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DOCKER FIELD GUIDE // 04

Verify Docker storage and network connections

Create named infrastructure first, attach containers explicitly, and test membership and name-based communication.

Scenario

Persistent data and service communication must survive routine cleanup and redeployment.

Practice this worldBrowse all Docker commands

BEFORE YOU START

Prerequisites and boundaries

  • Choose names that will not collide with existing volumes, networks, or containers.
  • Know which data must persist independently of a container lifecycle.
  • Use disposable sample data when practicing volume and cleanup commands.

OPERATIONAL REASONING

Why this sequence matters

The goal is not merely to memorize commands. Each inspection, change, and verification step reduces a different failure mode.

01

Create named resources first

Explicit infrastructure is easier to inspect, reuse, back up, and remove intentionally.

02

Inspect membership before testing

Network and mount metadata reveal whether the expected attachment actually occurred.

03

Test from the consumer

Name resolution and connectivity should be verified from the container that depends on the service.

STANDARD PROCEDURE

Create persistent storage and attach it to a container before inspecting the result.

Create and inspect storage before mounting it, then inspect and locate the resulting container.

  1. 01
    docker volume create appdataDocker volume create reference ↗
  2. 02
    docker volume inspect appdataDocker volume inspect reference ↗
  3. 03
    docker run -d --name myapp -v appdata:/app/data nginxDocker run -d reference ↗
  4. 04
  5. 05
    docker ps --filter name=myappDocker ps --filter reference ↗

INCIDENT RESPONSE

Create an isolated network and verify communication between two named containers.

Create the network first, attach both containers, inspect network membership, then test name-based communication from the client.

  1. 01
    docker network create appnetDocker network create reference ↗
  2. 02
    docker run -d --name web --network appnet nginxDocker run -d reference ↗
  3. 03
    docker run -d --name client --network appnet alpine sleep 3600Docker run -d reference ↗
  4. 04
    docker network inspect appnetDocker network inspect reference ↗
  5. 05
    docker exec client ping -c 3 webDocker exec client reference ↗

COMMON FAILURE MODES

What usually goes wrong

  • An anonymous volume preserved unexpected data or became difficult to identify.
  • Two containers used different networks and could not resolve each other by name.
  • Cleanup commands removed volumes that still contained the only copy of application data.

VERIFICATION

Evidence to collect

  • docker volume inspect shows the expected named volume and mountpoint metadata.
  • docker network inspect lists both intended containers.
  • A request from the client container reaches the service by its container or network alias.