Docker Compose | Kazami Blog

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Why use Compose?

Benefits of docker compose

Simplified control

Efficient collaboration

Rapid application development

Portability across environments

Extensive community and support

Example

Running simple apps behind proxy (Caddy). Create docker-compose.yaml and Caddyfile in same folder

use nano or any text editor to create it

save with ctrl+x and y to save

with docker compose file in these i am want run 2 apps with image caddy:2 and hashicorp/http-echo and to run it just use docker compose up -d your app will automatically run. its will download the container image if you don't have it, and runt 2 apps in same time

lets try to run it

docker compose up -d

after finish you can see its running

and you can check your container app running with define in our compose.yaml

its defined from our compose and if you need changes you can update the docker-compose.yaml example changes. is change container name

and when run docker compose up -d its make changes to our previous docker container

name container changes from caddy → caddy_http_server its make an update on the container easy. so even the normal way make changes without compose can do it like rename container, not all things can do by docker command its self.

✅ Things you can change (without recreating the container):

Change Type	Command
Container name	`docker rename old_name new_name`
Resource limits (some)	`docker update --memory 512m container_name`
Restart policy	`docker update --restart=always container_name`
CPU shares/limits	`docker update --cpus=1 container_name`
Labels (in limited ways)	Only via `docker commit` + new container
Environment (inside)	You can `docker exec` and change environment manually, but it's not persistent
Files/configs inside the container	Use `docker exec`, `docker cp`, or bind mounts
Volumes (mount new ones)	`docker cp` to move files in/out, but volumes themselves are set at creation
ㅤ	ㅤ

❌ Things you cannot change (must recreate container):

Change	Why?
Published ports (`-p`)	Docker’s port bindings are fixed at start time
Environment variables (`-e`)	Set at container creation
Command or entrypoint	Set at creation (`CMD`, `ENTRYPOINT`)
Volume definitions (`-v`)	Must be defined at container start
Network mode (`--network`)	Set at container start
Image version	You need to pull a new image and re-run

so its will crucial if our app cannot make any changes.

Example

🚫 Without Docker Compose

You’d have to run each container manually

Disadvantages:

Have to manually manage each container.

Must ensure correct start order (e.g., DB before app).

No easy way to define a full environment in one file.

Harder to replicate the setup on another machine or server.

✅ With Docker Compose

Run with:

Advantages:

📝 Declarative configuration: All setup in one YAML file.

🧩 Easy orchestration: Automatically handles dependencies like DB.

🔁 Reproducibility: Easily version-controlled, shared, and deployed.

🧼 Cleaner CLI: One command to bring the whole app up or down.

🛠️ Scalability: Easily scale services (docker-compose up --scale).

🧪 Better for testing: Great for CI pipelines and local dev environments.

✅ Summary Table

Feature	Without Compose	With Compose
Manual container start	✅	❌ (one command)
Easy config reuse/version	❌	✅
Multi-service support	🔧 Manual	✅ Native
Dependency management	❌	✅ (`depends_on`)
Networking between services	Manual setup	Auto-managed
Portability	❌	✅

And in my opinion i more like to use compose if to manage multiple container. its easy whenever i want to update or configure env

Why use Compose?

Benefits of docker compose

Example

✅ Things you can change (without recreating the container):

❌ Things you cannot change (must recreate container):

🚫 Without Docker Compose

✅ With Docker Compose

✅ Summary Table

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