Implement first TripleO 3 nodes job

For complex deployments (eg: High Availability, Network Isolation, etc),
2 nodes are not enough for TripleO as we deploy overcloud on a single
node.  We would like to extend our testing to test more realistic
deployments with one more node for the overcloud.

This patch does 2 things:
- Create centos-7-3-node in nodepool, that will run 2 subnodes.
- Implement experimental (non-voting) TripleO centos-7-3nodes-multinode

Change-Id: Ie204431d9a50dd8247d6393e916c5033ba0499d3

jenkins/jobs/projects.yaml

@@ -14473,6 +14473,14 @@
           node: 'centos-7-2-node'
           trigger: 'gate'
           branch-override: default
+      # Experimental job for multinode with 3 nodes
+      - '{trigger}-tripleo-ci-{jobname}{suffix}':
+          jobname: 'centos-7-3nodes-multinode'
+          suffix: '-nv'
+          type: '3nodes-multinode'
+          node: 'centos-7-3-node'
+          trigger: 'gate'
+          branch-override: default
       # non-voting check job for multinode
       - '{trigger}-tripleo-ci-{jobname}{suffix}':
           jobname: 'centos-7-nonha-multinode'

nodepool/nodepool.yaml

@@ -248,6 +248,25 @@ labels:
       - name: osic-cloud8
       - name: infracloud-vanilla
       - name: infracloud-chocolate
+  - name: centos-7-3-node
+    image: centos-7
+    ready-script: multinode_setup.sh
+    subnodes: 2
+    min-ready: 1
+    providers:
+      - name: rax-dfw
+      - name: rax-ord
+      - name: rax-iad
+      - name: ovh-gra1
+      - name: ovh-bhs1
+      - name: bluebox-sjc1
+      - name: internap-mtl01
+      - name: osic-cloud1-s3500
+      - name: osic-cloud1-s3700
+      - name: osic-cloud1-disk
+      - name: osic-cloud8
+      - name: infracloud-vanilla
+      - name: infracloud-chocolate
   - name: tripleo-centos-7
     image: centos-7
     ready-script: configure_mirror.sh

zuul/layout.yaml

@@ -5032,6 +5032,8 @@ projects:
       - periodic-tripleo-ci-centos-7-ovb-ha-mitaka
       - periodic-tripleo-ci-centos-7-ovb-ha-newton
       - periodic-tripleo-ci-centos-7-ovb-ha-tempest
+    experimental:
+      - gate-tripleo-ci-centos-7-3nodes-multinode-nv
     experimental-tripleo:
       - gate-tripleo-ci-centos-7-ovb-nonha
       - gate-tripleo-ci-centos-7-ovb-updates