From a25b8eefded6231b247d3eebe98c84363996674f Mon Sep 17 00:00:00 2001
From: Dmitry Filimonov <dmitry@pyroscope.io>
Date: Mon, 18 Jan 2021 14:04:43 -0800
Subject: [PATCH] improves homebrew support

---
 pkg/cli/cli.go       | 34 ++++++++++++++++++++++++++++++++++
 pkg/config/config.go |  8 ++++----
 2 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/pkg/cli/cli.go b/pkg/cli/cli.go
index e0bb91b78e..95a5eceb40 100644
--- a/pkg/cli/cli.go
+++ b/pkg/cli/cli.go
@@ -5,7 +5,9 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"path/filepath"
 	"reflect"
+	"runtime"
 	"strconv"
 	"strings"
 	"time"
@@ -47,6 +49,8 @@ func populateFlagSet(obj interface{}, flagSet *flag.FlagSet) {
 	t := reflect.TypeOf(v.Interface())
 	num := t.NumField()
 
+	installPrefix := getInstallPrefix()
+
 	for i := 0; i < num; i++ {
 		field := t.Field(i)
 		fieldV := v.Field(i)
@@ -68,6 +72,7 @@ func populateFlagSet(obj interface{}, flagSet *flag.FlagSet) {
 			flagSet.Var(val2, nameVal, descVal)
 		case reflect.TypeOf(""):
 			val := fieldV.Addr().Interface().(*string)
+			defaultValStr := strings.ReplaceAll(defaultValStr, "<installPrefix>", installPrefix)
 			flagSet.StringVar(val, nameVal, defaultValStr, descVal)
 		case reflect.TypeOf(true):
 			val := fieldV.Addr().Interface().(*bool)
@@ -104,6 +109,35 @@ func populateFlagSet(obj interface{}, flagSet *flag.FlagSet) {
 	}
 }
 
+// on mac pyroscope is usually installed via homebrew. homebrew installs under a prefix
+//   this is logic to figure out what prefix it is
+func getInstallPrefix() string {
+	if runtime.GOOS != "darwin" {
+		return ""
+	}
+
+	executablePath, err := os.Executable()
+	if err != nil {
+		// TODO: figure out what kind of errors might happen, handle it
+		return ""
+	}
+	cellarPath := filepath.Clean(filepath.Join(resolvePath(executablePath), "../../../.."))
+
+	if !strings.HasSuffix(cellarPath, "Cellar") {
+		// looks like it's not installed via homebrew
+		return ""
+	}
+
+	return filepath.Clean(filepath.Join(cellarPath, "../"))
+}
+
+func resolvePath(path string) string {
+	if res, err := filepath.EvalSymlinks(path); err == nil {
+		return res
+	}
+	return path
+}
+
 func printUsage(c *ffcli.Command) string {
 	return gradientBanner() + "\n" + DefaultUsageFunc(c)
 }
diff --git a/pkg/config/config.go b/pkg/config/config.go
index b24c4fcf4b..cd803fe0f8 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -14,7 +14,7 @@ type Config struct {
 }
 
 type Agent struct {
-	Config   string `def:"/etc/pyroscope/agent.yml" desc:"location of config file"`
+	Config   string `def:"<installPrefix>/etc/pyroscope/agent.yml" desc:"location of config file"`
 	LogLevel string `def:"info", desc:"debug|info|warn|error"`
 
 	// AgentCMD           []string
@@ -23,16 +23,16 @@ type Agent struct {
 	ServerAddress          string        `def:"http://localhost:4040" desc:"address of the pyroscope server"`
 	UpstreamThreads        int           `def:"4"`
 	UpstreamRequestTimeout time.Duration `def:"10s"`
-	UNIXSocketPath         string        `def:"/var/run/pyroscope-agent.sock" desc:"path to a UNIX socket file"`
+	UNIXSocketPath         string        `def:"<installPrefix>/var/run/pyroscope-agent.sock" desc:"path to a UNIX socket file"`
 }
 
 type Server struct {
-	Config   string `def:"/etc/pyroscope/server.yml" desc:"location of config file"`
+	Config   string `def:"<installPrefix>/etc/pyroscope/server.yml" desc:"location of config file"`
 	LogLevel string `def:"info", desc:"debug|info|warn|error"`
 	// TODO: fix, doesn't see to work
 	BadgerLogLevel string `def:"error", desc:"debug|info|warn|error"`
 
-	StoragePath string `def:"/var/lib/pyroscope"`
+	StoragePath string `def:"<installPrefix>/var/lib/pyroscope"`
 	ApiBindAddr string `def:":4040"`
 
 	CacheDimensionSize  int `def:"1000"`