Tool
Docker and containers
A container packages an application with everything it needs, so it behaves the same wherever it runs. It removes the 'works on my machine' problem and makes releases repeatable. We use Docker for most deployable software, and we say when it is not worth the trouble.
- 1,200+ clients helped
- Building since 2010
- 15 services, one team
- 50+ technologies
At a glance
What it is
Docker packages an application and everything it needs into a container, a sealed unit that runs the same way on a laptop, a test server, or in the cloud.
Problems it solves
Software that works on one machine fails on another because of small differences in versions and settings, and releases depend on one person's careful steps.
Who it suits
Teams deploying software to servers or the cloud, and developers who lose time to set-up and environment differences.
How to choose
Use containers when software must run the same in several places or be released often. Skip them for a single simple site on managed hosting.
What it means
A sealed box for software
Docker is a tool for building and running containers. A container holds an application plus its libraries and settings, and runs in isolation from other containers on the same machine. It is lighter than a full virtual machine.
The benefit is predictability. If it ran in the container in testing, it will run in the same container in production, because it is the same package.
Containers are a means, not a goal. They matter most when software is released often, runs in several places, or is built by several people with different machines.
Alternatives
Containers compared with other ways of deploying
Containers
Suits
Applications released often or run in several places.
- Trade-off
- A new skill, and a build process to maintain.
Virtual machines
Suits
Whole systems that must be isolated, or older software.
- Trade-off
- Heavier, and slower to start and update.
Platform hosting without containers
Suits
Standard applications on a host that handles the environment.
- Trade-off
- Less control over the environment.
Functions on demand
Suits
Short, event-driven pieces of code.
- Trade-off
- Awkward for long-running work.
Choosing the right approach
What containers do not do
A container does not make an application secure, fast, or well designed. It only makes it portable and repeatable. A badly built container is just a portable problem.
We build images from trusted bases, keep them small, scan them for known flaws, and avoid putting secrets inside them.
Where it fits
Do you need containers?
They are very common, but not always necessary.
What are you running?
Choose this when
A brochure site or a standard content platform on a host that handles it for you.
- What you get
- Probably no containers. The host already provides a repeatable environment.
- Keep in mind
- Adding containers here can be extra complexity for little gain.
Choose this when
A web application or API that you or a team release regularly.
- What you get
- Containers give each release the same package from the developer's machine to production.
- Keep in mind
- Invest in the build pipeline, or the benefit is lost.
Choose this when
Several applications, several teams, and a need to run and scale them together.
- What you get
- Containers plus an orchestrator such as Kubernetes, if the scale justifies it.
- Keep in mind
- Orchestration is a large step. Start with simpler container hosting if you can.
Typical uses
Where containers help most
A web application released every week
The same package passes through testing and goes live, so what was tested is what runs.
A team with different laptops
A new developer starts the whole application locally with one command, and gets the same setup as everyone else.
Scheduled and background jobs
Reports and data processing run in the same controlled environment as the application.
A move between hosts
A packaged application is easier to move from a server to a managed cloud service, or between clouds.
What DECHY can do
Working with Docker
Package
- Containerizing existing applications.
- Small, secure images with clear build steps.
Develop
- Local environments that start with one command.
- Matching test and live set-ups.
Release
- Pipelines that build, test, and deploy containers.
- Safe rollouts and quick rollbacks.
Run
- Hosting on managed container services.
- Monitoring and updates.
Common questions
Questions about Docker
Is a container the same as a virtual machine?
No. A virtual machine includes a whole operating system. Containers share the host's and are much lighter, which is why they start fast.
Do we need Kubernetes as well?
Not usually at first. Many applications run well on a managed container service. Kubernetes becomes useful at larger scale.
Can you containerize our existing application?
Usually, yes. We assess how it is built and configured, then package it and test it in a copy of your environment.
Are containers secure?
They help isolate applications, but security depends on how images are built and run. We follow practices that reduce risk and scan regularly.
Have a different question?
Tell us what you are weighing up and we will answer it plainly.
Ask a questionAlready a client? Email support@dechytech.com
Technical depth
How we build with Docker
What we settle early on Docker work: images, configuration, and delivery, so nothing surprises your team later.
We use multi-stage builds to keep final images small, pin base image versions, run as a non-root user, and scan images for known vulnerabilities in the pipeline.
- Settings through environment variables, and secrets from a secrets manager, never baked into images.
- Health checks and graceful shutdown so releases do not drop requests.
- Images built once in a pipeline such as GitHub Actions, and promoted unchanged from testing to production.
- Local environments with Compose so new developers are productive on the first day.
Tell us how your software is released
Describe how it runs and how a release happens today. We will say whether containers would help and how to adopt them without disruption.