Implement EKS support [#5]

I *think* this will work, but without access to an EKS cluster I can't
actually test it.

internal/helm/config.go

@@ -23,6 +23,8 @@ type Config struct {
 	ValuesFiles        []string `split_words:"true"`                 // Arguments to pass to --values in applicable helm commands
 	Namespace          string   ``                                   // Kubernetes namespace for all helm commands
 	KubeToken          string   `envconfig:"KUBERNETES_TOKEN"`       // Kubernetes authentication token to put in .kube/config
+	EKSCluster         string   `envconfig:"EKS_CLUSTER"`            // AWS EKS Cluster ID to put in .kube/config
+	EKSRoleARN         string   `envconfig:"EKS_ROLE_ARN"`           // AWS IAM role resource name to put in .kube/config
 	SkipTLSVerify      bool     `envconfig:"SKIP_TLS_VERIFY"`        // Put insecure-skip-tls-verify in .kube/config
 	Certificate        string   `envconfig:"KUBERNETES_CERTIFICATE"` // The Kubernetes cluster CA's self-signed certificate (must be base64-encoded)
 	APIServer          string   `envconfig:"API_SERVER"`             // The Kubernetes cluster's API endpoint

internal/helm/plan.go

@@ -142,6 +142,8 @@ func initKube(cfg Config) []Step {
 			APIServer:      cfg.APIServer,
 			ServiceAccount: cfg.ServiceAccount,
 			Token:          cfg.KubeToken,
+			EKSCluster:     cfg.EKSCluster,
+			EKSRoleARN:     cfg.EKSRoleARN,
 			TemplateFile:   kubeConfigTemplate,
 			ConfigFile:     kubeConfigFile,
 		},

internal/helm/plan_test.go

@@ -212,6 +212,8 @@ func (suite *PlanTestSuite) TestInitKube() {
 		Certificate:    "b2Ygd29rZW5lc3MK",
 		APIServer:      "123.456.78.9",
 		ServiceAccount: "helmet",
+		EKSCluster:     "eks_reader",
+		EKSRoleARN:     "arn:aws:iam::9631085:role/eksSpangleRole",
 	}
 
 	steps := initKube(cfg)
@@ -225,6 +227,8 @@ func (suite *PlanTestSuite) TestInitKube() {
 		APIServer:      "123.456.78.9",
 		ServiceAccount: "helmet",
 		Token:          "cXVlZXIgY2hhcmFjdGVyCg==",
+		EKSCluster:     "eks_reader",
+		EKSRoleARN:     "arn:aws:iam::9631085:role/eksSpangleRole",
 		TemplateFile:   kubeConfigTemplate,
 		ConfigFile:     kubeConfigFile,
 	}

internal/run/initkube.go

@@ -15,6 +15,8 @@ type InitKube struct {
 	APIServer      string
 	ServiceAccount string
 	Token          string
+	EKSCluster     string
+	EKSRoleARN     string
 	TemplateFile   string
 	ConfigFile     string
 
@@ -30,6 +32,8 @@ type kubeValues struct {
 	Namespace      string
 	ServiceAccount string
 	Token          string
+	EKSCluster     string
+	EKSRoleARN     string
 }
 
 // Execute generates a kubernetes config file from drone-helm3's template.
@@ -48,9 +52,12 @@ func (i *InitKube) Prepare(cfg Config) error {
 	if i.APIServer == "" {
 		return errors.New("an API Server is needed to deploy")
 	}
-	if i.Token == "" {
+	if i.Token == "" && i.EKSCluster == "" {
 		return errors.New("token is needed to deploy")
 	}
+	if i.Token != "" && i.EKSCluster != "" {
+		return errors.New("token cannot be used simultaneously with eksCluster")
+	}
 
 	if i.ServiceAccount == "" {
 		i.ServiceAccount = "helm"
@@ -70,6 +77,8 @@ func (i *InitKube) Prepare(cfg Config) error {
 		APIServer:      i.APIServer,
 		ServiceAccount: i.ServiceAccount,
 		Token:          i.Token,
+		EKSCluster:     i.EKSCluster,
+		EKSRoleARN:     i.EKSRoleARN,
 		Namespace:      cfg.Namespace,
 	}
 

internal/run/initkube_test.go

@@ -133,6 +133,33 @@ func (suite *InitKubeTestSuite) TestPrepareRequiredConfig() {
 	suite.Error(init.Prepare(cfg), "Token should be required.")
 }
 
+func (suite *InitKubeTestSuite) TestPrepareEKSConfig() {
+	templateFile, err := tempfile("kubeconfig********.yml.tpl", "hurgity burgity")
+	defer os.Remove(templateFile.Name())
+	suite.Require().Nil(err)
+
+	configFile, err := tempfile("kubeconfig********.yml", "")
+	defer os.Remove(configFile.Name())
+	suite.Require().Nil(err)
+
+	init := InitKube{
+		TemplateFile: templateFile.Name(),
+		ConfigFile:   configFile.Name(),
+		APIServer:    "eks.aws.amazonaws.com",
+		EKSCluster:   "it-is-an-eks-parrot",
+		EKSRoleARN:   "arn:aws:iam::19691207:role/mrPraline",
+	}
+
+	cfg := Config{}
+
+	suite.NoError(init.Prepare(cfg))
+	suite.Equal(init.values.EKSCluster, "it-is-an-eks-parrot")
+	suite.Equal(init.values.EKSRoleARN, "arn:aws:iam::19691207:role/mrPraline")
+
+	init.Token = "cGluaW5nIGZvciB0aGUgZmrDtnJkcw=="
+	suite.EqualError(init.Prepare(cfg), "token cannot be used simultaneously with eksCluster")
+}
+
 func (suite *InitKubeTestSuite) TestPrepareDefaultsServiceAccount() {
 	templateFile, err := tempfile("kubeconfig********.yml.tpl", "hurgity burgity")
 	defer os.Remove(templateFile.Name())

internal/run/kubeconfig_test.go

@@ -78,6 +78,23 @@ func (suite *KubeconfigTestSuite) TestSetsSkipTLSVerify() {
 	suite.Contains(contents, "insecure-skip-tls-verify: true")
 }
 
+func (suite *KubeconfigTestSuite) TestSetsEKSCluster() {
+	suite.initKube.Token = ""
+	suite.initKube.EKSCluster = "it-is-an-eks-parrot"
+	contents := suite.generateKubeconfig(Config{})
+	suite.Contains(contents, "command: aws-iam-authenticator")
+	suite.Contains(contents, `- "it-is-an-eks-parrot"`)
+}
+
+func (suite *KubeconfigTestSuite) TestSetsEKSRoleARN() {
+	suite.initKube.Token = ""
+	suite.initKube.EKSCluster = "it-is-an-eks-parrot"
+	suite.initKube.EKSRoleARN = "arn:aws:iam::19691207:role/mrPraline"
+	contents := suite.generateKubeconfig(Config{})
+	suite.Contains(contents, `- "-r"`)
+	suite.Contains(contents, `- "arn:aws:iam::19691207:role/mrPraline"`)
+}
+
 func (suite *KubeconfigTestSuite) generateKubeconfig(cfg Config) string {
 	suite.Require().NoError(suite.initKube.Prepare(cfg))
 	suite.Require().NoError(suite.initKube.Execute(cfg))