feat: Add Sprig template functions (#9005)

* feat: Add Sprig template functions

* Render wrapped return value, providing core template error.

Signed-off-by: Brian Topping <[email protected]>

* Don't need the local `default` function if Sprig is available

Signed-off-by: Brian Topping <[email protected]>

* Run linter

Signed-off-by: Brian Topping <[email protected]>

---------

Signed-off-by: Brian Topping <[email protected]>

docs-v2/content/en/docs/environment/templating.md

@@ -44,6 +44,5 @@ List of variables that are available for templating:
   * `IMAGE_NAME2`, `IMAGE_REPON`, `IMAGE_TAGN`, `IMAGE_DIGESTN` - the Nth artifact's image name, tag, and sha256 digest
 
 ### Template functions
-Besides the [built-in template functions](https://pkg.go.dev/text/template) in golang, skaffold also provides the following ones:
-- `default` : Default values can be specified using the `{{default "bar" .FOO}}` expression syntax, which results in "bar" if .FOO is nil or a zero value.
+In addition to the [built-in template functions](https://pkg.go.dev/text/template) in Golang and the [Sprig template functions](http://masterminds.github.io/sprig/), Skaffold also provides the following:
 - `cmd`: This allows users to use the result from external commands in template, for example `{{cmd "bash" "-c" "xxx xxx xxx"}}` can be used to execute bash script and get the result into the template.

go.mod

@@ -44,6 +44,7 @@ require (
 	github.com/AlecAivazis/survey/v2 v2.2.15
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/metric v0.35.1
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/trace v1.11.1
+	github.com/Masterminds/sprig v2.22.0+incompatible
 	github.com/acarl005/stripansi v0.0.0-20180116102854-5a71ef0e047d
 	github.com/ahmetb/dlog v0.0.0-20170105205344-4fb5f8204f26
 	github.com/blang/semver v3.5.1+incompatible
@@ -151,6 +152,7 @@ require (
 	github.com/BurntSushi/toml v1.2.1 // indirect
 	github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.35.1 // indirect
 	github.com/MakeNowJust/heredoc v0.0.0-20170808103936-bb23615498cd // indirect
+	github.com/Masterminds/goutils v1.1.1 // indirect
 	github.com/Masterminds/semver v1.5.0 // indirect
 	github.com/Microsoft/go-winio v0.6.0 // indirect
 	github.com/Microsoft/hcsshim v0.9.6 // indirect
@@ -224,6 +226,7 @@ require (
 	github.com/googleapis/enterprise-certificate-proxy v0.2.3 // indirect
 	github.com/googleapis/gax-go/v2 v2.8.0 // indirect
 	github.com/gorilla/mux v1.8.0 // indirect
+	github.com/huandu/xstrings v1.4.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 // indirect
 	github.com/jmespath/go-jmespath v0.4.0 // indirect
@@ -239,9 +242,11 @@ require (
 	github.com/mattn/go-runewidth v0.0.13 // indirect
 	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
 	github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b // indirect
+	github.com/mitchellh/copystructure v1.2.0 // indirect
 	github.com/mitchellh/go-wordwrap v1.0.0 // indirect
 	github.com/mitchellh/ioprogress v0.0.0-20180201004757-6a23b12fa88e // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
+	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/moby/locker v1.0.1 // indirect
 	github.com/moby/spdystream v0.2.0 // indirect
 	github.com/moby/sys/mount v0.2.0 // indirect

go.sum

@@ -187,10 +187,14 @@ github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapp
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/internal/resourcemapping v0.35.1/go.mod h1:H785fvlgotVZqht+1rHhXSs8EJ8uPVmpBYkTYO3ccpc=
 github.com/MakeNowJust/heredoc v0.0.0-20170808103936-bb23615498cd h1:sjQovDkwrZp8u+gxLtPgKGjk5hCxuy2hrRejBTA9xFU=
 github.com/MakeNowJust/heredoc v0.0.0-20170808103936-bb23615498cd/go.mod h1:64YHyfSL2R96J44Nlwm39UHepQbyR5q10x7iYa1ks2E=
+github.com/Masterminds/goutils v1.1.1 h1:5nUrii3FMTL5diU80unEVvNevw1nH4+ZV4DSLVJLSYI=
+github.com/Masterminds/goutils v1.1.1/go.mod h1:8cTjp+g8YejhMuvIA5y2vz3BpJxksy863GQaJW2MFNU=
 github.com/Masterminds/semver v1.5.0 h1:H65muMkzWKEuNDnfl9d70GUjFniHKHRbFPGBuZ3QEww=
 github.com/Masterminds/semver v1.5.0/go.mod h1:MB6lktGJrhw8PrUyiEoblNEGEQ+RzHPF078ddwwvV3Y=
 github.com/Masterminds/semver/v3 v3.0.3/go.mod h1:VPu/7SZ7ePZ3QOrcuXROw5FAcLl4a0cBrbBpGY/8hQs=
 github.com/Masterminds/semver/v3 v3.1.0/go.mod h1:VPu/7SZ7ePZ3QOrcuXROw5FAcLl4a0cBrbBpGY/8hQs=
+github.com/Masterminds/sprig v2.22.0+incompatible h1:z4yfnGrZ7netVz+0EDJ0Wi+5VZCSYp4Z0m2dk6cEM60=
+github.com/Masterminds/sprig v2.22.0+incompatible/go.mod h1:y6hNFY5UBTIWBxnzTeuNhlNS5hqE0NB0E6fgfo2Br3o=
 github.com/Microsoft/go-winio v0.4.11/go.mod h1:VhR8bwka0BXejwEJY73c50VrPtXAaKcyvVC4A4RozmA=
 github.com/Microsoft/go-winio v0.4.14/go.mod h1:qXqCSQ3Xa7+6tgxaGTIe4Kpcdsi+P8jBhyzoq1bpyYA=
 github.com/Microsoft/go-winio v0.4.15-0.20190919025122-fc70bd9a86b5/go.mod h1:tTuCMEN+UleMWgg9dVx4Hu52b1bJo+59jBh3ajtinzw=
@@ -1141,6 +1145,8 @@ github.com/hinshun/vt10x v0.0.0-20180616224451-1954e6464174/go.mod h1:DqJ97dSdRW
 github.com/honeycombio/beeline-go v1.10.0 h1:cUDe555oqvw8oD76BQJ8alk7FP0JZ/M/zXpNvOEDLDc=
 github.com/honeycombio/libhoney-go v1.16.0 h1:kPpqoz6vbOzgp7jC6SR7SkNj7rua7rgxvznI6M3KdHc=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
+github.com/huandu/xstrings v1.4.0 h1:D17IlohoQq4UcpqD7fDk80P7l+lwAmlFaBHgOipl2FU=
+github.com/huandu/xstrings v1.4.0/go.mod h1:y5/lhBue+AyNmUVz9RLU9xbLR0o4KIIExikq4ovT0aE=
 github.com/iancoleman/strcase v0.2.0/go.mod h1:iwCmte+B7n89clKwxIoIXy/HfoL7AsD47ZCWhYzw7ho=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
@@ -1329,6 +1335,8 @@ github.com/miekg/pkcs11 v1.0.3/go.mod h1:XsNlhZGX73bx86s2hdc/FuaLm2CPZJemRLMA+WT
 github.com/mistifyio/go-zfs v2.1.2-0.20190413222219-f784269be439+incompatible/go.mod h1:8AuVvqP/mXw1px98n46wfvcGfQ4ci2FwoAjKYxuo3Z4=
 github.com/mitchellh/cli v1.0.0/go.mod h1:hNIlj7HEI86fIcpObd7a0FcrxTWetlwJDGcceTlRvqc=
 github.com/mitchellh/cli v1.1.0/go.mod h1:xcISNoH86gajksDmfB23e/pu+B+GeFRMYmoHXxx3xhI=
+github.com/mitchellh/copystructure v1.2.0 h1:vpKXTN4ewci03Vljg/q9QvCGUDttBOGBIa15WveJJGw=
+github.com/mitchellh/copystructure v1.2.0/go.mod h1:qLl+cE2AmVv+CoeAwDPye/v+N2HKCj9FbZEVFJRxO9s=
 github.com/mitchellh/go-homedir v1.0.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
@@ -1350,6 +1358,8 @@ github.com/mitchellh/mapstructure v1.4.3/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RR
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
 github.com/mitchellh/osext v0.0.0-20151018003038-5e2d6d41470f/go.mod h1:OkQIRizQZAeMln+1tSwduZz7+Af5oFlKirV/MSYes2A=
+github.com/mitchellh/reflectwalk v1.0.2 h1:G2LzWKi524PWgd3mLHV8Y5k7s6XUvT0Gef6zxSIeXaQ=
+github.com/mitchellh/reflectwalk v1.0.2/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
 github.com/moby/buildkit v0.8.0 h1:isPRu9bp8xbMSvs8P6yHAc8vsYPFVNFKrOXHe/tzNXw=
 github.com/moby/buildkit v0.8.0/go.mod h1:/kyU1hKy/aYCuP39GZA9MaKioovHku57N6cqlKZIaiQ=
 github.com/moby/locker v1.0.1 h1:fOXqR41zeveg4fFODix+1Ch4mj/gT0NE1XJbp/epuBg=

pkg/skaffold/build/ko/builder.go

@@ -143,7 +143,7 @@ func expand(dryValues []string) ([]string, error) {
 		rawValue = strings.ReplaceAll(rawValue, "{{.Env.", "{{.")
 		expandedValue, err := util.ExpandEnvTemplate(rawValue, nil)
 		if err != nil {
-			return nil, fmt.Errorf("could not expand %s", rawValue)
+			return nil, err
 		}
 		expandedValues = append(expandedValues, expandedValue)
 	}

pkg/skaffold/util/env_template.go

@@ -22,20 +22,20 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
-	"reflect"
 	"sort"
 	"strings"
 	"text/template"
 
+	"github.com/Masterminds/sprig"
+
 	"github.com/GoogleContainerTools/skaffold/v2/pkg/skaffold/output/log"
 )
 
 // For testing
 var (
 	OSEnviron = os.Environ
 	funcsMap  = template.FuncMap{
-		"default": defaultFunc,
-		"cmd":     runCmdFunc,
+		"cmd": runCmdFunc,
 	}
 )
 
@@ -60,7 +60,7 @@ func ExpandEnvTemplateOrFail(s string, envMap map[string]string) (string, error)
 
 // ParseEnvTemplate is a simple wrapper to parse an env template
 func ParseEnvTemplate(t string) (*template.Template, error) {
-	return template.New("envTemplate").Funcs(funcsMap).Parse(t)
+	return template.New("envTemplate").Funcs(funcsMap).Funcs(sprig.FuncMap()).Parse(t)
 }
 
 // ExecuteEnvTemplate executes an envTemplate based on OS environment variables and a custom map
@@ -139,30 +139,6 @@ func MapToFlag(m map[string]*string, flag string) ([]string, error) {
 	return kvFlags, nil
 }
 
-// defaultFunc is a template function that behaves as sprig's default function.
-// See https://masterminds.github.io/sprig/defaults.html#default
-func defaultFunc(dflt, value interface{}) interface{} {
-	if value == nil {
-		return dflt
-	}
-	v := reflect.ValueOf(value)
-	switch v.Kind() {
-	case reflect.Array, reflect.Slice:
-		if v.Len() == 0 {
-			return dflt
-		}
-	case reflect.Ptr:
-		if v.IsNil() {
-			return dflt
-		}
-	default:
-		if v.IsZero() {
-			return dflt
-		}
-	}
-	return value
-}
-
 func runCmdFunc(name string, args ...string) (string, error) {
 	cmd := exec.Command(name, args...)
 	out, err := RunCmdOut(context.TODO(), cmd)

pkg/skaffold/util/env_template_test.go

@@ -180,26 +180,6 @@ func TestMapToFlag(t *testing.T) {
 	}
 }
 
-func TestDefaultFunc(t *testing.T) {
-	for _, empty := range []interface{}{nil, false, 0, "", []string{}} {
-		t.Run(fmt.Sprintf("empties: %v (%T)", empty, empty), func(t *testing.T) {
-			dflt := "default"
-			if defaultFunc(dflt, empty) != dflt {
-				t.Error("did not return default")
-			}
-		})
-	}
-	s := "string"
-	for _, nonEmpty := range []interface{}{&s, true, 1, "hoot", []string{"hoot"}} {
-		t.Run(fmt.Sprintf("non-empty: %v (%T)", nonEmpty, nonEmpty), func(t *testing.T) {
-			dflt := "default"
-			if defaultFunc(dflt, nonEmpty) == dflt {
-				t.Error("should not return default")
-			}
-		})
-	}
-}
-
 func TestRunCmdFunc(t *testing.T) {
 	tests := []struct {
 		description     string