Fail on missing env var

.drone.yml

@@ -41,6 +41,19 @@ steps:
   - go test -v ./cmd/plugin
   - go test -v ./pkg/deploy
 
+- name: vet
+  image: golang:1.16.3
+  pull: if-not-present
+  commands:
+  - go vet -race ./cmd/plugin
+  - go vet -race ./pkg/deploy
+
+- name: build-amd64
+  image: golang:1.16.3
+  pull: if-not-present
+  commands:
+  - bash build/linux_amd64.sh
+
 ---
 kind: pipeline
 name: publish

cmd/plugin/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"log"
 	"os"
 	"time"
@@ -11,6 +12,25 @@ import (
 	"github.com/aws/aws-sdk-go-v2/service/ecs"
 )
 
+func checkEnvVars() error {
+	requiredVars := []string{
+		"PLUGIN_AWS_REGION",
+		"PLUGIN_SERVICE",
+		"PLUGIN_CLUSTER",
+		"PLUGIN_CONTAINER",
+		"PLUGIN_IMAGE",
+	}
+
+	for _, v := range requiredVars {
+		if os.Getenv(v) == "" {
+			log.Printf("Required environment variable '%s' is missing\n", v)
+			return errors.New("env var not set")
+		}
+	}
+
+	return nil
+}
+
 func newECSClient(region string) *ecs.Client {
 	cfg, err := config.LoadDefaultConfig(
 		context.TODO(),
@@ -25,6 +45,11 @@ func newECSClient(region string) *ecs.Client {
 }
 
 func main() {
+	// Ensure all required env vars are present
+	if err := checkEnvVars(); err != nil {
+		os.Exit(1)
+	}
+
 	e := newECSClient(os.Getenv("PLUGIN_AWS_REGION"))
 
 	service := os.Getenv("PLUGIN_SERVICE")

cmd/plugin/main_test.go

@@ -1,7 +1,33 @@
 package main
 
-import "testing"
+import (
+	"os"
+	"testing"
+
+	"gotest.tools/assert"
+)
 
 func TestNewECSClient(t *testing.T) {
 	newECSClient("us-east-2")
 }
+
+func TestCheckEnvVarsAllVarsSet(t *testing.T) {
+	os.Setenv("PLUGIN_AWS_REGION", "us-east-2")
+	os.Setenv("PLUGIN_SERVICE", "some-service")
+	os.Setenv("PLUGIN_CLUSTER", "some-cluster")
+	os.Setenv("PLUGIN_CONTAINER", "some-container-name")
+	os.Setenv("PLUGIN_IMAGE", "some/image:with-tag")
+
+	err := checkEnvVars()
+
+	assert.Equal(t, nil, err)
+}
+
+func TestCheckEnvVarsMissing(t *testing.T) {
+	os.Unsetenv("PLUGIN_IMAGE")
+
+	err := checkEnvVars()
+
+	assert.Error(t, err, "env var not set")
+
+}