Docker - Containers

Please answer the quiz and click the "Test" button at the bottom right.

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).

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 3

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 4

How many ports are exposed by the container?

0
1
2
3
None of the above

Question 5

How many environment variables are given to the container process?

Question 6

Was the container run with the -it flags?

Yes
No
We couldn't know from the output.

Question 7

The container status is:

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

Question 8

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 9

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 10

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 11

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.