fix(docker): Default config available in WORKDIR

When running arbitrary commands in the container, the default configuration and
subscription file paths don't work. I've tested using `$ docker compose up
--workdir="/config" ...` and the s6-overlay base image bits seem to work just fine, the
output from running cron jobs appears. Then running `$ ytdl-sub sub` without options
"Just Works", so I think baking a `WORKDIR` into the image should be OK, but this should
be tested further before breaking everybody's deployments.

I tested locally by bringing up the compose services and confirming from the output that
the s6-overlay init and cron seem to be working correctly. Then I ran `$ ytdl-sub sub
--dry-run` using both `$ docker compose run ...` and `$ docker compose exec ...`. Before
this change, it exits immediately with a message about the subscriptions file
missing. After this change, it starts to download the `NOVA PBS` subscription. In the
GUI image, I also tested the same command in the VS Code web UI terminal.

docker/Dockerfile

@@ -7,9 +7,11 @@ FROM ghcr.io/linuxserver/baseimage-alpine:edge
 ENV OPENSSL_CONF="/etc/ssl"
 # For downloading thumbnails
 ENV SSL_CERT_DIR="/etc/ssl/certs/"
+# Working directory used at both build and run times:
+ENV DEFAULT_WORKSPACE="/config"
 
 COPY root/ /
-RUN mkdir -p /config && \
+RUN mkdir -pv "${DEFAULT_WORKSPACE}" && \
     apk update --no-cache && \
     apk upgrade --no-cache && \
     apk add --no-cache --repository=http://dl-3.alpinelinux.org/alpine/edge/main/ \
@@ -58,12 +60,12 @@ RUN mkdir -p /config && \
 # CONTAINER CONFIGS
 
 ENV EDITOR="nano" \
-HOME="/config" \
+HOME="${DEFAULT_WORKSPACE}" \
 DOCKER_MODS=linuxserver/mods:universal-stdout-logs|linuxserver/mods:universal-cron \
-DEFAULT_WORKSPACE=/config \
-CRON_SCRIPT="/config/cron" \
-CRON_WRAPPER_SCRIPT="/config/.cron_wrapper" \
-LOGS_TO_STDOUT=/config/.cron.log \
+CRON_SCRIPT="${DEFAULT_WORKSPACE}/cron" \
+CRON_WRAPPER_SCRIPT="${DEFAULT_WORKSPACE}/.cron_wrapper" \
+LOGS_TO_STDOUT="${DEFAULT_WORKSPACE}/.cron.log" \
 LSIO_FIRST_PARTY=false
 
-VOLUME /config
+VOLUME "${DEFAULT_WORKSPACE}"
+WORKDIR "${DEFAULT_WORKSPACE}"

docker/Dockerfile.gui

@@ -81,9 +81,10 @@ ENV EDITOR="nano" \
 HOME="/config" \
 DOCKER_MODS=linuxserver/mods:universal-stdout-logs|linuxserver/mods:universal-cron \
 DEFAULT_WORKSPACE=/config/ytdl-sub-configs \
-CRON_SCRIPT="/config/ytdl-sub-configs/cron" \
+CRON_SCRIPT="${DEFAULT_WORKSPACE}/cron" \
 CRON_WRAPPER_SCRIPT="/config/.cron_wrapper" \
 LOGS_TO_STDOUT=/config/.cron.log \
 LSIO_FIRST_PARTY=false
 
-VOLUME /config
+VOLUME /config
+WORKDIR "${DEFAULT_WORKSPACE}"

docker/Dockerfile.ubuntu

@@ -7,13 +7,15 @@ ARG DEBIAN_FRONTEND=noninteractive
 ENV OPENSSL_CONF="/etc/ssl"
 # For downloading thumbnails
 ENV SSL_CERT_DIR="/etc/ssl/certs/"
+# Working directory used at both build and run times:
+ENV DEFAULT_WORKSPACE="/config"
 
 ###############################################################################
 # YTDL-SUB INSTALL
 
 SHELL ["/bin/bash", "-c"]
 COPY root/ /
-RUN mkdir -p /config && \
+RUN mkdir -pv "${DEFAULT_WORKSPACE}" && \
     apt-get -y update && \
     apt-get -y upgrade && \
     apt-get install --no-install-recommends -y \
@@ -81,12 +83,12 @@ RUN mkdir -p /config && \
 # CONTAINER CONFIGS
 
 ENV EDITOR="nano" \
-HOME="/config" \
+HOME="${DEFAULT_WORKSPACE}" \
 DOCKER_MODS=linuxserver/mods:universal-stdout-logs|linuxserver/mods:universal-cron \
-DEFAULT_WORKSPACE=/config \
-CRON_SCRIPT="/config/cron" \
-CRON_WRAPPER_SCRIPT="/config/.cron_wrapper" \
-LOGS_TO_STDOUT=/config/.cron.log \
+CRON_SCRIPT="${DEFAULT_WORKSPACE}/cron" \
+CRON_WRAPPER_SCRIPT="${DEFAULT_WORKSPACE}/.cron_wrapper" \
+LOGS_TO_STDOUT="${DEFAULT_WORKSPACE}/.cron.log" \
 LSIO_FIRST_PARTY=false
 
-VOLUME /config
+VOLUME "${DEFAULT_WORKSPACE}"
+WORKDIR "${DEFAULT_WORKSPACE}"