Container states (created, running, paused, stopped) in Docker - Step-by-Step Execution

Process Flow - Container states (created, running, paused, stopped)

Container Created

↓

Container Running

↓

Paused

↓

Running

A container starts in 'created' state, then moves to 'running'. It can be paused and resumed back to running, or stopped to end.

Execution Sample

Docker

docker create alpine
docker start <container>
docker pause <container>
docker unpause <container>
docker stop <container>

Shows commands to create, start, pause, unpause, and stop a Docker container, changing its state step-by-step.

Process Table

Step	Command	Container State Before	Action	Container State After
1	docker create alpine	none	Create container	created
2	docker start <container>	created	Start container	running
3	docker pause <container>	running	Pause container	paused
4	docker unpause <container>	paused	Resume container	running
5	docker stop <container>	running	Stop container	stopped

💡 Container stopped, no further state changes without restart or removal.

Status Tracker

Container State	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5
state	none	created	running	paused	running	stopped

Key Moments - 3 Insights

Why can't we pause a container that is not running?

Because only a running container can be paused, as shown in step 3 where the state changes from running to paused. Pausing a non-running container is invalid.

What happens if we try to start a container that is already running?

Starting a running container has no effect; the state remains running as shown between steps 2 and 3.

Can a stopped container be resumed directly?

No, a stopped container must be started again to become running; unpause only works from paused state, not stopped.

Visual Quiz - 3 Questions

Look at the execution table, what is the container state after step 3?

A paused

B running

C stopped

D created

💡 Hint

Check the 'Container State After' column for step 3 in the execution table.

At which step does the container state change back to running after being paused?

A Step 5

B Step 2

C Step 4

D Step 1

💡 Hint

Look for the 'unpause' command and its effect in the execution table.

If we skip the pause command, what would be the container state after step 4?

A paused

B running

C created

D stopped

💡 Hint

Refer to the variable_tracker to see state changes without pausing.

Concept Snapshot

Docker container states:
- created: container exists but not running
- running: container is active
- paused: container temporarily frozen
- stopped: container halted
Use 'docker start', 'pause', 'unpause', 'stop' to change states.

Full Transcript

This visual execution shows how Docker container states change step-by-step. First, a container is created (state: created). Then it is started and becomes running. From running, it can be paused, freezing its processes. Unpausing resumes running. Finally, stopping the container ends it, moving to stopped state. Each command changes the container state as shown in the execution table and variable tracker. Understanding these states helps manage container lifecycle effectively.