Of Stack

Docker images export and import operations

  • 2021-10-16 05:36:05
  • OfStack

What should I do when I have configured the basic images before and need them elsewhere?

Answer: Importing and exporting mirrors.

1. Save the mirror image 


[root@wxtest1607 ~]# docker images
REPOSITORY        TAG         IMAGE ID      CREATED       SIZE
tomcat8          3.0         90457edaf6ff    6 hours ago     1.036 GB
[root@wxtest1607 lixr]# docker save 9045 > tomcat8-apr.tar
[root@wxtest1607 lixr]# ls -lh
 Total dosage  1.2G
-rw-r--r-- 1 root root 1005M 8 Month  24 17:42 tomcat8-apr.tar

2. Importing mirrors

At present, there is a shortage of CentOS7 server. The practice is to delete image first, and then import it. 


[root@wxtest1607 lixr]# docker images
REPOSITORY        TAG         IMAGE ID      CREATED       SIZE
tomcat8          3.0         90457edaf6ff    7 hours ago     1.036 GB
[root@wxtest1607 lixr]# docker rmi 9045
Untagged: tomcat8:3.0
Deleted: sha256:90457edaf6ff4ce328dd8a3131789c66e6bd89e1ce40096b89dd49d6e9d62bc8
Deleted: sha256:00df1d61992f2d87e7149dffa7afa5907df3296f5775c53e3ee731972e253600
[root@wxtest1607 lixr]# docker images
REPOSITORY        TAG         IMAGE ID      CREATED       SIZE
[root@wxtest1607 lixr]# docker load < tomcat8-apr.tar
60685807648a: Loading layer [==================================================>] 442.7 MB/442.7 MB
[root@wxtest1607 lixr]# yer [>                         ] 527.7 kB/442.7 MB
[root@wxtest1607 lixr]# docker images
REPOSITORY        TAG         IMAGE ID      CREATED       SIZE
<none>          <none>       90457edaf6ff    7 hours ago     1.036 GB
[root@wxtest1607 lixr]# docker tag 9045 tomcat8-apr:3.0
[root@wxtest1607 lixr]# 
[root@wxtest1607 lixr]# docker images
REPOSITORY        TAG         IMAGE ID      CREATED       SIZE
tomcat8-apr        3.0         90457edaf6ff    7 hours ago     1.036 GB

3. Export of containers 


[root@wxtest1607 lixr]# docker ps 
CONTAINER ID    IMAGE        COMMAND       CREATED       STATUS       PORTS                NAMES
b91d9ad83efa    9045        "/bin/bash"     18 seconds ago   Up 15 seconds                      trusting_colden
f680b58163ab    aa79        "/bin/bash"     8 hours ago     Up 8 hours                       stupefied_mayer
4db6aa9b8278    4052        "mysqld_safe"    21 hours ago    Up 21 hours     8080/tcp, 0.0.0.0:53307->3306/tcp  nostalgic_leavitt
7bcfe52af7a0    599d        "mysqld_safe"    21 hours ago    Up 21 hours     8080/tcp, 0.0.0.0:53306->3306/tcp  sleepy_hodgkin
[root@wxtest1607 lixr]# 
[root@wxtest1607 lixr]# 
[root@wxtest1607 lixr]# docker export b91d9ad83efa > tomcat80824.tar
[root@wxtest1607 lixr]# ls -lh
 Total dosage  2.1G
-rw-r--r-- 1 root root  943M 8 Month  24 18:37 tomcat80824.tar
-rw-r--r-- 1 root root 1005M 8 Month  24 17:42 tomcat8-apr.tar

b91d9ad83efa is the container after the mirror 90457edaf6ff is started.

The mirror export file is larger than the container export file.

4. Import of containers 


[root@wxtest1607 lixr]# docker import tomcat80824.tar
sha256:880fc96a6bb6abdfa949a56d40ef76f32f086fa11024ddcfb4e4e8b22041d5f2
[root@wxtest1607 lixr]# docker images
REPOSITORY        TAG         IMAGE ID      CREATED       SIZE
<none>          <none>       880fc96a6bb6    6 seconds ago    971.9 MB
[root@wxtest1607 lixr]# docker tag 880f tomcat80824:1.0
[root@wxtest1607 lixr]# docker images
REPOSITORY        TAG         IMAGE ID      CREATED       SIZE
tomcat80824        1.0         880fc96a6bb6    About a minute ago  971.9 MB
tomcat8-apr        3.0         90457edaf6ff    8 hours ago     1.036 GB

5. The difference between mirroring and container export and import

The difference between mirror import and container import:

1) Container import is to change the current container into a new image

2) Mirror import is the process of replication

Difference between save and export:

1) save saves all information about the image-including history

2) export only exports current information 


[root@wxtest1607 lixr]# docker history 880fc96a6bb6
IMAGE        CREATED       CREATED BY     SIZE        COMMENT
880fc96a6bb6    12 minutes ago             971.9 MB      Imported from -
[root@wxtest1607 lixr]# docker history 90457edaf6ff
IMAGE        CREATED       CREATED BY                   SIZE        COMMENT
90457edaf6ff    8 hours ago     /bin/bash                    434.4 MB      
<missing>      23 hours ago    /bin/bash                    406.5 MB      
<missing>      7 weeks ago     /bin/sh -c #(nop) CMD ["/bin/bash"]       0 B         
<missing>      7 weeks ago     /bin/sh -c #(nop) LABEL license=GPLv2      0 B         
<missing>      7 weeks ago     /bin/sh -c #(nop) LABEL vendor=CentOS      0 B         
<missing>      7 weeks ago     /bin/sh -c #(nop) LABEL name=CentOS Base Imag  0 B         
<missing>      7 weeks ago     /bin/sh -c #(nop) ADD file:b3bdbca0669a03490e  194.6 MB      
<missing>      7 weeks ago     /bin/sh -c #(nop) MAINTAINER The CentOS Proje  0 B

Supplement: docker images Explanation

docker images is used to view locally downloaded images 


[root@localhost ~]$ docker images
REPOSITORY     TAG         IMAGE ID      CREATED       SIZE
centos       latest       1e1148e4cc2c    2 weeks ago     202MB
ubuntu       latest       93fd78260bd1    5 weeks ago     86.2MB
REPOSITORY  #  Mirror warehouse 
TAG      #  Mirror label 
IMAGE ID   #  Mirror image ID
CREATED    #  Image creation time 
SIZE     #  Mirror size
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