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Web Server Rescue

Show Published Container Ports

You need to map container ports to host ports without scanning firewall rules.

Command

docker port web

What changed

Nothing changes. Docker reads port mapping metadata.

Danger

safe

When to use it

Use when HTTP, SSH, database, or admin ports are unreachable from outside the container.

When not to use it

Do not use it alone for firewall diagnosis; a published port can still be blocked upstream.

Undo or recovery

No undo needed because this command is read-only.

Expected output

80/tcp -> 0.0.0.0:8080

demo script

Disposable terminal steps

  1. docker port web
  2. docker ps --filter name=web --format 'table {{.Names}}\t{{.Ports}}'
Terminal transcript Demo JSON

simulated output

What it looks like

disposable vessel 
::fixture-ready::
$ docker port web
80/tcp -> 0.0.0.0:8080
::exit-code::0
$ docker ps --filter name=web --format 'table {{.Names}}\t{{.Ports}}'
fake docker: ps --filter name=web --format table {{.Names}}\t{{.Ports}}
::exit-code::0

YouTube Short

Find Docker port mappings.

If the app is unreachable, first confirm Docker published the port. docker port shows the mapping directly.

LinkedIn hook

When a service is unreachable, confirm Docker is publishing the port you think it is.

Question: What is your first check when a containerized web service is unreachable?

experiments

A/B tests to run

Metric: click_through_rate

A: Confirm Docker published the port you think it did.

B: Unreachable service? Check the Docker port map first.