Merge pull request 'README.md + Example + Docker build args + wmpidproxy fix' (#1) from readme into main

Reviewed-on: #1

README.md

@@ -5,6 +5,135 @@ It also has cron feature. It is designed to run in a container/docker.
 The Wingmate binary do not need any external dependency. 
 Just copy the binary, and exec from the entry point script.
 
-## Getting Started
+# Getting Started
-There are two docker examples [using alpine](docker/alpine/gettting-started.md)
+
-and [using debian bookworm](docker/bookworm/gettting-started.md)
+## Binaries
+
+There are three binaries in this project: `wingmate`, `wmpidproxy`, and `wmexec`.
+
+`wingmate` is the core binary. It reads config, starts, restarts services. It also
+runs cron. Read the [configuration](#configuration) section for files needed to run
+`wingmate`.
+
+`wmpidproxy` is a helper binary for monitoring _legacy style_ service (fork, exit
+initial proces, and continue in background). Read [here](#wingmate-pid-proxy-binary)
+for further details about `wmpidproxy`.
+
+`wmexec` is a helper binary for running process in different `user` or `group`.
+It also useful for setting the process as process group leader.
+Read [here](#wingmate-exec-binary) for further details about `wmexec`.
+
+## Building a container image based on wingmate image in Docker Hub
+
+Wingmate has no dependency other than `alpine` base image, so you just need to copy
+the binaries directly. If you have built your application into an `alpine` based image,
+all you need to do is copy whichever binary you need, crontab file (if you use cron)
+and add some shell script to glue them together. Here is a Dockerfile example.
+
+```Dockerfile
+# Dockerfile
+FROM suyono/wingmate:alpine as source
+
+FROM alpine:latest
+ADD --chmod=755 wingmate/ /etc/wingmate/
+ADD --chmod=755 entry.sh /usr/local/bin/entry.sh
+COPY --from=source /usr/local/bin/wingmate /usr/local/bin/wingmate
+COPY --from=source /usr/local/bin/wmpidproxy /usr/local/bin/wmpidproxy
+COPY --from=source /usr/local/bin/wmexec /usr/local/bin/wmexec
+ENTRYPOINT [ "/usr/local/bin/entry.sh" ]
+CMD [ "/usr/local/bin/wingmate" ]
+```
+You can find some examples for shell script in [alpine docker](docker/alpine) and 
+[bookworm docker](docker/bookworm).
+
+## Configuration
+
+When `wingmate` binary starts, it will look for some files. By default, it will
+try to read the content of `/etc/wingmate` directory. You can change the directory
+where it reads by setting `WINGMATE_CONFIG_PATH` environment variable. The structure
+inside the config path should look like this.
+
+```shell
+/etc
+ └── wingmate
+     ├── crontab
+     ├── crontab.d
+     │   ├── cron1.sh
+     │   ├── cron2.sh
+     │   └── cron3.sh
+     └── service
+         ├── one.sh
+         └── spawner.sh
+```
+
+First, `wingmate` will try to read the content of `service` directory. The content of
+this directory should be executables (either shell scripts or binaries). The wingmate
+will run every executable in `service` directory without going into any subdirectory.
+
+Next, `wingmate` will read the `crontab` file. `wingmate` expects the `crontab` file using
+common UNIX crontab file format. Something like this
+
+```shell
+ ┌───────────── minute (0–59)
+ │ ┌───────────── hour (0–23)
+ │ │ ┌───────────── day of the month (1–31)
+ │ │ │ ┌───────────── month (1–12)
+ │ │ │ │ ┌───────────── day of the week (0–6) (Sunday to Saturday)
+ │ │ │ │ │ 
+ │ │ │ │ │
+ │ │ │ │ │
+ * * * * * <commad or shell script or binary>
+```
+
+The command part only support simple command and arguments. Shell expression is not supported
+yet. It is recommended to write a shell script and put the path to shell script in
+the command part.
+
+# Appendix
+## Wingmate PID Proxy binary
+
+`wingmate` works by monitoring its direct children process. When it sees one of its children
+exited, it will start the child process again.
+
+Sometimes you find some services work by running in the background. It means it forks a new 
+process, disconnect the new child from terminal, exit the parent process, and continue 
+running in the child process. This kind of service usually write its background process
+PID in a pid file.
+
+To monitor the background services, `wingmate` utilizes `wmpidproxy`. `wmpidproxy` runs
+in foreground in-place of the background service. It also periodically check whether the
+background service is still running, in current implementation it checks every second.
+
+```shell
+wmpidproxy --pid-file <path to pid file> -- <background service binary/start script>
+```
+#### Example
+Running sshd background with `wingmate` and `wmpidproxy`: [here](example/ssh-docker)
+
+#### Note
+
+It is recommended to configure services to run in foreground if they support it. When services
+running in foreground, they are running as direct children process of `wingmate`.
+`wingmate` monitors children process effectively. Whenever a child process exited/terminated,
+`wingmate` will start it again quickly. Running in foreground also removes the overhead of running
+`wmpidproxy` together with the service.
+
+## Wingmate Exec binary
+
+`wingmate` runs all the services as its children using the same `uid`, `gid`, and in the
+same process group. You can use `wmexec` to run service in different `uid`, `gid`, or make
+the service process as its own process group leader.
+
+#### Syntax
+
+```shell
+wmexec [--user <uid>[:<gid>]] [--setsid] -- <target executable>
+```
+| Option   | Parameter | Description                                                                                              |
+|----------|-----------|----------------------------------------------------------------------------------------------------------|
+| --user   | uid[:gid] | Set the real user ID and the real group id. Uid and Gid can be either in numeric form or in name form    |
+| --setsid |           | Set the process become the leader of its own process group, effectively detaching from parent's terminal |
+
+#### Example
+
+You can find example for `wmexec` in [here](docker/alpine/etc/wingmate) and [here](docker/bookworm/etc/wingmate)

cmd/pidproxy/pidproxy.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"bufio"
+	"errors"
 	"log"
 	"os"
 	"os/exec"
@@ -92,13 +94,13 @@ func pidProxy(cmd *cobra.Command, args []string) error {
 		err error
 		pid int
 		sc  chan os.Signal
-		t   *time.Timer
+		t   *time.Ticker
 	)
 
 	sc = make(chan os.Signal, 1)
 	signal.Notify(sc, unix.SIGTERM)
 
-	t = time.NewTimer(time.Second)
+	t = time.NewTicker(time.Second)
 
 check:
 	for {
@@ -130,8 +132,6 @@ func readPid(pidFile string) (int, error) {
 	var (
 		file  *os.File
 		err   error
-		buf   []byte
-		n     int
 		pid64 int64
 	)
 
@@ -142,18 +142,15 @@ func readPid(pidFile string) (int, error) {
 		_ = file.Close()
 	}()
 
-	buf = make([]byte, 1024)
+	scanner := bufio.NewScanner(file)
-	n, err = file.Read(buf)
+	if scanner.Scan() {
-	if err != nil {
+		if pid64, err = strconv.ParseInt(scanner.Text(), 10, 64); err != nil {
-		return 0, err
+			return 0, err
+		}
+		return int(pid64), nil
+	} else {
+		return 0, errors.New("invalid scanner")
 	}
-
-	pid64, err = strconv.ParseInt(string(buf[:n]), 10, 64)
-	if err != nil {
-		return 0, err
-	}
-
-	return int(pid64), nil
 }
 
 func startProcess(arg0 string, args ...string) {

config/config.go

@@ -7,6 +7,7 @@ import (
 
 	"gitea.suyono.dev/suyono/wingmate"
 	"github.com/spf13/viper"
+	"golang.org/x/sys/unix"
 )
 
 const (
@@ -48,8 +49,11 @@ func Read() (*Config, error) {
 	if len(dirent) > 0 {
 		for _, d := range dirent {
 			if d.Type().IsRegular() {
-				serviceAvailable = true
+				svcPath := filepath.Join(svcdir, d.Name())
-				outConfig.ServicePaths = append(outConfig.ServicePaths, filepath.Join(svcdir, d.Name()))
+				if err = unix.Access(svcPath, unix.X_OK); err == nil {
+					serviceAvailable = true
+					outConfig.ServicePaths = append(outConfig.ServicePaths, svcPath)
+				}
 			}
 		}
 	}

config/config_test.go

@@ -0,0 +1,130 @@
+package config
+
+import (
+	"os"
+	"path"
+	"testing"
+
+	"gitea.suyono.dev/suyono/wingmate"
+	"github.com/spf13/viper"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRead(t *testing.T) {
+
+	type testEntry struct {
+		name     string
+		testFunc func(t *testing.T)
+	}
+
+	var (
+		configDir string
+		err       error
+	)
+
+	const serviceDir = "service"
+
+	setup := func(t *testing.T) {
+		if configDir, err = os.MkdirTemp("", "wingmate-*-test"); err != nil {
+			t.Fatal("setup", err)
+		}
+		viper.Set(EnvConfigPath, configDir)
+	}
+
+	tear := func(t *testing.T) {
+		if err = os.RemoveAll(configDir); err != nil {
+			t.Fatal("tear", err)
+		}
+	}
+
+	mkSvcDir := func(t *testing.T) {
+		if err := os.MkdirAll(path.Join(configDir, serviceDir), 0755); err != nil {
+			t.Fatal("create dir", err)
+		}
+	}
+
+	touchFile := func(t *testing.T, name string, perm os.FileMode) {
+		f, err := os.OpenFile(name, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, perm)
+		if err != nil {
+			t.Fatal("create file", err)
+		}
+		_ = f.Close()
+	}
+
+	_ = wingmate.NewLog(os.Stderr)
+	tests := []testEntry{
+		{
+			name: "positive",
+			testFunc: func(t *testing.T) {
+				mkSvcDir(t)
+				touchFile(t, path.Join(configDir, serviceDir, "one.sh"), 0755)
+				touchFile(t, path.Join(configDir, serviceDir, "two.sh"), 0755)
+
+				cfg, err := Read()
+				assert.Nil(t, err)
+				assert.ElementsMatch(
+					t,
+					cfg.ServicePaths,
+					[]string{
+						path.Join(configDir, serviceDir, "one.sh"),
+						path.Join(configDir, serviceDir, "two.sh"),
+					},
+				)
+			},
+		},
+		{
+			name: "with directory",
+			testFunc: func(t *testing.T) {
+				const subdir1 = "subdir1"
+				mkSvcDir(t)
+				assert.Nil(t, os.Mkdir(path.Join(configDir, serviceDir, subdir1), 0755))
+				touchFile(t, path.Join(configDir, serviceDir, subdir1, "one.sh"), 0755)
+				touchFile(t, path.Join(configDir, serviceDir, "two.sh"), 0755)
+				cfg, err := Read()
+				assert.Nil(t, err)
+				assert.ElementsMatch(
+					t,
+					cfg.ServicePaths,
+					[]string{
+						path.Join(configDir, serviceDir, "two.sh"),
+					},
+				)
+			},
+		},
+		{
+			name: "wrong mode",
+			testFunc: func(t *testing.T) {
+				mkSvcDir(t)
+				touchFile(t, path.Join(configDir, serviceDir, "one.sh"), 0755)
+				touchFile(t, path.Join(configDir, serviceDir, "two.sh"), 0644)
+
+				cfg, err := Read()
+				assert.Nil(t, err)
+				assert.ElementsMatch(
+					t,
+					cfg.ServicePaths,
+					[]string{
+						path.Join(configDir, serviceDir, "one.sh"),
+					},
+				)
+			},
+		},
+		{
+			name: "empty",
+			testFunc: func(t *testing.T) {
+				mkSvcDir(t)
+
+				_, err := Read()
+				assert.NotNil(t, err)
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			setup(t)
+			tt.testFunc(t)
+			tear(t)
+		})
+	}
+}

docker/alpine/gettting-started.md

@@ -1,54 +0,0 @@
-# Getting Started
-
-_Note: This document is for Alpine base image user, if you are using Debian/Ubuntu read [this one](../bookworm/gettting-started.md) instead._
-
-## Binaries
-
-There are three binaries in in this project: `wingmate`, `wmpidproxy`, and `wmexec`.
-
-`wingmate` is the core binary. It reads config, starts, restarts services. It also
-runs cron. Read [here](#wingmate-core-binary) for further details about `wingmate`.
-
-`wmpidproxy` is a helper binary for monitoring _legacy style_ service (fork, exit 
-initial proces, and continue in background). Read [here](#wingmate-pid-proxy-binary)
-for further details about `wmpidproxy`.
-
-`wmexec` is a helper binary for running process in different `user` or `group`.
-It also useful for setting the process as process group leader.
-Read [here](#wingmate-exec-binary) for further details about `wmexec`.
-
-## Building your image based on wingmate image in Docker Hub
-
-```Dockerfile
-FROM suyono/wingmate:alpine as source
-
-FROM alpine:latest
-ADD --chmod=755 wingmate/ /etc/wingmate/
-ADD --chmod=755 entry.sh /usr/local/bin/entry.sh
-COPY --from=source /usr/local/bin/wingmate /usr/local/bin/wingmate
-COPY --from=source /usr/local/bin/wmpidproxy /usr/local/bin/wmpidproxy
-COPY --from=source /usr/local/bin/wmexec /usr/local/bin/wmexec
-ENTRYPOINT [ "/usr/local/bin/entry.sh" ]
-CMD [ "/usr/local/bin/wingmate" ]
-```
-
-
-## Configuration
-
-```shell
-/etc
- └── wingmate
-     ├── crontab
-     ├── crontab.d
-     │   ├── cron1.sh
-     │   ├── cron2.sh
-     │   └── cron3.sh
-     └── service
-         ├── one.sh
-         └── spawner.sh
-```
-
-## Appendix
-### Wingmate core binary
-### Wingmate PID Proxy binary
-### Wingmate Exec binary

docker/bookworm/gettting-started.md

@@ -1,12 +0,0 @@
-```shell
-/etc
- └── wingmate
-     ├── crontab
-     ├── crontab.d
-     │   ├── cron1.sh
-     │   ├── cron2.sh
-     │   └── cron3.sh
-     └── service
-         ├── one.sh
-         └── spawner.sh
-```

example/ssh-docker/Dockerfile

@@ -0,0 +1,14 @@
+FROM suyono/wingmate:alpine as source
+
+FROM alpine:3.19
+
+RUN apk update && apk add tzdata openssh-server && \
+    ln -s /usr/share/zoneinfo/Australia/Sydney /etc/localtime && ssh-keygen -A
+
+COPY --from=source /usr/local/bin/wingmate /usr/local/bin/
+COPY --from=source /usr/local/bin/wmpidproxy /usr/local/bin/
+ADD --chmod=755 example/ssh-docker/entry.sh /usr/local/bin/entry.sh
+ADD --chmod=755 example/ssh-docker/etc /etc
+
+ENTRYPOINT [ "/usr/local/bin/entry.sh" ]
+CMD [ "/usr/local/bin/wingmate" ]

example/ssh-docker/entry.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+if [ $# -gt 0 ]; then
+    exec "$@"
+else
+    exec /usr/local/bin/wingmate
+fi

example/ssh-docker/etc/wingmate/service/sshd.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+exec /usr/local/bin/wmpidproxy --pid-file /var/run/sshd.pid -- /usr/sbin/sshd

go.mod

@@ -28,6 +28,7 @@ require (
 	github.com/spf13/cast v1.6.0 // indirect
 	github.com/spf13/jwalterweatherman v1.1.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/stretchr/objx v0.5.1 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect

go.sum

@@ -201,12 +201,15 @@ github.com/spf13/viper v1.17.0/go.mod h1:BmMMMLQXSbcHK6KAOiFLz0l5JHrU89OdIRHvsk0
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/objx v0.5.1 h1:4VhoImhV/Bm0ToFkXFi8hXNXwpDRZ/ynw3amt82mzq0=
+github.com/stretchr/objx v0.5.1/go.mod h1:/iHQpkQwBD6DLUmQ4pE+s1TXdob1mORJ4/UFdrifcy0=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/subosito/gotenv v1.6.0 h1:9NlTDc1FTs4qu0DDq7AEtTPNw6SVm7uBMsUCUjABIf8=