package checks import ( "errors" "net" "net/http" "os" "strconv" "time" "github.com/docker/distribution/health" ) // FileChecker checks the existence of a file and returns an error // if the file exists. func FileChecker(f string) health.Checker { return health.CheckFunc(func() error { if _, err := os.Stat(f); err == nil { return errors.New("file exists") } return nil }) } // HTTPChecker does a HEAD request and verifies that the HTTP status code // returned matches statusCode. func HTTPChecker(r string, statusCode int, timeout time.Duration, headers http.Header) health.Checker { return health.CheckFunc(func() error { client := http.Client{ Timeout: timeout, } req, err := http.NewRequest("HEAD", r, nil) if err != nil { return errors.New("error creating request: " + r) } for headerName, headerValues := range headers { for _, headerValue := range headerValues { req.Header.Add(headerName, headerValue) } } response, err := client.Do(req) if err != nil { return errors.New("error while checking: " + r) } if response.StatusCode != statusCode { return errors.New("downstream service returned unexpected status: " + strconv.Itoa(response.StatusCode)) } return nil }) } // TCPChecker attempts to open a TCP connection. func TCPChecker(addr string, timeout time.Duration) health.Checker { return health.CheckFunc(func() error { conn, err := net.DialTimeout("tcp", addr, timeout) if err != nil { return errors.New("connection to " + addr + " failed") } conn.Close() return nil }) }