Add support for storing data in bind-mounted directories

Dockerfile

@@ -33,8 +33,7 @@ RUN DEBIAN_FRONTEND=noninteractive \
 RUN wget -q -O /dokuwiki.tgz "http://download.dokuwiki.org/src/dokuwiki/dokuwiki-$DOKUWIKI_VERSION.tgz" && \
     if [ "$DOKUWIKI_CSUM" != "$(md5sum /dokuwiki.tgz | awk '{print($1)}')" ];then echo "Wrong md5sum of downloaded file!"; exit 1; fi && \
     mkdir /dokuwiki && \
-    tar -zxf dokuwiki.tgz -C /dokuwiki --strip-components 1 && \
-    rm dokuwiki.tgz
+    tar -zxf dokuwiki.tgz -C /dokuwiki --strip-components 1
 
 # Set up ownership
 RUN chown -R www-data:www-data /dokuwiki
@@ -44,8 +43,11 @@ ADD dokuwiki.conf /etc/lighttpd/conf-available/20-dokuwiki.conf
 RUN lighty-enable-mod dokuwiki fastcgi accesslog
 RUN mkdir /var/run/lighttpd && chown www-data.www-data /var/run/lighttpd
 
+COPY docker-startup.sh /startup.sh
+
 EXPOSE 80
 VOLUME ["/dokuwiki/data/","/dokuwiki/lib/plugins/","/dokuwiki/conf/","/dokuwiki/lib/tpl/","/var/log/"]
 
-ENTRYPOINT ["/usr/sbin/lighttpd", "-D", "-f", "/etc/lighttpd/lighttpd.conf"]
+ENTRYPOINT ["/startup.sh"]
+CMD ["run"]
 

README.md

@@ -12,6 +12,17 @@ You can now visit the install page to configure your new DokuWiki wiki.
 For example, if you are running container locally, you can acces the page 
 in browser by going to http://127.0.0.1/install.php
 
+### Run with bind mounts ###
+
+The run command above will store your data in internal Docker volumes. If you prefer to bind mount directories on your file system, then you can use the `-v` parameter, for example:
+
+    docker run -d -p 80:80 --name my_wiki \
+        -v /data/docker/dokuwiki/data:/dokuwiki/data \
+        -v /data/docker/dokuwiki/conf:/dokuwiki/conf \
+        -v /data/docker/dokuwiki/lib/plugins:/dokuwiki/lib/plugins \
+        -v /data/docker/dokuwiki/lib/tpl:/dokuwiki/lib/tpl \
+        -v /data/docker/dokuwiki/logs:/var/log
+
 ### Run a specific version ###
 
 When running the container you can specify version to download from docker registry by using couple provided tags like *stable* which contains current stable release (this is generaly the same as *latest*) or *oldstable*. You can also use specific version like *2016-06-26a*.
@@ -20,6 +31,8 @@ When running the container you can specify version to download from docker regis
 To upate the image:
 -------------------
 
+### With internal volumes ###
+
 First stop your container
 
 	docker stop my_wiki
@@ -42,6 +55,10 @@ afterwards you can remove data container if you want
 
 (or keep it for next update, takes no space anyway..)
 
+### With bind mounts ###
+
+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.
+
 Optimizing your wiki
 --------------------
 
@@ -55,3 +72,4 @@ Build your own
 --------------
 
 	docker build -t my_dokuwiki .
+

docker-startup.sh

@@ -0,0 +1,68 @@
+#!/bin/bash
+
+set -eu
+set -o pipefail
+
+# Updating DokuWiki may need to change files in directories which we hold in
+# volumes, e.g. `data` or `conf`. Therefore, we need to make sure these files
+# are there when the container is started, not only when it is created. We do
+# this by keeping track which version we last installed and update as necessary,
+# or fully populate these folders if this is the first run.
+
+dokudir=/dokuwiki
+verfile=.last-version
+
+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
+
+if [ "$1" = 'run' ] || [ "$1" = 'downgrade' ] || [ "$1" = 'overwrite' ]; then
+    # Check each volume directory in turn
+    for d in conf data lib/plugins lib/tpl; do
+        if [ -f "$dokudir/$d/$verfile" ]; then
+            volumever="$(date -f <(awk '{print $1}' "$dokudir/$d/$verfile" | tr -d '[:alpha:]') +%s)"
+        else
+            volumever=0
+        fi
+
+        if [ "$volumever" -eq "$containerver" ] && [ ! "$overwrite" -eq 1 ]; then
+            # Do nothing for equal versions
+            continue
+        elif [ "$volumever" -lt "$containerver" ] || [ "$downgrade" -eq 1 ] || [ "$overwrite" -eq 1 ]; then
+            # Update if the container version is newer than the volume version
+            # Or if overridden using `downgrade`
+            echo "Migrating $d..."
+            cp -r "$tmpdir/$d/"* "$dokudir/$d/"
+            cp "$tmpdir/VERSION" "$dokudir/$d/$verfile"
+        elif [ "$volumever" -gt "$containerver" ]; then
+            # Otherwise print an error message and stop
+            cat >&2 <<EOM
+This volume has perviously been used with a newer version of DokuWiki.
+If you want to force a downgrade (at your own risk!), run the \`downgrade\` command:
+    docker run ... andreipoe/dokuwiki donwgrade 
+EOM
+        exit 2
+        fi
+    done
+
+    # Ensure persmissions are set correctly
+    chown -R www-data:www-data "$dokudir"
+
+    # Run the web server
+    /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf
+else
+    # Handle custom commands otherwise
+    exec "$@"
+fi
+