Add flag utils (#10)

* add flag validation error util
* remove unused variable
* fix formatting
* cleanup signal unit
* CI: add newer Go versions to test against
* CI: bump versions of Github actions

.github/workflows/ci.yaml

@@ -13,12 +13,15 @@ jobs:
         go-version:
           - 1.16.x
           - 1.17.x
+          - 1.18.x
+          - 1.19.x
+          - 1.20.x
         os:
           - ubuntu-latest
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-go@v2
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v4
         with:
           go-version: ${{ matrix.go-version }}
       - run: go test ./...

group.go

@@ -204,8 +204,7 @@ type Group struct {
 	s []Service
 	x []ServiceContext
 
-	configured   bool
-	hsRegistered bool
+	configured bool
 }
 
 // Register will inspect the provided objects implementing the Unit interface to

pkg/flag/flag.go

@@ -0,0 +1,32 @@
+package flag
+
+import "fmt"
+
+// ValidationError provides the ability to create constant errors for run.Group
+// validation errors, e.g. incorrect flag values.
+type ValidationError string
+
+// Error implements the built-in error interface.
+func (v ValidationError) Error() string { return string(v) }
+
+// NewValidationError provides a convenient helper function to create flag
+// validation errors usable by run.Config implementations.
+func NewValidationError(flag string, reason error) error {
+	return fmt.Errorf(FlagErr, flag, reason)
+}
+
+const (
+	// FlagErr can be used as formatting string for flag related validation
+	// errors where the first variable lists the flag name and the second
+	// variable is the actual error.
+	FlagErr = "--%s error: %w"
+
+	// ErrRequired is returned when required config options are not provided.
+	ErrRequired ValidationError = "required"
+
+	// ErrInvalidPath is returned when a path config option is invalid.
+	ErrInvalidPath ValidationError = "invalid path"
+
+	// ErrInvalidVal is returned when the value passed into a flag argument is invalid.
+	ErrInvalidVal ValidationError = "invalid value"
+)

pkg/signal/handler.go

@@ -25,12 +25,6 @@ import (
 	"github.com/tetratelabs/run"
 )
 
-// Error allows for creating constant errors instead of sentinel ones.
-type Error string
-
-// Error implements error.
-func (e Error) Error() string { return string(e) }
-
 // Handler implements a unix signal handler as run.GroupService.
 type Handler struct {
 	// RefreshCallback is called when a syscall.SIGHUP is received.
@@ -40,11 +34,10 @@ type Handler struct {
 	RefreshCallback func() error
 
 	signal chan os.Signal
-	cancel chan struct{}
 }
 
 // Name implements run.Unit.
-func (h Handler) Name() string {
+func (h *Handler) Name() string {
 	return "signal"
 }
 
@@ -86,13 +79,3 @@ func (h *Handler) ServeContext(ctx context.Context) error {
 		}
 	}
 }
-
-// sendHUP is for test purposes
-func (h *Handler) sendHUP() {
-	h.signal <- syscall.SIGHUP
-}
-
-// sendQUIT is for test purposes
-func (h *Handler) sendQUIT() {
-	h.signal <- syscall.SIGQUIT
-}

pkg/signal/handler_test.go

@@ -16,6 +16,7 @@ package signal
 
 import (
 	"errors"
+	"syscall"
 	"testing"
 	"time"
 
@@ -108,3 +109,13 @@ func TestSignalHandlerSignals(t *testing.T) {
 
 	}
 }
+
+// sendHUP is for test purposes
+func (h *Handler) sendHUP() {
+	h.signal <- syscall.SIGHUP
+}
+
+// sendQUIT is for test purposes
+func (h *Handler) sendQUIT() {
+	h.signal <- syscall.SIGQUIT
+}

pkg/version/version.go

@@ -25,7 +25,9 @@ import (
 
 // gitDescribeHashIndexPattern matches the git describe hash index pattern in the version string.
 // The version string should be in the format:
-// 		<release tag>-<commits since release tag>-g<commit hash>-<branch name>
+//
+//	<release tag>-<commits since release tag>-g<commit hash>-<branch name>
+//
 // As an example: 0.6.6-rc1-15-g12345678-want-more-branch, the "g" prefix stands for "git"
 // (see: https://git-scm.com/docs/git-describe).
 var gitDescribeHashIndexPattern = regexp.MustCompile(`-[0-9]+(-g+)+`)
@@ -37,11 +39,12 @@ var gitCommitsAheadPattern = regexp.MustCompile(`[0-9]+`)
 // build is to be populated at build time using -ldflags -X.
 //
 // Example:
-//   VERSION_PATH    := github.com/tetratelabs/run/pkg/version
-//   VERSION_STRING  := $(shell git describe --tags --long)
-//   GIT_BRANCH_NAME := $(shell git rev-parse --abbrev-ref HEAD)
-//   GO_LINK_VERSION := -X ${VERSION_PATH}.build=${VERSION_STRING}-${GIT_BRANCH_NAME}
-//   go build -ldflags '${GO_LINK_VERSION}'
+//
+//	VERSION_PATH    := github.com/tetratelabs/run/pkg/version
+//	VERSION_STRING  := $(shell git describe --tags --long)
+//	GIT_BRANCH_NAME := $(shell git rev-parse --abbrev-ref HEAD)
+//	GO_LINK_VERSION := -X ${VERSION_PATH}.build=${VERSION_STRING}-${GIT_BRANCH_NAME}
+//	go build -ldflags '${GO_LINK_VERSION}'
 var build string
 
 // mainBranches is a list of (sorted) main branches/revisions.
@@ -85,7 +88,8 @@ func (g Git) String() string {
 
 // parseGit the given version string into a version object. The input version string
 // is in the format:
-//    <release tag>-<commits since release tag>-g<commit hash>-<branch name>
+//
+//	<release tag>-<commits since release tag>-g<commit hash>-<branch name>
 func parseGit(v string) Git {
 	// Here we try to find the "-<commits since release tag>-g"-part.
 	found := gitDescribeHashIndexPattern.FindStringIndex(v)