I can't access mounted volume of docker-postgres from host

Question

I create my container like this:

docker run --name postgresql -itd --restart always \
--publish 5432:5432 \
--volume /my/local/host:/var/lib/postgresql \
sameersbn/postgresql:9.4-11

but, when I do ls on the root directory, I see something like this:

drwxrwxr-x  3 messagebus messagebus 4,0K Ιαν  10 00:44 host/

or, in other words, I cannot access the /my/local/host directory. I have no idea about the messagebus user. is that normal? if this is the case, then how could I move the database from one machine to another in the future?

Answer 1

Try using a data container to hold your DB data. The pattern is described in the docs and is designed to promote clean separation between run-time and data.

$ docker create -v /var/lib/postgresql --name dbdata sameersbn/postgresql:9.4-11 
$ docker run --name postgresql1 -itd --restart always \
--publish 5432:5432 \
--volumes-from dbdata
sameersbn/postgresql:9.4-11

A separate data container makes backup and recovery simpler and more obvious

docker run --volumes-from dbdata -v $(pwd):/backup ubuntu tar cvf /backup/backup.tar /var/lib/postgresql

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The following posting I think gives a good explanation of data containers:

• https://medium.com/@ramangupta/why-docker-data-containers-are-good-589b3c6c749e#.zarkr5sxc