feat(webui): add cached image proxy with configurable dir

Add disk-backed image proxy support to the web UI and expose it via
`/api/image`. The proxy validates image URLs, fetches remote images with
a timeout, stores image bytes + metadata in a local cache, and serves
cached responses with proper content type and cache headers.

Also add `SCRAPPR_IMAGE_CACHE` (default `.cache/webui-images`) and pass it
through `cmd/outward-web` into `webui.Run`, with startup logging updated
to include the cache location.

This reduces repeated remote fetches and makes image delivery more
reliable for the UI.feat(webui): add cached image proxy with configurable dir

Add disk-backed image proxy support to the web UI and expose it via
`/api/image`. The proxy validates image URLs, fetches remote images with
a timeout, stores image bytes + metadata in a local cache, and serves
cached responses with proper content type and cache headers.

Also add `SCRAPPR_IMAGE_CACHE` (default `.cache/webui-images`) and pass it
through `cmd/outward-web` into `webui.Run`, with startup logging updated
to include the cache location.

This reduces repeated remote fetches and makes image delivery more
reliable for the UI.
This commit is contained in:
2026-03-16 09:56:47 +02:00
parent ad3385c63b
commit b9d035d71a
3 changed files with 262 additions and 15 deletions

View File

@@ -1,14 +1,19 @@
package webui
import (
"crypto/sha256"
"embed"
"encoding/json"
"fmt"
"io"
"io/fs"
"net/http"
"net/url"
"os"
"path/filepath"
"sort"
"strings"
"time"
"scrappr/internal/logx"
"scrappr/internal/model"
@@ -36,12 +41,28 @@ type CraftableEntry struct {
Recipes []model.Recipe `json:"recipes"`
}
func Run(addr, dataPath string) error {
type imageProxy struct {
cacheDir string
client *http.Client
}
type cachedImageMeta struct {
ContentType string `json:"content_type"`
SourceURL string `json:"source_url"`
SavedAt time.Time `json:"saved_at"`
}
func Run(addr, dataPath, imageCacheDir string) error {
catalog, err := loadCatalog(dataPath)
if err != nil {
return err
}
images, err := newImageProxy(imageCacheDir)
if err != nil {
return err
}
staticFS, err := fs.Sub(staticFiles, "static")
if err != nil {
return err
@@ -63,13 +84,15 @@ func Run(addr, dataPath string) error {
logx.Eventf("error", "catalog encode failed: %v", err)
}
})
mux.HandleFunc("/api/image", images.handle)
logx.Eventf(
"start",
"web UI listening on %s using %s (%d craftable items)",
"web UI listening on %s using %s (%d craftable items, image cache %s)",
displayAddr(addr),
dataPath,
len(catalog.Craftables),
imageCacheDir,
)
return http.ListenAndServe(addr, mux)
@@ -225,3 +248,228 @@ func setNoCache(w http.ResponseWriter) {
w.Header().Set("Pragma", "no-cache")
w.Header().Set("Expires", "0")
}
func newImageProxy(cacheDir string) (*imageProxy, error) {
if err := os.MkdirAll(cacheDir, 0o755); err != nil {
return nil, err
}
return &imageProxy{
cacheDir: cacheDir,
client: &http.Client{
Timeout: 20 * time.Second,
},
}, nil
}
func (p *imageProxy) handle(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodGet {
http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
return
}
rawURL := strings.TrimSpace(r.URL.Query().Get("url"))
if rawURL == "" {
http.Error(w, "missing url", http.StatusBadRequest)
return
}
if !isAllowedImageURL(rawURL) {
http.Error(w, "forbidden image host", http.StatusForbidden)
return
}
cacheKey := cacheKeyFor(rawURL)
if p.serveCached(w, cacheKey) {
return
}
contentType, body, sourceURL, err := p.fetchRemote(rawURL)
if err != nil {
logx.Eventf("warn", "image proxy failed for %s: %v", rawURL, err)
http.Error(w, "image unavailable", http.StatusBadGateway)
return
}
if err := p.storeCached(cacheKey, contentType, body, sourceURL); err != nil {
logx.Eventf("warn", "image cache store failed for %s: %v", rawURL, err)
}
w.Header().Set("Content-Type", contentType)
w.Header().Set("Cache-Control", "public, max-age=86400")
_, _ = w.Write(body)
}
func (p *imageProxy) serveCached(w http.ResponseWriter, cacheKey string) bool {
bodyPath := filepath.Join(p.cacheDir, cacheKey+".bin")
metaPath := filepath.Join(p.cacheDir, cacheKey+".json")
metaBytes, err := os.ReadFile(metaPath)
if err != nil {
return false
}
bodyBytes, err := os.ReadFile(bodyPath)
if err != nil {
return false
}
var meta cachedImageMeta
if err := json.Unmarshal(metaBytes, &meta); err != nil {
return false
}
if meta.ContentType == "" {
meta.ContentType = "image/png"
}
w.Header().Set("Content-Type", meta.ContentType)
w.Header().Set("Cache-Control", "public, max-age=86400")
_, _ = w.Write(bodyBytes)
return true
}
func (p *imageProxy) storeCached(cacheKey, contentType string, body []byte, sourceURL string) error {
bodyPath := filepath.Join(p.cacheDir, cacheKey+".bin")
metaPath := filepath.Join(p.cacheDir, cacheKey+".json")
meta := cachedImageMeta{
ContentType: contentType,
SourceURL: sourceURL,
SavedAt: time.Now(),
}
metaBytes, err := json.Marshal(meta)
if err != nil {
return err
}
if err := os.WriteFile(bodyPath, body, 0o644); err != nil {
return err
}
return os.WriteFile(metaPath, metaBytes, 0o644)
}
func (p *imageProxy) fetchRemote(rawURL string) (string, []byte, string, error) {
var lastErr error
for _, candidate := range imageCandidates(rawURL) {
req, err := http.NewRequest(http.MethodGet, candidate, nil)
if err != nil {
lastErr = err
continue
}
req.Header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36")
req.Header.Set("Accept", "image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8")
req.Header.Set("Accept-Language", "en-US,en;q=0.9")
req.Header.Set("Referer", "https://outward.fandom.com/")
req.Header.Set("Sec-Fetch-Dest", "image")
req.Header.Set("Sec-Fetch-Mode", "no-cors")
req.Header.Set("Sec-Fetch-Site", "cross-site")
resp, err := p.client.Do(req)
if err != nil {
lastErr = err
continue
}
body, readErr := io.ReadAll(resp.Body)
_ = resp.Body.Close()
if readErr != nil {
lastErr = readErr
continue
}
if resp.StatusCode != http.StatusOK {
lastErr = fmt.Errorf("status %d from %s", resp.StatusCode, candidate)
continue
}
contentType := resp.Header.Get("Content-Type")
if !strings.HasPrefix(contentType, "image/") {
contentType = "image/png"
}
logx.Eventf("cache", "fetched image %s", candidate)
return contentType, body, candidate, nil
}
if lastErr == nil {
lastErr = fmt.Errorf("no usable candidate")
}
return "", nil, "", lastErr
}
func imageCandidates(raw string) []string {
seen := map[string]bool{}
var out []string
push := func(value string) {
value = strings.TrimSpace(value)
if value == "" || seen[value] {
return
}
seen[value] = true
out = append(out, value)
}
normalized := normalizeRemoteImageURL(raw)
push(normalized)
push(removeQuery(normalized))
withoutRevision := strings.Replace(normalized, "/revision/latest", "", 1)
push(withoutRevision)
push(removeQuery(withoutRevision))
push(raw)
push(removeQuery(raw))
return out
}
func normalizeRemoteImageURL(raw string) string {
raw = strings.TrimSpace(raw)
if strings.HasPrefix(raw, "//") {
raw = "https:" + raw
}
query := ""
if idx := strings.Index(raw, "?"); idx >= 0 {
query = raw[idx:]
raw = raw[:idx]
}
const scaledMarker = "/revision/latest/scale-to-width-down/"
if idx := strings.Index(raw, scaledMarker); idx >= 0 {
raw = raw[:idx] + "/revision/latest"
}
return raw + query
}
func removeQuery(raw string) string {
if idx := strings.Index(raw, "?"); idx >= 0 {
return raw[:idx]
}
return raw
}
func cacheKeyFor(raw string) string {
sum := sha256.Sum256([]byte(strings.TrimSpace(raw)))
return fmt.Sprintf("%x", sum[:])
}
func isAllowedImageURL(raw string) bool {
parsed, err := url.Parse(strings.TrimSpace(raw))
if err != nil {
return false
}
host := strings.ToLower(parsed.Host)
if host != "static.wikia.nocookie.net" {
return false
}
return strings.Contains(parsed.Path, "/outward_gamepedia/images/")
}