@mrjana @alexellis2 Thanks for the suggestions. Please note that my basic Swarm functionality testing done per the creation of this forum topic was with docker-machine on x86 hardware with VirtualBox using 1.12.0.
I ran rpi-update and updated the kernel. However, I did not see a vxlan module with lsmod so I used modprobe and now it is visible.
Testing Procedure:
Used three Pi's with Docker 1.12.1-rc2, build 236317f, experimental, vxlan module loaded. Kernel 4.4.19-v7+.
docker swarm init
docker swarm join.....(for each Pi as needed)
1mmb8fgd9s8m9peodyr3x6qoc * rpi-2 Ready Active Leader
c26mil621fs4f0iwa1e8884ar rpi-3 Ready Active
em26jwtm7u3f800pkrl4fw2py rpi-4 Ready Active
docker network create chat -d overlay
docker service create --name mysql --network chat registry:5000/mysql
docker service create --name test --network chat -p 444:444 registry:5000/test
docker service ls
ID NAME REPLICAS IMAGE COMMAND
4n6r4fbiu0cl mysql 1/1 registry:5000/mysql
8h36vyo2luyy test 1/1 registry:5000/test
We can see here that the database and Node.js application is running on separate machines.
# docker node ps rpi-3
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR
1zfxjmkbqgz7c0q9ji26h7qkg mysql.1 registry:5000/mysql rpi-3 Running Running about a minute ago
# docker node ps rpi-2
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR
5dcwkxxdy4aunbvg6sk9q3wtw test.1 registry:5000/test rpi-2 Running Running about a minute ago
The service named test is running my Node.js app fine with database connectivity and is accessible from each host. More testing is needed with other apps but is looking good so far.
My only problem that remains now is with labels and constraints. That does not seem to be working right.
This command works and runs MySQL on rpi-3 as expected:
docker service create --name sql2 -l "node=rpi-3" --network chat registry:5000/mysql
Then I tried to run MySQL on a node and label that does not exist and it just went to a random node:
docker service create --name sql2 -l "node=rpi-1" --network chat registry:5000/mysql
For my final test, I created three MySQL services using the same label and they all went to random nodes which is not behavior that I would expect.
docker service create --name sql3 -l "node=rpi-4" --network chat registry:5000/mysql
docker service create --name sql2 -l "node=rpi-4" --network chat registry:5000/mysql
docker service create --name sql1 -l "node=rpi-4" --network chat registry:5000/mysql
