Add support for downloading an exported instance snapshot

builder/exoscale/builder.go

@@ -105,6 +105,7 @@ func (b *Builder) Run(ctx context.Context, ui packer.Ui, hook packer.Hook) (pack
 		&stepStopInstance{builder: b},
 		&stepSnapshotInstance{builder: b},
 		&stepExportSnapshot{builder: b},
+		&stepDownloadSnapshot{builder: b},
 		&stepRegisterTemplate{builder: b},
 		&stepCopyTemplate{builder: b},
 	}

builder/exoscale/config.go

@@ -37,6 +37,7 @@ type Config struct {
 	InstanceSecurityGroups     []string `mapstructure:"instance_security_groups"`
 	InstancePrivateNetworks    []string `mapstructure:"instance_private_networks"`
 	InstanceSSHKey             string   `mapstructure:"instance_ssh_key"`
+	SnapshotDownload           bool     `mapstructure:"snapshot_download"`
 	TemplateZones              []string `mapstructure:"template_zones"`
 	TemplateName               string   `mapstructure:"template_name"`
 	TemplateDescription        string   `mapstructure:"template_description"`

builder/exoscale/step_download_snapshot.go

@@ -0,0 +1,88 @@
+package exoscale
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+
+	"github.com/hashicorp/packer-plugin-sdk/multistep"
+	"github.com/hashicorp/packer-plugin-sdk/packer"
+)
+
+type stepDownloadSnapshot struct {
+	builder *Builder
+}
+
+func (s *stepDownloadSnapshot) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
+	var (
+		snapshotURL      = state.Get("snapshot_url").(string)
+		snapshotChecksum = state.Get("snapshot_checksum").(string)
+		ui               = state.Get("ui").(packer.Ui)
+	)
+
+	if !s.builder.config.SnapshotDownload {
+		return multistep.ActionContinue
+	}
+
+	ui.Say("Downloading compute instance snapshot")
+
+	if err := s.downloadSnapshot(ui, snapshotURL); err != nil {
+		ui.Error(fmt.Sprintf("Unable to download compute instance snapshot: %v", err))
+		return multistep.ActionHalt
+
+	}
+	if err := s.createChecksumFile(snapshotChecksum); err != nil {
+		ui.Error(fmt.Sprintf("Unable to create checksum file of the snapshot: %v", err))
+		return multistep.ActionHalt
+	}
+
+	return multistep.ActionContinue
+}
+
+func (s *stepDownloadSnapshot) downloadSnapshot(ui packer.Ui, snapshotURL string) error {
+	templateFile := s.builder.config.TemplateName + ".template"
+
+	out, err := os.Create(templateFile)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	resp, err := http.Get(snapshotURL)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("bad status: %s", resp.Status)
+	}
+
+	pf := ui.TrackProgress(templateFile, 0, 0, resp.Body)
+	defer pf.Close()
+
+	_, err = io.Copy(out, pf)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (s *stepDownloadSnapshot) createChecksumFile(snapshotChecksum string) error {
+	out, err := os.Create(s.builder.config.TemplateName + ".md5")
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	if _, err := out.WriteString(fmt.Sprintf("%s %s", snapshotChecksum, s.builder.config.TemplateName+".template")); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (s *stepDownloadSnapshot) Cleanup(_ multistep.StateBag) {}

docs/builders/exoscale.md

@@ -62,6 +62,9 @@ other OS, we recommend using the [QEMU][packerqemu] plugin combined with the
   will be created before creating the instance, and destroyed after a
   successful build.
 
+- `snapshot_download` (boolean) - Whether to download a snapshot of the compute
+  instance. Defaults to `false`.
+
 - `template_description` (string) - The description of the template.
 
 - `template_username` (string) - An optional username to be used to log into