refactor!: consolidate SSH handling

Closes coop-cloud/organising#389.
Closes coop-cloud/organising#341.
Closes coop-cloud/organising#326.
Closes coop-cloud/organising#380.
Closes coop-cloud/organising#360.

pkg/dns/common.go

@@ -1,7 +1,6 @@
 package dns
 
 import (
-	"context"
 	"fmt"
 	"net"
 	"os"
@@ -32,35 +31,12 @@ func NewToken(provider, providerTokenEnvVar string) (string, error) {
 
 // EnsureIPv4 ensures that an ipv4 address is set for a domain name
 func EnsureIPv4(domainName string) (string, error) {
-	var ipv4 string
-
-	// comrade librehosters DNS resolver -> https://www.privacy-handbuch.de/handbuch_93d.htm
-	freifunkDNS := "5.1.66.255:53"
-
-	resolver := &net.Resolver{
-		PreferGo: false,
-		Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
-			d := net.Dialer{
-				Timeout: time.Millisecond * time.Duration(10000),
-			}
-			return d.DialContext(ctx, "udp", freifunkDNS)
-		},
-	}
-
-	ctx := context.Background()
-	ips, err := resolver.LookupIPAddr(ctx, domainName)
+	ipv4, err := net.ResolveIPAddr("ip", domainName)
 	if err != nil {
-		return ipv4, err
+		return "", err
 	}
 
-	if len(ips) == 0 {
-		return ipv4, fmt.Errorf("unable to retrieve ipv4 address for %s", domainName)
-	}
-
-	ipv4 = ips[0].IP.To4().String()
-	logrus.Debugf("%s points to %s (resolver: %s)", domainName, ipv4, freifunkDNS)
-
-	return ipv4, nil
+	return ipv4.String(), nil
 }
 
 // EnsureDomainsResolveSameIPv4 ensures that domains resolve to the same ipv4 address