Add --env option that sets environment variables in the launched command (not in the container)

README.md

@@ -38,6 +38,9 @@ Path to build context to build the image from. This overrides `--image`/`OW_IMAG
 ### --volume=<volume>
 Volume to map to the container. `~` is expanded automatically. If the directory exists in the user's home directory it will be created to ensure it has the correct ownership and permissions.
 
+### --env=<key>=<value>
+Set the environment variable `key` to `value` in the command. **Note that this does not set environment variables in the container itself**.
+
 ## Environment variables
 ### OW_IMAGE
 Image to create the container with (default: `debian:stable`)

otherworld

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 from subprocess import call, check_call, check_output
 from time import sleep
+from itertools import chain
 import os
 import sys
 import json
@@ -60,8 +61,10 @@ def docker_create_user (container, user, uid=None):
 def docker_start (container):
     call(["docker", "start", container])
 
-def docker_exec (container, command, user):
-    call(["docker", "exec", "--user", user, "-ti", container] + command)
+def docker_exec (container, command, user, env={}):
+    call(["docker", "exec", "--user", user, "-ti"] + \
+         list(chain.from_iterable([["--env", f"{kv[0]}={kv[1]}"] for kv in env.items()])) + \
+         [container] + command)
 
 def docker_commit (container, image_name):
     call(["docker", "commit", container, image_name])
@@ -116,6 +119,8 @@ command_user = user
 user_volumes = USER_VOLUMES
 pull = False
 
+command_env = {}
+
 quiet = False
 while len(command) > 0:
     arg = command[0]
@@ -151,6 +156,11 @@ while len(command) > 0:
     elif arg.startswith("--volume="):
         user_volumes.append(arg[len("--volume="):])
         command = command[1:]
+    elif arg.startswith("--env="):
+        env_pair = arg[len("--env="):]
+        (key, value) = env_pair.split("=", 1)
+        command_env[key] = value
+        command = command[1:]
     elif arg == "--pull":
         command = command[1:]
         pull = True
@@ -195,4 +205,4 @@ except Exception:
 
 if not quiet:
     print(f">> Welcome to {container_name} (IP {container['NetworkSettings']['IPAddress']})")
-docker_exec(container_name, command, command_user)
+docker_exec(container_name, command, command_user, command_env)