Readme

Author: aidanhs

README.md

@@ -1,41 +1,56 @@
-# Docker Registry (golang implementation)
+# DLGrab (docker layer grab)
 
 ## Requirements
 
-You need to have docker >= 0.5.0 up and running.
+You need to have docker running on your local machine. Remote daemons won't
+work, though it wouldn't be hard to add them.
 
-## Limitations
+## Caveats
 
-This implementation doesn't provide all the features that are available in the Python implementation of the Docker Registry.
+DLGrab shims the api endpoints docker touches when pushing an image. If
+Docker starts expecting different responses from these endpoints, DLGrab may
+stop working.
 
-## Build and start docker image for registry
+That said, it's probably more robust that trying to export directly from the
+filesystem.
 
-    $ git clone https://github.com/docker/docker-registry.git docker-registry.git
-    $ cd docker-registry.git/contrib/golang_impl
-    $ docker build -t docker_registry/golang .
-    $ docker run -v /data:/data -d -p 80:80 docker_registry/golang
+## Build dlgrab
 
-__Notice__: -p 80:80 binds the registry to your local port 80. This is necessary because it seems you currently cannot delete images where
-the tag includes a port.
+    $ git clone https://github.com/aidanhs/dlgrab.git
+    $ cd dlgrab
+    $ make
+    $ ./dlgrab
 
-## Test / Use
+## Usage
 
-### Push test image to registry
+    $ ./dlgrab
+    Usage for ./dlgrab [flags...] LAYER
+      LAYER: layer id to export, or image name to export top layer of
+      --clean=false              Remove the temporary tag after use
+                                   WARNING: can trigger layer deletion if run on a layer with no children or other references
+      --debug=false              Set log level to debug
+      -h, --help=false           Print this help text
+      -o, --outdir="."           Directory to write layer to
+      -p=0                       Port to use, defaults to a random unallocated port
+      --registry-format=false    Output in the format a registry would use, rather than for an image export
 
-    $ docker build -t 127.0.0.1/test/test - << EOF
-    FROM ubuntu
-    RUN echo world > /hello
-    CMD cat /hello
-    EOF
-
-    $ docker push 127.0.0.1/test/test
-
-### Delete local registry image
-
-    $ docker rmi 127.0.0.1/test/test
-
-### Run test image
-
-    $ docker run 127.0.0.1/test/test
-
-Now the image is fetched from your local registry and executed. Should print out `world`.
+      The DOCKER_HOST environment variable overrides the default location to find the docker daemon
+    $ docker history ubuntu:14.04
+    IMAGE               CREATED             CREATED BY                                      SIZE
+    5ba9dab47459        2 weeks ago         /bin/sh -c #(nop) CMD [/bin/bash]               0 B
+    51a9c7c1f8bb        2 weeks ago         /bin/sh -c sed -i 's/^#\s*\(deb.*universe\)$/   1.895 kB
+    5f92234dcf1e        2 weeks ago         /bin/sh -c echo '#!/bin/sh' > /usr/sbin/polic   194.5 kB
+    27d47432a69b        2 weeks ago         /bin/sh -c #(nop) ADD file:62400a49cced0d7521   188.1 MB
+    511136ea3c5a        20 months ago                                                       0 B
+    $ ./dlgrab --clean 51a9c7c1f8bb # this layer is referenced by child images, so --clean is fine
+    Full layer id found: 51a9c7c1f8bb2fa19bcd09789a34e63f35abb80044bc10196e304f6634cc582c
+    Layer folder will be dumped into .
+    Writing file: json
+    Writing file: layer.tar
+    Export complete
+    $ ls 51a9c7c1f8bb2fa19bcd09789a34e63f35abb80044bc10196e304f6634cc582c
+    json  layer.tar  VERSION
+    $ tar tf 51a9c7c1f8bb2fa19bcd09789a34e63f35abb80044bc10196e304f6634cc582c/layer.tar 
+    etc/
+    etc/apt/
+    etc/apt/sources.list