feat(dns): allow setting an externally managed cluster domain (uc dns set)

* feat: add uc dns set

This allows manual setting of the cluster's domain name. I use this to
make the local cluster admin aware that this has been done.
(and then manually update the external dns)

```
% uc dns set ctrl.u.science.ru.nl
Set cluster domain: ctrl.u.science.ru.nl
Deploy the Caddy reverse proxy service ('uc caddy deploy') to enable internet access to your services via the reserved or your custom domain.

% uc dns show
ctrl.u.science.ru.nl

% uc dns set ctrl.u.science.ru.nl
Error: domain already reserved

% uc dns release
Released cluster domain: ctrl.u.science.ru.nl
```

See: #37

Signed-off-by: Miek Gieben <miek@miek.nl>

* docs

Signed-off-by: Miek Gieben <miek@miek.nl>

* check validatity

Signed-off-by: Miek Gieben <miek@miek.nl>

* No need to call out to update anything, as set doesnt use uncloud dns

Signed-off-by: Miek Gieben <miek@miek.nl>

* Ignore domain when there is no endpoint

Prevents this error, when you know what you're doing:

    Error: failed to update DNS records pointing to caddy service: create cluster domain records in Uncloud DNS: rpc error: code = Unknown desc = Post "/domains/ctrl.u.science.ru.nl/records": unsupported protocol scheme ""

Signed-off-by: Miek Gieben <miek@miek.nl>

* from main

Signed-off-by: Miek Gieben <miek@miek.nl>

* mise proto && make cli-docs

Signed-off-by: Miek Gieben <miek@miek.nl>

* Rebase and and generate protos again

Signed-off-by: Miek Gieben <miek@miek.nl>

* Rebase and fix

Signed-off-by: Miek Gieben <miek@miek.nl>

* feat(dns): allow setting an externally managed cluster domain

---------

Signed-off-by: Miek Gieben <miek@miek.nl>
Co-authored-by: Pasha Sviderski <me@psviderski.name>

pkg/client/compose/deploy.go

@@ -46,8 +46,8 @@ func NewDeploymentWithStrategy(ctx context.Context, cli Client, project *types.P
 		return nil, fmt.Errorf("get cluster domain: %w", err)
 	}
 	resolver := &deploy.ServiceSpecResolver{
-		// If the domain is not found (not reserved), an empty domain is used for the resolver.
-		ClusterDomain: domain,
+		// If no domain is configured, an empty domain is used for the resolver.
+		ClusterDomain: domain.Name,
 	}
 
 	return &Deployment{

pkg/client/deploy/deploy.go

@@ -306,8 +306,8 @@ func (d *Deployment) Plan(ctx context.Context) (ServicePlan, error) {
 		return ServicePlan{}, fmt.Errorf("get cluster domain: %w", err)
 	}
 	specResolver := &ServiceSpecResolver{
-		// If the domain is not found (not reserved), an empty domain is used for the resolver.
-		ClusterDomain: clusterDomain,
+		// If no domain is configured, an empty domain is used for the resolver.
+		ClusterDomain: clusterDomain.Name,
 	}
 
 	resolvedSpec, err := specResolver.Resolve(d.Spec)

pkg/client/dns.go

@@ -21,17 +21,21 @@ import (
 	"google.golang.org/grpc/status"
 )
 
-// GetDomain returns the cluster domain name or ErrNotFound if it hasn't been reserved yet.
-func (cli *Client) GetDomain(ctx context.Context) (string, error) {
+// GetDomain returns the cluster domain or api.ErrNotFound if none is configured.
+func (cli *Client) GetDomain(ctx context.Context) (api.ClusterDomain, error) {
 	domain, err := cli.ClusterClient.GetDomain(ctx, nil)
 	if err != nil {
-		if status.Convert(err).Code() == codes.NotFound {
-			return "", api.ErrNotFound
+		if status.Code(err) == codes.NotFound {
+			return api.ClusterDomain{}, api.ErrNotFound
 		}
-		return "", err
+		return api.ClusterDomain{}, err
 	}
 
-	return domain.Name, nil
+	return api.ClusterDomain{
+		Name: domain.Name,
+		// Older daemons (<0.21) omit Reserved and only support reserved domains.
+		Reserved: domain.Reserved == nil || domain.GetReserved(),
+	}, nil
 }
 
 var ErrNoReachableMachines = errors.New("no internet-reachable machines running service containers")
@@ -39,8 +43,17 @@ var ErrNoReachableMachines = errors.New("no internet-reachable machines running
 // CreateIngressRecords verifies which machines running the specified service (typically Caddy) are reachable from
 // the internet, then creates DNS records for the cluster domain pointing to those machines. It tests each machine
 // by sending HTTP requests to their public IPs. Only machines that respond correctly with their machine ID are included
-// in the resulting DNS configuration. Returns the created DNS records or an error.
+// in the resulting DNS configuration. The domain must be reserved in Uncloud DNS.
+// Returns the created DNS records or an error.
 func (cli *Client) CreateIngressRecords(ctx context.Context, serviceID string) ([]*pb.DNSRecord, error) {
+	domain, err := cli.GetDomain(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("get cluster domain: %w", err)
+	}
+	if !domain.Reserved {
+		return nil, status.Error(codes.FailedPrecondition, "cluster domain is not reserved in Uncloud DNS")
+	}
+
 	svc, err := cli.InspectService(ctx, serviceID)
 	if err != nil {
 		return nil, fmt.Errorf("inspect service '%s': %w", serviceID, err)