Cloud & DevOps
Dockerization: containerise your applications for reproducible deployments
Dockerizing an application means packaging it with its dependencies, configuration and runtime into a container image that runs the same way on a developer workstation, a staging server and production. It is the foundation of most modern deployment pipelines, whether they rely on Docker Compose, ECS or Kubernetes.
This service is for teams whose applications (Node.js, Java, Python, PHP) still depend on manual installation on servers, whose developer onboarding takes days, or who are preparing a migration to a container platform.
We write multi-stage Dockerfiles that produce lightweight images, set up Docker Compose for local development, configure a private registry, integrate image builds and scanning into CI, and harden runtime (non-root user, secrets, resource limits).
When do we step in?
Manual installation on every server
Every deployment replays a list of manual steps: language versions, extensions, system dependencies. A Docker image freezes all of it and removes differences between machines.
Developer onboarding takes too long
Running the application locally takes days of configuration. With Docker Compose, the application, its database and its supporting services start with a single command.
Preparing a migration to ECS or Kubernetes
These platforms only accept containers. Well-built, stateless images configured through environment variables are a prerequisite.
Existing images that are heavy or vulnerable
Your images weigh several gigabytes, ship build tools into production, run as root and accumulate known vulnerabilities. They slow down deployments and expose the infrastructure.
Legacy applications to isolate
An old application requires a PHP or Java version incompatible with the rest of the server. A container isolates it with its own versions without contaminating the host.
How we work
- 1
Application analysis
We identify system dependencies, files written to disk, configuration, side processes (scheduled tasks, workers) and health endpoints, in order to make the application stateless and configurable through environment variables.
- 2
Writing the Dockerfiles
Multi-stage Dockerfiles separating build and runtime, minimal base images (Alpine, distroless or slim), layer order optimised for caching, a .dockerignore file, a non-root user and a HEALTHCHECK instruction.
- 3
Development environment with Compose
A docker-compose file describing the application, database, cache and development tools, with hot reloading of code and persistent volumes for data.
- 4
Registry and build chain
Setting up a private registry (GitHub Container Registry, GitLab Registry, Amazon ECR), automated builds in CI tagged by commit and version, and build caching for fast builds.
- 5
Security and runtime
Image scanning with Trivy, secrets injected at runtime rather than baked into the image, read-only filesystem where possible, memory and CPU limits.
- 6
Deployment and documentation
Deployment to the target platform (Compose on a server, ECS, Kubernetes), logging to standard output, documented commands and handover to the team.
Technologies we use
- Docker and BuildKit
- Docker Compose
- Multi-stage Dockerfiles
- Alpine and distroless images
- GitHub Container Registry and Amazon ECR
- Trivy
- GitHub Actions and GitLab CI
- Node.js, Java, Python and PHP
- Nginx and Traefik
- Kubernetes and ECS
Why choose Agencei?
Genuinely optimised images
We measure image size and build time before and after. A production image must contain no compiler, no development dependencies and no secrets.
Application code expertise
Containerising sometimes requires adapting the application: externalised configuration, sessions off the disk, logs to standard output. We can make those changes in the code.
Security from the first image
Non-root user, vulnerability scanning in CI, updated base images and secrets managed outside the image are part of every delivery.
Ready for what comes next
The images we produce are ready for Kubernetes or ECS: stateless, environment-configured, with health probes and graceful shutdown on SIGTERM.
In brief
- What is this service?
- Dockerization packages an application and its dependencies into reproducible container images, with multi-stage Dockerfiles, Docker Compose for development, a private registry and CI/CD integration.
- Who is it for?
- Technical teams whose Node.js, Java, Python or PHP applications are still installed by hand, or who are preparing a deployment on ECS or Kubernetes.
- What problem does it solve?
- Removing differences between environments, speeding up developer onboarding, isolating legacy applications and producing lightweight, secure images.
- How long does it usually take?
- Often a few days for a standard application, several weeks for an older application requiring code adaptations or for a fleet of several services.
- What factors influence the price?
- The number of applications and supporting services, the state of the code (configuration, on-disk state), the languages involved, the expected security level and the target deployment platform.
- How does the engagement run?
- Application analysis, multi-stage Dockerfiles, Compose environment, registry and automated CI builds, image hardening, then deployment and documentation.
- What are the risks?
- Heavy or vulnerable images, secrets baked into the image, containers running as root, state written inside the container and lost on restart, and missing health probes.
- What alternatives exist?
- Virtual machines configured with Ansible, PaaS platforms that build containers for you, or a traditional installation when the application will never be deployed elsewhere.
Frequently asked questions
What is a multi-stage Dockerfile?
It is a Dockerfile that uses a first image to compile the application (with build tools) and then copies only the result into a minimal final image. The production image is much lighter and exposes a smaller attack surface.
Is Docker suitable for a production database?
It is possible, but we generally recommend a managed service (RDS, Cloud SQL) or a dedicated installation for production. In development and staging, however, a containerised database with a persistent volume is very convenient.
Is Docker Compose enough for production?
For a simple application on a single server, yes: Compose handles automatic restarts, networks and volumes. As soon as you need to spread load across several machines, autoscaling or zero-downtime deployments, an orchestration platform such as Kubernetes or ECS becomes relevant.
How should secrets be handled in containers?
Never in the image or the Dockerfile. Secrets are injected at runtime through environment variables, mounted files or a secrets manager (Docker secrets, AWS Secrets Manager, Vault). Image scanning in CI checks that no secret was baked in by mistake.
How long does it take to dockerize an application?
For a well-structured standard application, a few days is often enough. An older application with a lot of on-disk state or unusual system dependencies can take several weeks, including code adaptations.
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