Add a couple of questions on containers
Also, fixed some minor styling issues in random_question.py script.
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README.md
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README.md
@ -2,7 +2,7 @@
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:information_source: This repo contains questions and exercises on various technical topics, sometimes related to DevOps and SRE :)
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:bar_chart: There are currently **1825** questions
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:bar_chart: There are currently **1840** questions
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:books: To learn more about DevOps and SRE, check the resources in [devops-resources](https://github.com/bregman-arie/devops-resources) repository
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@ -6033,6 +6033,16 @@ It specifies the base layer of the image to be used. Every other instruction is
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* WORKDIR: sets the working directory inside the image filesystems for all the instructions following it
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* EXPOSE: exposes the specified port (it doesn't adds a new layer, rather documented as image metadata)
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* ENTRYPOINT: specifies the startup commands to run when a container is started from the image
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* ENV: sets an environment variable to the given value
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* USER: sets the user (and optionally the user group) to use while running the image
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</b></details>
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<details>
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<summary>What are some of the best practices regarding writing Dockerfiles that you are following?</summary><br><b>
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* Include only the packages you are going to use. Nothing else.
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* Specify a tag in FROM instruction. Not using a tag means you'll always pull the latest, which changes over time and might result in unexpected result.
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* Do not use environment variables to share secrets
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</b></details>
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<details>
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@ -6333,6 +6343,16 @@ you with more options/features compared to Docker Hub. One example is
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Swarm management which means you can create new swarms in Docker Cloud.
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</b></details>
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#### Containers - Security
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<details>
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<summary>A container can cause a kernel panic and bring down the whole host. What preventive actions can you apply to avoid it?</summary><br><b>
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* Install only the necessary packages in the container
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* Set volumes and container's filesystem to read only
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* DO NOT run containers with `--privilged` flag
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</b></details>
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#### Containers - Docker in Production
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<details>
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@ -9,4 +9,18 @@
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### Bonus
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Containerize the app of the project you forked using any containerization technology you would like.
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Containerize the app of the project you forked using any container engine you would like (e.g. Docker, Podman).<br>
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Once you successfully ran the application in a container, submit the Dockerfile to the original project (but be prepared that the maintainer might not need/want that).
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### Suggestions for Projects
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The following is a list of projects without CI (at least at the moment):
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Note: I wrote a script to find these (except the first project on the list, of course) based on some parameters in case you wonder why these projects specifically are listed.
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* [This one](https://github.com/bregman-arie/devops-exercises) - We don't have CI! help! :)
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* [image retrieval platform](https://github.com/skx6/image_retrieval_platform)
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* [FollowSpot](https://github.com/jenbrissman/FollowSpot)
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* [Pyrin](https://github.com/mononobi/pyrin)
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* [food-detection-yolov5](https://github.com/lannguyen0910/food-detection-yolov5)
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* [Lifely](https://github.com/sagnik1511/Lifely)
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@ -6,18 +6,9 @@
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https://github.com/bregman-arie/node-hello-world
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https://github.com/bregman-arie/flask-hello-world
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```
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`git clone https://github.com/bregman-arie/node-hello-world`
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2. Write a Dockerfile you'll use for building an image of the application (you can use any base image you would like)
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```
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FROM alpine
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LABEL maintainer="your name/email"
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RUN apk add --update nodejs nodejs-npm
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COPY . /src
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WORKDIR /src
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RUN npm install
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EXPOSE 8080
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ENTRYPOINT ["node", "./app.js"]
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```
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3. Build an image using the Dockerfile you've just wrote
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4. Verify the image exists
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5. [Optional] Push the image you've just built to a registry
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6. Run the application
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7. Verify the app is running
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54
exercises/devops/solutions/containerize_app.md
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54
exercises/devops/solutions/containerize_app.md
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## Containerize an Application
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1. Clone an open source project you would like to containerize. A couple of suggestions:
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```
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https://github.com/bregman-arie/node-hello-world
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https://github.com/bregman-arie/flask-hello-world
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```
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`git clone https://github.com/bregman-arie/node-hello-world`
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2. Write a Dockerfile you'll use for building an image of the application (you can use any base image you would like)
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```
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FROM alpine
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LABEL maintainer="your name/email"
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RUN apk add --update nodejs npm
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COPY . /src
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WORKDIR /src
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RUN npm install
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EXPOSE 3000
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ENTRYPOINT ["node", "./app.js"]
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```
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3. Build an image using the Dockerfile you've just wrote
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`docker image build -t web_app:latest .`
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4. Verify the image exists
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`docker image ls`
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5. [Optional] Push the image you've just built to a registry
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```
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docker login
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docker image tag web_app:latest <your username>/web_app:latest
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# Verify with "docker image ls"
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docker image push <your username>/web_app:latest
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```
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6. Run the application
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```
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docker container run -d -p 80:3000 web_app:latest
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```
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7. Verify the app is running
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```
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docker container ls
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docker logs <container ID/name>
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# In the browser, go to 127.0.0.1:80
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```
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@ -3,48 +3,51 @@ import optparse
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def main():
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""" Reads through README.md for question/answer pairs and adds them to a list to randomly select from and quiz yourself.
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- supports skipping quesitons with no documented answer with the -s flag
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"""Reads through README.md for question/answer pairs and adds them to a
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list to randomly select from and quiz yourself.
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Supports skipping quesitons with no documented answer with the -s flag
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"""
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parser = optparse.OptionParser()
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parser.add_option("-s", "--skip", action="store_true",help="skips questions without an answer.", default=False)
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parser.add_option("-s", "--skip", action="store_true",
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help="skips questions without an answer.",
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default=False)
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options, args = parser.parse_args()
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with open('README.md', 'r') as f:
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text = f.read()
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questions = []
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while True:
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question_start = text.find('<summary>') + 9
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question_end = text.find('</summary>')
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answer_end = text.find('</b></details>')
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if answer_end == -1:
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break
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question = text[question_start: question_end].replace('<br>', '').replace('<b>', '')
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answer = text[question_end + 17: answer_end]
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questions.append((question, answer))
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text = text[answer_end + 1:]
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num_questions = len(questions)
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while True:
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try:
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question, answer = questions[random.randint(0, num_questions)]
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if options.skip and not answer.strip():
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continue
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if input(f'Q: {question} ...Show answer? "y" for yes: ').lower() == 'y':
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print('A: ', answer)
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except KeyboardInterrupt:
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break
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print("\nGoodbye! See you next time.")
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if __name__ == '__main__':
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main()
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