Adding Regex support for Templater

Adding go code to templater to support generation of strings
based on the regular expression passed.

Closes: #438
Change-Id: Ife0c4f8d5dd8032408875c73ba098919470be9e9

go.mod

@@ -23,6 +23,7 @@ require (
 	github.com/gorilla/mux v1.7.4 // indirect
 	github.com/gregjones/httpcache v0.0.0-20190212212710-3befbb6ad0cc // indirect
 	github.com/hashicorp/go-cleanhttp v0.5.1 // indirect
+	github.com/lucasjones/reggen v0.0.0-20200904144131-37ba4fa293bb
 	github.com/morikuni/aec v1.0.0 // indirect
 	github.com/opencontainers/image-spec v1.0.1 // indirect
 	github.com/pkg/errors v0.9.1

go.sum

@@ -474,6 +474,8 @@ github.com/lucas-clemente/aes12 v0.0.0-20171027163421-cd47fb39b79f/go.mod h1:JpH
 github.com/lucas-clemente/quic-clients v0.1.0/go.mod h1:y5xVIEoObKqULIKivu+gD/LU90pL73bTdtQjPBvtCBk=
 github.com/lucas-clemente/quic-go v0.10.2/go.mod h1:hvaRS9IHjFLMq76puFJeWNfmn+H70QZ/CXoxqw9bzao=
 github.com/lucas-clemente/quic-go-certificates v0.0.0-20160823095156-d2f86524cced/go.mod h1:NCcRLrOTZbzhZvixZLlERbJtDtYsmMw8Jc4vS8Z0g58=
+github.com/lucasjones/reggen v0.0.0-20200904144131-37ba4fa293bb h1:w1g9wNDIE/pHSTmAaUhv4TZQuPBS6GV3mMz5hkgziIU=
+github.com/lucasjones/reggen v0.0.0-20200904144131-37ba4fa293bb/go.mod h1:5ELEyG+X8f+meRWHuqUOewBOhvHkl7M76pdGEansxW4=
 github.com/magiconair/properties v1.8.0/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
 github.com/magiconair/properties v1.8.1 h1:ZC2Vc7/ZFkGmsVC9KvOjumD+G5lXy2RtTKyzRKO2BQ4=
 github.com/magiconair/properties v1.8.1/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=

pkg/document/plugin/templater/templater.go

@@ -20,6 +20,7 @@ import (
 	"text/template"
 
 	sprig "github.com/Masterminds/sprig/v3"
+	"github.com/lucasjones/reggen"
 
 	"k8s.io/apimachinery/pkg/runtime"
 	"sigs.k8s.io/kustomize/kyaml/kio"
@@ -51,6 +52,7 @@ func (t *plugin) Filter(items []*yaml.RNode) ([]*yaml.RNode, error) {
 	funcMap := sprig.TxtFuncMap()
 	funcMap["toUint32"] = func(i int) uint32 { return uint32(i) }
 	funcMap["toYaml"] = toYaml
+	funcMap["regexGen"] = regexGen
 	tmpl, err := template.New("tmpl").Funcs(funcMap).Parse(t.Template)
 	if err != nil {
 		return nil, err
@@ -75,6 +77,18 @@ func (t *plugin) Filter(items []*yaml.RNode) ([]*yaml.RNode, error) {
 	return append(items, res.Nodes...), nil
 }
 
+// Generate Regex
+func regexGen(regex string, limit int) string {
+	if limit <= 0 {
+		panic("Limit cannot be less than or equal to 0")
+	}
+	str, err := reggen.Generate(regex, limit)
+	if err != nil {
+		panic(err)
+	}
+	return str
+}
+
 // Render input yaml as output yaml
 // This function is from the Helm project:
 // https://github.com/helm/helm

pkg/document/plugin/templater/templater_test.go

@@ -130,6 +130,57 @@ template: |
 			expectedOut: `touint32: 10
 `,
 		},
+		{
+			cfg: `
+apiVersion: airshipit.org/v1alpha1
+kind: Templater
+metadata:
+  name: notImportantHere
+values:
+  regex: "^[a-z]{5,10}$"
+  nomatchregex: "^[a-z]{0,4}$"
+  limit: 10
+template: |
+  truepassword: {{ regexMatch .regex (regexGen .regex (.limit|int)) }}
+  falsepassword: {{ regexMatch .nomatchregex (regexGen .regex (.limit|int)) }}
+`,
+			expectedOut: `truepassword: true
+falsepassword: false
+`,
+		}, {
+			cfg: `
+apiVersion: airshipit.org/v1alpha1
+kind: Templater
+metadata:
+  name: notImportantHere
+values:
+  name: test
+  regex: "^[a-z]{5,10}$"
+  limit: 0
+template: |
+  password: {{ regexGen .regex (.limit|int) }}
+`,
+			expectedErr: "template: tmpl:1:13: executing \"tmpl\" at " +
+				"<regexGen .regex (.limit | int)>: error calling regexGen: " +
+				"Limit cannot be less than or equal to 0",
+		},
+		{
+			cfg: `
+apiVersion: airshipit.org/v1alpha1
+kind: Templater
+metadata:
+  name: notImportantHere
+values:
+  name: test
+  regex: "^[a-z"
+  limit: 10
+template: |
+  password: {{ regexGen .regex (.limit|int) }}
+`,
+			expectedErr: "template: tmpl:1:13: executing \"tmpl\" " +
+				"at <regexGen .regex (.limit | int)>: error calling " +
+				"regexGen: error parsing regexp: missing closing ]: `[a-z`",
+		},
 	}
 
 	for _, tc := range testCases {