tcm: show TCM logs

Added support for showing TCM logs

@TarantoolBot
Title: Added support for showing TCM logs

This commit introduces the ability to view TCM logs using
the `tt tcm log` command.

This command works in couple with the `tt tcm start` command,
and show the logs of the TCM process that was running by it.

Command expect exists `tcm.log` file in the current directory.

**Usage example:**
```bash
tt tcm log --lines 100 --follow
```

This command will show the last 100 lines of the TCM log
file and continue to follow the log output.
This feature is useful for monitoring the TCM process.
Without the `--follow` flag, it will show the last 100 lines
of the log file and exit.

The command also supports following flags:
- `--no-color` to disable colored output
- `--no-format` to disable structured output

**Possible output:**
```text
{
  time: **2025-05-29T17:19:47.905335965+03:00**
  level: INFO
  msg: _tcm stopped_
  source: {
    file: "tcm/internal/app/tcm/server/server.go",
    function: "tcm/internal/server.(*TcmAPI).Close",
    line: 175
  }
}
{
  time: **2025-05-29T17:19:47.90451709+03:00**
  level: WARN
  msg: _retrying of unary invoker failed_
  attempt: 0,
  error: "rpc error: code = Canceled desc = latest balancer error:
    last connection error: connection error: desc = \"transport:
    Error while dialing: dial tcp 127.0.0.1:2379: connect:
    connection refused\"",
  source: {
    file: "go.etcd.io/etcd/client/[email protected]/retry_interceptor.go",
    function: "v3.(*Client).unaryClientInterceptor.func1",
    line: 63
  },
  target: "etcd-endpoints://0xc0003d2000/127.0.0.1:2379"
}
{
  time: **2025-05-29T17:19:47.90548212+03:00**
  level: ERROR
  msg: _fail to get entity from etcd_
  err: "context canceled",
  path: "/cluster/",
  source: {
    file: "tcm/internal/app/tcm/server.go",
    function: "tcm/internal/app/tcm/server.(*TcmAPI).validationKV",
    line: 17
  }
}
```

Closes #TNTP-1103

Author: dmyger

.cspell_project-words.txt

@@ -36,6 +36,7 @@ Svacer
 tarantool
 tarantoolctl
 tarantools
+tcm
 testdata
 testfull
 TNTP

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Added support for completion with shell `fish` see
   the command `tt completion fish`.
 - Repository use `pre-commit` hooks to check code style.
+- Added support for showing TCM logs with `tt tcm log` command.
 
 ### Changed
 

cli/cmd/tcm.go

@@ -3,17 +3,19 @@ package cmd
 import (
 	"errors"
 	"fmt"
-	"log"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"time"
 
+	"github.com/apex/log"
+	"github.com/fatih/color"
 	"github.com/jedib0t/go-pretty/v6/table"
 	"github.com/jedib0t/go-pretty/v6/text"
 	"github.com/spf13/cobra"
 	"github.com/tarantool/tt/cli/cmdcontext"
 	"github.com/tarantool/tt/cli/process_utils"
+	"github.com/tarantool/tt/cli/tail"
 	tcmCmd "github.com/tarantool/tt/cli/tcm"
 	libwatchdog "github.com/tarantool/tt/lib/watchdog"
 )
@@ -23,11 +25,12 @@ var tcmCtx = tcmCmd.TcmCtx{}
 const (
 	tcmPidFile      = "tcm.pid"
 	watchdogPidFile = "watchdog.pid"
+	logFileName     = "tcm.log"
 )
 
 func newTcmStartCmd() *cobra.Command {
 	tcmCmd := &cobra.Command{
-		Use:   "start",
+		Use:   "start [flags]",
 		Short: "Start tcm application",
 		Long: `Start to the tcm.
 		tt tcm start --watchdog
@@ -36,6 +39,8 @@ func newTcmStartCmd() *cobra.Command {
 	}
 	tcmCmd.Flags().StringVar(&tcmCtx.Executable, "path", "", "the path to the tcm binary file")
 	tcmCmd.Flags().BoolVar(&tcmCtx.Watchdog, "watchdog", false, "enables the watchdog")
+	tcmCmd.Flags().StringVar(&tcmCtx.Log.Level, "log-level", "INFO",
+		"log level for the tcm application")
 
 	return tcmCmd
 }
@@ -61,6 +66,30 @@ func newTcmStopCmd() *cobra.Command {
 	return tcmCmd
 }
 
+func newTcmLogCmd() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "log [flags]",
+		Short: "Show tcm application logs",
+		Long:  `Show logs for the tcm. tt tcm log`,
+		Run:   RunModuleFunc(internalTcmLog),
+	}
+
+	cmd.Flags().IntVarP(&tcmCtx.Log.Lines, "lines", "n", 10,
+		"Count of last lines to output")
+	cmd.Flags().BoolVarP(&tcmCtx.Log.IsFollow, "follow", "f", false,
+		"Output appended data as the log file grows")
+	cmd.Flags().BoolVar(&tcmCtx.Log.ForceColor, "color", false,
+		"Force colored output in logs")
+	cmd.Flags().BoolVar(&tcmCtx.Log.NoColor, "no-color", false,
+		"Disable colored output in logs")
+	cmd.Flags().BoolVar(&tcmCtx.Log.NoFormat, "no-format", false,
+		"Disable log formatting")
+
+	cmd.MarkFlagsMutuallyExclusive("color", "no-color")
+
+	return cmd
+}
+
 func NewTcmCmd() *cobra.Command {
 	tcmCmd := &cobra.Command{
 		Use:   "tcm",
@@ -70,12 +99,19 @@ func NewTcmCmd() *cobra.Command {
 		newTcmStartCmd(),
 		newTcmStatusCmd(),
 		newTcmStopCmd(),
+		newTcmLogCmd(),
 	)
 	return tcmCmd
 }
 
-func startTcmInteractive() error {
-	tcmApp := exec.Command(tcmCtx.Executable)
+func startTcmInteractive(logLevel string) error {
+	tcmApp := exec.Command(tcmCtx.Executable,
+		"--log.default.add-source",
+		"--log.default.output=file",
+		"--log.default.format=json",
+		"--log.default.level="+logLevel,
+		"--log.default.file.name="+logFileName,
+	)
 
 	if err := tcmApp.Start(); err != nil {
 		return err
@@ -90,7 +126,7 @@ func startTcmInteractive() error {
 		return err
 	}
 
-	log.Printf("(INFO): Interactive process PID %d written to %s\n", tcmApp.Process.Pid, tcmPidFile)
+	log.Infof("Interactive process PID %d written to %q\n", tcmApp.Process.Pid, tcmPidFile)
 	return nil
 }
 
@@ -114,7 +150,7 @@ func internalStartTcm(cmdCtx *cmdcontext.CmdCtx, args []string) error {
 	tcmCtx.Executable = cmdCtx.Cli.TcmCli.Executable
 
 	if !tcmCtx.Watchdog {
-		if err := startTcmInteractive(); err != nil {
+		if err := startTcmInteractive(tcmCtx.Log.Level); err != nil {
 			return err
 		}
 	} else {
@@ -164,14 +200,32 @@ func internalTcmStop(cmdCtx *cmdcontext.CmdCtx, args []string) error {
 		if err != nil {
 			return err
 		}
-		log.Println("Watchdog and TCM stopped")
+
+		log.Info("Watchdog and TCM stopped")
 	} else {
 		_, err := process_utils.StopProcess(tcmPidFile)
 		if err != nil {
 			return err
 		}
-		log.Println("TCM stopped")
+
+		log.Info("TCM stopped")
 	}
 
 	return nil
 }
+
+func internalTcmLog(cmdCtx *cmdcontext.CmdCtx, args []string) error {
+	if tcmCtx.Log.ForceColor {
+		color.NoColor = false
+	}
+
+	p := tcmCmd.NewLogPrinter(tcmCtx.Log.NoFormat, tcmCtx.Log.NoColor, os.Stdout)
+	if tcmCtx.Log.IsFollow {
+		f := tail.NewTailFollower(logFileName)
+		return tcmCmd.FollowLogs(f, p, tcmCtx.Log.Lines)
+	}
+
+	t := tail.NewTailReader(logFileName)
+
+	return tcmCmd.TailLogs(t, p, tcmCtx.Log.Lines)
+}