Allow substring replacement of numerics

This change adds the ability to use substring substitution to inject
numeric source values into string targets.  This is required for our
networking catalogue, since a numeric k8s API port needs to be inserted into
numeric and (sub)string targets in different phases.

Co-Authored-By: Ian Howell <ian.howell0@gmail.com>
Change-Id: I24beb46a2bda4e118406129a0a922b0c56142c76

pkg/document/plugin/replacement/v1alpha1/transformer.go

@@ -231,9 +231,17 @@ func applySubstringPattern(target interface{}, replacement interface{},
 		return replacement, nil
 	}
 
-	repl, ok := replacement.(string)
-	if !ok {
-		return nil, ErrPatternSubstring{Msg: "pattern-based substitution can only be applied with string replacement values"}
+	// if replacement is numeric, convert it to a string for the sake of
+	// substring substitution.
+	var replacementString string
+	switch t := replacement.(type) {
+	case uint, uint8, uint16, uint32, uint64, int, int8, int16, int32, int64:
+		replacementString = fmt.Sprint(t)
+	case string:
+		replacementString = t
+	default:
+		return nil, ErrPatternSubstring{Msg: "pattern-based substitution can only be applied " +
+			"with string or numeric replacement values"}
 	}
 
 	tgt, ok := target.(string)
@@ -248,7 +256,7 @@ func applySubstringPattern(target interface{}, replacement interface{},
 				substringPattern, tgt),
 		}
 	}
-	return p.ReplaceAllString(tgt, repl), nil
+	return p.ReplaceAllString(tgt, replacementString), nil
 }
 
 func updateMapField(m map[string]interface{}, pathToField []string, replacement interface{}) error {

pkg/document/plugin/replacement/v1alpha1/transformer_test.go

@@ -554,6 +554,65 @@ spec:
 			cfg: `
 apiVersion: airshipit.org/v1alpha1
 kind: ReplacementTransformer
+metadata:
+  name: test-for-numeric-conversion
+replacements:
+- source:
+    objref:
+      kind: Pod
+      name: pod
+    fieldref: spec.containers[0].image
+  target:
+    objref:
+      kind: Deployment
+    fieldrefs:
+    - spec.template.spec.containers[name=myapp-container].image%TAG%`,
+			in: `
+apiVersion: v1
+kind: Pod
+metadata:
+  name: pod
+spec:
+  containers:
+  - name: repl
+    image: 12345
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: deploy2
+spec:
+  template:
+    spec:
+      containers:
+      - image: busybox:TAG
+        name: myapp-container
+`,
+			expectedOut: `apiVersion: v1
+kind: Pod
+metadata:
+  name: pod
+spec:
+  containers:
+  - image: 12345
+    name: repl
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: deploy2
+spec:
+  template:
+    spec:
+      containers:
+      - image: busybox:12345
+        name: myapp-container
+`,
+		},
+		{
+			cfg: `
+apiVersion: airshipit.org/v1alpha1
+kind: ReplacementTransformer
 metadata:
   name: notImportantHere
 replacements: