checks.go

Documentation: github.com/docker/distribution/health/checks

     1  package checks
     2  
     3  import (
     4  	"errors"
     5  	"fmt"
     6  	"net"
     7  	"net/http"
     8  	"os"
     9  	"path/filepath"
    10  	"strconv"
    11  	"time"
    12  
    13  	"github.com/docker/distribution/health"
    14  )
    15  
    16  // FileChecker checks the existence of a file and returns an error
    17  // if the file exists.
    18  func FileChecker(f string) health.Checker {
    19  	return health.CheckFunc(func() error {
    20  		absoluteFilePath, err := filepath.Abs(f)
    21  		if err != nil {
    22  			return fmt.Errorf("failed to get absolute path for %q: %v", f, err)
    23  		}
    24  
    25  		_, err = os.Stat(absoluteFilePath)
    26  		if err == nil {
    27  			return errors.New("file exists")
    28  		} else if os.IsNotExist(err) {
    29  			return nil
    30  		}
    31  
    32  		return err
    33  	})
    34  }
    35  
    36  // HTTPChecker does a HEAD request and verifies that the HTTP status code
    37  // returned matches statusCode.
    38  func HTTPChecker(r string, statusCode int, timeout time.Duration, headers http.Header) health.Checker {
    39  	return health.CheckFunc(func() error {
    40  		client := http.Client{
    41  			Timeout: timeout,
    42  		}
    43  		req, err := http.NewRequest("HEAD", r, nil)
    44  		if err != nil {
    45  			return errors.New("error creating request: " + r)
    46  		}
    47  		for headerName, headerValues := range headers {
    48  			for _, headerValue := range headerValues {
    49  				req.Header.Add(headerName, headerValue)
    50  			}
    51  		}
    52  		response, err := client.Do(req)
    53  		if err != nil {
    54  			return errors.New("error while checking: " + r)
    55  		}
    56  		if response.StatusCode != statusCode {
    57  			return errors.New("downstream service returned unexpected status: " + strconv.Itoa(response.StatusCode))
    58  		}
    59  		return nil
    60  	})
    61  }
    62  
    63  // TCPChecker attempts to open a TCP connection.
    64  func TCPChecker(addr string, timeout time.Duration) health.Checker {
    65  	return health.CheckFunc(func() error {
    66  		conn, err := net.DialTimeout("tcp", addr, timeout)
    67  		if err != nil {
    68  			return errors.New("connection to " + addr + " failed")
    69  		}
    70  		conn.Close()
    71  		return nil
    72  	})
    73  }
    74
View as plain text