logs: stream corrosion logs with 'uc machine logs corrosion' from container instead of journal (fixes #392)

cmd/uncloud/machine/logs.go

@@ -3,11 +3,12 @@ package machine
 import (
 	"context"
 	"fmt"
+	"slices"
+	"strings"
 
 	"github.com/psviderski/uncloud/internal/cli"
 	"github.com/psviderski/uncloud/internal/cli/completion"
 	"github.com/psviderski/uncloud/internal/cli/logs"
-	"github.com/psviderski/uncloud/internal/journal"
 	"github.com/psviderski/uncloud/pkg/api"
 	"github.com/psviderski/uncloud/pkg/client"
 	"github.com/spf13/cobra"
@@ -19,14 +20,14 @@ func NewLogsCommand() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:     "logs [SERVICE...]",
 		Aliases: []string{"log"},
-		Short:   "View systemd service logs.",
+		Short:   "View system service logs.",
-		Long: `View logs from the specified systemd service(s) across all machines in the cluster.
+		Long: `View logs from the specified system service(s) across all machines in the cluster.
 Use -m to restrict to specific machines.
 
 Supported services:
-  uncloud            the Uncloud daemon
+  corrosion  the Corrosion distributed state store
   docker     the Docker daemon
-  uncloud-corrosion  the Corrosion distributed state store
+  uncloud    the Uncloud daemon
 
 If no services are specified, streams logs from the uncloud service.`,
 		Example: `  # View recent logs for the uncloud service.
@@ -37,7 +38,7 @@ If no services are specified, streams logs from the uncloud service.`,
   uc machine logs -f uncloud
 
   # View logs from multiple services.
-  uc machine logs uncloud docker uncloud-corrosion
+  uc machine logs uncloud docker corrosion
 
   # Show last 20 lines per machine (default is 100).
   uc machine logs -n 20 docker
@@ -49,7 +50,7 @@ If no services are specified, streams logs from the uncloud service.`,
   uc machine logs --since 3h --until 1h30m docker
 
   # View logs only from specific machines.
-  uc machine logs -m machine1,machine2 uncloud uncloud-corrosion`,
+  uc machine logs -m machine1,machine2 uncloud corrosion`,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			uncli := cmd.Context().Value("cli").(*cli.CLI)
 			return runLogs(cmd.Context(), uncli, args, options)
@@ -62,14 +63,14 @@ If no services are specified, streams logs from the uncloud service.`,
 	return cmd
 }
 
-func runLogs(ctx context.Context, uncli *cli.CLI, units []string, opts logs.Options) error {
+func runLogs(ctx context.Context, uncli *cli.CLI, services []string, opts logs.Options) error {
-	if len(units) == 0 {
+	if len(services) == 0 {
-		units = []string{journal.UnitUncloud}
+		services = []string{api.SystemServiceUncloud}
 	}
-
+	for _, service := range services {
-	for _, unit := range units {
+		if !slices.Contains(api.SystemServices, service) {
-		if !journal.ValidUnit(unit) {
+			return fmt.Errorf("invalid system service '%s'; valid services: %s",
-			return fmt.Errorf("invalid systemd service '%s'", unit)
+				service, strings.Join(api.SystemServices, ", "))
 		}
 	}
 
@@ -104,27 +105,27 @@ func runLogs(ctx context.Context, uncli *cli.CLI, units []string, opts logs.Opti
 		machineNames = append(machineNames, m.Machine.Name)
 	}
 
-	// Collect one log stream per unit. MachineLogs merges across machines internally.
+	// Collect one log stream per service. MachineLogs merges across machines internally.
-	unitStreams := make([]<-chan api.ServiceLogEntry, 0, len(units))
+	serviceStreams := make([]<-chan api.ServiceLogEntry, 0, len(services))
-	for _, unit := range units {
+	for _, service := range services {
-		ch, err := c.MachineLogs(ctx, unit, logsOpts)
+		ch, err := c.MachineLogs(ctx, service, logsOpts)
 		if err != nil {
-			return fmt.Errorf("stream logs for systemd service '%s': %w", unit, err)
+			return fmt.Errorf("stream logs for system service '%s': %w", service, err)
 		}
-		unitStreams = append(unitStreams, ch)
+		serviceStreams = append(serviceStreams, ch)
 	}
 
 	var stream <-chan api.ServiceLogEntry
-	if len(unitStreams) == 1 {
+	if len(serviceStreams) == 1 {
-		stream = unitStreams[0]
+		stream = serviceStreams[0]
 	} else {
 		// Each MachineLogs stream already runs its own inner merger with stall detection,
-		// so the outer merger across units skips it to avoid duplicate warnings.
+		// so the outer merger across services skips it to avoid duplicate warnings.
-		merger := client.NewLogMerger(unitStreams, client.LogMergerOptions{})
+		merger := client.NewLogMerger(serviceStreams, client.LogMergerOptions{})
 		stream = merger.Stream()
 	}
 
-	formatter := logs.NewFormatter(machineNames, units, opts.UTC)
+	formatter := logs.NewFormatter(machineNames, services, opts.UTC)
 
 	// Print merged logs.
 	for entry := range stream {

internal/cli/logs/formatter.go

@@ -129,7 +129,7 @@ func (f *Formatter) PrintEntry(entry api.ServiceLogEntry) {
 	output.WriteString(f.formatMachine(entry.Metadata.MachineName))
 	output.WriteString(" ")
 
-	// Service/container_id or service name for a systemd service.
+	// Service/container_id or service name for a system service.
 	output.WriteString(f.formatService(entry.Metadata.ServiceName, entry.Metadata.ContainerID, entry.Metadata.Hook))
 	output.WriteString(" ")
 
@@ -160,7 +160,7 @@ func (f *Formatter) printError(entry api.ServiceLogEntry) {
 			stringid.TruncateID(entry.Metadata.ContainerID),
 			entry.Metadata.MachineName)
 	} else {
-		msg = fmt.Sprintf("WARNING: log stream from systemd service '%s' on machine '%s'",
+		msg = fmt.Sprintf("WARNING: log stream from system service '%s' on machine '%s'",
 			entry.Metadata.ServiceName,
 			entry.Metadata.MachineName)
 	}

internal/journal/journal.go

@@ -10,31 +10,11 @@ import (
 	"github.com/psviderski/uncloud/pkg/api"
 )
 
-const (
-	UnitUncloud   = "uncloud"
-	UnitDocker    = "docker"
-	UnitCorrosion = "uncloud-corrosion"
-)
-
-func ValidUnit(unit string) bool {
-	switch unit {
-	case UnitUncloud:
-	case UnitDocker:
-	case UnitCorrosion:
-	default:
-		return false
-	}
-	return true
-}
-
 const journalctl = "journalctl"
 
 var commandContext = exec.CommandContext // allow override for test
 
 func logs(ctx context.Context, unit string, opts api.ServiceLogsOptions) (io.ReadCloser, func() error, error) {
-	if !ValidUnit(unit) {
-		return nil, nil, fmt.Errorf("journal logs: invalid unit: %s", unit)
-	}
 	args := []string{"-u", unit, "--no-hostname"}
 	args = append(args, "-n")
 	if opts.Tail > -1 {

internal/journal/logs.go

@@ -3,7 +3,6 @@ package journal
 import (
 	"bytes"
 	"context"
-	"fmt"
 	"slices"
 	"strconv"
 	"time"
@@ -13,10 +12,6 @@ import (
 
 // Logs streams logs from a service and returns entries via a channel.
 func Logs(ctx context.Context, unit string, opts api.ServiceLogsOptions) (<-chan api.LogEntry, error) {
-	if !ValidUnit(unit) {
-		return nil, fmt.Errorf("journal logs: invalid unit: %s", unit)
-	}
-
 	reader, wait, err := logs(ctx, unit, opts)
 	if err != nil {
 		return nil, err

internal/machine/corroservice/docker.go

@@ -17,8 +17,12 @@ import (
 	"github.com/psviderski/uncloud/pkg/api"
 )
 
+const (
 	// Image is the Corrosion image pinned to the uncloudd version.
-const Image = "ghcr.io/unlabs-dev/corrosion:2026.6.15"
+	Image = "ghcr.io/unlabs-dev/corrosion:2026.6.15"
+	// ContainerName is the name of the managed Corrosion container.
+	ContainerName = "uncloud-corrosion"
+)
 
 type DockerService struct {
 	Client *client.Client

internal/machine/docker/service.go

@@ -170,7 +170,9 @@ func (s *Service) ListImages(ctx context.Context, opts image.ListOptions) (Image
 
 // ContainerLogs streams logs from a container and returns demultiplexed entries via a channel.
 // The channel is closed when streaming completes or context is cancelled.
-func (s *Service) ContainerLogs(ctx context.Context, containerID string, opts api.ServiceLogsOptions) (<-chan api.LogEntry, error) {
+func (s *Service) ContainerLogs(
+	ctx context.Context, containerID string, opts api.ServiceLogsOptions,
+) (<-chan api.LogEntry, error) {
 	dockerOpts := container.LogsOptions{
 		ShowStdout: true,
 		ShowStderr: true,

internal/machine/machine.go

@@ -13,6 +13,7 @@ import (
 	"path/filepath"
 	"slices"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -139,7 +140,7 @@ func (c *Config) SetDefaults() (*Config, error) {
 		cfg.CorrosionService = &corroservice.DockerService{
 			Client:  cfg.DockerClient,
 			Image:   corroservice.Image,
-			Name:    "uncloud-corrosion",
+			Name:    corroservice.ContainerName,
 			DataDir: cfg.CorrosionDataDir,
 			RunDir:  cfg.CorrosionRunDir,
 			User:    fmt.Sprintf("%d:%d", uid, gid),
@@ -1217,7 +1218,7 @@ func (m *Machine) InspectService(
 // logsHeartbeatInterval is the interval at which heartbeat entries are sent when there are no logs to stream.
 const logsHeartbeatInterval = 200 * time.Millisecond
 
-// MachineLogs streams logs from a systemd service.
+// MachineLogs streams logs from a system service.
 func (m *Machine) MachineLogs(
 	req *pb.LogsRequest, stream grpc.ServerStreamingServer[pb.LogEntry],
 ) error {
@@ -1231,16 +1232,31 @@ func (m *Machine) MachineLogs(
 		Until:  req.Until,
 	}
 
-	logsCh, err := journal.Logs(ctx, req.Id, opts)
+	var logsCh <-chan api.LogEntry
+	var err error
+	log := slog.With("stream_id", fmt.Sprintf("%p", stream)[2:])
+	switch req.Id {
+	case api.SystemServiceUncloud, api.SystemServiceDocker:
+		// These run as systemd units whose names match the service name.
+		logsCh, err = journal.Logs(ctx, req.Id, opts)
+		log = log.With("unit", req.Id)
+	case api.SystemServiceCorrosion:
+		// Corrosion runs as a daemon-managed container, not a systemd unit, so read its logs
+		// from the container, the same way `uc logs` does for service containers.
+		logsCh, err = m.dockerService.ContainerLogs(ctx, corroservice.ContainerName, opts)
+		log = log.With("container", corroservice.ContainerName)
+	default:
+		return status.Errorf(codes.InvalidArgument, "unsupported system service %q; supported services: %s",
+			req.Id, strings.Join(api.SystemServices, ", "))
+	}
 	if err != nil {
 		if errdefs.IsNotFound(err) {
 			return status.Error(codes.NotFound, err.Error())
 		}
-		return status.Errorf(codes.Internal, "get journal logs: %v", err)
+		return status.Errorf(codes.Internal, "get logs: %v", err)
 	}
 
-	log := slog.With("unit", req.Id, "stream_id", fmt.Sprintf("%p", stream)[2:])
+	log.Debug("Starting system service logs streaming.",
-	log.Debug("Starting systemd service logs streaming.",
 		"follow", req.Follow, "tail", req.Tail, "since", req.Since, "until", req.Until)
 
 	// Heartbeats are needed only when following logs to let the client know when there are no new log entries

pkg/api/logs.go

@@ -16,6 +16,16 @@ const (
 	LogStreamHeartbeat
 )
 
+// System service names whose logs can be streamed via client.MachineLogs.
+const (
+	SystemServiceCorrosion = "corrosion"
+	SystemServiceDocker    = "docker"
+	SystemServiceUncloud   = "uncloud"
+)
+
+// SystemServices lists all system services that support log streaming.
+var SystemServices = []string{SystemServiceCorrosion, SystemServiceDocker, SystemServiceUncloud}
+
 type LogStreamType int
 
 // LogStreamTypeFromProto converts a protobuf LogEntry.StreamType to the internal LogStreamType.
@@ -61,7 +71,7 @@ type ServiceLogsOptions struct {
 	Machines []string
 }
 
-// ServiceLogEntry represents a single log entry from a service container or systemd service.
+// ServiceLogEntry represents a single log entry from a service container or system service.
 type ServiceLogEntry struct {
 	// Metadata may not be set if an error occurred (Err is not nil).
 	Metadata ServiceLogEntryMetadata

pkg/client/logs.go

@@ -156,11 +156,11 @@ func (cli *Client) ContainerLogs(
 	return ch, nil
 }
 
-// MachineLogs streams journal logs for the given systemd service across one or more machines in
+// MachineLogs streams logs for the given system service across one or more machines in
 // chronological order based on timestamps. If opts.Machines is empty, logs are streamed from all
 // machines in the cluster.
 func (cli *Client) MachineLogs(
-	ctx context.Context, unit string, opts api.ServiceLogsOptions,
+	ctx context.Context, service string, opts api.ServiceLogsOptions,
 ) (<-chan api.ServiceLogEntry, error) {
 	machines, err := cli.ListMachines(ctx, &api.MachineFilter{NamesOrIDs: opts.Machines})
 	if err != nil {
@@ -172,18 +172,18 @@ func (cli *Client) MachineLogs(
 
 	streams := make([]<-chan api.ServiceLogEntry, 0, len(machines))
 	for _, m := range machines {
-		ch, err := cli.systemdServiceLogs(ctx, m.Machine.Id, unit, opts)
+		ch, err := cli.systemServiceLogs(ctx, m.Machine.Id, service, opts)
 		if err != nil {
 			// TODO: cancel already-opened streams. Currently they leak until ctx is cancelled which could
 			//  be critical when used as SDK.
-			return nil, fmt.Errorf("stream logs from systemd service '%s' on machine '%s': %w",
+			return nil, fmt.Errorf("stream logs from system service '%s' on machine '%s': %w",
-				unit, m.Machine.Name, err)
+				service, m.Machine.Name, err)
 		}
 
-		// Enrich journal log entries with the systemd service name and machine metadata.
+		// Enrich log entries with the system service name and machine metadata.
 		metadata := api.ServiceLogEntryMetadata{
-			ServiceID:   unit,
+			ServiceID:   service,
-			ServiceName: unit,
+			ServiceName: service,
 			MachineID:   m.Machine.Id,
 			MachineName: m.Machine.Name,
 		}
@@ -194,14 +194,14 @@ func (cli *Client) MachineLogs(
 	return merger.Stream(), nil
 }
 
-// systemdServiceLogs streams log entries from a single systemd service on the specified machine.
+// systemServiceLogs streams log entries from a single system service on the specified machine.
-func (cli *Client) systemdServiceLogs(
+func (cli *Client) systemServiceLogs(
-	ctx context.Context, machineID, unit string, opts api.ServiceLogsOptions,
+	ctx context.Context, machineID, service string, opts api.ServiceLogsOptions,
 ) (<-chan api.LogEntry, error) {
 	proxyCtx := cli.ProxySingleMachineContext(ctx, machineID)
 
 	req := &pb.LogsRequest{
-		Id:     unit,
+		Id:     service,
 		Follow: opts.Follow,
 		Tail:   int32(opts.Tail),
 		Since:  opts.Since,

website/docs/9-cli-reference/uc_machine.md

@@ -22,7 +22,7 @@ Manage machines in the cluster.
 * [uc](uc.md)	 - A CLI tool for managing Uncloud resources such as machines, services, and volumes.
 * [uc machine add](uc_machine_add.md)	 - Add a remote machine to a cluster.
 * [uc machine init](uc_machine_init.md)	 - Initialise a new cluster with a remote machine as the first member.
-* [uc machine logs](uc_machine_logs.md)	 - View systemd service logs.
+* [uc machine logs](uc_machine_logs.md)	 - View system service logs.
 * [uc machine ls](uc_machine_ls.md)	 - List machines in a cluster.
 * [uc machine rename](uc_machine_rename.md)	 - Rename a machine in the cluster.
 * [uc machine rm](uc_machine_rm.md)	 - Remove a machine from a cluster and reset it.

website/docs/9-cli-reference/uc_machine_logs.md

@@ -1,16 +1,16 @@
 # uc machine logs
 
-View systemd service logs.
+View system service logs.
 
 ## Synopsis
 
-View logs from the specified systemd service(s) across all machines in the cluster.
+View logs from the specified system service(s) across all machines in the cluster.
 Use -m to restrict to specific machines.
 
 Supported services:
-  uncloud            the Uncloud daemon
+  corrosion  the Corrosion distributed state store
   docker     the Docker daemon
-  uncloud-corrosion  the Corrosion distributed state store
+  uncloud    the Uncloud daemon
 
 If no services are specified, streams logs from the uncloud service.
 
@@ -29,7 +29,7 @@ uc machine logs [SERVICE...] [flags]
   uc machine logs -f uncloud
 
   # View logs from multiple services.
-  uc machine logs uncloud docker uncloud-corrosion
+  uc machine logs uncloud docker corrosion
 
   # Show last 20 lines per machine (default is 100).
   uc machine logs -n 20 docker
@@ -41,7 +41,7 @@ uc machine logs [SERVICE...] [flags]
   uc machine logs --since 3h --until 1h30m docker
 
   # View logs only from specific machines.
-  uc machine logs -m machine1,machine2 uncloud uncloud-corrosion
+  uc machine logs -m machine1,machine2 uncloud corrosion
 ```
 
 ## Options