adding PM2 processes details as response of ping endpoint if LOG_LEVEL=DEBUG

internal/app/xhttp/handler.go

@@ -8,8 +8,10 @@ import (
 	"github.com/labstack/echo/v4"
 	"github.com/thecodingmachine/gotenberg/internal/app/xhttp/pkg/context"
 	"github.com/thecodingmachine/gotenberg/internal/app/xhttp/pkg/resource"
+	"github.com/thecodingmachine/gotenberg/internal/pkg/pm2"
 	"github.com/thecodingmachine/gotenberg/internal/pkg/printer"
 	"github.com/thecodingmachine/gotenberg/internal/pkg/xerror"
+	"github.com/thecodingmachine/gotenberg/internal/pkg/xlog"
 	"github.com/thecodingmachine/gotenberg/internal/pkg/xrand"
 	"github.com/thecodingmachine/gotenberg/internal/pkg/xtime"
 )
@@ -28,11 +30,24 @@ const (
 func pingHandler(c echo.Context) error {
 	const op string = "xhttp.pingHandler"
 	ctx := context.MustCastFromEchoContext(c)
-	ctx.XLogger().DebugOp(op, "handling ping request...")
-	if err := ctx.ProcessesHealthcheck(); err != nil {
+	logger := ctx.XLogger()
+	logger.DebugOp(op, "handling ping request...")
+	resolver := func() error {
+		if err := ctx.ProcessesHealthcheck(); err != nil {
+			return err
+		}
+		if logger.Level() != xlog.DebugLevel {
+			return nil
+		}
+		list, err := pm2.List()
+		if err != nil {
+			return err
+		}
+		return ctx.JSON(http.StatusOK, list)
+	}
+	if err := resolver(); err != nil {
 		return xerror.New(op, err)
 	}
-	// TODO return processes info
 	return nil
 }
 

internal/app/xhttp/handler_test.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	"github.com/labstack/echo/v4"
@@ -15,7 +16,26 @@ import (
 	"github.com/thecodingmachine/gotenberg/test"
 )
 
-// TODO test ping handler
+func TestPingHandler(t *testing.T) {
+	// should return 200.
+	config := conf.DefaultConfig()
+	srv := New(config)
+	srv = New(config)
+	req := httptest.NewRequest(http.MethodGet, pingEndpoint, nil)
+	test.AssertStatusCode(t, http.StatusOK, srv, req)
+	// should returns a JSON as
+	// LOG_LEVEL is "DEBUG".
+	os.Setenv(conf.LogLevelEnvVar, "DEBUG")
+	config, err := conf.FromEnv()
+	assert.Nil(t, err)
+	srv = New(config)
+	req = httptest.NewRequest(http.MethodGet, pingEndpoint, nil)
+	rec := httptest.NewRecorder()
+	srv.ServeHTTP(rec, req)
+	assert.Equal(t, "application/json; charset=UTF-8", rec.Header().Get("Content-type"))
+	assert.Equal(t, http.StatusOK, rec.Code)
+	os.Unsetenv(conf.LogLevelEnvVar)
+}
 
 func TestMergeHandler(t *testing.T) {
 	config := conf.DefaultConfig()

internal/pkg/pm2/pm2.go

@@ -1,7 +1,9 @@
 package pm2
 
 import (
+	"encoding/json"
 	"fmt"
+	"os/exec"
 
 	"github.com/thecodingmachine/gotenberg/internal/pkg/xerror"
 	"github.com/thecodingmachine/gotenberg/internal/pkg/xexec"
@@ -27,8 +29,68 @@ const (
 	restartCommand pm2Command = "restart"
 	stopCommand    pm2Command = "stop"
 	logsCommand    pm2Command = "logs"
+	jlistCommand   pm2Command = "jlist"
 )
 
+/*
+JListItem is a struct
+used for unmarshaling
+ONE item of the result
+of the command "pm2 jlist".
+*/
+type JListItem struct {
+	Name   string `json:"name"`
+	PM2Env struct {
+		Status string `json:"status"`
+	} `json:"pm2_env"`
+	Monit struct {
+		Memory int64   `json:"memory"`
+		CPU    float64 `json:"cpu"`
+	} `json:"monit"`
+}
+
+/*
+JList is a struct
+used for unmarshaling
+the result of the command
+"pm2 jlist".
+*/
+type JList []JListItem
+
+func (list JList) isOnline(p Process) bool {
+	const onlineStatus string = "online"
+	for _, item := range list {
+		if item.Name == p.binary() {
+			return item.PM2Env.Status == onlineStatus
+		}
+	}
+	return false
+}
+
+// List returns the
+// processes details.
+func List() (*JList, error) {
+	const op = "pm2.List"
+	resolver := func() (*JList, error) {
+		out, err := exec.
+			Command("pm2", string(jlistCommand)).
+			Output()
+		if err != nil {
+			return nil, err
+		}
+		data := &JList{}
+		if err := json.Unmarshal(out, data); err != nil {
+			return nil, err
+		}
+		return data, nil
+	}
+	list, err := resolver()
+	if err != nil {
+		return nil, xerror.New(op, err)
+	}
+	return list, nil
+}
+
 func start(logger xlog.Logger, process Process) error {
 	const (
 		op              string = "pm2.start"

internal/pkg/pm2/unoconv.go

@@ -32,10 +32,36 @@ func (p unoconvProcess) Start() error {
 }
 
 func (p unoconvProcess) IsViable() bool {
-	// TODO find a way to check if
-	// the unoconv listener
-	// is correctly started?
-	return true
+	const op string = "pm2.unoconvProcess.IsViable"
+	p.logger.DebugfOp(
+		op,
+		"checking '%s' viability via PM2",
+		p.Fullname(),
+	)
+	list, err := List()
+	if err != nil {
+		p.logger.ErrorfOp(
+			op,
+			"'%s' seems not viable as retrieving the list of processes via 'pm2 jlist' returned '%v'",
+			p.Fullname(),
+			err,
+		)
+		return false
+	}
+	if list.isOnline(p) {
+		p.logger.DebugfOp(
+			op,
+			"'%s' is viable as its status is 'online'",
+			p.Fullname(),
+		)
+		return true
+	}
+	p.logger.DebugfOp(
+		op,
+		"'%s' is not viable as its status is not 'online'",
+		p.Fullname(),
+	)
+	return false
 }
 
 func (p unoconvProcess) Stop() error {