Hello Erik,

Please find my comments inline

De : Erik Jacobs [mailto:ejac...@redhat.com]
Envoyé : mercredi 4 mai 2016 17:32
À : ABDALA Olga
Cc : dev@lists.openshift.redhat.com
Objet : Re: Three-tier application deployment on OpenShift origin


On Wed, May 4, 2016 at 8:30 AM, ABDALA Olga 
<olga.abd...@solucom.fr<mailto:olga.abd...@solucom.fr>> wrote:
Hello Erik,

Thank you for your inputs.
However, while trying to update the label for my Nodes, here is what I get:

[cid:image001.png@01D1A9DC.B8899A60]

labels are single key/value pairs. You are trying to add an additional zone 
label without specifying --overwrite. You cannot have multiple values for the 
same key.

Same thing if I try to update my pods’ labels.
[cid:image002.png@01D1A9DC.B8899A60]

Changing a pod label is not what you want to do. You want to change the pod 
nodeselector.

Ø  Yes I guess that is what I will have to change

For the NodeSelector, where can I find the pod configuration file, for me to 
specify the Node,  please?
Is it in the master-config.yaml file?

master-config.yaml is the master configuration, not a "pod configuration". "pod 
configuration" is kind of a strange statement. You probably mean "pod 
definition".

Ø  By « pod definition », do you mean the pod yaml file?

We'll ignore nodeselector and master-config because while it's a thing, it 
won't do what you want. If you're interested, docs here: 
https://docs.openshift.org/latest/admin_guide/managing_projects.html#setting-the-cluster-wide-default-node-selector.

Ø  After checking the docs, My question is : if the defaultNodeSelector in the 
master config file is set for a specific region, does that mean that pods will 
never be placed on the Nodes of that specific region?

What you want to change is the pod nodeselector. I linked to the docs:

https://docs.openshift.org/latest/dev_guide/deployments.html#assigning-pods-to-specific-nodes

Ø  Just to make sure ; by setting a value to the « nodeSelector », will that 
put my pod to the specified Node?

I don't know how you created your pods, so how you change/add nodeselector 
depends.

Ø  Actualy, I did not really ‘create’ the pods. What I did is, after creating a 
project and adding my application to the project, 1 pod was automatically 
created. From there, I simply increased the number of pods (from the web 
console) to as many as I wanted.

Ø  By the way, I wanted to set something clear in my head regarding the pods. 
Does the number of pods mean the number of the application’s ‘versions’?

Since you have builds, I am guessing that you used something like "new-app". 
new-app will have created a deploymentconfig. You would want to edit the 
deploymentconfig, find the pod template, and then add the nodeselector as shown 
in the docs above.


Thank you!

Olga

De : Erik Jacobs [mailto:ejac...@redhat.com<mailto:ejac...@redhat.com>]
Envoyé : mardi 3 mai 2016 16:57
À : ABDALA Olga
Cc : dev@lists.openshift.redhat.com<mailto:dev@lists.openshift.redhat.com>
Objet : Re: Three-tier application deployment on OpenShift origin

Hi Olga,

Some responses inline/


Erik M Jacobs, RHCA
Principal Technical Marketing Manager, OpenShift Enterprise
Red Hat, Inc.
Phone: 646.462.3745<tel:646.462.3745>
Email: ejac...@redhat.com<mailto:ejac...@redhat.com>
AOL Instant Messenger: ejacobsatredhat
Twitter: @ErikonOpen
Freenode: thoraxe

On Mon, Apr 25, 2016 at 9:34 AM, ABDALA Olga 
<olga.abd...@solucom.fr<mailto:olga.abd...@solucom.fr>> wrote:
Hello all,

I am done with my origin advanced installation (thanks to your useful help) 
which architecture is composed of 4 virtualized servers (on the same network):

-       1  Master

-       2 Nodes

-       1 VM hosting Ansible

My next steps are to implement/test some use cases with a three-tier App(each 
App’s tier being hosted on a different VM):

-       The horizontal scalability;

-       The load-balancing of the Nodes : Keep the system running even if one 
of the VMs goes down;

-       App’s monitoring using Origin API: Allow the Origin API to “tell” the 
App on which VM is hosted each tier. (I still don’t know how to test that 
though…)

There are some notions that are still not clear to me:

-       From my web console, how can I know on which Node has my App been 
deployed?

If you look in the Browse -> Pods -> select a pod, you should see the node 
where the pod is running.


-       How can I put each component of my App on a separated Node?

-       How does the “zones” concept in origin work?

These two are closely related.

1) In your case it sounds like you would want a zone for each tier: appserver, 
web server, db
2) This would require a node with a label of, for example, zone=appserver
3) When you create your pod (or replication controller, or deployment config) 
you would want to specify, via a nodeselector, which zone you want the pod(s) 
to land in

This stuff is scattered throughout the docs:

https://docs.openshift.org/latest/admin_guide/manage_nodes.html#updating-labels-on-nodes
https://docs.openshift.org/latest/dev_guide/deployments.html#assigning-pods-to-specific-nodes

I hope this helps.


Content of /etc/ansible/hosts of my Ansible hosting VM:
[masters]
sv5305.selfdeploy.loc
# host group for nodes, includes region info
[nodes]
sv5305.selfdeploy.loc openshift_node_labels="{'region': 'infra', 'zone': 
'default'}" openshift_schedulable=false
sv5306.selfdeploy.loc openshift_node_labels="{'region': 'primary', 'zone': 
'east'}"
sv5307.selfdeploy.loc openshift_node_labels="{'region': 'primary', 'zone': 
'west'}"

Thank you in advance.

Regards,

Olga


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