fix: Empty manifests result in empty output (#364)

Author: kavfixnel

cmd/generate.go

@@ -75,10 +75,6 @@ func NewGenerateCommand() *cobra.Command {
 				return err
 			}
 
-			if len(manifests) == 0 {
-				return fmt.Errorf("No manifests")
-			}
-
 			for _, manifest := range manifests {
 
 				template, err := kube.NewTemplate(manifest, cmdConfig.Backend)

cmd/generate_test.go

@@ -80,7 +80,7 @@ func TestMain(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		expected := "No manifests"
+		expected := ""
 		if !strings.Contains(string(out), expected) {
 			t.Fatalf("expected to contain: %s but got %s", expected, out)
 		}

docs/howitworks.md

@@ -337,3 +337,23 @@ spec:
       annotations:
         checksum/secret: <path:secrets/data/db#certs | sha256sum>
 ```
+
+### Error Handling
+
+#### Detecting errors in chained commands
+
+By default argocd-vault-plugin will read valid kubernetes YAMLs and replace variables with values from Vault.
+If a previous command failed and outputs nothing to stdout and AVP reads the input from stdin with
+the `-` argument, AVP will forward an empty YAML output downstream. To catch and prevent accientental errors
+in chained commands, please use the `-o pipefail` bash option like so:
+
+```bash
+$ sh -c '((>&2 echo "some error" && exit 1) | argocd-vault-plugin generate - | kubectl diff -f -); echo $?;'
+some error
+0
+
+$ set -o pipefail
+$ sh -c '((>&2 echo "some error" && exit 1) | argocd-vault-plugin generate - | kubectl diff -f -); echo $?;'
+some error
+1
+```