feat: add capacity_reservation_market_type configuration option

builder/common/run_config.go

@@ -156,6 +156,11 @@ type RunConfig struct {
 	// Provide the EC2 Capacity Reservation Group ARN that will be used by
 	// Packer.
 	CapacityReservationGroupArn string `mapstructure:"capacity_reservation_group_arn" required:"false"`
+	// The market type to use when launching instances with capacity reservations.
+	// Valid values are: `interruptible-capacity-reservation`, `capacity-block`, or empty string (for on-demand).
+	// Only set this when using interruptible capacity reservations or capacity blocks.
+	// Leave empty for standard on-demand capacity reservations. Defaults to empty string.
+	CapacityReservationMarketType string `mapstructure:"capacity_reservation_market_type" required:"false"`
 
 	// Packer normally stops the build instance after all provisioners have
 	// run. For Windows instances, it is sometimes desirable to [run
@@ -924,6 +929,20 @@ func (c *RunConfig) Prepare(ctx *interpolate.Context) []error {
 		errs = append(errs, fmt.Errorf(`capacity_reservation_preference only accepts 'none' or 'open' values`))
 	}
 
+	// Validate capacity_reservation_market_type
+	if c.CapacityReservationMarketType != "" {
+		switch c.CapacityReservationMarketType {
+		case "interruptible-capacity-reservation", "capacity-block":
+			// Valid market types
+		default:
+			errs = append(errs, fmt.Errorf(`capacity_reservation_market_type only accepts 'interruptible-capacity-reservation' or 'capacity-block' values`))
+		}
+		// Market type should only be used with a specific capacity reservation
+		if c.CapacityReservationId == "" && c.CapacityReservationGroupArn == "" {
+			errs = append(errs, fmt.Errorf(`capacity_reservation_market_type requires either capacity_reservation_id or capacity_reservation_group_arn to be set`))
+		}
+	}
+
 	var tenancy string
 	tenancies := []string{c.Placement.Tenancy, c.Tenancy}
 

builder/common/step_run_source_instance.go

@@ -31,6 +31,7 @@ type StepRunSourceInstance struct {
 	CapacityReservationPreference     string
 	CapacityReservationId             string
 	CapacityReservationGroupArn       string
+	CapacityReservationMarketType     string
 	Comm                              *communicator.Config
 	Ctx                               interpolate.Context
 	Debug                             bool
@@ -258,6 +259,9 @@ func (s *StepRunSourceInstance) Run(ctx context.Context, state multistep.StateBa
 	}
 
 	if s.CapacityReservationId != "" || s.CapacityReservationGroupArn != "" {
+		if runOpts.CapacityReservationSpecification == nil {
+			runOpts.CapacityReservationSpecification = &ec2.CapacityReservationSpecification{}
+		}
 		runOpts.CapacityReservationSpecification.CapacityReservationTarget = &ec2.CapacityReservationTarget{}
 
 		if s.CapacityReservationId != "" {
@@ -267,6 +271,13 @@ func (s *StepRunSourceInstance) Run(ctx context.Context, state multistep.StateBa
 		if s.CapacityReservationGroupArn != "" {
 			runOpts.CapacityReservationSpecification.CapacityReservationTarget.CapacityReservationResourceGroupArn = aws.String(s.CapacityReservationGroupArn)
 		}
+
+		// Set market type if specified for interruptible capacity reservations or capacity blocks
+		if s.CapacityReservationMarketType != "" {
+			runOpts.InstanceMarketOptions = &ec2.InstanceMarketOptionsRequest{
+				MarketType: aws.String(s.CapacityReservationMarketType),
+			}
+		}
 	}
 
 	if s.HostResourceGroupArn != "" {

builder/ebs/builder.go

@@ -271,6 +271,7 @@ func (b *Builder) Run(ctx context.Context, ui packersdk.Ui, hook packersdk.Hook)
 			CapacityReservationPreference:     b.config.CapacityReservationPreference,
 			CapacityReservationId:             b.config.CapacityReservationId,
 			CapacityReservationGroupArn:       b.config.CapacityReservationGroupArn,
+			CapacityReservationMarketType:     b.config.CapacityReservationMarketType,
 			Comm:                              &b.config.RunConfig.Comm,
 			Ctx:                               b.config.ctx,
 			Debug:                             b.config.PackerDebug,

builder/ebssurrogate/builder.go

@@ -308,6 +308,7 @@ func (b *Builder) Run(ctx context.Context, ui packersdk.Ui, hook packersdk.Hook)
 			CapacityReservationPreference:     b.config.CapacityReservationPreference,
 			CapacityReservationId:             b.config.CapacityReservationId,
 			CapacityReservationGroupArn:       b.config.CapacityReservationGroupArn,
+			CapacityReservationMarketType:     b.config.CapacityReservationMarketType,
 			Comm:                              &b.config.RunConfig.Comm,
 			Ctx:                               b.config.ctx,
 			Debug:                             b.config.PackerDebug,

builder/ebsvolume/builder.go

@@ -254,6 +254,7 @@ func (b *Builder) Run(ctx context.Context, ui packersdk.Ui, hook packersdk.Hook)
 			CapacityReservationPreference:     b.config.CapacityReservationPreference,
 			CapacityReservationId:             b.config.CapacityReservationId,
 			CapacityReservationGroupArn:       b.config.CapacityReservationGroupArn,
+			CapacityReservationMarketType:     b.config.CapacityReservationMarketType,
 			Comm:                              &b.config.RunConfig.Comm,
 			Ctx:                               b.config.ctx,
 			Debug:                             b.config.PackerDebug,