Dockerfile for microservices - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Dockerfile in the context of microservices?

A Dockerfile is a simple text file that contains instructions to build a Docker image. For microservices, it defines how to package each service with its code, dependencies, and environment so it can run independently.

beginner

Why do microservices use Dockerfiles?

Microservices use Dockerfiles to create isolated, consistent environments for each service. This helps developers run, test, and deploy services independently without conflicts.

beginner

What is the purpose of the 'FROM' instruction in a Dockerfile?

The 'FROM' instruction sets the base image for the Docker image. It tells Docker which starting point to use, like a basic operating system or runtime environment needed for the microservice.

beginner

How does the 'COPY' instruction help in a Dockerfile for microservices?

The 'COPY' instruction copies files or folders from your local machine into the Docker image. This is how your microservice code and configuration files get included inside the container.

beginner

What does the 'CMD' instruction do in a Dockerfile?

The 'CMD' instruction specifies the command to run when the container starts. For microservices, it usually runs the service application so it begins listening for requests.

Which Dockerfile instruction sets the base image for a microservice?

A RUN

B COPY

C FROM

D CMD

The FROM instruction defines the base image for the Docker image.

What is the main purpose of a Dockerfile in microservices?

A To build a Docker image for each service

B To write the service code

C To deploy services to the cloud

D To monitor service health

Dockerfiles are used to build Docker images that package each microservice.

Which instruction copies your microservice code into the Docker image?

A COPY

B RUN

C EXPOSE

D ENV

COPY copies files from your local machine into the Docker image.

What does the CMD instruction do in a Dockerfile?

A Sets environment variables

B Copies files into the image

C Runs commands during image build

D Specifies the command to run when the container starts

CMD defines the command that runs when the container starts.

Why is it important to have a separate Dockerfile for each microservice?

A To avoid using Docker Compose

B To ensure each service runs in its own isolated environment

C To reduce the number of containers

D To combine all services into one container

Each microservice needs its own Dockerfile to run independently and avoid conflicts.

Explain the key instructions you would include in a Dockerfile for a simple microservice.

Think about how to build the image step-by-step.

Describe why Dockerfiles are essential for deploying microservices in containers.

Consider the benefits of packaging services with their dependencies.