docker helper: set uid and gid

Makefile

@@ -10,6 +10,7 @@ image:
 shell:
 	${DOCKER} run --rm -it \
 		-p 4000:4000 \
+		-u `id -u`:`id -g` \
 		-v ${PWD}:/src/gh/pages-gem \
 		${TAG} \
 		/bin/bash
@@ -22,6 +23,7 @@ server:
 		(echo -E "specify SITE e.g.: SITE=/path/to/site make server"; exit 1) && \
 	${DOCKER} run --rm -it \
 		-p 4000:4000 \
+		-u `id -u`:`id -g` \
 		-v ${PWD}:/src/gh/pages-gem \
 		-v `realpath ${SITE}`:/src/site \
 		-w /src/site \

contrib/func.sh

@@ -5,5 +5,9 @@
 function github-pages {
   _path=${1:-.}
   _port=${2:-4000}
-  docker run --rm -v `realpath $_path`:/src/site -p $_port:4000 gh-pages
+  docker run --rm \
+    -p $_port:4000 \
+    -u `id -u`:`id -g` \
+    -v `realpath $_path`:/src/site \
+    gh-pages
 }