Minor fixes based on comments to PR #9.

Changes included:

* Obtain the current dokuwiki released from the DOKUWIKI_VERSION
environment variable set in the Dockerfile.
* Only unpack the bundled dokuwiki release if we actually need to
copy over new files.
* Clean up the temporary copy of dokuwiki when we are done copying files
from it.
* Use `exec` to run the http server at the end of the startup script.
* Document the `donwgrade` and `overwrite` comamnds.

Dockerfile

@@ -9,7 +9,7 @@ FROM ubuntu:16.04
 MAINTAINER Miroslav Prasil <miroslav@prasil.info>
 
 # Set the version you want of Twiki
-ARG DOKUWIKI_VERSION=2017-02-19e
+ENV DOKUWIKI_VERSION=2017-02-19e
 ARG DOKUWIKI_CSUM=09bf175f28d6e7ff2c2e3be60be8c65f
 
 # Update & install packages & cleanup afterwards

README.md

@@ -59,6 +59,16 @@ afterwards you can remove data container if you want
 
 Just stop the old container and run the new one with the same `-v` mapping. Since the data is on your file system, you do not need to do anything special to preserve it between containers.
 
+#### Handling changes in bundled files inside volumes ####
+
+If you mount a volume that has previously been used with a newer version of DokuWiki than that installed in the current contaier, the newer files will _not_ be overwritten by those bundled with the current (older) version of DokuWiki. If you want to force a downgrade (at your own risk!), run the container with the `downgrade` command:
+
+    docker run ... mprasil/dokuwiki donwgrade
+
+Additionally, if you make any changes to the files bundled with DokuWiki that are located in your volumes, these can be restored to the original version using the `overwrite` command:
+
+    docker run ... mprasil/dokuwiki overwrite
+
 Optimizing your wiki
 --------------------
 

docker-startup.sh

@@ -10,19 +10,15 @@ set -o pipefail
 # or fully populate these folders if this is the first run.
 
 dokudir=/dokuwiki
+tmpdir=/tmp/dokuwiki
 verfile=.last-version
+containerver="$(date -f <(echo "$DOKUWIKI_VERSION" | tr -d '[:alpha:]') +%s)"
 
 if [ ! -d "$dokudir" ]; then
     echo "DokuWiki does not appear to be installed correctly at: $dokudir." >&2
     exit 1
 fi
 
-# Unpack a temporary copy
-tmpdir=/tmp/dokuwiki
-mkdir "$tmpdir"
-tar -zxf /dokuwiki.tgz -C "$tmpdir" --strip-components 1
-containerver="$(date -f <(awk '{print $1}' "$tmpdir/VERSION" | tr -d '[:alpha:]') +%s)"
-
 # Check for downgrade/overwrite parameters
 if [ "$1" = 'downgrade' ]; then downgrade=1; else downgrade=0; fi
 if [ "$1" = 'overwrite' ]; then overwrite=1; else overwrite=0; fi
@@ -40,7 +36,13 @@ if [ "$1" = 'run' ] || [ "$1" = 'downgrade' ] || [ "$1" = 'overwrite' ]; then
             # Do nothing for equal versions
             continue
         elif [ "$volumever" -lt "$containerver" ] || [ "$downgrade" -eq 1 ] || [ "$overwrite" -eq 1 ]; then
-            # Update if the container version is newer than the volume version
+            # First, unpack a temporary copy of the current DokuWiki version
+            if [ ! -d "$tmpdir" ]; then
+                mkdir "$tmpdir"
+                tar -zxf /dokuwiki.tgz -C "$tmpdir" --strip-components 1
+            fi
+
+            # Then, update if the container version is newer than the volume version
             # Or if overridden using `downgrade`
             echo "Migrating $d..."
             cp -r "$tmpdir/$d/"* "$dokudir/$d/"
@@ -50,17 +52,20 @@ if [ "$1" = 'run' ] || [ "$1" = 'downgrade' ] || [ "$1" = 'overwrite' ]; then
             cat >&2 <<EOM
 This volume has perviously been used with a newer version of DokuWiki.
 If you want to force a downgrade (at your own risk!), run the \`downgrade\` command:
-    docker run ... andreipoe/dokuwiki donwgrade 
+    docker run ... mprasil/dokuwiki donwgrade
 EOM
         exit 2
         fi
     done
 
+    # Clean up any temporary files
+    rm -rf "$tmpdir"
+
     # Ensure persmissions are set correctly
     chown -R www-data:www-data "$dokudir"
 
     # Run the web server
-    /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf
+    exec /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf
 else
     # Handle custom commands otherwise
     exec "$@"