distribution/health/checks/checks.go

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package checks
import (
"errors"
"fmt"
"net"
"net/http"
"os"
"path/filepath"
"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 {
absoluteFilePath, err := filepath.Abs(f)
if err != nil {
return fmt.Errorf("failed to get absolute path for %q: %v", f, err)
}
_, err = os.Stat(absoluteFilePath)
if err == nil {
return errors.New("file exists")
} else if os.IsNotExist(err) {
return nil
}
return err
})
}
// 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
})
}