From e020a95865a1eea25ba2a940cba09e3c9acc28f3 Mon Sep 17 00:00:00 2001
From: cbrockington <cbrockington@palantir.com>
Date: Wed, 17 Oct 2018 13:28:18 +0100
Subject: [PATCH] Print the status to stdout or stderr. (#63)

In adherence with http://refspecs.linuxbase.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/iniscrptact.html
referenced in the README, status should "print the current status of the service".
Previously go-init will log status to a file however this is not the conventional
meaning of "print".
---
 README.md          |  3 ++
 init/cli/status.go | 98 ++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 85 insertions(+), 16 deletions(-)

diff --git a/README.md b/README.md
index 229866de..f0c87371 100644
--- a/README.md
+++ b/README.md
@@ -149,5 +149,8 @@ command used to launch a specific subProcesses, and its subsequent stdout and st
 `var/log/${SUB_PROCESS}-startup.log` files. `go-init` does not launch each `subProcess` as a child process of the
 primary process.
 
+Note that while the specification states that the `status` command prints the status of the service, the exact wording
+used to denote that status is not defined and subsequently subject to change without warning.
+
 # License
 This repository is made available under the [Apache 2.0 License](http://www.apache.org/licenses/LICENSE-2.0).
diff --git a/init/cli/status.go b/init/cli/status.go
index 18e795cd..844b32e7 100644
--- a/init/cli/status.go
+++ b/init/cli/status.go
@@ -15,6 +15,9 @@
 package cli
 
 import (
+	"fmt"
+	"os"
+
 	"github.com/palantir/pkg/cli"
 	"github.com/pkg/errors"
 
@@ -35,27 +38,90 @@ If exit code is nonzero, writes an error message to stderr and var/log/startup.l
 	Action: executeWithLoggers(status, NewAlwaysAppending()),
 }
 
+var (
+	Running = ServiceState{
+		Description: "Running",
+		Applicable: func(serviceStatus *serviceStatus, err error) bool {
+			return err == nil && len(serviceStatus.notRunningCmds) == 0
+		},
+		ExitStatus: func(serviceStatus *serviceStatus, err error) (int, error) {
+			return 0, nil
+		},
+	}
+	Dead = ServiceState{
+		Description: "Process dead but pidfile exists.",
+		Applicable: func(serviceStatus *serviceStatus, err error) bool {
+			return err == nil && len(serviceStatus.notRunningCmds) > 0 && len(serviceStatus.writtenPids) > 0
+		},
+		ExitStatus: func(serviceStatus *serviceStatus, err error) (int, error) {
+			return 1, errors.Errorf("commands '%v' are not running but there is a record of commands '%v' "+
+				"having been started", commandNames(serviceStatus.notRunningCmds), serviceStatus.writtenPids)
+		},
+	}
+	NotRunning = ServiceState{
+		Description: "Service not running",
+		Applicable: func(serviceStatus *serviceStatus, err error) bool {
+			return err == nil && len(serviceStatus.notRunningCmds) > 0 && len(serviceStatus.writtenPids) == 0
+		},
+		ExitStatus: func(serviceStatus *serviceStatus, err error) (int, error) {
+			return 3, errors.Errorf("commands '%v' are not running", commandNames(serviceStatus.notRunningCmds))
+		},
+	}
+	ErrorState = ServiceState{
+		Description: "Failed to determine service status",
+		Applicable: func(serviceStatus *serviceStatus, err error) bool {
+			return err != nil
+		},
+		ExitStatus: func(serviceStatus *serviceStatus, err error) (int, error) {
+			if err != nil {
+				return 4, errors.Wrap(err, "failed to determine service status")
+			}
+			return 4, errors.Errorf("failed to determine service status")
+		},
+	}
+)
+
 func status(ctx cli.Context, loggers launchlib.ServiceLoggers) error {
 	// Executed with logging for errors, however we discard the verbose logging of getServiceStatus
 	serviceStatus, err := getServiceStatus(ctx, &DevNullLoggers{})
-	if err != nil {
-		return logErrorAndReturnWithExitCode(ctx, errors.Wrap(err, "failed to determine service status"), 4)
-	}
-	if len(serviceStatus.notRunningCmds) > 0 {
-		notRunningCmdNames := make([]string, 0, len(serviceStatus.notRunningCmds))
-		for name := range serviceStatus.notRunningCmds {
-			notRunningCmdNames = append(notRunningCmdNames, name)
+	var matched *ServiceState
+	for _, state := range []ServiceState{ErrorState, NotRunning, Dead, Running} {
+		if state.Applicable(serviceStatus, err) {
+			matched = &state
+			break
 		}
-		if len(serviceStatus.writtenPids) > 0 {
-			return logErrorAndReturnWithExitCode(
-				ctx,
-				errors.Errorf("commands '%v' are not running but there is a record of commands '%v'"+
-					"having been started", notRunningCmdNames, serviceStatus.writtenPids),
-				1,
-			)
+	}
+
+	// If no state has matched, default to error state
+	if matched == nil {
+		matched = &ErrorState
+	}
+
+	code, err := matched.ExitStatus(serviceStatus, err)
+	if code != 0 {
+		fmt.Fprintln(os.Stderr, matched.Description)
+		if err != nil {
+			return logErrorAndReturnWithExitCode(ctx, err, code)
 		}
-		return logErrorAndReturnWithExitCode(ctx, errors.Errorf("commands '%v' are not running",
-			notRunningCmdNames), 3)
+		// Non-zero exit codes can only be reported through cli.WithExitCode which must include an errors, though that
+		// error can be empty.  Returning no error gives an exit code of 0
+		return cli.WithExitCode(code, errors.New(""))
 	}
+
+	fmt.Println(matched.Description)
 	return nil
 }
+
+type ServiceState struct {
+	Description string
+	Applicable  func(serviceStatus *serviceStatus, err error) bool
+	ExitStatus  func(serviceStatus *serviceStatus, err error) (int, error)
+}
+
+func commandNames(commands map[string]CommandContext) []string {
+	names := make([]string, 0, len(commands))
+	for name := range commands {
+		names = append(names, name)
+	}
+	return names
+}