implement sandbox runner

internal/execution/sandbox.go

@@ -0,0 +1,107 @@
+package execution
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+type Result struct {
+	Stdout string `json:"stdout"`
+	Stderr string `json:"stderr"`
+	Code   int    `json:"code"`
+}
+
+func Run(ctx context.Context, language string, sourceCode string, stdin string) (*Result, error) {
+	// create a temp dir
+	tempDir, err := os.MkdirTemp("", "codehere")
+	if err != nil {
+		return nil, err
+	}
+	// makes sure temp directory and contents are deleted when run is done
+	defer os.RemoveAll(tempDir)
+
+	filePath := filepath.Join(tempDir, "main.py")
+
+	// write source code to file named main.py
+	err = os.WriteFile(filePath, []byte(sourceCode), 0644)
+	if err != nil {
+		return nil, err
+	}
+
+	// get executiontimeout variable to time
+	timeoutStr := os.Getenv("EXECUTION_TIMEOUT")
+	if timeoutStr == "" {
+		timeoutStr = "10s"
+	}
+	timeout, err := time.ParseDuration(timeoutStr)
+	if err != nil {
+		return nil, err
+	}
+
+	// enforce hard timeout
+	ctx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	// get memory limit from env variable
+	memoryLimit := os.Getenv("SANDBOX_MEMORY_LIMIT")
+	if memoryLimit == "" {
+		memoryLimit = "256m"
+	}
+
+	args := []string{
+		"run", "--rm", "-i",
+		"--network=none",
+		"--read-only",
+		"--memory=" + memoryLimit,
+		"--memory-swap=" + memoryLimit,
+		"--cpus=0.5",
+		"--pids-limit=64",
+		"--tmpfs", "/tmp:rw,noexec,nosuid,size=64m",
+		"-v", fmt.Sprintf("%s:/code:ro", tempDir),
+		"python:3.12-slim",
+		"sh", "-c", "python /code/main.py",
+	}
+
+	// run da command and pipe stdin to container i think
+	cmd := exec.CommandContext(ctx, "docker", args...)
+	cmd.Stdin = strings.NewReader(stdin)
+
+	//capture studout/stderr from the container
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	err = cmd.Run()
+
+	// do you know you have 10 seconds....
+	// 10? 10, 10, yes....
+	if ctx.Err() == context.DeadlineExceeded {
+		return &Result{
+			Stdout: stdout.String(),
+			Stderr: "execution timed out (" + timeoutStr + "s limit)",
+			Code:   -1,
+		}, nil
+	}
+
+	exitCode := 0
+	if err != nil {
+		if exitErr, ok := err.(*exec.ExitError); ok {
+			exitCode = exitErr.ExitCode()
+		} else {
+			return nil, err
+		}
+	}
+	// WHEN THE GO FILE FINALLY TURNS GREEN 🥹🥹🥹
+	return &Result{
+		Stdout: stdout.String(),
+		Stderr: stderr.String(),
+		Code:   exitCode,
+	}, nil
+}