Regex in Windows Batch to automate Docker run - regex

Question

I am trying to automate the process of sending my temporary Amazon AWS keys as environment variables to a Docker image using Windows. I have a file, credentials.txt that contains my AWS credentials (the 3 ids are always the same, but the string values change regularly). I am using Windows command prompt.
Input:
(includes 2 empty lines at end) credentials.txt:
[default]
aws_access_key_id = STR/+ing1
aws_secret_access_key = STR/+ing2
aws_session_token = STR/+ing3
Desired output:
I need to issue the following command in order to run a Docker image (substituting the strings with the actual strings):
docker run -e AWS_ACCESS_KEY_ID=STR/+ing1 -e AWS_SECRET_ACCESS_KEY=STR/+ing2 -e AWS_SESSION_TOKEN=STR/+ing3 my-aws-container
My idea is to try to use regex on credentials.txt to convert it to:
SET aws_access_key_id=STR/+ing1
SET aws_secret_access_key=STR/+ing2
SET aws_session_token=STR/+ing3
And then run:
docker run -e AWS_ACCESS_KEY_ID=%aws_access_key_id% -e AWS_SECRET_ACCESS_KEY=%aws_secret_access_key% -e AWS_SESSION_TOKEN=%aws_session_token% my-aws-container
Does anyone have any advice on how to achieve this?

Answer 1

You can parse your credentials.txt with a for /f loop to set the variables (effectively removing the spaces):
for /f "tokens=1,3" %%a in ('type credentials.txt ^| find "="') do set "%%a=%%b"
and then run the last code line from your question:
docker run -e AWS_ACCESS_KEY_ID=%aws_access_key_id% -e AWS_SECRET_ACCESS_KEY=%aws_secret_access_key% -e AWS_SESSION_TOKEN=%aws_session_token% my-aws-container
Note: the values should not contain spaces or commas.

Answer 2

I've had a go in python that seems to work. Someone else may have a better answer.
I create the python file:
docker_run.py
import re
import os
myfile = 'C:/fullpath/credentials'
with open(myfile,'r') as f:
mystr = f.read()
vals = re.findall('=[\s]*([^\n]+)',mystr)
keys = ['AWS_ACCESS_KEY_ID','AWS_SECRET_ACCESS_KEY','AWS_SESSION_TOKEN']
environment_vars = ''.join([' -e ' + k + '=' + v for k,v in zip(keys,vals)])
cmd = 'docker run'+environment_vars+' my-aws-container'
os.system(cmd)
Then from command prompt I run:
python docker_run.py
This succeeds in running docker
(note: I tried using exec() in the final line rather than os.system(), but got the error "SyntaxError: invalid syntax")