Starting, Stopping, Inspecting and Deleting Containers

By the end of this exercise, you should be able to:

Restart containers which have exited
Distinguish between stopping and killing a container
Fetch container metadata using docker container inspect
Delete containers

Starting and Restarting Containers

Start by running a IIS web server in the background, and check that it's really running:
```
PS: node-0 Administrator> docker container run -d `
    --name demo microsoft/nanoserver ping 8.8.8.8 -t
PS: node-0 Administrator> docker container ls
```
Note how we called the container demo for easier identification later on.

Stop the container using docker container stop, and check that the container is indeed stopped:

PS: node-0 Administrator> docker container stop demo
PS: node-0 Administrator> docker container ls -a

Inspecting a Container

Start your demo container again, then inspect the container details using docker container inspect:
```
PS: node-0 Administrator> docker container start demo
PS: node-0 Administrator> docker container inspect demo
```
You get a JSON object describing the container's config, metadata and state.
Find the container's IP and long ID in the JSON output of inspect. If you know the key name of the property you're looking for, try piping to select-string:
```
PS: node-0 Administrator> docker container inspect demo | select-string IPAddress
```
The output should look similar to this:
```
"SecondaryIPAddresses": null,
"IPAddress": "",
        "IPAddress": "172.20.137.22",
```
Now try to use select-string for Cmd, the main process being run by this container. select-string's simple text search doesn't always return helpful results:
```
PS: node-0 Administrator> docker container inspect demo | select-string Cmd

"Cmd": [
```
A more powerful way to filter this JSON is with the --format flag. Syntax follows Go's text/template package: http://golang.org/pkg/text/template/. For example, to find the Cmd value we tried to select-string for above, instead try:
```
PS: node-0 Administrator> docker container inspect --format='{{.Config.Cmd}}' demo

[ping 8.8.8.8 -t]
```
This time, we get a the value of the Config.Cmd key from the inspect JSON.
Keys nested in the JSON returned by docker container inspect can be chained together in this fashion. Try modifying this example to return the IP address you selected previously.
Finally, we can extract all the key/value pairs for a given object using the json function:
```
PS: node-0 Administrator> docker container inspect --format='{{json .Config}}' demo
```
Try adding | jq to this command to get the same output a little bit easier to read.

Deleting Containers

Start three containers in background mode, then stop the first one.
List only exited containers using the --filter flag we learned earlier, and the option status=exited.
Delete the container you stopped above with docker container rm, and do the same listing operation as above to confirm that it has been removed:
```
PS: node-0 Administrator> docker container rm <container ID>
PS: node-0 Administrator> docker container ls
```
Now do the same to one of the containers that's still running; notice docker container rm won't delete a container that's still running, unless we pass it the force flag -f. Delete the second container you started above:
```
PS: node-0 Administrator> docker container rm -f <container ID>
```
Try using the docker container ls flags we learned previously to remove the last container that was run, or all stopped containers. Recall that you can pass the output of one shell command cmd-A into a variable of another command cmd-B with syntax like cmd-B $(cmd-A).

Conclusion

In this exercise, you saw the basics of managing the container lifecycle. Containers can be restarted when stopped, and are only truly gone once they've been removed.

Also keep in mind the docker container inspect command we saw, for examining container metadata, state and config; this is often the first place to look when trying to troubleshoot a failed container.