The goal of this lab exercise is to explore the use of docker-compose to automate full stack/end-to-end system integration tests. Docker-compose facilitates the creation of an entire environment of services along with their dependencies using easy to understand scripting language. The system we will use in this lab consists of a Flask simple webapp that keeps track and displays the number of visitors. The Flask app uses a Redis instance to store and counts the number of visitors. Docker-compose will be used to bring up the Flask app and its Redis dependency. Besides the app, a test driver script running on a separate container will be used to initiate an http query, parse the result, and assert the output.
Readings: -
- Docker compose quick tutorial
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- Docker compose version 3 reference
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Steps: 1-Read the docker-compose tutorial carefully and follow the instructions to build the environment. 2-Build and run docker compose: $sudo docker-compose -f ./docker-compose.yml -p lab-4 build $sudo docker-compose -f ./docker-compose.yml -p lab-4 up -d 3-Open-up a browser and type in and navigate to (localhost:5000); you should see the Hello World message. 4-On a command terminal, use curl to retrieve the page: $curl http://localhost:5000/ You should see the following: Hello World! I have been seen 10 times. 5-Use the following command to parse out the number of visits from the html page $curl -s http://localhost:5000/ |sed \'s/Hello World.*\\([0-9]\\{1,\\}\\) times./\\1/\' You should see the number of times the page has been visited so far 11 6-Next step is put the above curl and parsing logic in a bash script; the bash script represents a test script and should print out PASSED or FAILED. 7-Add a new docker image into the docker environment. The added image is used to drive and run the testing script.
Files provided: 1-app.py: Flask app 2-docker-compose.yml: docker compose file where environment specification will be provided 3-Dockerfile.app: a docker file used for building of docker Flask app image. 4-requirements.txt: python module dependencies.
Deliverables: 1-test.sh script: script that use curl, parses out the visits number and prints out PASSED or FAILED. 2-Dockerfile.test: docker file for the test machine image. 3-New docker-compose.yml file: the new docker-compose file with the test driver machine/image added to the test environment. 4-Screenshots showing:
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- Successful building of docker compose environment
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- Successful run of the end to end test
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Some useful commands: To show running services $sudo docker-compose ps --services web redis test_client Get logs for a specific container $sudo docker logs lab-4_test_client_1 Test Passed! To build/rebuild docker-compose $sudo docker-compose -f ./docker-compose.yml -p lab-4 build To bring the entire environment up $sudo docker-compose -f ./docker-compose.yml -p lab-4 up -d To bring the entire environment down $sudo docker-compose -f ./docker-compose.yml -p lab-4 down
