Dockerイメージからコンテナを開始する方法（開発者向けチュートリアル）

Docker container features

• Isolation: Containers run in isolated environments; applications will not conflict with one another, even if they use different sets of dependencies or libraries.
• Lightweight: Containers share the host operating system kernel, so they are small and have faster startup times than VMs.
• Portability: Containers are deterministic and can run on any system using Docker, ensuring consistency across development, test, and production environments.
• Scalability: Containers can be easily replicated and scaled, supporting fast deployment and management of microservices.
• Resource Efficiency: Containers consume fewer resources than VMs, allowing for higher density and efficient utilization of computing resources.

Features of a Docker Image

• Multi-Level Stack: Images are built with layers using Dockerfiles. Each instruction in a Dockerfile adds a layer, so images should be optimized to rebuild only changed layers.
• Reusability: Base images such as Ubuntu or Node.js can be reused across projects, saving development time and resources.
• Versioning: Images can be tagged for versioning, making it easier to roll back to previous versions if needed.
• Modularity: Changes to an image are incremental, enabling straightforward updates without rebuilding the entire image.
• Available on Docker Hub: Public and private image registries facilitate easy sharing and deployment of images.

How to create a Docker container

The Dockerfile is a text file providing instructions to create your Docker image. In this file, you specify the base image, dependencies, application code, environment variables, and commands to run the application. Here is a simple example:

# Use an official Node.js runtime as a parent image
FROM node:18

# Set the working directory in the container
WORKDIR /app

# Copy package.json and install dependencies
COPY package.json /app
RUN npm install

# Copy the rest of the application code
COPY . /app

# Expose the application’s port
EXPOSE 3000

# Define the command to run the application
CMD ["node", "app.js"]

Build the Docker Image

Use the Dockerfile to create your Docker image. At the terminal command line, from the directory containing your Dockerfile, execute:

Make sure Docker Desktop is installed before executing the below command.

docker build -t my-app .

docker build -t my-app .

This command creates an image named my-app. To confirm that it has been created, execute:

docker images

docker images

Run the Docker Container

With an image, you can create a Docker container and then run it using the docker run command. The Docker daemon will start and monitor the process either in detached mode (background) or in the foreground.

docker run -d -p 3000:3000 --name my-running-app my-app

docker run -d -p 3000:3000 --name my-running-app my-app

• -d: Run the container in detached mode.
• -p 3000:3000: Map the host's port 3000 to port 3000 in the container.
• --name my-running-app: Assign a user-defined name to the container.

Verify Container

To check the running Docker containers, use:

docker ps

docker ps

The above command shows the details of running containers, including container ID, name, image name, etc.

Stop and Remove Container

# Stop container
docker stop dazzling_snyder

# Remove container
docker rm dazzling_snyder

# Stop container
docker stop dazzling_snyder

# Remove container
docker rm dazzling_snyder

Install and Run IronSecureDoc

docker pull ironsoftwareofficial/ironsecuredoc

docker pull ironsoftwareofficial/ironsecuredoc

docker container run --rm -p 8080:8080 -e ENVIRONMENT=Development -e HTTP_PORTS=8080 ironsoftwareofficial/ironsecuredoc:latest

docker container run --rm -p 8080:8080 -e ENVIRONMENT=Development -e HTTP_PORTS=8080 ironsoftwareofficial/ironsecuredoc:latest

Using IronSecureDoc container

IronSecureDoc enables users to install and run Docker to redact, certify, or encrypt files through its REST API.

For instance, to encrypt a document, you can make a POST request to the IronSecureDoc API:

curl -X 'POST' \
  'http://localhost:8080/v1/document-services/pdfs/encrypt?user_password=demo' \
  -H 'accept: */*' \
  -H 'Content-Type: multipart/form-data' \
  -F 'pdf_file=@test.pdf;type=application/pdf'

curl -X 'POST' \
  'http://localhost:8080/v1/document-services/pdfs/encrypt?user_password=demo' \
  -H 'accept: */*' \
  -H 'Content-Type: multipart/form-data' \
  -F 'pdf_file=@test.pdf;type=application/pdf'

This forwards the document to IronSecureDoc, which processes and encrypts the data accordingly.