[openstack-dev] [Magnum] Magnum Quick-Start: Need clarification on Kubernetes/Redis example

Dane Leblanc (leblancd) leblancd at cisco.com
Mon Jul 13 16:55:36 UTC 2015


Does anyone have recent experience getting the Kubernetes/Redis example to work in the Magnum developer Quick-Start guide?:
    https://github.com/openstack/magnum/blob/master/doc/source/dev/dev-quickstart.rst#exercising-the-services-using-devstack

I can get everything in the Kubernetes/Redis example to work except for the last step. Here's what the quick-start guide says for this step:
"Now log into one of the other container hosts and access a redis slave from there:
ssh minion@$(nova list | grep 10.0.0.4 | awk '{print $13}')
REDIS_ID=$(docker ps | grep redis:v1 | grep k8s_redis | tail -n +2 | awk '{print $1}')
docker exec -i -t $REDIS_ID redis-cli

127.0.0.1:6379> get replication:test
"true"
^D

exit

There are four redis instances, one master and three slaves, running across the bay, replicating data between one another."

What I'm seeing is a bit different:

(1)    I have to use 'sudo docker' instead of 'docker'.  (No big deal.)

(2)    I see one master redis instance on one minion and one slave redis instance on a second minion (each has its own associated sentinel container as expected).

(3)    The redis-cli command times out with "Could not connect to Redis at 127.0.0.1:6379: Connection refused". HOWEVER, if I add a host IP and port for the redis master minion ("-h 10.100.84.2 -p 6379"), the example works.

Here is the failing case, without the host/port arguments:

[minion at k8-4gmqfvntvm-0-6fymzzw3wrjx-kube-minion-zjdejo5sffxv ~]$ REDIS_ID=$(sudo docker ps | grep redis:v1 | grep k8s_redis | awk '{print $1}')
[minion at k8-4gmqfvntvm-0-6fymzzw3wrjx-kube-minion-zjdejo5sffxv ~]$ sudo docker exec -i -t $REDIS_ID redis-cli
Could not connect to Redis at 127.0.0.1:6379: Connection refused
not connected> [minion at k8-4gmqfvntvm-0-6fymzzw3wrjx-kube-minion-zjdejo5sffxv ~]$

And here is the working case, using "-h 10.100.84.2 -p 6379":

[minion at k8-4gmqfvntvm-0-6fymzzw3wrjx-kube-minion-zjdejo5sffxv ~]$ REDIS_ID=$(sudo docker ps | grep redis:v1 | grep k8s_redis | awk '{print $1}')
[minion at k8-4gmqfvntvm-0-6fymzzw3wrjx-kube-minion-zjdejo5sffxv ~]$ sudo docker exec -i -t $REDIS_ID redis-cli -h 10.100.84.2 -p 6379
10.100.84.2:6379> get replication:test
"true"
10.100.84.2:6379>

Note that I determined the '10.100.84.2' address for the redis master by running the following on the master minion:

[minion at k8-4gmqfvntvm-1-6pnrx2hnxa3d-kube-minion-bh6nynhayhfy ~]$ sudo docker exec -i -t $REDIS_ID ip addr show dev eth0
5: eth0: <BROADCAST,UP,LOWER_UP> mtu 1472 qdisc noqueue state UP
    link/ether 02:42:0a:64:54:02 brd ff:ff:ff:ff:ff:ff
    inet 10.100.84.2/24 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::42:aff:fe64:5402/64 scope link
       valid_lft forever preferred_lft forever
[minion at k8-4gmqfvntvm-1-6pnrx2hnxa3d-kube-minion-bh6nynhayhfy ~]$

So I'm looking for confirmation as to whether or not using the "-h 10.100.84.2 -p 6379" arguments is the right way to test this configuration? Is this a successful test?

Thanks,
Dane

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