Docker Start Container From Image (Developer Tutorial)

What is Docker?

Docker is an open-source platform that automatically deploys and manages applications within lightweight, portable containers. Containers package an application along with its dependencies, which include libraries and configuration files, so it can run consistently across different environments. This consistency makes development and testing more straightforward because applications can run identically on diverse systems—whether on a developer's laptop, a server, or a cloud environment. Scalability in application management means developing, shipping, and running containers efficiently, which Docker facilitates.

Docker images make the specification of a consistent runtime environment much easier for developers. Most prebuilt images can be found in an open registry called Docker Hub, which developers can use directly or customize. For applications involving multiple containers, tools like Docker Compose orchestrate the container, whereas Kubernetes can manage even more complex scaling and automation. Docker has become an essential tool in software development and DevOps.

What is a Docker container?

A Docker container is essentially an application with all its dependencies—such as libraries, binaries, and configuration files—packed into a lightweight standalone executable entity. Containers designed in isolation run on top of a host operating system's kernel, avoiding interference from any other running software. Being easy to start, stop, or delete makes them ideal for testing, deployment, and scaling.

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.

What is a Docker image?

A Docker image is a blueprint for creating containers. It is read-only and layered, detailing the system files and dependencies needed to get an application running. Dockerfiles are used to create images, specifying how to build a Docker image, which might involve tasks such as installing software or copying files. Every change to a Dockerfile creates a new image layer, maintaining efficiency and modularity.

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

What is IronSecureDoc?

IronSecureDoc Docker is a containerized document processing solution by Iron Software that can automatically process documents in a Docker environment without human intervention. It offers complex document workflows and maximum data protection with encryption, digital signing, decryption, watermarking, and more for PDF and document files. It ensures consistent and scalable isolated deployments across platforms, making it suitable for DevOps and CI/CD pipeline integration.

This containerized approach enhances document handling in applications that require automation and high security, compatible with microservices and cloud-native environments. IronSecureDoc is especially useful for developers who create applications that require reliable automatic document processing in a controlled and portable Docker context.

Install and Run IronSecureDoc

Execute the following command from the Command Prompt or a terminal window to download the IronSecureDoc Docker image from the repository:

docker pull ironsoftwareofficial/ironsecuredoc

docker pull ironsoftwareofficial/ironsecuredoc

After pulling the Docker image, initiate another command to start an IronSecureDoc container.

Creating a new Container for 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

The above docker run command creates a container instance of IronSecureDoc.

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.

Conclusion

In simple terms, Docker simplifies application deployment because a developer can create a container from an image, ensuring uniformity in a portable and scalable environment. This results in the efficient running of applications across platforms and facilitates resource utilization, enhancing DevOps and CI/CD pipelines.

Similarly, IronSecureDoc Docker utilizes Docker's containerized architecture to offer secure, automated document processing solutions. Together, Docker and IronSecureDoc provide powerful tools for building secure, scalable applications in modern software development. For more information on licensing IronSecureDoc, click this licensing page, and for details about the many products of Iron Software, visit the library suite page.