How to export multiple docker images to another machine?



If you want to export all images at once, create one big tar file:

docker save $(docker images -q) -o /path/to/save/mydockersimages.tar

If you want to save multiples images in one .tar file:

IDS=$(docker images | awk '{if ($1 ~ /^(debian|centos)/) print $3}')
docker save $IDS -o /path/to/save/somedockersimages.tar

Finally, if you want to export multiple many images, with one .tar file per images (not disk efficient: common layer are saved in each .tar file):

docker images | awk '{if ($1 ~ /^(openshift|centos)/) print $1 " " $2 " " $3 }' | tr -c "a-z A-Z0-9_.\n-" "%" | while read REPOSITORY TAG IMAGE_ID
  echo "== Saving $REPOSITORY $TAG $IMAGE_ID =="
  docker  save   -o /path/to/save/$REPOSITORY-$TAG-$IMAGE_ID.tar $IMAGE_ID

You may also want to save the list of images so that the restored images can be tagged:

docker images | sed '1d' | awk '{print $1 " " $2 " " $3}' > mydockersimages.list

On the remote machine, you can load (import) the images:

docker load -i /path/to/save/mydockersimages.tar

and tag the imported images:

        echo "== Tagging $REPOSITORY $TAG $IMAGE_ID =="
        docker tag "$IMAGE_ID" "$REPOSITORY:$TAG"
done < mydockersimages.list

How to resolve the issue of “Docker CE on RHEL – Requires: container-selinux >= 2.9”


Installing the Selinux from the Centos repository worked for me:
1. Go to
2. Find the latest version for container-selinux i.e. container-selinux-2.21-1.el7.noarch.rpm
3. Run the following command on your terminal: $ sudo yum install -y**Add_current_container-selinux_package_here**
4. The command should looks like the following $ sudo yum install -y
Note: the container version is constantly being updated, that is why you should look for the latest version in the Centos’ repository

How to import a private key into a java keystore


You cannot, but you can convert the private key and certificate into a java keystore. Below are the steps:

Step one: Convert x509 Cert and Key to a pkcs12 file

openssl pkcs12 -export -in server.crt -inkey server.key \
               -out server.p12 -name [some-alias] \
               -CAfile ca.crt -caname root

Note: Make sure you put a password on the p12 file – otherwise you’ll get a null reference exception when you try to import it. (In case anyone else had this headache). (Thanks jocull!)

Note 2: You might want to add the -chainoption to preserve the full certificate chain. (Thanks Mafuba)

Step two: Convert the pkcs12 file to a java keystore

keytool -importkeystore \
        -deststorepass [changeit] -destkeypass [changeit] -destkeystore server.keystore \
        -srckeystore server.p12 -srcstoretype PKCS12 -srcstorepass some-password \
        -alias [some-alias]

How to fix ranger tagsync issue

  1. Check the log /var/log/ranger/tagsync/tagsync.out, if it complains missing classes, copy two jar files: commons-codec-1.4.jar and commons-compress-1.4.1.jar from /usr/hdp/current/hadoop-client/lib/ to /usr/hdp/current/ranger-tagsync/lib/.