From: W. Trevor King <wking@tremily.us>
Date: Fri, 20 Jun 2014 04:36:55 +0000 (-0700)
Subject: portage: Shift the emphasis from a running to a non-running container
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=bdc781050683a91554b87dd9216fca61ec429cff;p=dockerfile.git

portage: Shift the emphasis from a running to a non-running container

Not messing with ENTRYPOINT makes it easier to run an interactive
container with:

  $ docker run --rm -i -t wking/portage

if you want to poke around.
---

diff --git a/portage/Dockerfile.template b/portage/Dockerfile.template
index 7c321f9..ca846f3 100644
--- a/portage/Dockerfile.template
+++ b/portage/Dockerfile.template
@@ -1,4 +1,4 @@
-# Copyright (C) 2013 W. Trevor King <wking@tremily.us>
+# Copyright (C) 2013-2014 W. Trevor King <wking@tremily.us>
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are met:
@@ -28,10 +28,7 @@ MAINTAINER ${MAINTAINER}
 # -volumes-from doesn't map names, so we need to shift /portage to
 #  /usr/portage.  Add a statically-linked BusyBox for RUN commands.
 ADD busybox /bin/sh
-ENTRYPOINT ["/bin/sh"]
 RUN mkdir /usr/
 RUN mv /portage /usr/portage
 VOLUME ["/usr/portage"]
-
-# We need a dummy process for this container
-CMD ["tail", "-f", "/portage/profiles/repo_name"]
+CMD sh
diff --git a/portage/README.md b/portage/README.md
index 2fbac74..0fd20a7 100644
--- a/portage/README.md
+++ b/portage/README.md
@@ -1,9 +1,9 @@
 Use volume mounts to avoid including the Portage tree in your images:
 
-    $ docker run -d --name portage wking/portage
+    $ docker run --name portage wking/portage
 
-This exports a [VOLUME][] which you can [mount][volumes-from] from
-another container:
+The container will exit immediately, but you can still
+[mount][volumes-from] it's exported [VOLUME][] from another container:
 
     $ docker run --volumes-from portage -i -t wking/gentoo /bin/bash
     d1a49abc4b3c / # ls /usr/portage/
@@ -11,8 +11,8 @@ another container:
     …
 
 Changes (e.g. distfiles downloads) are preserved between mounts by the
-continuously-running `portage` container.  Let's install something in
-the first container:
+shared `portage` container.  Let's install something in the first
+container:
 
     d1a49abc4b3c / # emerge -av netcat
     …
@@ -44,13 +44,11 @@ will still be local to your client containers, so you'll get
 promptings for reading the news on both `d1a49abc4b3c` and
 `187adaf8babd`.
 
-You can use container volumes even if their container is not running.
-For example:
+You can use container volumes even if their container is not running
+(as above), but it may be useful to leave the container running so you
+don't remove it up by accident.  For example:
 
-    $ docker run --name portage wking/portage true
-
-However, it may be useful to leave the container running so you don't
-remove it up by accident.
+    $ docker run -d --name portage wking/portage /bin/sh -c 'tail -f /usr/portage/profiles/repo_name'
 
 [VOLUME]: http://docs.docker.io/en/latest/use/builder/#volume
 [volumes-from]: http://docs.docker.io/en/latest/use/working_with_volumes/#mount-volumes-from-an-existing-container