init

checks.go

@@ -0,0 +1,136 @@
+package watchdog
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"time"
+)
+
+// DefaultTimeout is used to limit checks duration
+const DefaultTimeout = time.Second * 10
+
+// GetHTTP creates a CheckFunc that operates as follows.
+// The check calls GET method for provided addr using http.DefaultClient.
+// If request fails within specified timeout the returned status is StatusDown.
+// The function then tries to read response body. If it fails,
+// the returned status is StatusDown.
+// If request secceeds but reponse code is not 200, the returned
+// status is StatusPartiallyAvailable and response body is contained in the
+// returned error.
+//
+// GetHTTP return an error if addr can not be parsed with url.Parse.
+// If zero timeout is provided then the DefaultTimeout (10 second) is used.
+func GetHTTP(addr string, timeout time.Duration) (CheckFunc, error) {
+	u, err := url.Parse(addr)
+	if err != nil {
+		return nil, fmt.Errorf("coulf not parse URL: %w", err)
+	}
+
+	if timeout == 0 {
+		timeout = DefaultTimeout
+	}
+
+	return func(ctx context.Context) (Status, error) {
+		ctx, cancel := context.WithTimeout(ctx, timeout)
+		defer cancel()
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), nil)
+		if err != nil {
+			return StatusUnknown, fmt.Errorf("failed to create http request: %w", err)
+		}
+
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			return StatusDown, fmt.Errorf("do request failed: %w", err)
+		}
+
+		defer resp.Body.Close()
+
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return StatusDown, fmt.Errorf("err reading response body: %w", err)
+		}
+
+		if resp.StatusCode != http.StatusOK {
+			return StatusDown, fmt.Errorf("got HTTP response code %d, body: %s", resp.StatusCode, string(body))
+		}
+
+		return StatusOK, nil
+	}, nil
+}
+
+// HeadHTTP creates a CheckFunc that operates as follows.
+// The check calls GET method for provided addr using http.DefaultClient.
+// If request fails within specified timeout the returned status is StatusDown.
+//
+// If request secceeds but reponse code is not 200, the returned
+// status is StatusPartiallyAvailable.
+//
+// HeadHTTP return an error if addr can not be parsed with url.Parse.
+// If zero timeout is provided then the DefaultTimeout (10 second) is used.
+func HeadHTTP(addr string, timeout time.Duration) (CheckFunc, error) {
+	u, err := url.Parse(addr)
+	if err != nil {
+		return nil, fmt.Errorf("coulf not parse URL: %w", err)
+	}
+
+	if timeout == 0 {
+		timeout = DefaultTimeout
+	}
+
+	return func(ctx context.Context) (Status, error) {
+		ctx, cancel := context.WithTimeout(ctx, timeout)
+		defer cancel()
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodHead, u.String(), nil)
+		if err != nil {
+			return StatusUnknown, fmt.Errorf("failed to create http request: %w", err)
+		}
+
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			return StatusDown, fmt.Errorf("do request failed: %w", err)
+		}
+
+		defer resp.Body.Close()
+
+		if resp.StatusCode != http.StatusOK {
+			return StatusDown, fmt.Errorf("got HTTP response code %d", resp.StatusCode)
+		}
+
+		return http.StatusOK, nil
+	}, nil
+}
+
+// DialTCP creates a CheckFunc that may be used to check tcp connectivity
+// to a host.
+// The check tries to net.DialTimeout to the provided addr. If it fails,
+// the returned status is StatusDown.
+//
+// No validation of addr is made.
+// If zero timeout is provided then the DefaultTimeout (10 second) is used.
+func DialTCP(addr string, timeout time.Duration) (CheckFunc, error) {
+	if timeout == 0 {
+		timeout = DefaultTimeout
+	}
+
+	return func(ctx context.Context) (Status, error) {
+		deadline := time.Now().Add(timeout)
+		if t, ok := ctx.Deadline(); ok && t.Before(deadline) {
+			deadline = t
+		}
+
+		conn, err := net.DialTimeout("tcp", addr, time.Until(deadline))
+		if err != nil {
+			return StatusDown, fmt.Errorf("error dialing: %w", err)
+		}
+
+		defer conn.Close()
+
+		return StatusOK, nil
+	}, nil
+}