Chapter 6: Docker Images and Containers
6.5 Port publish -p — host port to container port
docker run -d --name badge-api -p 8080:8080 badge-api-hello:0.1
# host:container
Meaning: traffic that hits the host on counter 8080 goes to the container on counter 8080. You can map differently: -p 3000:8080 means host 3000 → container 8080.
| Idea | Reminder |
|---|---|
| Server / laptop IP | The building address |
| Host port | Shop counter on the building street side |
| Container port | Counter inside the app box |
EXPOSE |
Label on the box — not the street door |
Safety. Publish only what you need. Do not publish database ports to the world on a public VM. For labs on a cloud VM, lock Security Groups the way the AWS course taught — we do not re-open VPC design here.
Ravindra Bagale's Tip
Khup students DB port -p 5432:5432 public VM var sodtat. Lab asel tari SG tight theva; prod madhe DB private network / non-public. Only required counters publish kara. Dhyan rakho!
Practice task
Explain -p 3000:8080 in one building/shop-counter sentence. Who knocks on 3000? Who listens on 8080?