Add HTTP retries and the possibility to ignore image download errors (#33)

added HTTP retry and --ignoreerrors which ignores image download errors, fix #30

README.md

@@ -99,14 +99,16 @@ To install after building either copy the binary or execute `sudo make install`.
 ```
 Usage: kleingebaeck [-dvVhmoc] [<ad-listing-url>,...]
 Options:
---user    -u <uid>      Backup ads from user with uid <uid>.
+-u --user    <uid>      Backup ads from user with uid <uid>.
---debug   -d            Enable debug output.
+-d --debug              Enable debug output.
---verbose -v            Enable verbose output.
+-v --verbose            Enable verbose output.
---outdir  -o <dir>      Set output dir (default: current directory)
+-o --outdir  <dir>      Set output dir (default: current directory)
---limit   -l <num>      Limit the ads to download to <num>, default: load all.
+-l --limit   <num>      Limit the ads to download to <num>, default: load all.
---config  -c <file>     Use config file <file> (default: ~/.kleingebaeck).
+-c --config  <file>     Use config file <file> (default: ~/.kleingebaeck).
---manual  -m            Show manual.
+   --ignoreerrors       Ignore HTTP errors, may lead to incomplete ad backup.
---help    -h            Show usage.
+-m --manual             Show manual.
+-h --help               Show usage.
+-V --version            Show program version.
 
 If one  or more <ad-listing-url>'s  are specified, only  backup those,
 otherwise backup all ads of the given user.

config.go

@@ -33,7 +33,7 @@ import (
 )
 
 const (
-	VERSION         string = "0.1.1"
+	VERSION         string = "0.1.2"
 	Baseuri         string = "https://www.kleinanzeigen.de"
 	Listuri         string = "/s-bestandsliste.html"
 	Defaultdir      string = "."
@@ -51,15 +51,16 @@ const Usage string = `This is kleingebaeck, the kleinanzeigen.de backup tool.
 Usage: kleingebaeck [-dvVhmoclu] [<ad-listing-url>,...]
 
 Options:
---user    -u <uid>      Backup ads from user with uid <uid>.
+-u --user    <uid>      Backup ads from user with uid <uid>.
---debug   -d            Enable debug output.
+-d --debug              Enable debug output.
---verbose -v            Enable verbose output.
+-v --verbose            Enable verbose output.
---outdir  -o <dir>      Set output dir (default: current directory)
+-o --outdir  <dir>      Set output dir (default: current directory)
---limit   -l <num>      Limit the ads to download to <num>, default: load all.
+-l --limit   <num>      Limit the ads to download to <num>, default: load all.
---config  -c <file>     Use config file <file> (default: ~/.kleingebaeck).
+-c --config  <file>     Use config file <file> (default: ~/.kleingebaeck).
---manual  -m            Show manual.
+   --ignoreerrors       Ignore HTTP errors, may lead to incomplete ad backup.
---help    -h            Show usage.
+-m --manual             Show manual.
---version -V            Show program version.
+-h --help               Show usage.
+-V --version            Show program version.
 
 If one  or more ad listing url's  are specified, only  backup those,
 otherwise backup all ads of the given user.`
@@ -76,6 +77,7 @@ type Config struct {
 	Adnametemplate   string `koanf:"adnametemplate"`
 	Loglevel         string `koanf:"loglevel"`
 	Limit            int    `koanf:"limit"`
+	IgnoreErrors     bool   `koanf:"ignoreerrors"`
 	Adlinks          []string
 	StatsCountAds    int
 	StatsCountImages int

http.go

@@ -15,22 +15,18 @@ You should have received a copy of the GNU General Public License
 along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
-// FIXME: we could also incorporate
-// https://github.com/kdkumawat/golang/blob/main/http-retry/http/retry-client.go
-
 package main
 
 import (
-	"fmt"
+	"bytes"
+	"io"
 	"log/slog"
+	"math"
 	"math/rand"
 	"net/http"
-	"net/http/httputil"
+	"time"
-	"os"
 )
 
-type loggingTransport struct{}
-
 var letters = []rune("ABCDEF0123456789")
 
 func getid() string {
@@ -41,25 +37,87 @@ func getid() string {
 	return string(b)
 }
 
-func (s *loggingTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+const RetryCount = 3
-	resp, err := http.DefaultTransport.RoundTrip(req)
 
+type loggingTransport struct{}
+
+// escalating timeout, $retry^2 seconds
+func backoff(retries int) time.Duration {
+	return time.Duration(math.Pow(2, float64(retries))) * time.Second
+}
+
+// only retry in case of errors or certain non 200 HTTP codes
+func shouldRetry(err error, resp *http.Response) bool {
+	if err != nil {
+		return true
+	}
+
+	if resp.StatusCode == http.StatusBadGateway ||
+		resp.StatusCode == http.StatusServiceUnavailable ||
+		resp.StatusCode == http.StatusGatewayTimeout {
+		return true
+	}
+
+	return false
+}
+
+// Body needs to be drained, otherwise we can't reuse the http.Response
+func drainBody(resp *http.Response) {
+	if resp != nil {
+		if resp.Body != nil {
+			_, err := io.Copy(io.Discard, resp.Body)
+			if err != nil {
+				// unable to copy data? uff!
+				panic(err)
+			}
+			resp.Body.Close()
+		}
+	}
+}
+
+// our logging transport with retries
+func (t *loggingTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 	// just requred for debugging
 	id := getid()
-	slog.Debug("REQUEST", "id", id, "uri", req.URL, "host", req.Host)
-	slog.Debug("RESPONSE", "id", id, "status", resp.StatusCode, "contentlength", resp.ContentLength)
 
-	if len(os.Getenv("DEBUGHTTP")) > 0 {
+	// clone the request body, put into request on retry
-		fmt.Println("DEBUGHTTP Request ===>")
+	var bodyBytes []byte
-		bytes, _ := httputil.DumpRequestOut(req, true)
+	if req.Body != nil {
-		fmt.Printf("%s\n", bytes)
+		bodyBytes, _ = io.ReadAll(req.Body)
-
+		req.Body = io.NopCloser(bytes.NewBuffer(bodyBytes))
-		fmt.Println("<=== DEBUGHTTP Response")
-		for header, value := range resp.Header {
-			fmt.Printf("%s: %s\n", header, value)
 	}
-		fmt.Printf("Status: %s %s\nContent-Length: %d\n\n\n", resp.Proto, resp.Status, resp.ContentLength)
 
+	slog.Debug("REQUEST", "id", id, "uri", req.URL, "host", req.Host)
+
+	// first try
+	resp, err := http.DefaultTransport.RoundTrip(req)
+	if err == nil {
+		slog.Debug("RESPONSE", "id", id, "status", resp.StatusCode,
+			"contentlength", resp.ContentLength)
+	}
+
+	// enter retry check and loop, if first req were successfull, leave loop immediately
+	retries := 0
+	for shouldRetry(err, resp) && retries < RetryCount {
+		time.Sleep(backoff(retries))
+
+		// consume any response to reuse the connection.
+		drainBody(resp)
+
+		// clone the request body again
+		if req.Body != nil {
+			req.Body = io.NopCloser(bytes.NewBuffer(bodyBytes))
+		}
+
+		// actual retry
+		resp, err = http.DefaultTransport.RoundTrip(req)
+
+		if err == nil {
+			slog.Debug("RESPONSE", "id", id, "status", resp.StatusCode,
+				"contentlength", resp.ContentLength, "retry", retries)
+		}
+
+		retries++
 	}
 
 	return resp, err

kleingebaeck.1

@@ -133,7 +133,7 @@
 .\" ========================================================================
 .\"
 .IX Title "KLEINGEBAECK 1"
-.TH KLEINGEBAECK 1 "2024-01-12" "1" "User Commands"
+.TH KLEINGEBAECK 1 "2024-01-16" "1" "User Commands"
 .\" For nroff, turn off justification.  Always turn off hyphenation; it makes
 .\" way too many mistakes in technical documents.
 .if n .ad l
@@ -142,18 +142,19 @@
 kleingebaeck \- kleinanzeigen.de backup tool
 .SH "SYNOPSYS"
 .IX Header "SYNOPSYS"
-.Vb 11
+.Vb 12
 \&    Usage: kleingebaeck [\-dvVhmoc] [<ad\-listing\-url>,...]
 \&    Options:
-\&    \-\-user    \-u <uid>      Backup ads from user with uid <uid>.
+\&    \-u \-\-user    <uid>      Backup ads from user with uid <uid>.
-\&    \-\-debug   \-d            Enable debug output.
+\&    \-d \-\-debug              Enable debug output.
-\&    \-\-verbose \-v            Enable verbose output.
+\&    \-v \-\-verbose            Enable verbose output.
-\&    \-\-outdir  \-o <dir>      Set output dir (default: current directory)
+\&    \-o \-\-outdir  <dir>      Set output dir (default: current directory)
-\&    \-\-limit   \-l <num>      Limit the ads to download to <num>, default: load all.
+\&    \-l \-\-limit   <num>      Limit the ads to download to <num>, default: load all.
-\&    \-\-config  \-c <file>     Use config file <file> (default: ~/.kleingebaeck).
+\&    \-c \-\-config  <file>     Use config file <file> (default: ~/.kleingebaeck).
-\&    \-\-manual  \-m            Show manual.
+\&       \-\-ignoreerrors       Ignore HTTP errors, may lead to incomplete ad backup.
-\&    \-\-help    \-h            Show usage.
+\&    \-m \-\-manual             Show manual.
-\&    \-\-version \-V            Show program version.
+\&    \-h \-\-help               Show usage.
+\&    \-V \-\-version            Show program version.
 .Ve
 .SH "DESCRIPTION"
 .IX Header "DESCRIPTION"

kleingebaeck.go

@@ -7,15 +7,16 @@ NAME
 SYNOPSYS
         Usage: kleingebaeck [-dvVhmoc] [<ad-listing-url>,...]
         Options:
-        --user    -u <uid>      Backup ads from user with uid <uid>.
+        -u --user    <uid>      Backup ads from user with uid <uid>.
-        --debug   -d            Enable debug output.
+        -d --debug              Enable debug output.
-        --verbose -v            Enable verbose output.
+        -v --verbose            Enable verbose output.
-        --outdir  -o <dir>      Set output dir (default: current directory)
+        -o --outdir  <dir>      Set output dir (default: current directory)
-        --limit   -l <num>      Limit the ads to download to <num>, default: load all.
+        -l --limit   <num>      Limit the ads to download to <num>, default: load all.
-        --config  -c <file>     Use config file <file> (default: ~/.kleingebaeck).
+        -c --config  <file>     Use config file <file> (default: ~/.kleingebaeck).
-        --manual  -m            Show manual.
+           --ignoreerrors       Ignore HTTP errors, may lead to incomplete ad backup.
-        --help    -h            Show usage.
+        -m --manual             Show manual.
-        --version -V            Show program version.
+        -h --help               Show usage.
+        -V --version            Show program version.
 
 DESCRIPTION
     This tool can be used to backup ads on the german ad page

kleingebaeck.pod

@@ -6,15 +6,16 @@ kleingebaeck - kleinanzeigen.de backup tool
     
     Usage: kleingebaeck [-dvVhmoc] [<ad-listing-url>,...]
     Options:
-    --user    -u <uid>      Backup ads from user with uid <uid>.
+    -u --user    <uid>      Backup ads from user with uid <uid>.
-    --debug   -d            Enable debug output.
+    -d --debug              Enable debug output.
-    --verbose -v            Enable verbose output.
+    -v --verbose            Enable verbose output.
-    --outdir  -o <dir>      Set output dir (default: current directory)
+    -o --outdir  <dir>      Set output dir (default: current directory)
-    --limit   -l <num>      Limit the ads to download to <num>, default: load all.
+    -l --limit   <num>      Limit the ads to download to <num>, default: load all.
-    --config  -c <file>     Use config file <file> (default: ~/.kleingebaeck).
+    -c --config  <file>     Use config file <file> (default: ~/.kleingebaeck).
-    --manual  -m            Show manual.
+       --ignoreerrors       Ignore HTTP errors, may lead to incomplete ad backup.
-    --help    -h            Show usage.
+    -m --manual             Show manual.
-    --version -V            Show program version.
+    -h --help               Show usage.
+    -V --version            Show program version.
 
 =head1 DESCRIPTION
 

main.go

@@ -1,5 +1,5 @@
 /*
-Copyright © 2023 Thomas von Dein
+Copyright © 2023-2024 Thomas von Dein
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by

main_test.go

@@ -114,6 +114,7 @@ const EMPTYPAGE string = `DOCTYPE html>
 
 const (
 	EMPTYURI       string = `https://www.kleinanzeigen.de/s-anzeige/empty/1`
+	INVALID503URI  string = `https://www.kleinanzeigen.de/s-anzeige/503/1`
 	INVALIDPATHURI string = `https://www.kleinanzeigen.de/anzeige/name/1`
 	INVALID404URI  string = `https://www.kleinanzeigen.de/anzeige/name/1/foo/bar`
 	INVALIDURI     string = `https://foo.bar/weird/things`
@@ -228,6 +229,12 @@ var invalidtests = []Tests{
 		expect:   "error loading config file",
 		exitcode: 1,
 	},
+	{
+		name:     "503",
+		args:     base + " " + INVALID503URI,
+		expect:   "could not get page via HTTP",
+		exitcode: 1,
+	},
 }
 
 type AdConfig struct {
@@ -410,6 +417,12 @@ func InitInvalidSources() []Adsource {
 			content: GetTemplate(nil, empty, "<html>HTTP 404: /eine-anzeige/ does not exist!</html>"),
 			status:  404,
 		},
+		{
+			// valid ad page but 503
+			uri:     fmt.Sprintf("%s/s-anzeige/503/1", Baseuri),
+			content: GetTemplate(nil, empty, "<html>HTTP 503: service unavailable</html>"),
+			status:  503,
+		},
 	}
 
 	return ads

scrape.go

@@ -44,9 +44,6 @@ func Get(uri string, client *http.Client) (io.ReadCloser, error) {
 		return nil, err
 	}
 
-	slog.Debug("response", "code", res.StatusCode, "status",
-		res.Status, "size", res.ContentLength)
-
 	if res.StatusCode != 200 {
 		return nil, errors.New("could not get page via HTTP")
 	}
@@ -165,11 +162,10 @@ func ScrapeImages(c *Config, ad *Ad, addir string, client *http.Client) error {
 		imguri := imguri
 		file := filepath.Join(c.Outdir, addir, fmt.Sprintf("%d.jpg", img))
 		g.Go(func() error {
-			err := Getimage(imguri, file, client)
+			err := Getimage(c, imguri, file, client)
 			if err != nil {
 				return err
 			}
-			slog.Info("wrote ad image", "image", file)
 
 			return nil
 		})
@@ -186,10 +182,13 @@ func ScrapeImages(c *Config, ad *Ad, addir string, client *http.Client) error {
 }
 
 // fetch an image
-func Getimage(uri, fileName string, client *http.Client) error {
+func Getimage(c *Config, uri, fileName string, client *http.Client) error {
 	slog.Debug("fetching ad image", "uri", uri)
 	req, err := http.NewRequest("GET", uri, nil)
 	if err != nil {
+		if c.IgnoreErrors {
+			slog.Info("Failed to download image, error ignored", "error", err.Error())
+		}
 		return err
 	}
 
@@ -210,5 +209,6 @@ func Getimage(uri, fileName string, client *http.Client) error {
 		return err
 	}
 
+	slog.Info("wrote ad image", "image", fileName)
 	return nil
 }