Health server runs on 127.0.0.1:9999, fix #272

internal/healthcheck/health.go

@@ -0,0 +1,21 @@
+package healthcheck
+
+import (
+	"context"
+	"fmt"
+	"net"
+)
+
+func healthCheck(ctx context.Context, resolver *net.Resolver) (err error) {
+	// TODO use mullvad API if current provider is Mullvad
+	const domainToResolve = "github.com"
+	ips, err := resolver.LookupIP(ctx, "ip", domainToResolve)
+	switch {
+	case err != nil:
+		return fmt.Errorf("cannot resolve github.com: %s", err)
+	case len(ips) == 0:
+		return fmt.Errorf("resolved no IP addresses for %s", domainToResolve)
+	default:
+		return nil
+	}
+}