Make default image name image_{CONTAINER_NAME}, and use debian:stable as fallback.

README.md

@@ -21,7 +21,7 @@ These are arguments that go between `otherworld` and the command.
 Name to assign to container (default: `otherworld_$USER`)
 
 ### --image=<image>
-Image to create the container with (default: `debian:stable`)
+Image to create the container with (default: `image_$CONTAINER_NAME`, or `debian:stable` if that image does not exist)
 
 ### --sudo
 Runs command as root, instead of current user.

otherworld

@@ -7,7 +7,7 @@ import sys
 import json
 
 CONTAINER_NAME = "otherworld"
-IMAGE_NAME = "debian:stable"
+DEFAULT_IMAGE_NAME = "debian:stable"
 
 def create_x11_mapping ():
     home = os.environ["HOME"]
@@ -110,7 +110,7 @@ def expand_user_volumes (volumes):
 
 user = os.environ["USER"]
 uid = int(check_output(["id", "-u"]).strip())
-image_name = os.environ.get("OW_IMAGE", IMAGE_NAME)
+image_name = os.environ.get("OW_IMAGE", None)
 container_name = os.environ.get("OW_CONTAINER", f"{CONTAINER_NAME}_{user}")
 build_path = None
 
@@ -144,9 +144,6 @@ while len(command) > 0:
     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:]
@@ -177,7 +174,19 @@ 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 [], get_generated_image_name(container_name))
-    elif pull:
+    else:
+        if image_name is None:
+            image_name = get_generated_image_name(container_name)
+            try:
+                docker_inspect(image_name)
+                if not quiet:
+                    print(f">> Using default otherworld image {image_name}")
+            except Exception:
+                if not quiet:
+                    print(f">> Default otherworld image {image_name} not found, falling back to {DEFAULT_IMAGE_NAME}")
+                image_name = DEFAULT_IMAGE_NAME
+
+        if pull:
             docker_pull(image_name)
 
     if not quiet: