[Agent] Replace dockerapi container with Redis-based control bus

data/Dockerfiles/agent/internal/commands/shell.go

@@ -0,0 +1,60 @@
+package commands
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os/exec"
+)
+
+// RunOptions configures a single Run invocation.
+type RunOptions struct {
+	// Stdin, if non-nil, is written to the process stdin.
+	Stdin []byte
+	// CombinedOutputCap limits the captured output (truncated at the end).
+	// 0 means unlimited. The agent uses ~1 MiB for cat-queue, smaller for
+	// status-style commands.
+	OutputCap int
+}
+
+// RunResult is what every shell-style command returns.
+type RunResult struct {
+	Stdout   string `json:"stdout,omitempty"`
+	Stderr   string `json:"stderr,omitempty"`
+	ExitCode int    `json:"exit_code"`
+}
+
+// Run executes argv[0] argv[1:] under ctx (the bus deadline). It does not
+// translate exit codes to errors — callers inspect r.ExitCode themselves so
+// they can map e.g. "queue id not found" exit codes to ErrNotFound.
+func Run(ctx context.Context, opts RunOptions, argv ...string) (*RunResult, error) {
+	if len(argv) == 0 {
+		return nil, fmt.Errorf("commands.Run: empty argv")
+	}
+	cmd := exec.CommandContext(ctx, argv[0], argv[1:]...)
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	if opts.Stdin != nil {
+		cmd.Stdin = bytes.NewReader(opts.Stdin)
+	}
+	err := cmd.Run()
+
+	out := stdout.String()
+	errOut := stderr.String()
+	if opts.OutputCap > 0 {
+		if len(out) > opts.OutputCap {
+			out = out[:opts.OutputCap] + "\n…(truncated)"
+		}
+		if len(errOut) > opts.OutputCap {
+			errOut = errOut[:opts.OutputCap] + "\n…(truncated)"
+		}
+	}
+
+	exit := 0
+	if exitErr, ok := err.(*exec.ExitError); ok {
+		exit = exitErr.ExitCode()
+		err = nil
+	}
+	return &RunResult{Stdout: out, Stderr: errOut, ExitCode: exit}, err
+}