commit 770823e909c7dac4d790f2e2d03e6fde4e064eba
Author: Knut Ahlers <knut@ahlers.me>
Date:   Mon Jul 23 14:51:32 2018 +0200

    Initial version

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..fdeda75
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+request-log
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..fa3a38d
--- /dev/null
+++ b/main.go
@@ -0,0 +1,266 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"regexp"
+	"strings"
+	"sync"
+	"text/template"
+	"time"
+
+	"github.com/Luzifer/rconfig"
+	"github.com/montanaflynn/stats"
+	log "github.com/sirupsen/logrus"
+)
+
+const dateFormat = time.RFC1123
+
+var (
+	cfg = struct {
+		DisableLog     bool          `flag:"no-log" default:"false" description:"Disable response body logging"`
+		Interval       time.Duration `flag:"interval,i" default:"1s" description:"Check interval"`
+		LogDir         string        `flag:"log-dir,l" default:"./request-log/" description:"Directory to log non-matched requests to"`
+		LogRetention   time.Duration `flag:"log-retention" default:"24h" description:"When to clean up file from log-dir"`
+		Match          string        `flag:"match,m" default:".*" description:"RegExp to match the response body against to validate it"`
+		Timeout        time.Duration `flag:"timeout,t" default:"30s" description:"Timeout for the request"`
+		URL            string        `flag:"url,u" default:"" description:"URL to query" validate:"nonzero"`
+		VersionAndExit bool          `flag:"version" default:"false" description:"Prints current version and exits"`
+	}{}
+
+	version = "dev"
+)
+
+type checkStatus uint
+
+func (c checkStatus) String() string {
+	return map[checkStatus]string{
+		statusUnknown: "UNKN",
+		statusFailed:  "FAIL",
+		statusOk:      "OKAY",
+	}[c]
+}
+
+const (
+	statusUnknown checkStatus = iota
+	statusOk
+	statusFailed
+)
+
+type checkResult struct {
+	DumpFile  string
+	Durations []time.Duration
+	Message   string
+	Start     time.Time
+	Status    checkStatus
+
+	lock        sync.RWMutex
+	lastLineLen int
+}
+
+func newCheckResult(status checkStatus, message string, duration time.Duration) *checkResult {
+	return &checkResult{
+		Durations: []time.Duration{duration},
+		Message:   message,
+		Start:     time.Now(),
+		Status:    status,
+	}
+}
+
+func (c *checkResult) AddDuration(d time.Duration) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	c.Durations = append(c.Durations, d)
+}
+
+func (c checkResult) DurationStats() string {
+	c.lock.RLock()
+	defer c.lock.RUnlock()
+
+	var (
+		s             = stats.LoadRawData(c.Durations)
+		min, avg, max float64
+		err           error
+	)
+	if min, err = s.Min(); err != nil {
+		min = 0
+	}
+	if avg, err = s.Median(); err != nil {
+		avg = 0
+	}
+	if max, err = s.Max(); err != nil {
+		max = 0
+	}
+
+	return fmt.Sprintf("%s/%s/%s",
+		time.Duration(min).Round(time.Microsecond).String(),
+		time.Duration(avg).Round(time.Microsecond).String(),
+		time.Duration(max).Round(time.Microsecond).String(),
+	)
+}
+
+func (c checkResult) Equals(r *checkResult) bool {
+	return c.Status == r.Status && c.Message == r.Message
+}
+
+func (c *checkResult) Print() {
+	tpl := strings.Join([]string{
+		`[{{ .Start.Format "` + dateFormat + `" }}]`,
+		`({{ .Status }})`,
+		`{{ .Message }}`,
+		`({{ .DurationStats }})`,
+		`{{ if ne .DumpFile "" }}(Resp: {{ .DumpFile }}){{ end }}`,
+	}, " ")
+	templ := template.Must(template.New("result").Parse(tpl))
+
+	buf := new(bytes.Buffer)
+	templ.Execute(buf, c)
+
+	if c.lastLineLen > 0 {
+		fmt.Fprintf(os.Stdout, "\r%s\r", strings.Repeat(" ", c.lastLineLen))
+	}
+
+	c.lastLineLen = buf.Len()
+	buf.WriteTo(os.Stdout)
+}
+
+func init() {
+	if err := rconfig.ParseAndValidate(&cfg); err != nil {
+		log.Fatalf("Unable to parse commandline options: %s", err)
+	}
+
+	if cfg.VersionAndExit {
+		fmt.Printf("webcheck %s\n", version)
+		os.Exit(0)
+	}
+}
+
+func main() {
+	http.DefaultClient.Timeout = cfg.Timeout
+	matcher, err := regexp.Compile(cfg.Match)
+	if err != nil {
+		log.WithError(err).Fatal("Matcher regexp does not compile")
+	}
+
+	lastResult := newCheckResult(statusUnknown, "Uninitialized", 0)
+
+	for range time.Tick(cfg.Interval) {
+		var (
+			body   *bytes.Buffer
+			result *checkResult
+		)
+
+		if !cfg.DisableLog {
+			body = new(bytes.Buffer)
+		}
+
+		result = doCheck(cfg.URL, matcher, body)
+
+		if !result.Equals(lastResult) {
+			fmt.Println()
+			lastResult = result
+
+			if result.Status == statusFailed {
+				fn, err := dumpRequest(body)
+				if err != nil {
+					log.WithError(err).Fatal("Could not dump request")
+				}
+				lastResult.DumpFile = fn
+			}
+		} else {
+			lastResult.AddDuration(result.Durations[0])
+		}
+
+		lastResult.Print()
+	}
+}
+
+func doCheck(url string, match *regexp.Regexp, responseBody io.Writer) *checkResult {
+	req, _ := http.NewRequest("GET", url, nil)
+
+	respStart := time.Now()
+	resp, err := http.DefaultClient.Do(req)
+	respDuration := time.Since(respStart)
+	if err != nil {
+		return newCheckResult(
+			statusFailed,
+			fmt.Sprintf("HTTP request failed: %s", err),
+			respDuration,
+		)
+	}
+	defer resp.Body.Close()
+
+	body := new(bytes.Buffer)
+	if _, err = io.Copy(body, resp.Body); err != nil {
+		return newCheckResult(
+			statusFailed,
+			"Was not able to read response body",
+			respDuration,
+		)
+	}
+
+	if responseBody != nil {
+		if err = resp.Header.Write(responseBody); err != nil {
+			return newCheckResult(
+				statusFailed,
+				"Was not able to copy headers",
+				respDuration,
+			)
+		}
+		fmt.Fprintln(responseBody)
+		if _, err = responseBody.Write(body.Bytes()); err != nil {
+			return newCheckResult(
+				statusFailed,
+				"Was not able to copy body",
+				respDuration,
+			)
+		}
+	}
+
+	if resp.StatusCode < 200 || resp.StatusCode > 299 {
+		return newCheckResult(
+			statusFailed,
+			fmt.Sprintf("Status code was != 2xx: %d", resp.StatusCode),
+			respDuration,
+		)
+	}
+
+	if !match.Match(body.Bytes()) {
+		return newCheckResult(
+			statusFailed,
+			"Response body does not match regexp",
+			respDuration,
+		)
+	}
+
+	return newCheckResult(
+		statusOk,
+		fmt.Sprintf("Status was %d and text matched", resp.StatusCode),
+		respDuration,
+	)
+}
+
+func dumpRequest(body io.Reader) (string, error) {
+	if body == nil {
+		return "", nil
+	}
+
+	if err := os.MkdirAll(cfg.LogDir, 0755); err != nil {
+		return "", err
+	}
+
+	f, err := ioutil.TempFile(cfg.LogDir, "request")
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	_, err = io.Copy(f, body)
+
+	return f.Name(), err
+}