How to create file and mount file system as read only? - docker

Question

I have the following Dockerfile (I've removed what is not relevant):
FROM centos:centos6
ENV TERM=xterm
ARG INSTALL_WKHTMLTOPDF=no
ARG WKHTMLTOPDF_VERSION=latest
ARG INSTALL_PDFTK=no
ARG PDFTK_VERSION=latest
ARG PHP_VERSION=default
...
COPY container-files /
...
EXPOSE 80 9001
WORKDIR /var/www/html
ENTRYPOINT bash -C '/entrypoint.sh';'bash'
The entrypoint.sh is as follow:
#!/bin/bash
set -e
if [ "$UID" == 0 ]; then
uid=1000;
else
uid=${UID};
fi
if [ -z "${GID}" ]; then
gid=1000;
else
gid=${GID};
fi
echo "UID: $uid"
echo "GID: $gid"
touch /var/log/xdebug.log
chown apache:root /var/log/xdebug.log
rm -f /var/run/apache2/apache2.pid
exec httpd -DFOREGROUND "$#"
And finally the docker-compose.yml file:
version: '3.4'
services:
erx:
image: arx_dev
ports:
- "80:80"
environment:
VHOST_DOCUMENT_ROOT: /var/www/html
volumes:
- ./server_logs:/var/log/:ro
After build the image and try docker-compose up -d it does not start because touch can't create the file in a RO filesystem.
PS F:\Development\docker\rx> docker logs rx_erx_1
UID: 1000
GID: 1000
touch: cannot touch `/var/log/xdebug.log': Read-only file system
PS F:\Development\docker\rx>
How I can create the file and then mount the /var/log as read only? I would like to check some logs from the host directly and avoid bash into the container. Any ideas?