I wrote quick "Hands-on" for beginners to cover docker basics with simple containers so I won't go into details of complex application, service definitions or swarms. What I want to do is run a webserver inside a container with persistent data
Check Docker
Let’s check if docker is running
ubuntu@docker-host:~$ docker version
Client:
Version: 1.12.6
API version: 1.24
Go version: go1.6.3
Git commit: 78d1802
Built: Tue Jan 31 23:47:34 2017
OS/Arch: linux/amd64
Server:
Version: 1.12.6
API version: 1.24
Go version: go1.6.3
Git commit: 78d1802
Built: Tue Jan 31 23:47:34 2017
OS/Arch: linux/amd64
For now there are no images available but this will change in a little:
ubuntu@docker-host:~$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZ
There are also no running containers:
ubuntu@docker-host:~$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
Maybe also quickly check the network configuration especially what IP’s our docker host has:
ubuntu@docker-host:~$ ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 02:75:fc:25:d7:25 brd ff:ff:ff:ff:ff:ff
inet 10.0.2.15/24 brd 10.0.2.255 scope global enp0s3
valid_lft forever preferred_lft forever
inet6 fe80::75:fcff:fe25:d725/64 scope link
valid_lft forever preferred_lft forever
3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 08:00:27:08:be:4c brd ff:ff:ff:ff:ff:ff
inet 192.168.33.10/24 brd 192.168.33.255 scope global enp0s8
valid_lft forever preferred_lft forever
inet6 fe80::a00:27ff:fe08:be4c/64 scope link
valid_lft forever preferred_lft forever
4: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
link/ether 02:42:d4:b5:a1:57 brd ff:ff:ff:ff:ff:ff
inet 172.17.0.1/16 scope global docker0
valid_lft forever preferred_lft forever
Get your first image
Images have to be downloaded to the docker host once in order to be able to create containers. You can simply pull images with pull command{.external-link}
$ docker pull [OPTIONS] NAME[:TAG|@DIGEST]
Once done, you can see the images with images command{.external-link}. So let’s pull the webserver image ngnix and then check
ubuntu@docker-host:~$ docker pull nginx
....
57168433389f: Extracting [===============================================> ] 20.64 MB/21.53 MB
57168433389f: Extracting [================================================> ] 20.87 MB/21.53 MB
57168433389f: Extracting [=================================================> ] 21.1 MB/21.53 MB
57168433389f: Extracting [=================================================> ] 21.33 MB/21.53 MB
57168433389f: Extracting [==================================================>] 21.53 MB/21.53 MB
57168433389f: Pull complete
332ec8285c50: Extracting [==================================================>] 193 B/193 B
332ec8285c50: Extracting [==================================================>] 193 B/193 B
332ec8285c50: Pull complete
Digest: sha256:c15f1fb8fd55c60c72f940a76da76a5fccce2fefa0dd9b17967b9e40b0355316
Status: Downloaded newer image for nginx:latest
ubuntu@docker-host:~$ images
REPOSITORY TAG IMAGE ID CREATED SIZE
nginx latest 46102226f2fd 12 hours ago 109.
Details on how this image is composed can be found by checking the image description on Docker-Hub, in the original Dockerfile or by inspecting the image with the docker inspect{.external-link} nginx command
Start your first container
A container can be started by docker run{.external-link} command:
ubuntu@docker-host:~$ docker run nginx
As you can see, so far nothing else happens. Well not entirely true, let’s quickly open another terminal and check whether we have a running container
ubuntu@docker-host:~$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a4a7e4f36d5b nginx "nginx -g 'daemon off" 3 minutes ago Up 3 minutes 80/tcp pedantic_yonath
So there is a container running and it is named “pedantic_yonath” - this name is given automatically by docker, but you can force a proper name by aggregating parameter -name. So when the container is running, then we should be able to connect to the webserver right? Well first we need to figure out the ip address of the container, which can be simply achieved by inspect command
ubuntu@docker-host:~$ docker inspect pedantic_yonath
[
{
"Id": "a4a7e4f36d5b5c19d6f67381726dbe54b5feec81aeec150b816a81d8a671fd0f",
"Created": "2017-04-26T13:54:36.632963616Z",
"Path": "nginx",
"Args": [
"-g",
"daemon off;"
],
...
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.2",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:ac:11:00:02"
}
}
}
}
]
ubuntu@docker-host:~$ docker inspect --format='{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' pedantic_yonath
172.17.0.2