actions (#2)

Allow actions that execute shell commands to be configured in a TOML
config file, and triggered via API request.

Author: metachris

README.md

@@ -7,12 +7,12 @@ It currently does the following things:
 - **Event log**: Services inside a TDX instance can record events they want exposed to the operator
  used to record and query events. Useful to record service startup/shutdown, errors, progress updates,
  hashes, etc.
+- **Actions**: Ability to execute shell commands via API
 
 Future features:
 
 - Operator can set a password for http-basic-auth (persisted, for all future requests)
 - Operator-provided configuration (i.e. config values, secrets, etc.)
-- Restart of services / execution of scripts
 
 ---
 
@@ -29,7 +29,20 @@ $ echo "hello world" > pipe.fifo
 $ curl localhost:3535/api/v1/new_event?message=this+is+a+test
 
 # Query events (plain text or JSON is supported)
-$ curl -s localhost:3535/api/v1/events?format=text
+$ curl localhost:3535/api/v1/events?format=text
 2024-10-23T12:04:01Z     hello world
 2024-10-23T12:04:07Z     this is a test
 ```
+
+ ## Actions
+
+ Actions are shell commands that can be executed via API. The commands are defined in the config file,
+ see [systemapi-config.toml](./systemapi-config.toml) for examples.
+
+```bash
+# Start the server
+$ go run cmd/system-api/main.go --config systemapi-config.toml
+
+# Execute the example action
+$ curl -v localhost:3535/api/v1/actions/echo_test
+```

cmd/system-api/main.go

@@ -34,6 +34,11 @@ var flags []cli.Flag = []cli.Flag{
 		Value: true,
 		Usage: "log debug messages",
 	},
+	&cli.StringFlag{
+		Name:  "config",
+		Value: "",
+		Usage: "config file",
+	},
 }
 
 func main() {
@@ -50,7 +55,7 @@ func main() {
 	}
 }
 
-func runCli(cCtx *cli.Context) error {
+func runCli(cCtx *cli.Context) (err error) {
 	listenAddr := cCtx.String("listen-addr")
 	pipeFile := cCtx.String("pipe-file")
 	logJSON := cCtx.Bool("log-json")
@@ -59,6 +64,7 @@ func runCli(cCtx *cli.Context) error {
 	logTags := map[string]string{
 		"version": common.Version,
 	}
+	configFile := cCtx.String("config")
 
 	log := common.SetupLogger(&common.LoggingOpts{
 		JSON:           logJSON,
@@ -68,12 +74,24 @@ func runCli(cCtx *cli.Context) error {
 		Tags:           logTags,
 	})
 
+	var config *systemapi.SystemAPIConfig
+	if configFile != "" {
+		config, err = systemapi.LoadConfigFromFile(configFile)
+		if err != nil {
+			log.Error("Error loading config", "err", err)
+			return err
+		}
+		log.Info("Loaded config", "config-file", config)
+	}
+
 	// Setup and start the server (in the background)
-	server, err := systemapi.NewServer(&systemapi.HTTPServerConfig{
+	cfg := &systemapi.HTTPServerConfig{
 		ListenAddr:   listenAddr,
 		Log:          log,
 		PipeFilename: pipeFile,
-	})
+		Config:       config,
+	}
+	server, err := systemapi.NewServer(cfg)
 	if err != nil {
 		return err
 	}

common/utils.go

@@ -5,6 +5,8 @@ import (
 	"strconv"
 )
 
+// GetEnvInt returns the value of the environment variable named by key, or defaultValue if the environment variable
+// doesn't exist or is not a valid integer
 func GetEnvInt(key string, defaultValue int) int {
 	if value, ok := os.LookupEnv(key); ok {
 		val, err := strconv.Atoi(value)
@@ -14,3 +16,11 @@ func GetEnvInt(key string, defaultValue int) int {
 	}
 	return defaultValue
 }
+
+// GetEnv returns the value of the environment variable named by key, or defaultValue if the environment variable doesn't exist
+func GetEnv(key, defaultValue string) string {
+	if value, ok := os.LookupEnv(key); ok {
+		return value
+	}
+	return defaultValue
+}

go.mod

@@ -8,16 +8,21 @@ require (
 	github.com/ethereum/go-ethereum v1.14.9
 	github.com/go-chi/chi/v5 v5.1.0
 	github.com/go-chi/httplog/v2 v2.1.1
+	github.com/pelletier/go-toml/v2 v2.2.3
+	github.com/stretchr/testify v1.9.0
 	github.com/urfave/cli/v2 v2.27.2
 )
 
 require (
 	github.com/btcsuite/btcd/btcec/v2 v2.3.4 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.4 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.2.0 // indirect
 	github.com/holiman/uint256 v1.3.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/xrash/smetrics v0.0.0-20240312152122-5f08fbb34913 // indirect
 	golang.org/x/crypto v0.22.0 // indirect
 	golang.org/x/sys v0.25.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -18,8 +18,14 @@ github.com/go-chi/httplog/v2 v2.1.1 h1:ojojiu4PIaoeJ/qAO4GWUxJqvYUTobeo7zmuHQJAx
 github.com/go-chi/httplog/v2 v2.1.1/go.mod h1:/XXdxicJsp4BA5fapgIC3VuTD+z0Z/VzukoB3VDc1YE=
 github.com/holiman/uint256 v1.3.1 h1:JfTzmih28bittyHM8z360dCjIA9dbPIBlcTI6lmctQs=
 github.com/holiman/uint256 v1.3.1/go.mod h1:EOMSn4q6Nyt9P6efbI3bueV4e1b3dGlUCXeiRV4ng7E=
+github.com/pelletier/go-toml/v2 v2.2.3 h1:YmeHyLY8mFWbdkNWwpr+qIL2bEqT0o95WSdkNHvL12M=
+github.com/pelletier/go-toml/v2 v2.2.3/go.mod h1:MfCQTFTvCcUyyvvwm1+G6H/jORL20Xlb6rzQu9GuUkc=
+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/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf35Ld67mk=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/urfave/cli/v2 v2.27.2 h1:6e0H+AkS+zDckwPCUrZkKX38mRaau4nL2uipkJpbkcI=
 github.com/urfave/cli/v2 v2.27.2/go.mod h1:g0+79LmHHATl7DAcHO99smiR/T7uGLw84w8Y42x+4eM=
 github.com/xrash/smetrics v0.0.0-20240312152122-5f08fbb34913 h1:+qGGcbkzsfDQNPPe9UDgpxAWQrhbbBXOYJFQDq/dtJw=
@@ -28,3 +34,7 @@ golang.org/x/crypto v0.22.0 h1:g1v0xeRhjcugydODzvb3mEM9SQ0HGp9s/nh3COQ/C30=
 golang.org/x/crypto v0.22.0/go.mod h1:vr6Su+7cTlO45qkww3VDJlzDn0ctJvRgYbC2NvXHt+M=
 golang.org/x/sys v0.25.0 h1:r+8e+loiHxRqhXVl6ML1nO3l1+oFoWbnlu2Ehimmi34=
 golang.org/x/sys v0.25.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+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.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

systemapi-config.toml

@@ -0,0 +1,5 @@
+[actions]
+# reboot = "reboot"
+# rbuilder_restart = "/etc/init.d/rbuilder restart"
+# rbuilder_stop = "/etc/init.d/rbuilder stop"
+echo_test = "echo test"

systemapi/config.go

@@ -0,0 +1,28 @@
+package systemapi
+
+import (
+	"os"
+
+	toml "github.com/pelletier/go-toml/v2"
+)
+
+type SystemAPIConfig struct {
+	Actions map[string]string
+}
+
+func LoadConfigFromFile(path string) (*SystemAPIConfig, error) {
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	return LoadConfig(content)
+}
+
+func LoadConfig(content []byte) (*SystemAPIConfig, error) {
+	cfg := &SystemAPIConfig{}
+	err := toml.Unmarshal(content, cfg)
+	if err != nil {
+		return nil, err
+	}
+	return cfg, nil
+}

systemapi/config_test.go

@@ -0,0 +1,16 @@
+package systemapi
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestLoadConfig(t *testing.T) {
+	path := "../systemapi-config.toml"
+	cfg, err := LoadConfigFromFile(path)
+	require.NoError(t, err)
+	require.NotNil(t, cfg)
+	require.NotEmpty(t, cfg.Actions)
+	require.Equal(t, "echo test", cfg.Actions["echo_test"])
+}

systemapi/server.go

@@ -3,24 +3,23 @@ package systemapi
 
 import (
 	"bufio"
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
 	"net/http"
 	"os"
+	"os/exec"
 	"strings"
 	"sync"
 	"syscall"
 	"time"
 
-	"github.com/flashbots/system-api/common"
 	chi "github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
 	"github.com/go-chi/httplog/v2"
 )
 
-var MaxEvents = common.GetEnvInt("MAX_EVENTS", 1000)
-
 type HTTPServerConfig struct {
 	ListenAddr   string
 	Log          *httplog.Logger
@@ -31,6 +30,8 @@ type HTTPServerConfig struct {
 	GracefulShutdownDuration time.Duration
 	ReadTimeout              time.Duration
 	WriteTimeout             time.Duration
+
+	Config *SystemAPIConfig
 }
 
 type Event struct {
@@ -86,6 +87,7 @@ func (s *Server) getRouter() http.Handler {
 	mux.Get("/livez", s.handleLivenessCheck)
 	mux.Get("/api/v1/new_event", s.handleNewEvent)
 	mux.Get("/api/v1/events", s.handleGetEvents)
+	mux.Get("/api/v1/actions/{action}", s.handleAction)
 
 	if s.cfg.EnablePprof {
 		s.log.Info("pprof API enabled")
@@ -191,3 +193,40 @@ func (s *Server) handleGetEvents(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 }
+
+func (s *Server) handleAction(w http.ResponseWriter, r *http.Request) {
+	action := chi.URLParam(r, "action")
+	s.log.Info("Received action", "action", action)
+
+	if s.cfg.Config == nil {
+		w.WriteHeader(http.StatusNotImplemented)
+		return
+	}
+
+	cmd, ok := s.cfg.Config.Actions[action]
+	if !ok {
+		w.WriteHeader(http.StatusNotImplemented)
+		return
+	}
+
+	s.log.Info("Executing action", "action", action, "cmd", cmd)
+	stdout, stderr, err := Shellout(cmd)
+	if err != nil {
+		s.log.Error("Failed to execute action", "action", action, "cmd", cmd, "err", err, "stderr", stderr)
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+
+	s.log.Info("Action executed", "action", action, "cmd", cmd, "stdout", stdout, "stderr", stderr)
+	w.WriteHeader(http.StatusOK)
+}
+
+func Shellout(command string) (string, string, error) {
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	cmd := exec.Command(ShellToUse, "-c", command)
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	err := cmd.Run()
+	return stdout.String(), stderr.String(), err
+}

systemapi/vars.go

@@ -0,0 +1,8 @@
+package systemapi
+
+import "github.com/flashbots/system-api/common"
+
+var (
+	MaxEvents  = common.GetEnvInt("MAX_EVENTS", 1000)
+	ShellToUse = common.GetEnv("SHELL_TO_USE", "/bin/ash")
+)