From 73785007cb7ffb66a30da02bb4752e20e59005ba Mon Sep 17 00:00:00 2001
From: Pavel Sviderski <me@psviderski.name>
Date: Thu, 28 Nov 2024 13:54:10 +1000
Subject: [PATCH] init ucind (Uncloud in Docker) provisioner

---
 internal/ucind/cluster.go   | 82 +++++++++++++++++++++++++++++++++++++
 internal/ucind/provision.go | 18 ++++++++
 2 files changed, 100 insertions(+)
 create mode 100644 internal/ucind/cluster.go
 create mode 100644 internal/ucind/provision.go

diff --git a/internal/ucind/cluster.go b/internal/ucind/cluster.go
new file mode 100644
index 00000000..373e60e2
--- /dev/null
+++ b/internal/ucind/cluster.go
@@ -0,0 +1,82 @@
+package ucind
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"github.com/docker/docker/api/types/network"
+	"github.com/docker/docker/client"
+)
+
+const (
+	ClusterNameLabel = "ucind.cluster.name"
+	ManagedLabel     = "ucind.managed"
+)
+
+type Cluster struct {
+	Name string
+}
+
+type CreateClusterOptions struct {
+	Machines int
+}
+
+func (p *Provisioner) CreateCluster(ctx context.Context, name string, opts CreateClusterOptions) error {
+	_, err := p.InspectCluster(ctx, name)
+	if err == nil {
+		return fmt.Errorf("cluster with name '%s' already exists", name)
+	}
+	if !errors.Is(err, ErrNotFound) {
+		return fmt.Errorf("inspect cluster '%s': %w", name, err)
+	}
+
+	netOpts := network.CreateOptions{
+		Labels: map[string]string{
+			ClusterNameLabel: name,
+			ManagedLabel:     "",
+		},
+	}
+	// Docker network name is the same as the cluster name.
+	if _, err = p.client.NetworkCreate(ctx, name, netOpts); err != nil {
+		return fmt.Errorf("create Docker network '%s': %w", name, err)
+	}
+
+	// TODO: create machines (containers) with the cluster name label.
+
+	return nil
+}
+
+func (p *Provisioner) InspectCluster(ctx context.Context, name string) (*Cluster, error) {
+	// Docker network name is the same as the cluster name.
+	net, err := p.client.NetworkInspect(ctx, name, network.InspectOptions{})
+	if err != nil {
+		if client.IsErrNotFound(err) {
+			return nil, ErrNotFound
+		}
+		return nil, fmt.Errorf("inspect Docker network '%s': %w", name, err)
+	}
+
+	if _, ok := net.Labels[ManagedLabel]; !ok {
+		// The network with the cluster name exists, but it's not managed by ucind.
+		return nil, ErrNotFound
+	}
+
+	// TODO: list containers (machines) with the cluster name label and include them in the cluster struct.
+
+	return &Cluster{
+		Name: name,
+	}, nil
+}
+
+func (p *Provisioner) RemoveCluster(ctx context.Context, name string) error {
+	if _, err := p.InspectCluster(ctx, name); err != nil {
+		return err
+	}
+
+	// TODO: remove machines (containers) with the cluster name label.
+
+	if err := p.client.NetworkRemove(ctx, name); err != nil {
+		return fmt.Errorf("remove Docker network '%s': %w", name, err)
+	}
+	return nil
+}
diff --git a/internal/ucind/provision.go b/internal/ucind/provision.go
new file mode 100644
index 00000000..94cea9ef
--- /dev/null
+++ b/internal/ucind/provision.go
@@ -0,0 +1,18 @@
+package ucind
+
+import (
+	"errors"
+	"github.com/docker/docker/client"
+)
+
+var ErrNotFound = errors.New("not found")
+
+type Provisioner struct {
+	client *client.Client
+}
+
+func NewProvisioner(cli *client.Client) *Provisioner {
+	return &Provisioner{
+		client: cli,
+	}
+}