Docker Certification (How it Works for Developers)

What is Docker?

Docker is a free, open-source containerization platform that makes it easier to develop, deploy, and maintain applications. It provides a lightweight container that includes an application and all its dependencies, allowing it to run in various environments—from the developer's personal computer to a production server. These containers are more efficient and faster because they share the operating system kernel of the host system, unlike traditional virtual machines.

Docker is not just about the engine; it provides a model to create, manage, and share containers. A key component of this model is Docker images, shared via Docker Hub—a special type of repository for storing and distributing container images. Docker is prominent in cloud-based development workflows and DevOps for its scalability, portability, and efficiency. Docker is available in two versions: Docker Community Edition and Docker Enterprise Edition.

What is a Docker certificate?

A Docker certificate is a digital document used to establish secure communications between a Docker client and a Docker server, such as a Docker daemon or a Docker registry, using HTTPS. It is a crucial component of Docker's TLS configuration, ensuring secure client-server interactions. This is particularly useful when deploying Docker in production or distributed environments.

Features of Docker Certificates

• TLS/SSL Authentication: TLS/SSL certificates authenticate clients and servers to confirm their legitimacy.
• Encryption: Certificates encrypt data transmission between client and server, ensuring data privacy.
• Mutual Authentication: Mutual TLS uses certificates for bi-directional authentication between client and server, ensuring security by requiring verification of both parties before data exchange.

Types of Certificates in Docker

• Server Certificate: Authenticates the Docker daemon to clients. It is installed on the server hosting Docker.
• Client Certificate: Granted to clients for authentication with a server, signed by a trusted CA.
• CA Certificate: Used by both parties, issued to sign server or client certificates to build trust.

Using a Custom Certificate Authority (CA)

To trust a custom CA, configure Docker to recognize it by storing the CA certificate in /etc/docker/certs.d/<your-registry>/ca.crt on your Docker host.

Using Docker with TLS

The Docker daemon can be secured with TLS by generating server and client certificates and configuring Docker to use them for communication.

Generate Certificates

To generate the necessary certificates using OpenSSL:

# Generate CA private key
openssl genrsa -aes256 -out ca-key.pem 4096

# Generate CA certificate
openssl req -new -x509 -days 365 -key ca-key.pem -sha256 -out ca.pem

# Generate CA private key
openssl genrsa -aes256 -out ca-key.pem 4096

# Generate CA certificate
openssl req -new -x509 -days 365 -key ca-key.pem -sha256 -out ca.pem

Generate client and server keys and certificates:

# Generate server private key
openssl genrsa -out server-key.pem 4096

# Create server certificate signing request (CSR)
openssl req -subj "/CN=your-server" -sha256 -new -key server-key.pem -out server.csr

# Sign the server certificate using the CA
openssl x509 -req -days 365 -sha256 -in server.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out server-cert.pem

# Generate server private key
openssl genrsa -out server-key.pem 4096

# Create server certificate signing request (CSR)
openssl req -subj "/CN=your-server" -sha256 -new -key server-key.pem -out server.csr

# Sign the server certificate using the CA
openssl x509 -req -days 365 -sha256 -in server.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out server-cert.pem

Finally, configure Docker to use these certificates by placing them in the appropriate directories and updating the Docker daemon configuration.

Configure Docker Daemon

Modify the Docker daemon configuration to use the generated certificates:

{
  "tls": true,
  "tlsverify": true,
  "tlscacert": "/etc/docker/ca.pem",
  "tlscert": "/etc/docker/server-cert.pem",
  "tlskey": "/etc/docker/server-key.pem",
  "hosts": ["tcp://0.0.0.0:2376", "unix:///var/run/docker.sock"]
}

Restart the Docker daemon to apply these settings.

Docker Certification Exam

The Docker Certified Associate (DCA) is an esteemed certification validating expertise in Docker capabilities. It entails approximately 55 multiple-choice and multiple-select questions in a 90-minute online proctored exam, covering domains such as orchestration, image management, installation and configuration, networking, security, and storage. Though there are no strict prerequisites, having at least six months of practical Docker experience is recommended. The certification is valid for two years. Preparation includes studying Docker documentation, practicing CLI commands, and using mock exams, enhancing career prospects in DevOps and container orchestration. Learn more about Docker training here.

What is IronSecureDoc?

IronSecureDoc is a product by Iron Software designed to secure documents, notably PDFs, through robust encryption and user permissions. Organizations benefit from advanced AES-256 encryption protocols, restricting access to sensitive information. Custom permissions govern printing, editing, or copying, thus enforcing authorized access. It supports password protection and digital signatures, ensuring document integrity and security, with watermarking options.

IronSecureDoc is developer-friendly, adaptable to applications running through Docker or other environments, crucial in industries like health, finance, and legal, where document confidentiality is paramount.

How Certificates Enhance IronSecureDoc Security

• Authentication: Allows user or system authentication on secured documents, granting only authorized access, vital for compliance, especially in regulated sectors like finance and healthcare.
• Encryption: Utilizes public key encryption to ensure only individuals with corresponding private keys can access files, preventing unauthorized access.
• Digital Signatures: Supports digital signing, confirming document origin and integrity, thereby building trust and fulfilling legal standards for digital transactions.

Install and Running IronSecureDoc

To pull the IronSecureDoc Docker image from the repository, execute:

docker pull ironsoftwareofficial/ironsecuredoc

docker pull ironsoftwareofficial/ironsecuredoc

Use the below command to run IronSecureDoc in a Docker container:

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

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

This command creates a running instance of IronSecureDoc.

Using IronSecureDoc

IronSecureDoc's REST API allows document redaction, certification, and encryption upon installation and launch in Docker. See documentation for more details.

To encrypt a document via IronSecureDoc API, use:

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 command sends the document to IronSecureDoc for encryption.

Conclusion

Docker certificates and IronSecureDoc offer a secure framework for managing documents in containerized environments. Docker certificates ensure encrypted and authenticated communication between Docker clients and servers, supporting the secure deployment and management of container-hosted applications like IronSecureDoc. This framework limits access to trusted entities, preventing unauthorized actions within server environments.

IronSecureDoc enhances document-specific security through encryption, access control, and digital signatures, protecting both infrastructure and sensitive data. For licensing information about IronSecureDoc, visit this page. For more about Iron Software's offerings, click here.