Run an arbitrary script in a bash script via Docker containers. See `build_and_run_demo.sh` to build and run demo.

build_and_run_demo.sh

#!/bin/bash
set -e
docker build --build-arg=GCLOUD_VERSION=226.0.0 -t gcloud-bash -f Dockerfile-gcloud-bash .
docker build -t flask-bash -f Dockerfile-flask-bash .

PORT=5000
docker run -d --name flask-server -p ${PORT}:${PORT} -e PORT=${PORT} flask-bash
echo "3 second sleep for server warmup..."
sleep 3
curl -X POST "localhost:${PORT}/do"

# Cleanup
docker stop flask-server
docker container rm flask-server

Dockerfile-flask-bash

FROM gcloud-bash

# Common utils also used with gcloud/bash
RUN apt-get update -qqy \
  && apt-get -qqy install python3-virtualenv python3-pip\
  && apt-get -qyy autoremove \
  && rm -rf /var/lib/apt/lists/* /var/cache/apt/*

RUN pip3 install flask flask-api

# Copy server and example script
COPY server.py script.sh ./
RUN chmod +x script.sh

# Boot server
CMD ["python3","server.py"]

Dockerfile-gcloud-bash

FROM buildpack-deps:jessie

ARG GCLOUD_VERSION
ARG GCLOUD_AUTO_UPGRADE

# Common utils also used with gcloud/bash
RUN apt-get update -qqy \
  && apt-get -qqy install jq \
  && apt-get -qyy autoremove \
  && rm -rf /var/lib/apt/lists/* /var/cache/apt/*

COPY install_gcloud.sh ./
RUN chmod +x install_gcloud.sh && ./install_gcloud.sh ${GCLOUD_VERSION} ${GCLOUD_AUTO_UPGRADE}\
  && rm install_gcloud.sh

# Add to path
# See also /opt/gcloud/google-cloud-sdk/path.bash.inc
ENV PATH="/opt/gcloud/google-cloud-sdk/bin:${PATH}"

install_gcloud.sh

#!/bin/bash
set -e

GCLOUD_VERSION=$1
GCLOUD_AUTO_UPGRADE=$2 # use latest

if [ -x "/root/google-cloud-sdk" ]; then
    echo "Skipping gcloud install, already installed"
else
    echo "Installing gcloud [${GCLOUD_VERSION}] from installer.sh"
    mkdir /opt/gcloud -p
    cd /opt/gcloud

    wget --quiet -O gcloud.tgz "https://dl.google.com/dl/cloudsdk/channels/rapid/downloads/google-cloud-sdk-${GCLOUD_VERSION}-linux-x86_64.tar.gz"
    tar -xf gcloud.tgz
    rm gcloud.tgz

    ./google-cloud-sdk/install.sh --quiet
    source /opt/gcloud/google-cloud-sdk/path.bash.inc

    gcloud components install --quiet kubectl alpha beta

    if [ "${GCLOUD_AUTO_UPGRADE}" = 'true' ]; then
        echo "Upgrade to latest gcloud version"
        gcloud components update --quiet
    fi

fi

gcloud --version # Sanity check

script.sh

#!/bin/bash
set -e

echo "This is an EMPTY example script"

server.py

#!bin/python3
import os
from flask import Flask, jsonify
from flask_api.status import HTTP_200_OK, HTTP_500_INTERNAL_SERVER_ERROR
from subprocess import Popen, PIPE, TimeoutExpired
from signal import SIGTERM

app = Flask(__name__)

# Target script is assumed to be in the same directory
TARGET_COMMAND='./script.sh'
TIMEOUT_SECONDS=60

@app.route('/do', methods=['POST'])
def index():
    # Make all children in same process group so we can clean up things spawned by bash script
    process = Popen(['bash', '-c', TARGET_COMMAND], stdout=PIPE, stderr=PIPE, preexec_fn=os.setsid)

    try:
        out, err = process.communicate(timeout=TIMEOUT_SECONDS)

        if err:
            return prepare_json(err.decode("utf-8"), success=False), HTTP_500_INTERNAL_SERVER_ERROR

        return prepare_json(out.decode("utf-8")), HTTP_200_OK

    except TimeoutExpired as e:
        os.killpg(os.getpgid(process.pid), SIGTERM) # Send term to bash and all process groups

        return prepare_json('Process timedout in [%d] seconds' % (TIMEOUT_SECONDS,), success=False), HTTP_500_INTERNAL_SERVER_ERROR

    except Exception as e:
        os.killpg(os.getpgid(process.pid), SIGTERM) # Send term to bash and all process groups

        return prepare_json('Process exception', success=False), HTTP_500_INTERNAL_SERVER_ERROR

def prepare_json(message, success=True):

    result = {
        'success': success,
        'message': message.strip()
    }

    return jsonify(result)

if __name__ == '__main__':
    port=os.environ['PORT']
    app.run(debug=False,host='0.0.0.0',port=port)