Docker does not support including a Dockerfile in another Dockerfile, luckily the Dockerfile plus project comes to the rescue.
Simply setup your Dockerfile with:
# syntax = edrevo/dockerfile-plus:0.1.0
INCLUDE+ someDockerfile
FROM someimage
You might need to enable Docker buildkit in order to use this extension, simply set the environment variable:
DOCKER_BUILDKIT=1
When running applications in containers, we might have log files that are relevant to monitor but are not automatically printed with the container output.
A workaround for this is to force the redirect in our Dockerfile by adding a symbolic link:
RUN ln -sf /dev/stdout /path/to/logfile.log
Can also be applied to /dev/stderr of course
Sometimes a Java based app running in a container requires UTF8 encoding. Not all available images enable that by default, this can be fixed by adding one line to your Dockerfile setting the JAVA_TOOL_OPTIONS environment variable:
ENV JAVA_TOOL_OPTIONS -Dfile.encoding=UTF8
This also works outside containers of course.
I recently needed to make a script automatable, meaning I had to provide all inputs to it from the CLI command used to execute it, rather than wait for it to prompt me during execution.
Turns out Python has a nice module dedicated to this: argparse
The usage is very simple and will also create the help menu automatically for us:
import argparse
parser = argparse.ArgumentParser("myScript")
parser.add_argument("-a_flag_input", help="This is a true/false flag", action='store_true')
parser.add_argument("-a_string_input", help="This is a string input", type=str)
args = parser.parse_args()
options = vars(args)
print(args)
if options["a_flag_input"]:
print("a_string_input")
Basically, we define each input parameter along with its type, if the input is a flag (true/false) we can specify an action on it to determine the value it would receive if set.
The inputs will be collected in a Namespace object, which we can convert to dictionary and get easy access to the inputs from the code.