Fix downloading agent manifest from upstream (#461)

Author: MichaelKatsoulis

internal/configuration/locations/locations.go

@@ -23,8 +23,7 @@ const (
 
 	fieldsCachedDir = "cache/fields"
 
-	kubernetesDeployerElasticAgentYmlFile = "elastic-agent.yml"
-	terraformDeployerYmlFile              = "terraform-deployer.yml"
+	terraformDeployerYmlFile = "terraform-deployer.yml"
 )
 
 var (
@@ -84,11 +83,6 @@ func (loc LocationManager) KubernetesDeployerDir() string {
 	return filepath.Join(loc.stackPath, kubernetesDeployerDir)
 }
 
-// KubernetesDeployerAgentYml returns the Kubernetes Deployer Elastic Agent yml
-func (loc LocationManager) KubernetesDeployerAgentYml() string {
-	return filepath.Join(loc.stackPath, kubernetesDeployerDir, kubernetesDeployerElasticAgentYmlFile)
-}
-
 // TerraformDeployerDir returns the Terraform Directory
 func (loc LocationManager) TerraformDeployerDir() string {
 	return filepath.Join(loc.stackPath, terraformDeployerDir)

internal/install/install.go

@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
-	"strings"
 	"time"
 
 	"github.com/pkg/errors"
@@ -60,11 +59,6 @@ func EnsureInstalled() error {
 		return errors.Wrap(err, "writing stack resources failed")
 	}
 
-	err = writeKubernetesDeployerResources(elasticPackagePath)
-	if err != nil {
-		return errors.Wrap(err, "writing Kubernetes deployer resources failed")
-	}
-
 	err = writeTerraformDeployerResources(elasticPackagePath)
 	if err != nil {
 		return errors.Wrap(err, "writing Terraform deployer resources failed")
@@ -172,26 +166,6 @@ func writeStackResources(elasticPackagePath *locations.LocationManager) error {
 
 }
 
-func writeKubernetesDeployerResources(elasticPackagePath *locations.LocationManager) error {
-	err := os.MkdirAll(elasticPackagePath.KubernetesDeployerDir(), 0755)
-	if err != nil {
-		return errors.Wrapf(err, "creating directory failed (path: %s)", elasticPackagePath.KubernetesDeployerDir())
-	}
-
-	appConfig, err := Configuration()
-	if err != nil {
-		return errors.Wrap(err, "can't read application configuration")
-	}
-
-	err = writeStaticResource(err, elasticPackagePath.KubernetesDeployerAgentYml(),
-		strings.ReplaceAll(kubernetesDeployerElasticAgentYml, "{{ ELASTIC_AGENT_IMAGE_REF }}",
-			appConfig.DefaultStackImageRefs().ElasticAgent))
-	if err != nil {
-		return errors.Wrap(err, "writing static resource failed")
-	}
-	return nil
-}
-
 func writeTerraformDeployerResources(elasticPackagePath *locations.LocationManager) error {
 	terraformDeployer := elasticPackagePath.TerraformDeployerDir()
 	err := os.MkdirAll(terraformDeployer, 0755)

internal/install/static_kubernetes_elastic_agent_yml.go

@@ -49,3 +49,21 @@ func modifyKubernetesResources(action string, definitionPaths ...string) ([]byte
 	}
 	return output, nil
 }
+
+// applyKubernetesResourcesStdin applies a Kubernetes manifest provided as stdin.
+// It returns the resources created as output and an error
+func applyKubernetesResourcesStdin(input []byte) ([]byte, error) {
+	// create kubectl apply command
+	kubectlCmd := exec.Command("kubectl", "apply", "-f", "-", "-o", "yaml")
+	//Stdin of kubectl command is the manifest provided
+	kubectlCmd.Stdin = bytes.NewReader(input)
+	errOutput := new(bytes.Buffer)
+	kubectlCmd.Stderr = errOutput
+
+	logger.Debugf("run command: %s", kubectlCmd)
+	output, err := kubectlCmd.Output()
+	if err != nil {
+		return nil, errors.Wrapf(err, "kubectl apply failed (stderr=%q)", errOutput.String())
+	}
+	return output, nil
+}

internal/kubectl/kubectl.go

@@ -84,6 +84,22 @@ func Apply(definitionPaths ...string) error {
 	return nil
 }
 
+// ApplyStdin function adds resources to the Kubernetes cluster based on provided stdin.
+func ApplyStdin(input []byte) error {
+	logger.Debugf("Apply Kubernetes stdin")
+	out, err := applyKubernetesResourcesStdin(input)
+	if err != nil {
+		return errors.Wrap(err, "can't modify Kubernetes resources (apply stdin)")
+	}
+
+	logger.Debugf("Handle \"apply\" command output")
+	err = handleApplyCommandOutput(out)
+	if err != nil {
+		return errors.Wrap(err, "can't handle command output")
+	}
+	return nil
+}
+
 func handleApplyCommandOutput(out []byte) error {
 	logger.Debugf("Extract resources from command output")
 	resources, err := extractResources(out)
@@ -113,6 +129,11 @@ func waitForReadyResources(resources []resource) error {
 	kubeClient.Log = func(s string, i ...interface{}) {
 		logger.Debugf(s, i...)
 	}
+	// In case of elastic-agent daemonset Wait will not work as expected
+	// because in single node clusters one pod of the daemonset can always
+	// be unavailable (DaemonSet.spec.updateStrategy.rollingUpdate.maxUnavailable defaults to 1).
+	// daemonSetReady will return true regardless of the pod not being ready yet.
+	// Can be solved with multi-node clusters.
 	err := kubeClient.Wait(resList, readinessTimeout)
 	if err != nil {
 		return errors.Wrap(err, "waiter failed")