config: prefix environment variables with BESZEL_AGENT_ (#502)

beszel/cmd/agent/agent.go

@@ -22,11 +22,12 @@ func main() {
 	}
 
 	// Try to get the key from the KEY environment variable.
-	pubKey := []byte(os.Getenv("KEY"))
+	key, _ := agent.GetEnv("KEY")
+	pubKey := []byte(key)
 
 	// If KEY is not set, try to read the key from the file specified by KEY_FILE.
 	if len(pubKey) == 0 {
-		keyFile, exists := os.LookupEnv("KEY_FILE")
+		keyFile, exists := agent.GetEnv("KEY_FILE")
 		if !exists {
 			log.Fatal("Must set KEY or KEY_FILE environment variable")
 		}
@@ -38,7 +39,8 @@ func main() {
 	}
 
 	addr := ":45876"
-	if portEnvVar, exists := os.LookupEnv("PORT"); exists {
+	// TODO: change env var to ADDR
+	if portEnvVar, exists := agent.GetEnv("PORT"); exists {
 		// allow passing an address in the form of "127.0.0.1:45876"
 		if !strings.Contains(portEnvVar, ":") {
 			portEnvVar = ":" + portEnvVar

beszel/internal/agent/agent.go

@@ -28,16 +28,26 @@ type Agent struct {
 }
 
 func NewAgent() *Agent {
-	return &Agent{
+	newAgent := &Agent{
 		sensorsContext: context.Background(),
-		memCalc:        os.Getenv("MEM_CALC"),
 		fsStats:        make(map[string]*system.FsStats),
 	}
+	newAgent.memCalc, _ = GetEnv("MEM_CALC")
+	return newAgent
+}
+
+// GetEnv retrieves an environment variable with a "BESZEL_AGENT_" prefix, or falls back to the unprefixed key.
+func GetEnv(key string) (value string, exists bool) {
+	if value, exists = os.LookupEnv("BESZEL_AGENT_" + key); exists {
+		return value, exists
+	}
+	// Fallback to the old unprefixed key
+	return os.LookupEnv(key)
 }
 
 func (a *Agent) Run(pubKey []byte, addr string) {
 	// Set up slog with a log level determined by the LOG_LEVEL env var
-	if logLevelStr, exists := os.LookupEnv("LOG_LEVEL"); exists {
+	if logLevelStr, exists := GetEnv("LOG_LEVEL"); exists {
 		switch strings.ToLower(logLevelStr) {
 		case "debug":
 			a.debug = true
@@ -52,7 +62,7 @@ func (a *Agent) Run(pubKey []byte, addr string) {
 	slog.Debug(beszel.Version)
 
 	// Set sensors context (allows overriding sys location for sensors)
-	if sysSensors, exists := os.LookupEnv("SYS_SENSORS"); exists {
+	if sysSensors, exists := GetEnv("SYS_SENSORS"); exists {
 		slog.Info("SYS_SENSORS", "path", sysSensors)
 		a.sensorsContext = context.WithValue(a.sensorsContext,
 			common.EnvKey, common.EnvMap{common.HostSysEnvKey: sysSensors},
@@ -60,7 +70,7 @@ func (a *Agent) Run(pubKey []byte, addr string) {
 	}
 
 	// Set sensors whitelist
-	if sensors, exists := os.LookupEnv("SENSORS"); exists {
+	if sensors, exists := GetEnv("SENSORS"); exists {
 		a.sensorsWhitelist = make(map[string]struct{})
 		for _, sensor := range strings.Split(sensors, ",") {
 			if sensor != "" {

beszel/internal/agent/disk.go

@@ -3,18 +3,17 @@ package agent
 import (
 	"beszel/internal/entities/system"
 	"log/slog"
-	"time"
-
 	"os"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"github.com/shirou/gopsutil/v4/disk"
 )
 
 // Sets up the filesystems to monitor for disk usage and I/O.
 func (a *Agent) initializeDiskInfo() {
-	filesystem := os.Getenv("FILESYSTEM")
+	filesystem, _ := GetEnv("FILESYSTEM")
 	efPath := "/extra-filesystems"
 	hasRoot := false
 
@@ -79,7 +78,7 @@ func (a *Agent) initializeDiskInfo() {
 	}
 
 	// Add EXTRA_FILESYSTEMS env var values to fsStats
-	if extraFilesystems, exists := os.LookupEnv("EXTRA_FILESYSTEMS"); exists {
+	if extraFilesystems, exists := GetEnv("EXTRA_FILESYSTEMS"); exists {
 		for _, fs := range strings.Split(extraFilesystems, ",") {
 			found := false
 			for _, p := range partitions {

beszel/internal/agent/docker.go

@@ -208,7 +208,7 @@ func (dm *dockerManager) deleteContainerStatsSync(id string) {
 
 // Creates a new http client for Docker or Podman API
 func newDockerManager(a *Agent) *dockerManager {
-	dockerHost, exists := os.LookupEnv("DOCKER_HOST")
+	dockerHost, exists := GetEnv("DOCKER_HOST")
 	if exists {
 		slog.Info("DOCKER_HOST", "host", dockerHost)
 	} else {
@@ -242,7 +242,7 @@ func newDockerManager(a *Agent) *dockerManager {
 
 	// configurable timeout
 	timeout := time.Millisecond * 2100
-	if t, set := os.LookupEnv("DOCKER_TIMEOUT"); set {
+	if t, set := GetEnv("DOCKER_TIMEOUT"); set {
 		timeout, err = time.ParseDuration(t)
 		if err != nil {
 			slog.Error(err.Error())

beszel/internal/agent/network.go

@@ -2,7 +2,6 @@ package agent
 
 import (
 	"log/slog"
-	"os"
 	"strings"
 	"time"
 
@@ -15,7 +14,7 @@ func (a *Agent) initializeNetIoStats() {
 
 	// map of network interface names passed in via NICS env var
 	var nicsMap map[string]struct{}
-	nics, nicsEnvExists := os.LookupEnv("NICS")
+	nics, nicsEnvExists := GetEnv("NICS")
 	if nicsEnvExists {
 		nicsMap = make(map[string]struct{}, 0)
 		for _, nic := range strings.Split(nics, ",") {