Parallelise deployments of multiple HSes (#282)

This should halve the time it takes to deploy federation tests, and given
deploying the containers is by far the largest contributor to time in
the tests, this should roughly halve the runtime of federation tests.

Author: kegsay

internal/docker/deployer.go

@@ -20,6 +20,7 @@ import (
 	"log"
 	"net/http"
 	"net/url"
+	"sync"
 
 	"github.com/docker/docker/client"
 
@@ -80,27 +81,52 @@ func (d *Deployer) Deploy(ctx context.Context, blueprintName string) (*Deploymen
 		return nil, fmt.Errorf("Deploy: %w", err)
 	}
 	d.networkID = networkID
-	for _, img := range images {
+
+	// deploy images in parallel
+	var mu sync.Mutex // protects mutable values like the counter and errors
+	var wg sync.WaitGroup
+	wg.Add(len(images)) // ensure we wait until all images have deployed
+	deployImg := func(img types.ImageSummary) error {
+		defer wg.Done()
+		mu.Lock()
 		d.Counter++
+		counter := d.Counter
+		mu.Unlock()
 		contextStr := img.Labels["complement_context"]
 		hsName := img.Labels["complement_hs_name"]
 		asIDToRegistrationMap := asIDToRegistrationFromLabels(img.Labels)
 
 		// TODO: Make CSAPI port configurable
 		deployment, err := deployImage(
-			d.Docker, img.ID, 8008, fmt.Sprintf("complement_%s_%s_%s_%d", d.config.PackageNamespace, d.DeployNamespace, contextStr, d.Counter),
+			d.Docker, img.ID, 8008, fmt.Sprintf("complement_%s_%s_%s_%d", d.config.PackageNamespace, d.DeployNamespace, contextStr, counter),
 			d.config.PackageNamespace, blueprintName, hsName, asIDToRegistrationMap, contextStr, networkID, d.config.SpawnHSTimeout)
 		if err != nil {
 			if deployment != nil && deployment.ContainerID != "" {
 				// print logs to help debug
 				printLogs(d.Docker, deployment.ContainerID, contextStr)
 			}
-			return nil, fmt.Errorf("Deploy: Failed to deploy image %+v : %w", img, err)
+			return fmt.Errorf("Deploy: Failed to deploy image %+v : %w", img, err)
 		}
+		mu.Lock()
 		d.log("%s -> %s (%s)\n", contextStr, deployment.BaseURL, deployment.ContainerID)
 		dep.HS[hsName] = *deployment
+		mu.Unlock()
+		return nil
+	}
+
+	var lastErr error
+	for _, img := range images {
+		go func(i types.ImageSummary) {
+			err := deployImg(i)
+			if err != nil {
+				mu.Lock()
+				lastErr = err
+				mu.Unlock()
+			}
+		}(img)
 	}
-	return dep, nil
+	wg.Wait()
+	return dep, lastErr
 }
 
 // Destroy a deployment. This will kill all running containers.