Explanation how view log files

Fix #137

* Better description how to find log files
* Change default log to file but can be overridden by env var

README.md

@@ -53,6 +53,7 @@ docker run -d \
   -e DB_DATABASE='ninja' \
   -e DB_USERNAME='ninja' \
   -e DB_PASSWORD='ninja' \
+  -e LOG=errorlog \
   -p '9000:9000' \
   invoiceninja/invoiceninja
 ```
@@ -67,6 +68,32 @@ Run `cp .env.example .env` and change the environment variables as needed.
 The file assumes that all your persistent data is mounted from `/srv/invoiceninja/`.
 Once started, the application should be accessible at http://localhost:8000.
 
+
+## Debugging your Docker setup
+
+Even when running your Invoice Ninja setup with Docker - errors can occur. Depending on where the error happens - the webserver, Invoice Ninja or the database - different log files can be responsible. 
+
+### Show logs without `docker-compose`
+
+If you are not running the `docker-compose` you first need to find the container id for your php container with `docker ps`. Then you can run
+
+```shell
+docker logs -f <CONTAINER NAME>
+```
+
+This gives you a constant output of the log files for the php container.
+
+### Show logs with `docker-compose`
+
+If you are running the `docker-compose` setup you can output all logs, from all containers, with the following command
+
+```shell
+docker-compose logs -f
+```
+
+If you better want a physical log file in in your `storage/logs` folder, just remove this line `-e LOG=errorlog` from the [usage](#usage) command or change it to `-e LOG=single`. Both works.
+
+
 ### Known issues
 
 Phantomjs doesn't work on linux alpine https://github.com/ariya/phantomjs/issues/14186.

alpine/Dockerfile

@@ -52,7 +52,6 @@ RUN curl -o ninja.zip -SL https://download.invoiceninja.com/ninja-v${INVOICENINJ
 ######
 # DEFAULT ENV
 ######
-ENV LOG errorlog
 ENV SELF_UPDATER_SOURCE ''
 ENV PHANTOMJS_BIN_PATH /usr/local/bin/phantomjs