Docker - Containers - multichoice questions

Question 1

You are trying to run a docker container based on the Ubuntu image, with the -it flags, and get the below error:

docker run ubuntu -it

docker: Error response from daemon: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: exec: "-it": executable file not found in $PATH: unknown.
ERRO[0005] error waiting for container: context canceled

What is the root cause?

Docker daemon is not up and running. Execute sudo systemctl start docker.
The machine cannot run containers.
Docker recognizes the -it flags as the container command. Execute docker run -it ubuntu instead.
The ubuntu docker image doesn't exist on the machine. Execute docker pull ubuntu before.

Question 2

From the perspective of the host machine, a running Docker container is essentially considered as just another process within the system. However, inside the container itself, the running process operates within its own isolated environment, perceiving itself as the sole process within that system.

Choose the correct sentence(s) regarding the process id:

The PID of the container as it is seen from the host machine is the same as it seen within the container.
The PID of the container as it is seen from the host machine is different from the PID as it is seen within the container.
The PID of the container as it is seen within the container is 1.
The PID of the container is the same as the docker daemon's PID (dockerd).

Question 3

After a while, what is the status of the container started by:

docker run ubuntu ps

Running
Stopped
Existed
Created
None of the above.

Question 4

When running docker run -e MYSQL_ROOT_PASSWORD=1234 mysql, what is the main process name of the container as it's seen from the host machine?

mysqld
dockerd
containerd
runc
None of the above

Based on the below output of docker inspect 303ce6e8af55 on some running container:

[
    {
        "Id": "303ce6e8af55f0bd6a431a01dcc3dbca140bdcc5b55d4f1e21c6a3fcba3e5810",
        "Created": "2023-05-08T08:11:49.412947069Z",
        "Path": "docker-entrypoint.sh",
        "Args": [
            "mysqld"
        ],
        "State": {
            "Status": "running",
            "Running": true,
            "Paused": false,
            "Restarting": false,
            "OOMKilled": false,
            "Dead": false,
            "Pid": 294355,
            "ExitCode": 0,
            "Error": "",
            "StartedAt": "2023-05-08T08:11:51.873706592Z",
            "FinishedAt": "0001-01-01T00:00:00Z"
        },
        "Image": "sha256:8189e588b0e8fcc95b0d764d6f7bdb55b5b41e9249157177d73781058f603ca9",
        "ResolvConfPath": "/var/lib/docker/containers/303ce6e8af55f0bd6a431a01dcc3dbca140bdcc5b55d4f1e21c6a3fcba3e5810/resolv.conf",
        "HostnamePath": "/var/lib/docker/containers/303ce6e8af55f0bd6a431a01dcc3dbca140bdcc5b55d4f1e21c6a3fcba3e5810/hostname",
        "HostsPath": "/var/lib/docker/containers/303ce6e8af55f0bd6a431a01dcc3dbca140bdcc5b55d4f1e21c6a3fcba3e5810/hosts",
        "LogPath": "/var/lib/docker/containers/303ce6e8af55f0bd6a431a01dcc3dbca140bdcc5b55d4f1e21c6a3fcba3e5810/303ce6e8af55f0bd6a431a01dcc3dbca140bdcc5b55d4f1e21c6a3fcba3e5810-json.log",
        "Name": "/tender_keldysh",
        "RestartCount": 0,
        "Driver": "overlay2",
        "Platform": "linux",
        "MountLabel": "",
        "ProcessLabel": "",
        "AppArmorProfile": "docker-default",
        "ExecIDs": null,
        "HostConfig": {
            "Binds": null,
            "ContainerIDFile": "",
            "LogConfig": {
                "Type": "json-file",
                "Config": {}
            },
            "NetworkMode": "default",
            "PortBindings": {},
            "RestartPolicy": {
                "Name": "no",
                "MaximumRetryCount": 0
            },
            "AutoRemove": false,
            "VolumeDriver": "",
            "VolumesFrom": null,
            "CapAdd": null,
            "CapDrop": null,
            "CgroupnsMode": "host",
            "Dns": [],
            "DnsOptions": [],
            "DnsSearch": [],
            "ExtraHosts": null,
            "GroupAdd": null,
            "IpcMode": "private",
            "Cgroup": "",
            "Links": null,
            "OomScoreAdj": 0,
            "PidMode": "",
            "Privileged": false,
            "PublishAllPorts": false,
            "ReadonlyRootfs": false,
            "SecurityOpt": null,
            "UTSMode": "",
            "UsernsMode": "",
            "ShmSize": 67108864,
            "Runtime": "runc",
            "ConsoleSize": [
                0,
                0
            ],
            "Isolation": "",
            "CpuShares": 0,
            "Memory": 0,
            "NanoCpus": 0,
            "CgroupParent": "",
            "BlkioWeight": 0,
            "BlkioWeightDevice": [],
            "BlkioDeviceReadBps": null,
            "BlkioDeviceWriteBps": null,
            "BlkioDeviceReadIOps": null,
            "BlkioDeviceWriteIOps": null,
            "CpuPeriod": 0,
            "CpuQuota": 0,
            "CpuRealtimePeriod": 0,
            "CpuRealtimeRuntime": 0,
            "CpusetCpus": "",
            "CpusetMems": "",
            "Devices": [],
            "DeviceCgroupRules": null,
            "DeviceRequests": null,
            "KernelMemory": 0,
            "KernelMemoryTCP": 0,
            "MemoryReservation": 0,
            "MemorySwap": 0,
            "MemorySwappiness": null,
            "OomKillDisable": false,
            "PidsLimit": null,
            "Ulimits": null,
            "CpuCount": 0,
            "CpuPercent": 0,
            "IOMaximumIOps": 0,
            "IOMaximumBandwidth": 0,
            "MaskedPaths": [
                "/proc/asound",
                "/proc/acpi",
                "/proc/kcore",
                "/proc/keys",
                "/proc/latency_stats",
                "/proc/timer_list",
                "/proc/timer_stats",
                "/proc/sched_debug",
                "/proc/scsi",
                "/sys/firmware"
            ],
            "ReadonlyPaths": [
                "/proc/bus",
                "/proc/fs",
                "/proc/irq",
                "/proc/sys",
                "/proc/sysrq-trigger"
            ]
        },
        "GraphDriver": {
            "Data": {
                "LowerDir": "/var/lib/docker/overlay2/0527b66c2da10505245168d1f084e150f9e56e4d42624569e1215536ec68231e-init/diff:/var/lib/docker/overlay2/d583e5274db743d86305fcfd36400a8a7a284f85709be7867bc0aa0b4cfaf32c/diff:/var/lib/docker/overlay2/0894921d7fe333aecd2516569141b5b70bfc2176128bf702eb7a974b8b7d183f/diff:/var/lib/docker/overlay2/c85383b79b37477fcbc236d42a5c5d228aea3f6933545e766a18029bc15b325d/diff:/var/lib/docker/overlay2/e7b712edcfed325a29bd24988e0d333fe8319398d3b38f71693af0a42e0a44a1/diff:/var/lib/docker/overlay2/ec9e92d41afa2d9fce8319582088669a16a48410d4e6ada53808d3089edc1765/diff:/var/lib/docker/overlay2/dc8021555938324415ceb966ce65bf42d6073797506032e69ed20448a7782e12/diff:/var/lib/docker/overlay2/040dae4ad608f96f9d68bee713db988728c6eadb6b516fabbf7d6b894be3b38d/diff:/var/lib/docker/overlay2/977da7c8267e343cad6a45505a2b590751988723e82b010a3e244f7132c0eeac/diff:/var/lib/docker/overlay2/da5008015b904ebf4b70df8d72c7a52567153d1586a0f7725d30036cd872f5ac/diff:/var/lib/docker/overlay2/253485cdcce0d7e45d6da86be4bee0dace9eef58fbf02bc1f009b3c7a95ab54d/diff:/var/lib/docker/overlay2/b89da9e305923e3c37291ad5f0cd90696d6f2e5e76f0fca87d1e1bcf9178714d/diff",
                "MergedDir": "/var/lib/docker/overlay2/0527b66c2da10505245168d1f084e150f9e56e4d42624569e1215536ec68231e/merged",
                "UpperDir": "/var/lib/docker/overlay2/0527b66c2da10505245168d1f084e150f9e56e4d42624569e1215536ec68231e/diff",
                "WorkDir": "/var/lib/docker/overlay2/0527b66c2da10505245168d1f084e150f9e56e4d42624569e1215536ec68231e/work"
            },
            "Name": "overlay2"
        },
        "Mounts": [
            {
                "Type": "volume",
                "Name": "d6865699c2f97b1abd429d41e9902e29f1a909355242ef1f6f4bb7abf0dd296e",
                "Source": "/var/lib/docker/volumes/d6865699c2f97b1abd429d41e9902e29f1a909355242ef1f6f4bb7abf0dd296e/_data",
                "Destination": "/var/lib/mysql",
                "Driver": "local",
                "Mode": "",
                "RW": true,
                "Propagation": ""
            }
        ],
        "Config": {
            "Hostname": "303ce6e8af55",
            "Domainname": "",
            "User": "",
            "AttachStdin": false,
            "AttachStdout": true,
            "AttachStderr": true,
            "ExposedPorts": {
                "3306/tcp": {},
                "33060/tcp": {}
            },
            "Tty": false,
            "OpenStdin": false,
            "StdinOnce": false,
            "Env": [
                "MYSQL_ROOT_PASSWORD=1234",
                "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
                "GOSU_VERSION=1.16",
                "MYSQL_MAJOR=8.0",
                "MYSQL_VERSION=8.0.33-1.el8",
                "MYSQL_SHELL_VERSION=8.0.33-1.el8"
            ],
            "Cmd": [
                "mysqld"
            ],
            "Image": "mysql",
            "Volumes": {
                "/var/lib/mysql": {}
            },
            "WorkingDir": "",
            "Entrypoint": [
                "docker-entrypoint.sh"
            ],
            "OnBuild": null,
            "Labels": {}
        },
        "NetworkSettings": {
            "Bridge": "",
            "SandboxID": "ee1dd90916d4b1078246e248676863a4d3c0ab454bef7a1bc5476da95aa0f176",
            "HairpinMode": false,
            "LinkLocalIPv6Address": "",
            "LinkLocalIPv6PrefixLen": 0,
            "Ports": {
                "3306/tcp": null,
                "33060/tcp": null
            },
            "SandboxKey": "/var/run/docker/netns/ee1dd90916d4",
            "SecondaryIPAddresses": null,
            "SecondaryIPv6Addresses": null,
            "EndpointID": "6cf6a9c5505da1d30922219bccbd91c6fea71aaa3c67ab53163b99144e40bd11",
            "Gateway": "172.17.0.1",
            "GlobalIPv6Address": "",
            "GlobalIPv6PrefixLen": 0,
            "IPAddress": "172.17.0.3",
            "IPPrefixLen": 16,
            "IPv6Gateway": "",
            "MacAddress": "02:42:ac:11:00:03",
            "Networks": {
                "bridge": {
                    "IPAMConfig": null,
                    "Links": null,
                    "Aliases": null,
                    "NetworkID": "c870c05c5ce1e9d7a8711ada1826eead7e54ecf4847f61e43be30e672008bdbd",
                    "EndpointID": "6cf6a9c5505da1d30922219bccbd91c6fea71aaa3c67ab53163b99144e40bd11",
                    "Gateway": "172.17.0.1",
                    "IPAddress": "172.17.0.3",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "02:42:ac:11:00:03",
                    "DriverOpts": null
                }
            }
        }
    }
]

Answer the bellow 6 questions.

Question 5

What is the IP address of the container?

172.17.0.1.
172.17.0.3.
127.0.0.1.
IP v6: 02:42:ac:11:00:03.

Question 6

How many ports are exposed by the container?

0
1
2
3
None of the above

Question 7

How many environment variables are given to the container process?

Question 8

Was the container run with the -it flags?

Yes
No
We couldn't know from the output.

Question 9

The container status is:

Exited
Created
Running
Restarting
We couldn't know from the output.

Question 10

What is the PID of the container as it is seen from the host machine?

1
294355
67108864
We couldn't know from the output.

Question 11

The official mysql image is running by the following command: docker run -e MYSQL_ROOT_PASSWORD=1234 mysql.

Choose the correct answer:

The MySQL database is accessible from the host machine by localhost:3306.
The MySQL database is accessible from the host machine by localhost:8080.
The MySQL database is accessible from the host machine by localhost:80.
The database can never be accessed from the host machine.
None of the above

Question 12

The official mysql image is running by the following command: docker run -e MYSQL_ROOT_PASSWORD=1234 mysql.

Which of the below docker commands can help with debugging the /var/run/mysqld/mysqld.sock file, which is located within the container?

docker exec
docker logs
docker run
docker ps

Question 13

When the docker service is restarted by (under default docker daemon configurations):

sudo systemctl restart docker

What happens to the running containers?

Running containers are killed.
Running containers are stopped.
Nothing happens since Docker doesn't run the containers itself, but runc does.
None of the above.

Question 14

Which command(s) can help you to resolve the following error:

Error response from daemon: You cannot remove a running container 76004df79402d330992abe9f423715904fb590663f797fee3bca4e9e877f0ac0. Stop the container before attempting removal or force remove

docker run 76004df794
docker kill --signal STOP 76004df794
docker top 76004df794
docker stop 76004df794
docker pause 76004df794

Question 15

What is the docker image name with which the below container is running?

docker run --name mybusy busybox wget localhost

mybusy
busybox
wget
localhost
None of the above

Question 16

Consider the bellow two docker run commands:

docker run -p 8080:80 nginx
docker run -p 8080:80 nginx

Assume there are no other containers running on the host machine. Choose the correct sentence:

The commands create and run two different containers successfully.
The second command does nothing since the first command runs the nginx container image successfully.
The seconds command will fail since you are not able to run two different containers from the nginx image.
The seconds command will fail since port 8080 is bound to the first container.

Question 17

The following command has run successfully:

docker run -it ubuntu /bin/bash

What can be id for sure regarding the container:

The ubuntu image existed on the machine before the command was executed.
The binary /bin/bash exists in the container's file system.
The -it flags allow you to run within the container every command that is available on the host machine.
None of the above.

Question 18

You are trying to run an nginx container using the following command:

docker run --name some-nginx -e DEBUG=true nginx

But encounter the following error:

docker: Error response from daemon: Conflict. The container name "/some-nginx" is already in use by container "761aacef37cfe438f77fe92d6e4a2eeecc6d72c9cea9eb5f73d5af5a1ae377d2". You have to remove (or rename) that container to be able to reuse that name.
See 'docker run --help'

Which command can help you resolve the problem?

docker run --force --name some-nginx -e DEBUG=true nginx
docker rm some-nginx
docker kill some-nginx
docker rename some-nginx some-ng