Restarting containers in Docker - Step-by-Step Execution

Process Flow - Restarting containers

Identify container

↓

Run restart command

↓

Stop container

↓

Start container

↓

Container running again

The flow shows how Docker stops a container and then starts it again to restart.

Execution Sample

Docker

docker restart my_container

This command stops and then starts the container named 'my_container'.

Process Table

Step	Action	Container State Before	Container State After	Output
1	Identify container 'my_container'	running	running	Container found
2	Stop container	running	stopped	Container stopped
3	Start container	stopped	running	Container started
4	Restart complete	running	running	Container restarted successfully

💡 Restart finishes after container is running again.

Status Tracker

Variable	Start	After Step 2	After Step 3	Final
container_state	running	stopped	running	running

Key Moments - 2 Insights

Why does the container state change from running to stopped before starting again?

Because the restart command first stops the container to reset its state, then starts it fresh. See execution_table steps 2 and 3.

What happens if the container is already stopped before restart?

Docker will start the container directly without stopping it first, but the restart command always ensures the container ends up running.

Visual Quiz - 3 Questions

Look at the execution table, what is the container state after step 2?

A running

B paused

C stopped

D exited

💡 Hint

Check the 'Container State After' column for step 2 in the execution_table.

At which step does the container start running again?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Look at the 'Container State After' column and find when it changes back to running.

If the container was stopped before restart, what would change in the execution table?

A Step 1 would show 'stopped' state

B Step 2 would be skipped

C Step 3 would be skipped

D No steps would change

💡 Hint

Check the 'Container State Before' column at step 1 and think about initial container state.

Concept Snapshot

docker restart <container_name>
- Stops the container if running
- Starts the container again
- Ensures container ends up running
- Useful to apply changes or recover
- Simple one-command restart

Full Transcript

Restarting a Docker container means stopping it first and then starting it again. The command 'docker restart my_container' does this in two steps: it stops the container if it is running, then starts it fresh. This resets the container's state and helps apply changes or fix issues. The container state changes from running to stopped, then back to running. If the container was already stopped, Docker just starts it. This process ensures the container is running at the end.