Can't find docker secrets' folder ('/run/secrets')

Question

I played with https://labs.play-with-docker.com/.

I chose the template of 3 Managers and 2 Workers:

I went to manager1 and created a secret:

echo "mydatabasepassword" | docker secret create db_pass -

I checked and the secret is exist:

I wanted to check the secrets folder but it doesn't exist:

I also tried like this:
Any idea where can it be ?

Following Bret Fisher answer, here is an example:

*I could get the name of the container only from the manager leader.

Answer 1

Secrets are stored on the manager host in the encrypted raft db, so you can't view them from host. To see them in a container you need to assign them on docker service create, so:

docker service create --secret=db_pass --name example nginx

Then from the node that was assigned the container you can see the text file in the container (container name will be different):

docker exec example.1.m1c4bvubej64xc1csclnq7y3r cat /run/secrets/db_pass

Answer 2

As per the docs:

When you grant a newly-created or running service access to a secret, the decrypted secret is mounted into the container in an in-memory filesystem. The location of the mount point within the container defaults to /run/secrets/ in Linux containers

The secrets are stored in the encrypted Raft logs for the swarm.

(To learn more about the encrypted Raft logs, see here.)