feat: add Deployment, Strategy, Operation primitives to compose service deployments

internal/cli/client/deploy.go

@@ -0,0 +1,177 @@
+package client
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"uncloud/internal/api"
+)
+
+// Strategy defines how a service should be deployed or updated. Different implementations can provide various
+// deployment patterns such as rolling updates, blue/green deployments, etc.
+type Strategy interface {
+	// Plan returns the operation to reconcile the service to the desired state.
+	// If the service does not exist (new deployment), svc will be nil.
+	Plan(ctx context.Context, cli *Client, svc *api.Service, spec api.ServiceSpec) (Operation, error)
+}
+
+// Operation represents a single atomic operation in a deployment process.
+// Operations can be composed to form complex deployment strategies.
+type Operation interface {
+	Execute(ctx context.Context, cli *Client) error
+}
+
+// Deployment manages the process of creating or updating a service to match a desired state.
+// It coordinates the validation, planning, and execution of deployment operations.
+type Deployment struct {
+	Service  *api.Service
+	Spec     api.ServiceSpec
+	Strategy Strategy
+	cli      *Client
+	plan     Operation
+}
+
+// NewDeployment creates a new deployment for the given service specification.
+// If strategy is nil, a default RollingStrategy will be used.
+func (cli *Client) NewDeployment(spec api.ServiceSpec, strategy Strategy) (*Deployment, error) {
+	if strategy == nil {
+		strategy = &RollingStrategy{}
+	}
+
+	return &Deployment{
+		Spec:     spec,
+		Strategy: strategy,
+		cli:      cli,
+	}, nil
+}
+
+// Plan returns a plan of operations to reconcile the service to the desired state.
+// If a plan has already been created, the same plan will be returned.
+func (d *Deployment) Plan(ctx context.Context) (Operation, error) {
+	if d.plan != nil {
+		return d.plan, nil
+	}
+
+	// Validate the new spec before planning.
+	if err := d.Validate(ctx); err != nil {
+		return nil, fmt.Errorf("invalid deployment: %w", err)
+	}
+
+	plan, err := d.Strategy.Plan(ctx, d.cli, d.Service, d.Spec)
+	if err != nil {
+		return nil, fmt.Errorf("create plan using %T: %w", d.Strategy, err)
+	}
+	d.plan = plan
+
+	return plan, nil
+}
+
+// Validate checks if the deployment specification is valid.
+func (d *Deployment) Validate(ctx context.Context) error {
+	if err := d.Spec.Validate(); err != nil {
+		return fmt.Errorf("invalid service spec: %w", err)
+	}
+
+	if d.Service == nil && d.Spec.Name != "" {
+		svc, err := d.cli.InspectService(ctx, d.Spec.Name)
+		if err == nil {
+			d.Service = &svc
+		} else if !errors.Is(err, ErrNotFound) {
+			return fmt.Errorf("inspect service: %w", err)
+		}
+	}
+	// d.Service will be nil if the service doesn't exist yet (first deployment).
+	if d.Service == nil {
+		return nil
+	}
+
+	fmt.Printf("Service: %v\n", d.Service)
+	if d.Service.Name != d.Spec.Name {
+		return errors.New("service name cannot be changed")
+	}
+	if d.Service.Mode != d.Spec.Mode {
+		return errors.New("service mode cannot be changed")
+	}
+
+	return nil
+}
+
+// Run executes the deployment plan. It will create a new plan if one hasn't been created yet.
+// The deployment will either create a new service or update an existing one to match the desired specification.
+func (d *Deployment) Run(ctx context.Context) error {
+	// TODO: create or get the plan, and run it.
+	return nil
+}
+
+// RollingStrategy implements a rolling update deployment pattern where containers are updated one at a time
+// to minimize service disruption.
+type RollingStrategy struct{}
+
+func (s *RollingStrategy) Plan(
+	ctx context.Context, cli *Client, svc *api.Service, spec api.ServiceSpec,
+) (Operation, error) {
+	switch spec.Mode {
+	case "", api.ServiceModeReplicated:
+		return s.planReplicated(ctx, cli, svc, spec)
+	case api.ServiceModeGlobal:
+		return s.planGlobal(ctx, cli, svc, spec)
+	default:
+		return nil, fmt.Errorf("unsupported service mode: %s", spec.Mode)
+	}
+}
+
+// planReplicated creates a plan for a replicated service deployment.
+func (s *RollingStrategy) planReplicated(
+	ctx context.Context, cli *Client, svc *api.Service, spec api.ServiceSpec,
+) (Operation, error) {
+	return nil, errors.New("not implemented")
+}
+
+// planGlobal creates a plan for a global service deployment.
+func (s *RollingStrategy) planGlobal(
+	ctx context.Context, cli *Client, svc *api.Service, spec api.ServiceSpec,
+) (Operation, error) {
+	// TODO
+	// - Prepare a map of machineID to the current container
+	// - Fetch a list of existing machines
+	// - For each machine, check if there is a container on it
+	// - If doesn't exist, add a RunContainerOperation
+	// - If exists, check if there are host port bindings that conflict with the new spec
+	// - If there are conflicts, add a RemoveContainerOperation and a RunContainerOperation
+	// - If there are no conflicts, add a RunContainerOperation and a RemoveContainerOperation
+	return nil, errors.New("not implemented")
+}
+
+// RunContainerOperation creates and starts a new container on a specific machine.
+type RunContainerOperation struct {
+	Spec      api.ServiceSpec
+	MachineID string
+}
+
+func (o *RunContainerOperation) Execute(ctx context.Context, cli *Client) error {
+	return nil
+}
+
+// RemoveContainerOperation stops and removes a container from a specific machine.
+type RemoveContainerOperation struct {
+	ContainerID string
+	MachineID   string
+}
+
+func (o *RemoveContainerOperation) Execute(ctx context.Context, cli *Client) error {
+	return nil
+}
+
+// SequenceOperation is a composite operation that executes a sequence of operations in order.
+type SequenceOperation struct {
+	Operations []Operation
+}
+
+func (o *SequenceOperation) Execute(ctx context.Context, cli *Client) error {
+	for _, op := range o.Operations {
+		if err := op.Execute(ctx, cli); err != nil {
+			return err
+		}
+	}
+	return nil
+}