Modificando una imagen

Podemos modificar una imagen existente y guardarla con un nombre diferente:

# docker run -it ubuntu bash
root@d66f7a3268e6:/#

Fijaros en que el prompt del interprete de ordenes ha cambiado e indica el numero que identifica de manera unica al contenedor que hemos lanzado. Este numero cambia para cada nueva instancia que lanzamos.

root@d66f7a3268e6:/# apt-get update
root@d66f7a3268e6:/# apt-get install apache2
apt-get install apache2
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  apache2-bin apache2-data apache2-utils ...
The following NEW packages will be installed:
  apache2 apache2-bin apache2-data apache2-utils ...
0 upgraded, 57 newly installed, 0 to remove and 4 not upgraded.
Need to get 22.6 MB/22.6 MB of archives.
After this operation, 102 MB of additional disk space will be used.
Do you want to continue? [Y/n] 
...
root@d66f7a3268e6:/#

Escribo 'Y' y pulso enter para comenzar la instalacion del servidor web apache2.

root@d66f7a3268e6:/# exit

# docker commit -m "Imagen de ubuntu con apache2" -a "profe" d66f7a3268e6 ubuntu/apache2
sha256:b68ef77405104a6ea2de6fde986a519a2fc9710b26d9ae8ec2553f5050c51fd3

# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
ubuntu/apache2      latest              b68ef7740510        36 seconds ago      260MB

# docker run -it -p 8888:80 ubuntu/apache2
# service apache2 start
 * Starting Apache httpd web server apache2                                     AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message
 *

Y ahora si abro un navegador web al localhost al puerto 8888, me aparece la pagina que indica que apache esta funcionando correctamente.