Class: Insika::Sandbox::Docker

Inherits:
Object
  • Object
show all
Defined in:
lib/insika/sandbox/docker.rb

Overview

Isolated exec provider: runs the command inside a throwaway Docker container (docker run --rm) with the sandbox root bind-mounted at a fixed workdir. This is the isolation boundary the local provider is NOT — a real target for UNTRUSTED shell execution.

"Narrowest sandbox that supports the task": only the risky part — shell exec — is containerized. The FS tools (read/write/edit/grep) keep operating on the host path, confined by the Boundary; the container sees the SAME bytes through the bind mount, so a file the model writes is immediately visible to a subsequent bash call and vice-versa.

Defaults are conservative: --network none (no egress from the container), a memory cap and a cpu cap, and a minimal image. All are overridable via the profile's sandbox config (config-over-code).

Constant Summary collapse

DEFAULTS = 
{
  "image" => "alpine:3.20",
  "network" => "none",
  "memory" => "512m",
  "cpus" => "1.0",
  "workdir" => "/workspace",
  "shell" => "/bin/sh",
  "docker_bin" => "docker"
}.freeze

Instance Method Summary collapse

Constructor Details

#initialize(config = {}) ⇒ Docker

Returns a new instance of Docker.



33
34
35
36
37
38
39
40
41
42
 
# File 'lib/insika/sandbox/docker.rb', line 33

def initialize(config = {})
  cfg = DEFAULTS.merge(config.transform_keys(&:to_s).compact)
  @image      = cfg["image"]
  @network    = cfg["network"]
  @memory     = cfg["memory"]
  @cpus       = cfg["cpus"].to_s
  @workdir    = cfg["workdir"]
  @shell      = cfg["shell"]
  @docker_bin = cfg["docker_bin"]
end

Instance Method Details

#argv(command, root:, name:) ⇒ Object

PURE argv builder — unit-testable without Docker present. --name lets the timeout teardown docker kill the exact container (killing the client process alone does not stop it).



47
48
49
50
51
52
 
# File 'lib/insika/sandbox/docker.rb', line 47

def argv(command, root:, name:)
  [@docker_bin, "run", "--rm", "--name", name,
   "--network", @network, "--memory", @memory, "--cpus", @cpus,
   "--volume", "#{root}:#{@workdir}:rw", "--workdir", @workdir,
   @image, @shell, "-c", command.to_s]
end

#available? ⇒ Boolean

Whether the Docker daemon is reachable. Used at boot to fail fast (or warn) instead of discovering it mid-turn.

Returns:

  • (Boolean) 


65
66
67
68
69
 
# File 'lib/insika/sandbox/docker.rb', line 65

def available?
  system(@docker_bin, "version", out: File::NULL, err: File::NULL)
rescue StandardError
  false
end

#exec(command, root:, timeout:, max_output:) ⇒ Object 



54
55
56
57
58
59
60
61
 
# File 'lib/insika/sandbox/docker.rb', line 54

def exec(command, root:, timeout:, max_output:)
  name = "harness-sbx-#{SecureRandom.hex(8)}"
  Runner.run(argv(command, root: root, name: name),
             chdir: root, timeout: timeout, max_output: max_output,
             # On the wall-clock deadline, stop the container by name; the
             # `--rm` then removes it. Squelch output — this is teardown.
             kill: -> { system(@docker_bin, "kill", name, out: File::NULL, err: File::NULL) })
end

#to_s ⇒ Object 



71
 
# File 'lib/insika/sandbox/docker.rb', line 71

def to_s = "docker(#{@image}, network=#{@network})"