Added extkingpin module

README.md

@@ -1,8 +1,6 @@
 # tools
 
-[![copyright module docs](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/efficientgo/tools/copyright)
-[![core module docs](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/efficientgo/tools/core)
-[![e2e module docs](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/efficientgo/tools/e2e)
+[![copyright module docs](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/efficientgo/tools/copyright) [![core module docs](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/efficientgo/tools/core) [![e2e module docs](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/efficientgo/tools/e2e)
 
 Set of lightweight tools, packages and modules that every open-source Go project always needs with almost no dependencies.
 
@@ -207,3 +205,25 @@ or via [bingo](https://github.com/bwplotka/bingo) if want to pin it:
 go install github.com/bwplotka/bingo
 bingo get -u github.com/efficientgo/tools/copyright
 ```
+
+### Module `github.com/efficientgo/tools/extkingpin`
+
+This module provides the PathOrContent flag type which defines two flags to fetch bytes. Either from file (\*-file flag) or content (\* flag). Also returns the content of a YAML file with substituted environment variables.
+
+```go mdox-gen-exec="sh -c 'tail -n +6 extkingpin/doc.go'"
+// PathOrContent is a flag type that defines two flags to fetch bytes. Either from file (*-file flag) or content (* flag).
+// Also returns content of YAML file with substituted environment variables.
+// Follows K8s convention, i.e $(...), as mentioned here https://kubernetes.io/docs/tasks/inject-data-application/define-interdependent-environment-variables/.
+
+// RegisterPathOrContent registers PathOrContent flag in kingpinCmdClause.
+
+// Content returns the content of the file when given or directly the content that has been passed to the flag.
+// It returns an error when:
+// * The file and content flags are both not empty.
+// * The file flag is not empty but the file can't be read.
+// * The content is empty and the flag has been defined as required.
+
+// Option is a functional option type for PathOrContent objects.
+// WithRequired allows you to override default required option.
+// WithEnvSubstitution allows you to override default envSubstitution option.
+```

extkingpin/doc.go

@@ -0,0 +1,20 @@
+// Copyright (c) The EfficientGo Authors.
+// Licensed under the Apache License 2.0.
+
+package extkingpin
+
+// PathOrContent is a flag type that defines two flags to fetch bytes. Either from file (*-file flag) or content (* flag).
+// Also returns content of YAML file with substituted environment variables.
+// Follows K8s convention, i.e $(...), as mentioned here https://kubernetes.io/docs/tasks/inject-data-application/define-interdependent-environment-variables/.
+
+// RegisterPathOrContent registers PathOrContent flag in kingpinCmdClause.
+
+// Content returns the content of the file when given or directly the content that has been passed to the flag.
+// It returns an error when:
+// * The file and content flags are both not empty.
+// * The file flag is not empty but the file can't be read.
+// * The content is empty and the flag has been defined as required.
+
+// Option is a functional option type for PathOrContent objects.
+// WithRequired allows you to override default required option.
+// WithEnvSubstitution allows you to override default envSubstitution option.

extkingpin/go.mod

@@ -0,0 +1,11 @@
+module github.com/efficientgo/tools/extkingpin
+
+go 1.15
+
+require (
+	github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 // indirect
+	github.com/alecthomas/units v0.0.0-20210208195552-ff826a37aa15 // indirect
+	github.com/pkg/errors v0.9.1
+	github.com/stretchr/testify v1.7.0 // indirect
+	gopkg.in/alecthomas/kingpin.v2 v2.2.6
+)

extkingpin/go.sum

@@ -0,0 +1,21 @@
+github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 h1:JYp7IbQjafoB+tBA3gMyHYHrpOtNuDiK/uB5uXxq5wM=
+github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
+github.com/alecthomas/units v0.0.0-20210208195552-ff826a37aa15 h1:AUNCr9CiJuwrRYS3XieqF+Z9B9gNxo/eANAJCF2eiN4=
+github.com/alecthomas/units v0.0.0-20210208195552-ff826a37aa15/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6 h1:jMFz6MfLP0/4fUyZle81rXUoxOBFi19VUFKVDOQfozc=
+gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

extkingpin/pathorcontent.go

@@ -0,0 +1,130 @@
+// Copyright (c) The EfficientGo Authors.
+// Licensed under the Apache License 2.0.
+
+// Taken from Thanos project.
+//
+// Copyright (c) The Thanos Authors.
+// Licensed under the Apache License 2.0.
+package extkingpin
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"regexp"
+
+	"github.com/pkg/errors"
+	"gopkg.in/alecthomas/kingpin.v2"
+)
+
+// PathOrContent is a flag type that defines two flags to fetch bytes. Either from file (*-file flag) or content (* flag).
+type PathOrContent struct {
+	flagName string
+
+	envSubstitution bool
+	required        bool
+
+	path    *string
+	content *string
+}
+
+// Option is a functional option type for PathOrContent objects.
+type Option func(*PathOrContent)
+
+type FlagClause interface {
+	Flag(name, help string) *kingpin.FlagClause
+}
+
+// RegisterPathOrContent registers PathOrContent flag in kingpinCmdClause.
+func RegisterPathOrContent(cmd FlagClause, flagName string, help string, opts ...Option) *PathOrContent {
+	fileFlagName := fmt.Sprintf("%s-file", flagName)
+	contentFlagName := flagName
+
+	fileHelp := fmt.Sprintf("Path to %s", help)
+	fileFlag := cmd.Flag(fileFlagName, fileHelp).PlaceHolder("<file-path>").String()
+
+	contentHelp := fmt.Sprintf("Alternative to '%s' flag (mutually exclusive). Content of %s", fileFlagName, help)
+	contentFlag := cmd.Flag(contentFlagName, contentHelp).PlaceHolder("<content>").String()
+
+	p := &PathOrContent{
+		flagName:        flagName,
+		path:            fileFlag,
+		content:         contentFlag,
+		required:        false,
+		envSubstitution: false,
+	}
+	for _, opt := range opts {
+		opt(p)
+	}
+	return p
+}
+
+// Content returns the content of the file when given or directly the content that has been passed to the flag.
+// It returns an error when:
+// * The file and content flags are both not empty.
+// * The file flag is not empty but the file can't be read.
+// * The content is empty and the flag has been defined as required.
+func (p *PathOrContent) Content() ([]byte, error) {
+	fileFlagName := fmt.Sprintf("%s-file", p.flagName)
+
+	if len(*p.path) > 0 && len(*p.content) > 0 {
+		return nil, errors.Errorf("both %s and %s flags set.", fileFlagName, p.flagName)
+	}
+
+	var content []byte
+	if len(*p.path) > 0 {
+		c, err := ioutil.ReadFile(*p.path)
+		if err != nil {
+			return nil, errors.Wrapf(err, "loading file %s for %s", *p.path, fileFlagName)
+		}
+		content = c
+	} else {
+		content = []byte(*p.content)
+	}
+
+	if len(content) == 0 && p.required {
+		return nil, errors.Errorf("flag %s or %s is required for running this command and content cannot be empty.", fileFlagName, p.flagName)
+	}
+	if p.envSubstitution {
+		replace, err := expandEnv(content)
+		if err != nil {
+			return nil, err
+		}
+		content = replace
+	}
+	return content, nil
+}
+
+// WithRequired allows you to override default required option.
+func WithRequired() Option {
+	return func(p *PathOrContent) {
+		p.required = true
+	}
+}
+
+// WithEnvSubstitution allows you to override default envSubstitution option.
+func WithEnvSubstitution() Option {
+	return func(p *PathOrContent) {
+		p.envSubstitution = true
+	}
+}
+
+// expandEnv returns content of YAML file with substituted environment variables.
+// Follows K8s convention, i.e $(...), as mentioned here https://kubernetes.io/docs/tasks/inject-data-application/define-interdependent-environment-variables/.
+func expandEnv(b []byte) (r []byte, err error) {
+	var envRe = regexp.MustCompile(`\$\(([a-zA-Z_0-9]+)\)`)
+	r = envRe.ReplaceAllFunc(b, func(n []byte) []byte {
+		if err != nil {
+			return nil
+		}
+		n = n[2 : len(n)-1]
+
+		v, ok := os.LookupEnv(string(n))
+		if !ok {
+			err = errors.Errorf("found reference to unset environment variable %q", n)
+			return nil
+		}
+		return []byte(v)
+	})
+	return r, err
+}