distribution/health/checks/checks.go

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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) health.Checker {
return health.CheckFunc(func() error {
client := http.Client{
Timeout: timeout,
}
response, err := client.Head(r)
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
})
}