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MGS2001: path read denied by sandbox

A spell tried to read a file outside the workspace and outside the configured allowlist.

[MGS2001] fs read denied: /home/user/.aws/credentials

Why

The sandbox confines every magus subprocess and every in-process spell to the workspace plus a curated allowlist of cache and system paths. Reads of dotfile-style credential stores in $HOME are exactly what compromised supply-chain packages target, so they are denied by default.

Resolution

  1. If this is a malicious spell (the path is a credential file you never asked the spell to touch): do not lift the restriction. This is the system working as intended. Uninstall the spell and report it.

  2. If this is a legitimate spell that needs to read an external path (e.g. it reads ~/.terraform.d/plugins to discover providers): add the path to your workspace's magus.yaml:

    sandbox:
  allow:
    - path: ~/.terraform.d/plugins
      mode: ro

    mode: ro is read-only; mode: rw permits writes. Use the narrowest mode that lets the workflow succeed.

  3. If you want to disable sandbox for one invocation while you investigate:

    MAGUS_SANDBOX_ENABLED=0 magus run build

    Do not set sandbox.enabled: false in magus.yaml to silence a real warning.

sandbox diagnosticsLanding page for the sandbox that confines magus spells to the workspace, plus its MGS2xxx diagnostics for denied reads, writes, execs, and env leaks. MGS2002: path write deniedFires when a spell tries to write to a file outside the workspace and outside the sandbox allowlist, blocking persistence and tampering attacks. Sandbox modelThe threat model and allowlist semantics that magus enforces around spell execution, and how the MGS2xxx diagnostics map onto that model. magus stdlibReference for every magus stdlib module - fs, os, http, json, yaml, crypto, and the rest of the magusfile API surface.
MGS2001sandboxsecuritypermissionsreadallowlistcredentials
Last updated (b022d75e)
Glossary

Workspace

The magus root directory that owns a set of projects and shared config; the unit magus operates over. See workspace.

Target

A named operation (build, test, ...) you invoke with magus run <target>; it may compose a spell's tool-native operations and depend on other targets. See targets.

Spell

A language/runtime adapter (e.g. go, md) that maps generic targets onto a toolchain's real commands. See spells.

Cache

The content-addressed store magus consults before running a target, so unchanged work is skipped. See cache.

Sandbox

The restricted filesystem and environment a target runs in, so builds stay reproducible and side-effect-free. See sandbox.

CI

An ordinary magusfile-defined target you compose yourself with magus\needs - magus does not hardcode its stages. Magus.RunCI treats it specially only in that it strips the rw charm, it is the anchor magus affected ci keys off, and a selected scope with no project declaring it is a load error rather than a silent no-op. See targets.

Conventions

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