// NewCachingSingleHostReverseProxy constructs a caching reverse proxy handler for
// target. If cache is nil, a volatile, in-memory cache is used.
func NewCachingSingleHostReverseProxy(target *url.URL, cache httpcache.Cache) *httputil.ReverseProxy {
proxy := NewSingleHostReverseProxy(target)
if cache == nil {
cache = httpcache.NewMemoryCache()
}
proxy.Transport = httpcache.NewTransport(cache)
return proxy
}
func main() {
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "apiproxy proxies and mocks HTTP APIs.\n\n")
fmt.Fprintf(os.Stderr, "Usage:\n\n")
fmt.Fprintf(os.Stderr, "\tapiproxy [options] url\n\n")
fmt.Fprintf(os.Stderr, "url is the base URL of the HTTP server to proxy.\n\n")
fmt.Fprintf(os.Stderr, "The options are:\n\n")
flag.PrintDefaults()
fmt.Fprintln(os.Stderr)
fmt.Fprintln(os.Stderr)
fmt.Fprintf(os.Stderr, "Example usage:\n\n")
fmt.Fprintf(os.Stderr, "\tTo run a caching proxy at http://localhost:8080 with target http://example.com:\n")
fmt.Fprintf(os.Stderr, "\t $ apiproxy http://example.com\n\n")
fmt.Fprintf(os.Stderr, "\t... and never revalidate cached responses:\n")
fmt.Fprintf(os.Stderr, "\t $ apiproxy -never-revalidate http://example.com\n\n")
fmt.Fprintf(os.Stderr, "\t... and only revalidate cached responses older than an hour:\n")
fmt.Fprintf(os.Stderr, "\t $ apiproxy -only-revalidate-older-than=1h http://example.com\n\n")
fmt.Fprintln(os.Stderr)
os.Exit(1)
}
flag.Parse()
if flag.NArg() != 1 {
flag.Usage()
}
targetURL, err := url.Parse(flag.Arg(0))
if err != nil {
fmt.Fprintf(os.Stderr, "Error parsing URL %q: %s\n", flag.Arg(0), err)
os.Exit(1)
}
var onlyRevalOlderThan time.Duration
if *onlyRevalOlderThanStr != "" {
onlyRevalOlderThan, err = time.ParseDuration(*onlyRevalOlderThanStr)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to parse duration %q: %s\n", *onlyRevalOlderThanStr, err)
os.Exit(1)
}
}
proxy := apiproxy.NewCachingSingleHostReverseProxy(targetURL, httpcache.NewMemoryCache())
cachingTransport := proxy.Transport.(*httpcache.Transport)
cachingTransport.Transport = &apiproxy.RevalidationTransport{
Check: apiproxy.ValidatorFunc(func(url *url.URL, age time.Duration) bool {
if *neverRevalidate {
return true
}
if *onlyRevalOlderThanStr != "" {
return age <= onlyRevalOlderThan
}
return false
}),
}
http.Handle("/", handlers.CombinedLoggingHandler(os.Stdout, proxy))
fmt.Fprintf(os.Stderr, "Starting proxy on %s with target %s\n", *bindAddr, targetURL.String())
err = http.ListenAndServe(*bindAddr, nil)
if err != nil {
log.Fatalf("ListenAndServe: %s", err)
}
}