I’ve been using docker a lot, and\u00c2\u00a0on occasion I need to transfer images between two machines that are on a local network. If a particular image is large, I might not want to download it twice from two machines, so I download it on one machine and transfer it to the other over the local network.<\/p>\n
Now, I could stand up a local docker registry and use that, but it’s a bit of work. Instead, I’ve found that the quickest and easiest solution is to combine the docker ‘save’ and ‘load’ commands with a bit of netcat magic, and it’s pretty fast and easy. (Update: <\/strong>you can do it easily using SSH too, see the end of the post). Check it out.<\/p>\n First, on the destination\u00c2\u00a0machine (make sure your firewall allows traffic to the specified port, in this case 1234<\/em>):<\/p>\n Next, on the source machine, transfer the image (virtuald\/etcd:0.4.6<\/em>) to the destination IP\u00c2\u00a0(192.168.0.42<\/em>):<\/p>\n And that’s it!<\/p>\n The sad thing is that docker save\/load doesn’t show a status message when saving\/loading, so it might look like it’s not doing anything. However, using the -v flag for netcat shows when the connection is successfully opened\/closed, so that’s something.<\/p>\n Security warning:\u00c2\u00a0<\/strong>Obviously, running netcat like this is a *huge* security hole while its up and listening, as anyone who can connect to the port can upload arbitrary images into your docker registry. This is mitigated a bit since netcat will immediately disconnect after the first client disconnects, but still risky on an untrusted network. Only use this on trusted networks<\/span>!<\/p>\n Note:\u00c2\u00a0<\/strong>due to this bug<\/a>, you’ll want to be using docker 1.2+, otherwise you may get unexpected results.<\/p>\n Update! <\/strong>As Joshua Barratt<\/a> points out, since this method generalizes to any transport that allows piping via stdin\/stdout, you can also do the transfer via SSH too, which is certainly more secure. Use the -C option to enable compression for faster transfers (thanks Andreas Steffan<\/a>).<\/p>\n Update II:\u00c2\u00a0<\/strong>As a number of people have pointed out, you can use PV to show a status message:<\/p>\n I’ve been using docker a lot, and\u00c2\u00a0on occasion I need to transfer images between two machines that are on a local network. If a particular image is large, I might not want to download it twice from two machines, so I download it on one machine and transfer it to the other over the local […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[59,47],"tags":[],"_links":{"self":[{"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/posts\/465"}],"collection":[{"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/comments?post=465"}],"version-history":[{"count":8,"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/posts\/465\/revisions"}],"predecessor-version":[{"id":473,"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/posts\/465\/revisions\/473"}],"wp:attachment":[{"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/media?parent=465"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/categories?post=465"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.virtualroadside.com\/blog\/index.php\/wp-json\/wp\/v2\/tags?post=465"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}nc -v -l 1234 | docker load<\/pre>\n
docker save virtuald\/etcd:0.4.6 | nc -v 192.168.0.42 1234<\/pre>\n
docker save virtuald\/etcd:0.4.6 | ssh -C 192.168.0.42 \u00e2\u20ac\u02dcdocker load\u00e2\u20ac\u2122<\/pre>\n
docker save virtuald\/etcd:0.4.6 | pv | ssh -C 192.168.0.42 'docker load'<\/pre>\n","protected":false},"excerpt":{"rendered":"