatal("Failed to write agent private key", "path", agentPrivKeyPath, "err", err)
+		}
+		err = os.WriteFile(agentPubKeyPath, marshalPubKey, 0644)
+		if err != nil {
+			logger.Logger.Fatal("Failed to write agent public key", "path", agentPubKeyPath, "err", err)
+		}
+
+		// we can continue now
+		break
+	case err != nil:
+		logger.Logger.Fatal("Failed to read agent private key", "path", agentPrivKeyPath, "err", err)
+	}
+
+	privKey, err := ssh.ParsePrivateKey(agentPrivKeyBytes)
+	if err != nil {
+		logger.Logger.Fatal("Failed to parse agent private key file", "path", agentPrivKeyPath, "err", err)
+	}
+
+	return privKey
+}

cmd/orchid/conf.go

@@ -7,6 +7,7 @@ type startUpConfig struct {
 	Acme     acmeConfig                `yaml:"acme"`
 	LE       renewal.LetsEncryptConfig `yaml:"letsEncrypt"`
 	Domains  []string                  `yaml:"domains"`
+	AgentKey string                    `yaml:"agentKey"`
 }
 
 type acmeConfig struct {

cmd/orchid/main.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 	"github.com/1f349/mjwt"
 	"github.com/1f349/orchid"
+	"github.com/1f349/orchid/agent"
 	httpAcme "github.com/1f349/orchid/http-acme"
 	"github.com/1f349/orchid/logger"
 	"github.com/1f349/orchid/renewal"
@@ -78,7 +79,7 @@ func runDaemon(wd string, conf startUpConfig) {
 	certDir := filepath.Join(wd, "renewal-certs")
 	keyDir := filepath.Join(wd, "renewal-keys")
 
-	wg := &sync.WaitGroup{}
+	wg := new(sync.WaitGroup)
 	acmeProv, err := httpAcme.NewHttpAcmeProvider(filepath.Join(wd, "tokens.yml"), conf.Acme.PresentUrl, conf.Acme.CleanUpUrl, conf.Acme.RefreshUrl)
 	if err != nil {
 		logger.Logger.Fatal("HTTP Acme Error", "err", err)
@@ -87,6 +88,10 @@ func runDaemon(wd string, conf startUpConfig) {
 	if err != nil {
 		logger.Logger.Fatal("Service Error", "err", err)
 	}
+	certAgent, err := agent.NewAgent(wg, db, loadAgentPrivateKey(wd), certDir, keyDir)
+	if err != nil {
+		logger.Logger.Fatal("Failed to create agent", "err", err)
+	}
 	srv := servers.NewApiServer(conf.Listen, db, mJwtVerify, conf.Domains)
 	logger.Logger.Info("Starting API server", "listen", srv.Addr)
 	go utils.RunBackgroundHttp(logger.Logger, srv)
@@ -94,6 +99,7 @@ func runDaemon(wd string, conf startUpConfig) {
 	exitReload.ExitReload("Violet", func() {}, func() {
 		// stop renewal service and api server
 		renewalService.Shutdown()
+		certAgent.Shutdown()
 		srv.Close()
 	})
 }

database/agent.sql.go

@@ -0,0 +1,98 @@
+// Code generated by sqlc. DO NOT EDIT.
+// versions:
+//   sqlc v1.28.0
+// source: agent.sql
+
+package database
+
+import (
+	"context"
+	"database/sql"
+)
+
+const findAgentToSync = `-- name: FindAgentToSync :many
+SELECT agents.id as agent_id, agents.address, agents.user, agents.dir, agents.fingerprint, cert.id as cert_id, cert.not_after as cert_not_after
+FROM agents
+         INNER JOIN agent_certs
+                    ON agent_certs.agent_id = agents.id
+         INNER JOIN certificates AS cert
+                    ON cert.id = agent_certs.cert_id
+WHERE (agents.last_sync IS NULL OR agents.last_sync < cert.updated_at)
+  AND (agent_certs.not_after IS NULL OR agent_certs.not_after IS NOT cert.not_after)
+ORDER BY agents.last_sync NULLS FIRST
+`
+
+type FindAgentToSyncRow struct {
+	AgentID      int64        `json:"agent_id"`
+	Address      string       `json:"address"`
+	User         string       `json:"user"`
+	Dir          string       `json:"dir"`
+	Fingerprint  string       `json:"fingerprint"`
+	CertID       int64        `json:"cert_id"`
+	CertNotAfter sql.NullTime `json:"cert_not_after"`
+}
+
+func (q *Queries) FindAgentToSync(ctx context.Context) ([]FindAgentToSyncRow, error) {
+	rows, err := q.db.QueryContext(ctx, findAgentToSync)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []FindAgentToSyncRow
+	for rows.Next() {
+		var i FindAgentToSyncRow
+		if err := rows.Scan(
+			&i.AgentID,
+			&i.Address,
+			&i.User,
+			&i.Dir,
+			&i.Fingerprint,
+			&i.CertID,
+			&i.CertNotAfter,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
+const updateAgentCertNotAfter = `-- name: UpdateAgentCertNotAfter :exec
+UPDATE agent_certs
+SET not_after = ?
+WHERE agent_id = ?
+  AND cert_id = ?
+`
+
+type UpdateAgentCertNotAfterParams struct {
+	NotAfter sql.NullTime `json:"not_after"`
+	AgentID  int64        `json:"agent_id"`
+	CertID   int64        `json:"cert_id"`
+}
+
+func (q *Queries) UpdateAgentCertNotAfter(ctx context.Context, arg UpdateAgentCertNotAfterParams) error {
+	_, err := q.db.ExecContext(ctx, updateAgentCertNotAfter, arg.NotAfter, arg.AgentID, arg.CertID)
+	return err
+}
+
+const updateAgentLastSync = `-- name: UpdateAgentLastSync :exec
+UPDATE agents
+SET last_sync = ?
+WHERE agents.id = ?
+`
+
+type UpdateAgentLastSyncParams struct {
+	LastSync sql.NullTime `json:"last_sync"`
+	ID       int64        `json:"id"`
+}
+
+func (q *Queries) UpdateAgentLastSync(ctx context.Context, arg UpdateAgentLastSyncParams) error {
+	_, err := q.db.ExecContext(ctx, updateAgentLastSync, arg.LastSync, arg.ID)
+	return err
+}

database/migrations/20250129211955_agent.up.sql

@@ -0,0 +1,21 @@
+CREATE TABLE IF NOT EXISTS agents
+(
+    id          INTEGER PRIMARY KEY AUTOINCREMENT,
+    address     TEXT     NOT NULL,
+    user        TEXT     NOT NULL,
+    dir         TEXT     NOT NULL,
+    fingerprint TEXT     NOT NULL,
+    last_sync   DATETIME NULL DEFAULT NULL
+);
+
+CREATE TABLE IF NOT EXISTS agent_certs
+(
+    agent_id  INTEGER NOT NULL,
+    cert_id   INTEGER NOT NULL,
+    not_after INTEGER NULL DEFAULT NULL,
+
+    PRIMARY KEY (agent_id, cert_id),
+
+    FOREIGN KEY (agent_id) REFERENCES agents (id),
+    FOREIGN KEY (cert_id) REFERENCES certificates (id)
+);

database/models.go

@@ -9,6 +9,21 @@ import (
 	"time"
 )
 
+type Agent struct {
+	ID          int64        `json:"id"`
+	Address     string       `json:"address"`
+	User        string       `json:"user"`
+	Dir         string       `json:"dir"`
+	Fingerprint string       `json:"fingerprint"`
+	LastSync    sql.NullTime `json:"last_sync"`
+}
+
+type AgentCert struct {
+	AgentID  int64        `json:"agent_id"`
+	CertID   int64        `json:"cert_id"`
+	NotAfter sql.NullTime `json:"not_after"`
+}
+
 type Certificate struct {
 	ID         int64         `json:"id"`
 	Owner      string        `json:"owner"`
@@ -16,9 +31,9 @@ type Certificate struct {
 	AutoRenew  bool          `json:"auto_renew"`
 	Active     bool          `json:"active"`
 	Renewing   bool          `json:"renewing"`
-	NotAfter   sql.NullTime  `json:"not_after"`
 	UpdatedAt  time.Time     `json:"updated_at"`
 	TempParent sql.NullInt64 `json:"temp_parent"`
+	NotAfter   sql.NullTime  `json:"not_after"`
 	RenewRetry sql.NullTime  `json:"renew_retry"`
 }
 

database/queries/agent.sql

@@ -0,0 +1,21 @@
+-- name: FindAgentToSync :many
+SELECT agents.id as agent_id, agents.address, agents.user, agents.dir, agents.fingerprint, cert.id as cert_id, cert.not_after as cert_not_after
+FROM agents
+         INNER JOIN agent_certs
+                    ON agent_certs.agent_id = agents.id
+         INNER JOIN certificates AS cert
+                    ON cert.id = agent_certs.cert_id
+WHERE (agents.last_sync IS NULL OR agents.last_sync < cert.updated_at)
+  AND (agent_certs.not_after IS NULL OR agent_certs.not_after IS NOT cert.not_after)
+ORDER BY agents.last_sync NULLS FIRST;
+
+-- name: UpdateAgentLastSync :exec
+UPDATE agents
+SET last_sync = ?
+WHERE agents.id = ?;
+
+-- name: UpdateAgentCertNotAfter :exec
+UPDATE agent_certs
+SET not_after = ?
+WHERE agent_id = ?
+  AND cert_id = ?;

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/1f349/mjwt v0.4.1
 	github.com/1f349/violet v0.0.14
 	github.com/AlecAivazis/survey/v2 v2.3.7
+	github.com/bramvdbogaerde/go-scp v1.5.0
 	github.com/charmbracelet/log v0.4.0
 	github.com/go-acme/lego/v4 v4.21.0
 	github.com/golang-jwt/jwt/v4 v4.5.1
@@ -17,6 +18,7 @@ require (
 	github.com/mrmelon54/certgen v0.0.2
 	github.com/mrmelon54/exit-reload v0.0.2
 	github.com/stretchr/testify v1.10.0
+	golang.org/x/crypto v0.32.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 
@@ -46,7 +48,6 @@ require (
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/spf13/afero v1.12.0 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
-	golang.org/x/crypto v0.32.0 // indirect
 	golang.org/x/exp v0.0.0-20250128182459-e0ece0dbea4c // indirect
 	golang.org/x/mod v0.22.0 // indirect
 	golang.org/x/net v0.34.0 // indirect

go.sum

@@ -12,6 +12,8 @@ github.com/aymanbagabas/go-osc52/v2 v2.0.1 h1:HwpRHbFMcZLEVr42D4p7XBqjyuxQH5SMiE
 github.com/aymanbagabas/go-osc52/v2 v2.0.1/go.mod h1:uYgXzlJ7ZpABp8OJ+exZzJJhRNQ2ASbcXHWsFqH8hp8=
 github.com/becheran/wildmatch-go v1.0.0 h1:mE3dGGkTmpKtT4Z+88t8RStG40yN9T+kFEGj2PZFSzA=
 github.com/becheran/wildmatch-go v1.0.0/go.mod h1:gbMvj0NtVdJ15Mg/mH9uxk2R1QCistMyU7d9KFzroX4=
+github.com/bramvdbogaerde/go-scp v1.5.0 h1:a9BinAjTfQh273eh7vd3qUgmBC+bx+3TRDtkZWmIpzM=
+github.com/bramvdbogaerde/go-scp v1.5.0/go.mod h1:on2aH5AxaFb2G0N5Vsdy6B0Ml7k9HuHSwfo1y0QzAbQ=
 github.com/cenkalti/backoff/v4 v4.3.0 h1:MyRJ/UdXutAwSAT+s3wNd7MfTIcy71VQueUuFK343L8=
 github.com/cenkalti/backoff/v4 v4.3.0/go.mod h1:Y3VNntkOUPxTVeUxJ/G5vcM//AlwfmyYozVcomhLiZE=
 github.com/charmbracelet/lipgloss v1.0.0 h1:O7VkGDvqEdGi93X+DeqsQ7PKHDgtQfF8j8/O2qFMQNg=

sqlc.yaml

@@ -13,3 +13,7 @@ sql:
             go_type: database/sql.NullTime
           - column: certificates.renew_retry
             go_type: database/sql.NullTime
+          - column: agents.last_sync
+            go_type: database/sql.NullTime
+          - column: agent_certs.not_after
+            go_type: database/sql.NullTime