split into main and internal package"

6 files changed, 361 insertions, 0 deletions

diff --git a/internal/check.go b/internal/check.go
new file mode 100644
index 0000000..44e878d
--- /dev/null
+++ b/internal/check.go
@@ -0,0 +1,48 @@
+package internal
+
+import (
+	"bytes"
+	"context"
+	"os/exec"
+	"strings"
+)
+
+type check struct {
+	Plugin string
+	Args   []string
+}
+
+type namedCheck struct {
+	check
+	name string
+}
+
+type checkResult struct {
+	name   string
+	output string
+	status nagiosCode
+}
+
+func (c check) execute(ctx context.Context, name string) checkResult {
+	cmd := exec.CommandContext(ctx, c.Plugin, c.Args...)
+
+	var bytes bytes.Buffer
+	cmd.Stdout = &bytes
+	cmd.Stderr = &bytes
+
+	if err := cmd.Run(); err != nil {
+		if ctx.Err() == context.DeadlineExceeded {
+			return checkResult{name, "Check command timed out", critical}
+		}
+	}
+
+	// Remove Nagios perf data from output and trim whitespaces
+	parts := strings.Split(bytes.String(), "|")
+	output := strings.TrimSpace(parts[0])
+
+	return checkResult{name, output, nagiosCode(cmd.ProcessState.ExitCode())}
+}
+
+func (c namedCheck) execute(ctx context.Context) checkResult {
+	return c.check.execute(ctx, c.name)
+}
diff --git a/internal/config.go b/internal/config.go
new file mode 100644
index 0000000..39e2209
--- /dev/null
+++ b/internal/config.go
@@ -0,0 +1,58 @@
+package internal
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+)
+
+type config struct {
+	EmailTo          string
+	EmailFrom        string
+	SMTPServer       string `json:"omitempty"`
+	StateDir         string `json:"omitempty"`
+	CheckTimeoutS    int
+	CheckConcurrency int
+	Checks           map[string]check
+}
+
+func newConfig(configFile string) (config, error) {
+	var config config
+
+	// Open the file
+	file, err := os.Open(configFile)
+	if err != nil {
+		return config, err
+	}
+	defer file.Close()
+
+	// Read the file content
+	bytes, err := ioutil.ReadAll(file)
+	if err != nil {
+		return config, err
+	}
+
+	// Parse the JSON content
+	err = json.Unmarshal(bytes, &config)
+	if err != nil {
+		return config, err
+	}
+
+	if config.SMTPServer == "" {
+		hostname, err := os.Hostname()
+		if err != nil {
+			panic(err)
+		}
+		config.SMTPServer = fmt.Sprintf("%s:25", hostname)
+		log.Println("Set SMTPServer to " + config.SMTPServer)
+	}
+
+	if config.StateDir == "" {
+		config.StateDir = "."
+		log.Println("Set StateDir to " + config.StateDir)
+	}
+
+	return config, nil
+}
diff --git a/internal/execute.go b/internal/execute.go
new file mode 100644
index 0000000..d8f426f
--- /dev/null
+++ b/internal/execute.go
@@ -0,0 +1,59 @@
+package internal
+
+import (
+	"context"
+	"log"
+	"sync"
+	"time"
+)
+
+func execute(state state, config config) state {
+	limiterCh := make(chan struct{}, config.CheckConcurrency)
+	inputCh := make(chan namedCheck)
+	outputCh := make(chan checkResult)
+
+	go func() {
+		for name, check := range config.Checks {
+			inputCh <- namedCheck{check, name}
+		}
+		close(inputCh)
+	}()
+
+	var outputWg sync.WaitGroup
+	outputWg.Add(1)
+
+	go func() {
+		for checkResult := range outputCh {
+			state.update(checkResult)
+		}
+		outputWg.Done()
+	}()
+
+	var inputWg sync.WaitGroup
+	inputWg.Add(len(config.Checks))
+
+	for check := range inputCh {
+		go func(check namedCheck) {
+			limiterCh <- struct{}{}
+			defer func() {
+				<-limiterCh
+				inputWg.Done()
+			}()
+
+			ctx, cancel := context.WithTimeout(context.Background(),
+				time.Duration(config.CheckTimeoutS)*time.Second)
+			defer cancel()
+
+			outputCh <- check.execute(ctx)
+		}(check)
+	}
+
+	inputWg.Wait()
+	log.Println("All checks completed!")
+	close(outputCh)
+
+	outputWg.Wait()
+	log.Println("All outputs collected!")
+
+	return state
+}
diff --git a/internal/nagioscode.go b/internal/nagioscode.go
new file mode 100644
index 0000000..b5dc892
--- /dev/null
+++ b/internal/nagioscode.go
@@ -0,0 +1,23 @@
+package internal
+
+type nagiosCode int
+
+const (
+	ok       nagiosCode = 0
+	warning  nagiosCode = 1
+	critical nagiosCode = 2
+	unknown  nagiosCode = 3
+)
+
+func (n nagiosCode) Str() string {
+	switch n {
+	case 0:
+		return "OK"
+	case 1:
+		return "WARNING"
+	case 2:
+		return "CRITICAL"
+	default:
+		return "UNKNOWN"
+	}
+}
diff --git a/internal/notify.go b/internal/notify.go
new file mode 100644
index 0000000..7d8fc5a
--- /dev/null
+++ b/internal/notify.go
@@ -0,0 +1,33 @@
+package internal
+
+import (
+	"fmt"
+	"log"
+	"net/smtp"
+)
+
+func notify(config config, subject, body string) error {
+	log.Println("notify", subject, body)
+
+	headers := make(map[string]string)
+	headers["From"] = config.EmailFrom
+	headers["To"] = config.EmailTo
+	headers["Subject"] = subject
+	headers["MIME-Version"] = "1.0"
+	headers["Content-Type"] = "text/plain; charset=\"utf-8\""
+
+	header := ""
+	for k, v := range headers {
+		header += fmt.Sprintf("%s: %s\r\n", k, v)
+	}
+
+	message := header + "\r\n" + body
+	log.Println("Using SMTP server", config.SMTPServer)
+
+	return smtp.SendMail(config.SMTPServer, nil, config.EmailFrom,
+		[]string{config.EmailTo}, []byte(message))
+}
+
+func notifyError(config config, err error) error {
+	return notify(config, fmt.Sprintf("GOGIOS: An error occured: %v", err), err.Error())
+}
diff --git a/internal/state.go b/internal/state.go
new file mode 100644
index 0000000..012bdf5
--- /dev/null
+++ b/internal/state.go
@@ -0,0 +1,140 @@
+package internal
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+)
+
+type checkState struct {
+	Status     nagiosCode
+	PrevStatus nagiosCode
+	output     string
+}
+
+type state struct {
+	stateFile string
+	checks    map[string]checkState
+}
+
+func readState(config config) (state, error) {
+	s := state{
+		stateFile: fmt.Sprintf("%s/state.json", config.StateDir),
+		checks:    make(map[string]checkState),
+	}
+
+	if _, err := os.Stat(s.stateFile); err != nil {
+		// OK, may be first run with no state yet.
+		return s, nil
+	}
+
+	file, err := os.Open(s.stateFile)
+	if err != nil {
+		return s, err
+	}
+	defer file.Close()
+
+	bytes, err := ioutil.ReadAll(file)
+	if err != nil {
+		return s, err
+	}
+
+	if err := json.Unmarshal(bytes, &s.checks); err != nil {
+		return s, err
+	}
+
+	var obsolete []string
+	for name := range s.checks {
+		if _, ok := config.Checks[name]; !ok {
+			obsolete = append(obsolete, name)
+		}
+	}
+
+	for _, name := range obsolete {
+		delete(s.checks, name)
+		log.Printf("State of %s is obsolete (removed)", name)
+	}
+
+	return s, nil
+}
+
+func (s state) update(result checkResult) {
+	prevStatus := unknown
+	prevState, ok := s.checks[result.name]
+	if ok {
+		prevStatus = prevState.Status
+	}
+
+	checkState := checkState{result.status, prevStatus, result.output}
+	s.checks[result.name] = checkState
+	log.Println(result.name, checkState)
+}
+
+func (s state) persist() error {
+	jsonData, err := json.Marshal(s.checks)
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(s.stateFile, jsonData, os.ModePerm)
+}
+
+func (s state) report() (string, string, bool) {
+	var sb strings.Builder
+	var changed bool
+
+	f := func(filter func(n nagiosCode) bool) int {
+		var count int
+		for name, checkState := range s.checks {
+			if !filter(checkState.Status) {
+				continue
+			}
+			count++
+
+			if checkState.Status != checkState.PrevStatus {
+				sb.WriteString(nagiosCode(checkState.PrevStatus).Str())
+				sb.WriteString("->")
+				changed = true
+			}
+
+			sb.WriteString(nagiosCode(checkState.Status).Str())
+			sb.WriteString(": ")
+			sb.WriteString(name)
+			sb.WriteString(" ==>> ")
+			sb.WriteString(checkState.output)
+			sb.WriteString("\n")
+		}
+
+		return count
+	}
+
+	sb.WriteString("This is the recent Gogios report!\n\n")
+
+	numCriticals := f(func(n nagiosCode) bool { return n == 2 })
+	if numCriticals > 0 {
+		sb.WriteString("\n")
+	}
+
+	numWarnings := f(func(n nagiosCode) bool { return n == 1 })
+	if numWarnings > 0 {
+		sb.WriteString("\n")
+	}
+
+	numUnknowns := f(func(n nagiosCode) bool { return n > 2 })
+	if numUnknowns > 0 {
+		sb.WriteString("\n")
+	}
+
+	numOks := f(func(n nagiosCode) bool { return n == 0 })
+	if numOks > 0 {
+		sb.WriteString("\n")
+	}
+
+	sb.WriteString("Have a nice day!\n")
+	subject := fmt.Sprintf("GOGIOS Report [C:%d W:%d U:%d OK:%d]",
+		numCriticals, numWarnings, numUnknowns, numOks)
+
+	return subject, sb.String(), changed
+}