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

Also add an --image option (without argument) that uses this image. Not documented because I'm not sure I like this interface.

README.md

@@ -29,12 +29,18 @@ Runs command as root, instead of current user.
 ### --rm
 Removes the specified container.
 
+### --commit
+Commits the container to an image named `image_$CONTAINER_NAME`.
+
 ### --build=<path>
-Path to build context to build the image from. This overrides `--image`/`OW_IMAGE`.
+Path to build context to build the image from. This overrides `--image`/`OW_IMAGE`. The resulting image is named `image_$CONTAINER_NAME`
 
 ### --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
@@ -33,6 +34,11 @@ USER_VOLUMES = ["~/otherworld"]
 BACKGROUND_COMMAND = None
 DEFAULT_COMMAND = ["bash"]
 
+GENERATED_IMAGE_NAME_TEMPLATE = "image_{container_name}"
+
+def get_generated_image_name (container_name):
+    return GENERATED_IMAGE_NAME_TEMPLATE.format(container_name=container_name)
+
 def docker_inspect (container):
     return json.loads(check_output(["docker", "inspect", container]))
 
@@ -55,8 +61,13 @@ def docker_create_user (container, user, uid=None):
 def docker_start (container):
     call(["docker", "start", container])
 
-def docker_exec (container, command, user):
+def docker_exec (container, command, user, env={}):
-    call(["docker", "exec", "--user", user, "-ti", container] + command)
+    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])
 
 def docker_rm (container):
     call(["docker", "rm", "-f", container])
@@ -108,6 +119,8 @@ command_user = user
 user_volumes = USER_VOLUMES
 pull = False
 
+command_env = {}
+
 quiet = False
 while len(command) > 0:
     arg = command[0]
@@ -119,12 +132,21 @@ while len(command) > 0:
             print(f">> Removing container: {container_name}")
         docker_rm(container_name)
         sys.exit(0)
+    elif arg == "--commit":
+        image_name = get_generated_image_name(container_name)
+        if not quiet:
+            print(f">> Committing container: {container_name} to image: {image_name}")
+        docker_commit(container_name, image_name)
+        sys.exit(0)
     elif arg == "--sudo":
         command_user = "root"
         command = command[1:]
     elif arg.startswith("--container="):
         container_name = arg[len("--container="):]
         command = command[1:]
+    elif arg.startswith("--image"):
+        image_name = get_generated_image_name(container_name)
+        command = command[1:]
     elif arg.startswith("--image="):
         image_name = arg[len("--image="):]
         command = command[1:]
@@ -134,6 +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
@@ -149,7 +176,7 @@ try:
 except Exception:
     build_path = resolve_build_path(build_path)
     if build_path is not None:
-        image_name = docker_build(build_path, ["--pull"] if pull else [], f"image_{container_name}")
+        image_name = docker_build(build_path, ["--pull"] if pull else [], get_generated_image_name(container_name))
     elif pull:
         docker_pull(image_name)
 
@@ -178,4 +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)