fix(docker): add explicit env allowlist for container credentials (#1436)

Docker terminal sessions are secret-dark by default. This adds
terminal.docker_forward_env as an explicit allowlist for env vars
that may be forwarded into Docker containers.

Values resolve from the current shell first, then fall back to
~/.hermes/.env. Only variables the user explicitly lists are
forwarded — nothing is auto-exposed.

Cherry-picked from PR #1449 by @teknium1, conflict-resolved onto
current main.

Fixes #1436
Supersedes #1439

cli-config.yaml.example

@@ -123,6 +123,12 @@ terminal:
 #   lifetime_seconds: 300
 #   docker_image: "nikolaik/python-nodejs:python3.11-nodejs20"
 #   docker_mount_cwd_to_workspace: true   # Explicit opt-in: mount your launch cwd into /workspace
+#   # Optional: explicitly forward selected env vars into Docker.
+#   # These values come from your current shell first, then ~/.hermes/.env.
+#   # Warning: anything forwarded here is visible to commands run in the container.
+#   docker_forward_env:
+#     - "GITHUB_TOKEN"
+#     - "NPM_TOKEN"
 
 # -----------------------------------------------------------------------------
 # OPTION 4: Singularity/Apptainer container

cli.py

@@ -161,6 +161,7 @@ def load_cli_config() -> Dict[str, Any]:
             "timeout": 60,
             "lifetime_seconds": 300,
             "docker_image": "python:3.11",
+            "docker_forward_env": [],
             "singularity_image": "docker://python:3.11",
             "modal_image": "python:3.11",
             "daytona_image": "nikolaik/python-nodejs:python3.11-nodejs20",
@@ -325,6 +326,7 @@ def load_cli_config() -> Dict[str, Any]:
         "timeout": "TERMINAL_TIMEOUT",
         "lifetime_seconds": "TERMINAL_LIFETIME_SECONDS",
         "docker_image": "TERMINAL_DOCKER_IMAGE",
+        "docker_forward_env": "TERMINAL_DOCKER_FORWARD_ENV",
         "singularity_image": "TERMINAL_SINGULARITY_IMAGE",
         "modal_image": "TERMINAL_MODAL_IMAGE",
         "daytona_image": "TERMINAL_DAYTONA_IMAGE",

gateway/run.py

@@ -107,6 +107,7 @@ if _config_path.exists():
                 "timeout": "TERMINAL_TIMEOUT",
                 "lifetime_seconds": "TERMINAL_LIFETIME_SECONDS",
                 "docker_image": "TERMINAL_DOCKER_IMAGE",
+                "docker_forward_env": "TERMINAL_DOCKER_FORWARD_ENV",
                 "singularity_image": "TERMINAL_SINGULARITY_IMAGE",
                 "modal_image": "TERMINAL_MODAL_IMAGE",
                 "daytona_image": "TERMINAL_DAYTONA_IMAGE",

hermes_cli/config.py

@@ -118,6 +118,7 @@ DEFAULT_CONFIG = {
         "cwd": ".",  # Use current directory
         "timeout": 180,
         "docker_image": "nikolaik/python-nodejs:python3.11-nodejs20",
+        "docker_forward_env": [],
         "singularity_image": "docker://nikolaik/python-nodejs:python3.11-nodejs20",
         "modal_image": "nikolaik/python-nodejs:python3.11-nodejs20",
         "daytona_image": "nikolaik/python-nodejs:python3.11-nodejs20",

tests/tools/test_docker_environment.py

@@ -1,4 +1,5 @@
 import logging
+from io import StringIO
 import subprocess
 import sys
 import types
@@ -211,3 +212,64 @@ def test_auto_mount_replaces_persistent_workspace_bind(monkeypatch, tmp_path):
     assert f"{project_dir}:/workspace" in run_args_str
     assert "/sandboxes/docker/test-persistent-auto-mount/workspace:/workspace" not in run_args_str
 
+
+class _FakePopen:
+    def __init__(self, cmd, **kwargs):
+        self.cmd = cmd
+        self.kwargs = kwargs
+        self.stdout = StringIO("")
+        self.stdin = None
+        self.returncode = 0
+
+    def poll(self):
+        return self.returncode
+
+
+def _make_execute_only_env(forward_env=None):
+    env = docker_env.DockerEnvironment.__new__(docker_env.DockerEnvironment)
+    env.cwd = "/root"
+    env.timeout = 60
+    env._forward_env = forward_env or []
+    env._prepare_command = lambda command: (command, None)
+    env._timeout_result = lambda timeout: {"output": f"timed out after {timeout}", "returncode": 124}
+    env._inner = type("Inner", (), {
+        "container_id": "test-container",
+        "config": type("Cfg", (), {"executable": "/usr/bin/docker", "env": {}})(),
+    })()
+    return env
+
+
+def test_execute_uses_hermes_dotenv_for_allowlisted_env(monkeypatch):
+    env = _make_execute_only_env(["GITHUB_TOKEN"])
+    popen_calls = []
+
+    def _fake_popen(cmd, **kwargs):
+        popen_calls.append(cmd)
+        return _FakePopen(cmd, **kwargs)
+
+    monkeypatch.delenv("GITHUB_TOKEN", raising=False)
+    monkeypatch.setattr(docker_env, "_load_hermes_env_vars", lambda: {"GITHUB_TOKEN": "value_from_dotenv"})
+    monkeypatch.setattr(docker_env.subprocess, "Popen", _fake_popen)
+
+    result = env.execute("echo hi")
+
+    assert result["returncode"] == 0
+    assert "GITHUB_TOKEN=value_from_dotenv" in popen_calls[0]
+
+
+def test_execute_prefers_shell_env_over_hermes_dotenv(monkeypatch):
+    env = _make_execute_only_env(["GITHUB_TOKEN"])
+    popen_calls = []
+
+    def _fake_popen(cmd, **kwargs):
+        popen_calls.append(cmd)
+        return _FakePopen(cmd, **kwargs)
+
+    monkeypatch.setenv("GITHUB_TOKEN", "value_from_shell")
+    monkeypatch.setattr(docker_env, "_load_hermes_env_vars", lambda: {"GITHUB_TOKEN": "value_from_dotenv"})
+    monkeypatch.setattr(docker_env.subprocess, "Popen", _fake_popen)
+
+    env.execute("echo hi")
+
+    assert "GITHUB_TOKEN=value_from_shell" in popen_calls[0]
+    assert "GITHUB_TOKEN=value_from_dotenv" not in popen_calls[0]

tests/tools/test_parse_env_var.py

@@ -30,6 +30,28 @@ class TestParseEnvVar:
             result = _parse_env_var("TERMINAL_DOCKER_VOLUMES", "[]", json.loads, "valid JSON")
             assert result == ["/host:/container"]
 
+    def test_get_env_config_parses_docker_forward_env_json(self):
+        with patch.dict("os.environ", {
+            "TERMINAL_ENV": "docker",
+            "TERMINAL_DOCKER_FORWARD_ENV": '["GITHUB_TOKEN", "NPM_TOKEN"]',
+        }, clear=False):
+            config = _tt_mod._get_env_config()
+            assert config["docker_forward_env"] == ["GITHUB_TOKEN", "NPM_TOKEN"]
+
+    def test_create_environment_passes_docker_forward_env(self):
+        fake_env = object()
+        with patch.object(_tt_mod, "_DockerEnvironment", return_value=fake_env) as mock_docker:
+            result = _tt_mod._create_environment(
+                "docker",
+                image="python:3.11",
+                cwd="/root",
+                timeout=180,
+                container_config={"docker_forward_env": ["GITHUB_TOKEN"]},
+            )
+
+        assert result is fake_env
+        assert mock_docker.call_args.kwargs["forward_env"] == ["GITHUB_TOKEN"]
+
     def test_falls_back_to_default(self):
         with patch.dict("os.environ", {}, clear=False):
             # Remove the var if it exists, rely on default

tools/environments/docker.py

@@ -7,6 +7,7 @@ persistence via bind mounts.
 
 import logging
 import os
+import re
 import shutil
 import subprocess
 import sys
@@ -30,6 +31,42 @@ _DOCKER_SEARCH_PATHS = [
 ]
 
 _docker_executable: Optional[str] = None  # resolved once, cached
+_ENV_VAR_NAME_RE = re.compile(r"^[A-Za-z_][A-Za-z0-9_]*$")
+
+
+def _normalize_forward_env_names(forward_env: list[str] | None) -> list[str]:
+    """Return a deduplicated list of valid environment variable names."""
+    normalized: list[str] = []
+    seen: set[str] = set()
+
+    for item in forward_env or []:
+        if not isinstance(item, str):
+            logger.warning("Ignoring non-string docker_forward_env entry: %r", item)
+            continue
+
+        key = item.strip()
+        if not key:
+            continue
+        if not _ENV_VAR_NAME_RE.match(key):
+            logger.warning("Ignoring invalid docker_forward_env entry: %r", item)
+            continue
+        if key in seen:
+            continue
+
+        seen.add(key)
+        normalized.append(key)
+
+    return normalized
+
+
+def _load_hermes_env_vars() -> dict[str, str]:
+    """Load ~/.hermes/.env values without failing Docker command execution."""
+    try:
+        from hermes_cli.config import load_env
+
+        return load_env() or {}
+    except Exception:
+        return {}
 
 
 def find_docker() -> Optional[str]:
@@ -171,6 +208,7 @@ class DockerEnvironment(BaseEnvironment):
         persistent_filesystem: bool = False,
         task_id: str = "default",
         volumes: list = None,
+        forward_env: list[str] | None = None,
         network: bool = True,
         host_cwd: str = None,
         auto_mount_cwd: bool = False,
@@ -181,6 +219,7 @@ class DockerEnvironment(BaseEnvironment):
         self._base_image = image
         self._persistent = persistent_filesystem
         self._task_id = task_id
+        self._forward_env = _normalize_forward_env_names(forward_env)
         self._container_id: Optional[str] = None
         logger.info(f"DockerEnvironment volumes: {volumes}")
         # Ensure volumes is a list (config.yaml could be malformed)
@@ -355,8 +394,12 @@ class DockerEnvironment(BaseEnvironment):
         if effective_stdin is not None:
             cmd.append("-i")
         cmd.extend(["-w", work_dir])
-        for key in self._inner.config.forward_env:
-            if (value := os.getenv(key)) is not None:
+        hermes_env = _load_hermes_env_vars() if self._forward_env else {}
+        for key in self._forward_env:
+            value = os.getenv(key)
+            if value is None:
+                value = hermes_env.get(key)
+            if value is not None:
                 cmd.extend(["-e", f"{key}={value}"])
         for key, value in self._inner.config.env.items():
             cmd.extend(["-e", f"{key}={value}"])

tools/terminal_tool.py

@@ -505,6 +505,7 @@ def _get_env_config() -> Dict[str, Any]:
     return {
         "env_type": env_type,
         "docker_image": os.getenv("TERMINAL_DOCKER_IMAGE", default_image),
+        "docker_forward_env": _parse_env_var("TERMINAL_DOCKER_FORWARD_ENV", "[]", json.loads, "valid JSON"),
         "singularity_image": os.getenv("TERMINAL_SINGULARITY_IMAGE", f"docker://{default_image}"),
         "modal_image": os.getenv("TERMINAL_MODAL_IMAGE", default_image),
         "daytona_image": os.getenv("TERMINAL_DAYTONA_IMAGE", default_image),
@@ -562,6 +563,7 @@ def _create_environment(env_type: str, image: str, cwd: str, timeout: int,
     disk = cc.get("container_disk", 51200)
     persistent = cc.get("container_persistent", True)
     volumes = cc.get("docker_volumes", [])
+    docker_forward_env = cc.get("docker_forward_env", [])
 
     if env_type == "local":
         lc = local_config or {}
@@ -576,6 +578,7 @@ def _create_environment(env_type: str, image: str, cwd: str, timeout: int,
             volumes=volumes,
             host_cwd=host_cwd,
             auto_mount_cwd=cc.get("docker_mount_cwd_to_workspace", False),
+            forward_env=docker_forward_env,
         )
     
     elif env_type == "singularity":

website/docs/reference/environment-variables.md

@@ -80,6 +80,7 @@ For native Anthropic auth, Hermes prefers Claude Code's own credential files whe
 |----------|-------------|
 | `TERMINAL_ENV` | Backend: `local`, `docker`, `ssh`, `singularity`, `modal`, `daytona` |
 | `TERMINAL_DOCKER_IMAGE` | Docker image (default: `python:3.11`) |
+| `TERMINAL_DOCKER_FORWARD_ENV` | JSON array of env var names to explicitly forward into Docker terminal sessions |
 | `TERMINAL_DOCKER_VOLUMES` | Additional Docker volume mounts (comma-separated `host:container` pairs) |
 | `TERMINAL_DOCKER_MOUNT_CWD_TO_WORKSPACE` | Advanced opt-in: mount the launch cwd into Docker `/workspace` (`true`/`false`, default: `false`) |
 | `TERMINAL_SINGULARITY_IMAGE` | Singularity image or `.sif` path |

website/docs/user-guide/configuration.md

@@ -488,6 +488,8 @@ terminal:
   # Docker-specific settings
   docker_image: "nikolaik/python-nodejs:python3.11-nodejs20"
   docker_mount_cwd_to_workspace: false  # SECURITY: off by default. Opt in to mount the launch cwd into /workspace.
+  docker_forward_env:              # Optional explicit allowlist for env passthrough
+    - "GITHUB_TOKEN"
   docker_volumes:                    # Additional explicit host mounts
     - "/home/user/projects:/workspace/projects"
     - "/home/user/data:/data:ro"     # :ro for read-only
@@ -555,6 +557,24 @@ This is useful for:
 
 Can also be set via environment variable: `TERMINAL_DOCKER_VOLUMES='["/host:/container"]'` (JSON array).
 
+### Docker Credential Forwarding
+
+By default, Docker terminal sessions do not inherit arbitrary host credentials. If you need a specific token inside the container, add it to `terminal.docker_forward_env`.
+
+```yaml
+terminal:
+  backend: docker
+  docker_forward_env:
+    - "GITHUB_TOKEN"
+    - "NPM_TOKEN"
+```
+
+Hermes resolves each listed variable from your current shell first, then falls back to `~/.hermes/.env` if it was saved with `hermes config set`.
+
+:::warning
+Anything listed in `docker_forward_env` becomes visible to commands run inside the container. Only forward credentials you are comfortable exposing to the terminal session.
+:::
+
 ### Optional: Mount the Launch Directory into `/workspace`
 
 Docker sandboxes stay isolated by default. Hermes does **not** pass your current host working directory into the container unless you explicitly opt in.

website/docs/user-guide/features/tools.md

@@ -135,6 +135,8 @@ All container backends run with security hardening:
 - Full namespace isolation
 - Persistent workspace via volumes, not writable root layer
 
+Docker can optionally receive an explicit env allowlist via `terminal.docker_forward_env`, but forwarded variables are visible to commands inside the container and should be treated as exposed to that session.
+
 ## Background Process Management
 
 Start background processes and manage them:

website/docs/user-guide/security.md

@@ -212,6 +212,7 @@ Container resources are configurable in `~/.hermes/config.yaml`:
 terminal:
   backend: docker
   docker_image: "nikolaik/python-nodejs:python3.11-nodejs20"
+  docker_forward_env: []  # Explicit allowlist only; empty keeps secrets out of the container
   container_cpu: 1        # CPU cores
   container_memory: 5120  # MB (default 5GB)
   container_disk: 51200   # MB (default 50GB, requires overlay2 on XFS)
@@ -227,6 +228,10 @@ terminal:
 For production gateway deployments, use `docker`, `modal`, or `daytona` backend to isolate agent commands from your host system. This eliminates the need for dangerous command approval entirely.
 :::
 
+:::warning
+If you add names to `terminal.docker_forward_env`, those variables are intentionally injected into the container for terminal commands. This is useful for task-specific credentials like `GITHUB_TOKEN`, but it also means code running in the container can read and exfiltrate them.
+:::
+
 ## Terminal Backend Security Comparison
 
 | Backend | Isolation | Dangerous Cmd Check | Best For |