feat: add the ability to read from external files

Signed-off-by: Jesús Fernández <jesus.fernandez@nexthink.com>

README.md

@@ -116,6 +116,8 @@ about `crossplane beta render`.
 | [`getResourceCondition`](example/functions/getResourceCondition) | Helper function to retreive conditions of resources |
 | [`setResourceNameAnnotation`](example/inline)                    | Returns the special resource-name annotation with given name |
 | [`include`](example/functions/include)                           | Outputs template as a string                        |
+| [`readFile`](example/functions/readfile)                         | Outputs the contents of a given file                |
+| [`readFiles`](example/functions/readfile)                        | Outputs the contents of multiple files              |
 
 ## Developing this function
 

example/read-file/composition.yaml

@@ -0,0 +1,19 @@
+apiVersion: apiextensions.crossplane.io/v1
+kind: Composition
+metadata:
+  name: example-read-file
+spec:
+  compositeTypeRef:
+    apiVersion: example.crossplane.io/v1beta1
+    kind: XR
+  mode: Pipeline
+  pipeline:
+    - step: render-templates
+      functionRef:
+        name: function-go-templating
+      input:
+        apiVersion: gotemplating.fn.crossplane.io/v1beta1
+        kind: GoTemplate
+        source: FileSystem
+        filesystem:
+          dirPath: ./templates

example/read-file/deployment_runtime_configuration.yaml

@@ -0,0 +1,32 @@
+apiVersion: pkg.crossplane.io/v1beta1
+kind: DeploymentRuntimeConfig
+metadata:
+  name: function-go-templating
+spec:
+  deploymentTemplate:
+    metadata:
+      labels:
+        kubernetes.io/part-of: crossplane
+    spec:
+      selector: {}
+      template:
+        spec:
+          containers:
+          - name: package-runtime
+            args:
+            - --debug
+            volumeMounts:
+            - mountPath: /templates
+              name: templates
+              readOnly: true
+            - mountPath: /files
+              name: files
+              readOnly: true
+          volumes:
+          - name: templates
+            configMap:
+              name: read-file-example-templates
+          - name: files
+            configMap:
+              name: read-file-example-files
+

example/read-file/functions.yaml

@@ -0,0 +1,8 @@
+apiVersion: pkg.crossplane.io/v1beta1
+kind: Function
+metadata:
+  name: function-go-templating
+spec:
+  package: xpkg.upbound.io/crossplane-contrib/function-go-templating:v0.4.0
+  runtimeConfigRef:
+    name: function-go-templating

example/read-file/kustomization.yaml

@@ -0,0 +1,14 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+- composition.yaml
+- functions.yaml
+configMapGenerator:
+- name: read-file-example-templates
+  files:
+  - templates/workspace.yaml
+- name: read-file-example-files
+  files:
+  - terraform/workspace.tf
+generatorOptions:
+  disableNameSuffixHash: true

example/read-file/templates/workspace.yaml

@@ -0,0 +1,20 @@
+{{- $spec := .observed.composite.resource.spec }}
+---
+apiVersion: tf.upbound.io/v1beta1
+kind: Workspace
+metadata:
+  annotations: {{ setResourceNameAnnotation "workspace" }}
+  labels:
+    testing.upbound.io/example-name: test-read-file
+  name: observe-only-workspace
+spec:
+  forProvider:
+    source: Inline
+    module: {{ readFile "files/workspace.tf" | quote }}
+{{/* Alternatively
+    module: {{ readFiles "files/*.tf" "\n" | quote }}
+*/}}
+    varmap:
+      region: {{ $spec.region }}
+  providerConfigRef:
+    name: default

example/read-file/terraform/workspace.tf

@@ -0,0 +1,17 @@
+provider "aws" {
+  region = var.region
+}
+
+data "aws_regions"  "available" {
+  all_regions = true
+}
+
+output "available_regions" {
+  value = join(",", data.aws_regions.available.names)
+}
+
+variable "region" {
+  description = "AWS region"
+  type        = string
+}
+

example/read-file/xr.yaml

@@ -0,0 +1,6 @@
+apiVersion: example.crossplane.io/v1beta1
+kind: XR
+metadata:
+  name: example
+spec:
+  region: us-east-1

function_maps.go

@@ -3,12 +3,13 @@ package main
 import (
 	"fmt"
 	"math/rand"
+	"os"
+	"path/filepath"
 	"strings"
 	"text/template"
 	"time"
 
 	"gopkg.in/yaml.v3"
-
 	sprig "github.com/Masterminds/sprig/v3"
 	"github.com/crossplane-contrib/function-go-templating/input/v1beta1"
 	xpv1 "github.com/crossplane/crossplane-runtime/apis/common/v1"
@@ -24,6 +25,8 @@ var funcMaps = []template.FuncMap{
 		"toYaml":                    toYaml,
 		"fromYaml":                  fromYaml,
 		"getResourceCondition":      getResourceCondition,
+		"readFile":                  readFile,
+		"readFiles":                 readFiles,
 		"setResourceNameAnnotation": setResourceNameAnnotation,
 	},
 }
@@ -103,4 +106,33 @@ func initInclude(t *template.Template) func(string, interface{}) (string, error)
 		return buf.String(), err
 	}
 
-}
+}
+
+func readFiles(pattern string, sep string) (string, error) {
+	filenames, err := getFiles(pattern)
+	if err != nil {
+		return "", err
+	}
+	contents := []string{}
+	for _, f := range filenames {
+		content, _ := readFile(f)
+		contents = append(contents, content)
+	}
+	return strings.Join(contents, sep), nil
+}
+
+func readFile(filename string) (string, error) {
+	content, err := os.ReadFile(filename)
+	if err != nil {
+		return "", err
+	}
+	return string(content), nil
+}
+
+func getFiles(pattern string) ([]string, error) {
+	matches, err := filepath.Glob(pattern)
+	if err != nil {
+		return nil, err
+	}
+	return matches, nil
+}

function_maps_test.go

@@ -328,3 +328,75 @@ Must capture output: {{$var}}
 		})
 	}
 }
+
+func Test_getFiles(t *testing.T) {
+	type args struct {
+		pattern string
+	}
+	type want struct {
+		rsp []string
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   args
+		want   want
+	}{
+		"GetFilesWithGivenPattern": {
+			reason: "Should return list of files matching *test.go",
+			args: args{
+				pattern: "testdata/*.txt",
+			},
+			want: want{
+				rsp: []string{
+					"testdata/sample.txt",
+					"testdata/testfile.txt",
+				},
+			},
+		},
+	}
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			rsp, _ := getFiles(tc.args.pattern)
+
+			if diff := cmp.Diff(tc.want.rsp, rsp, protocmp.Transform()); diff != "" {
+				t.Errorf("%s\ngetFiles(...): -want rsp, +got rsp:\n%s", tc.reason, diff)
+			}
+		})
+	}
+}
+
+func Test_readFiles(t *testing.T) {
+	type args struct {
+		pattern string
+	}
+	type want struct {
+		rsp string
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   args
+		want   want
+	}{
+		"ReadFile": {
+			reason: "Should return contents of testdata/*.txt",
+			args: args{
+				pattern: "testdata/*.txt",
+			},
+			want: want{
+				rsp: "Hello world",
+			},
+		},
+	}
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			rsp, _ := readFiles(tc.args.pattern, " ")
+
+			if diff := cmp.Diff(tc.want.rsp, rsp, protocmp.Transform()); diff != "" {
+				t.Errorf("%s\readFile(...): -want rsp, +got rsp:\n%s", tc.reason, diff)
+			}
+		})
+	}
+}
+

testdata/sample.txt

@@ -0,0 +1 @@
+Hello

testdata/testfile.txt

@@ -0,0 +1 @@
+world