Fixes #2: Make role work with nodes joining master.

README.md

@@ -22,6 +22,10 @@ Available variables are listed below, along with default values (see `defaults/m
 
 Kubernetes packages to be installed on the server. You can either provide a list of package names, or set `name` and `state` to have more control over whether the package is `present`, `absent`, `latest`, etc.
 
+    kubernetes_role: master
+
+Whether the particular server will serve as a Kubernetes `master` (default) or `node`. The master will have `kubeadm init` run on it to intialize the entire K8s control plane, while `node`s will have `kubeadm join` run on them to join them to the `master`.
+
     kubernetes_kubelet_extra_args: ""
 
 Extra args to pass to `kubelet` during startup. E.g. to allow `kubelet` to start up even if there is swap is enabled on your server, set this to: `"--fail-swap-on=false"`.
@@ -34,11 +38,16 @@ Whether to remove the taint that denies pods from being deployed to the Kubernet
 
 Whether to enable the Kubernetes web dashboard UI (only accessible on the master itself, or proxied).
 
+    kuberenetes_debug: False
+
+Whether to show extra debug info in Ansible's logs (e.g. the output of the `kubeadm init` command).
+
     kubernetes_pod_network_cidr: '10.0.1.0/16'
+    kubernetes_apiserver_advertise_address: ''
     kubernetes_version: 'stable-1.10'
     kubernetes_ignore_preflight_errors: 'all'
 
-Options passed to `kubeadm init` when initializing the Kubernetes master.
+Options passed to `kubeadm init` when initializing the Kubernetes master. The `apiserver_advertise_address` defaults to `ansible_default_ipv4.address` if it's left empty.
 
     kubernetes_apt_release_channel: main
     kubernetes_apt_repository: "deb http://apt.kubernetes.io/ kubernetes-xenial {{ kubernetes_apt_release_channel }}"
@@ -54,9 +63,9 @@ Yum repository options for Kubernetes installation.
 
 None.
 
-## Example Playbook
+## Example Playbooks
 
-For a single node (master) Kubernetes cluster:
+### Single node (master-only) cluster
 
 ```yaml
 - hosts: all
@@ -69,6 +78,35 @@ For a single node (master) Kubernetes cluster:
     - geerlingguy.kubernetes
 ```
 
+### Two or more nodes (single master) cluster
+
+Master inventory vars:
+
+```yaml
+kubernetes_role: "master"
+```
+
+Node(s) inventory vars:
+
+```yaml
+kubernetes_role: "node"
+```
+
+Playbook:
+
+```yaml
+- hosts: all
+
+  vars:
+    kubernetes_allow_pods_on_master: True
+
+  roles:
+    - geerlingguy.docker
+    - geerlingguy.kubernetes
+```
+
+Then, log into the Kubernetes master, and run `kubectl get nodes` as root, and you should see a list of all the servers.
+
 ## License
 
 MIT / BSD

defaults/main.yml

@@ -9,12 +9,16 @@ kubernetes_packages:
   - name: kubernetes-cni
     state: present
 
+kubernetes_role: master
+
 kubernetes_kubelet_extra_args: ""
 
 kubernetes_allow_pods_on_master: True
 kubernetes_enable_web_ui: True
+kuberenetes_debug: False
 
 kubernetes_pod_network_cidr: '10.0.1.0/16'
+kubernetes_apiserver_advertise_address: ''
 kubernetes_version: 'stable-1.10'
 kubernetes_ignore_preflight_errors: 'all'
 

tasks/main.yml

@@ -35,57 +35,17 @@
     path: /etc/kubernetes/admin.conf
   register: kubernetes_init_stat
 
-- name: Initialize the Kubernetes master with kubeadm init.
+# Set up master.
-  command: >
+- include_tasks: master-setup.yml
-    kubeadm init
+  when: kubernetes_role == 'master'
-    --pod-network-cidr={{ kubernetes_pod_network_cidr }}
-    --apiserver-advertise-address={{ ansible_default_ipv4.address }}
-    --kubernetes-version {{ kubernetes_version }}
-    --ignore-preflight-errors={{ kubernetes_ignore_preflight_errors }}
-  register: kubeadmin_init
-  failed_when: False
-  when: kubernetes_init_stat.stat.exists == False
 
-- name: Print the init output to screen.
+# Set up nodes.
-  debug: var=kubeadmin_init.stdout
+- name: Get the kubeadm join command from the Kubernetes master.
-  when: kubernetes_init_stat.stat.exists == False
+  shell: kubeadm token create --print-join-command
-
-- name: Ensure .kube directory exists.
-  file:
-    path: ~/.kube
-    state: directory
-
-- name: Symlink the kubectl admin.conf to ~/.kube/conf.
-  file:
-    src: /etc/kubernetes/admin.conf
-    dest: ~/.kube/config
-    state: link
-
-- name: Configure Flannel networking.
-  command: "{{ item }}"
-  with_items:
-    - kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
-    - kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/k8s-manifests/kube-flannel-rbac.yml
-  register: flannel_result
-  changed_when: "'created' in flannel_result.stdout"
-
-# TODO: Check if taint exists with something like `kubectl describe nodes`
-# instead of using kubernetes_init_stat.stat.exists check.
-- name: Allow pods on master node (if configured).
-  command: "kubectl taint nodes --all node-role.kubernetes.io/master-"
-  when:
-    - kubernetes_allow_pods_on_master
-    - kubernetes_init_stat.stat.exists == False
-
-- name: Check if Kubernetes Dashboard UI service already exists.
-  shell: kubectl get services --namespace kube-system | grep -q kubernetes-dashboard
   changed_when: False
-  failed_when: False
+  when: kubernetes_role == 'master'
-  register: kubernetes_dashboard_service
+  run_once: True
-  when: kubernetes_enable_web_ui
+  register: kubernetes_join_command
 
-- name: Enable the Kubernetes Web Dashboard UI (if configured).
+- include_tasks: node-setup.yml
-  command: "kubectl create -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard.yaml"
+  when: kubernetes_role == 'node'
-  when:
-    - kubernetes_enable_web_ui
-    - kubernetes_dashboard_service is failed

tasks/master-setup.yml

@@ -0,0 +1,57 @@
+---
+- name: Initialize Kubernetes master with kubeadm init.
+  command: >
+    kubeadm init
+    --pod-network-cidr={{ kubernetes_pod_network_cidr }}
+    --apiserver-advertise-address={{ kubernetes_apiserver_advertise_address | default(ansible_default_ipv4.address) }}
+    --kubernetes-version {{ kubernetes_version }}
+    --ignore-preflight-errors={{ kubernetes_ignore_preflight_errors }}
+  register: kubeadmin_init
+  failed_when: False
+  when: kubernetes_init_stat.stat.exists == False
+
+- name: Print the init output to screen.
+  debug: var=kubeadmin_init.stdout
+  when:
+    - kuberenetes_debug
+    - kubernetes_init_stat.stat.exists == False
+
+- name: Ensure .kube directory exists.
+  file:
+    path: ~/.kube
+    state: directory
+
+- name: Symlink the kubectl admin.conf to ~/.kube/conf.
+  file:
+    src: /etc/kubernetes/admin.conf
+    dest: ~/.kube/config
+    state: link
+
+- name: Configure Flannel networking.
+  command: "{{ item }}"
+  with_items:
+    - kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
+    - kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/k8s-manifests/kube-flannel-rbac.yml
+  register: flannel_result
+  changed_when: "'created' in flannel_result.stdout"
+
+# TODO: Check if taint exists with something like `kubectl describe nodes`
+# instead of using kubernetes_init_stat.stat.exists check.
+- name: Allow pods on master node (if configured).
+  command: "kubectl taint nodes --all node-role.kubernetes.io/master-"
+  when:
+    - kubernetes_allow_pods_on_master
+    - kubernetes_init_stat.stat.exists == False
+
+- name: Check if Kubernetes Dashboard UI service already exists.
+  shell: kubectl get services --namespace kube-system | grep -q kubernetes-dashboard
+  changed_when: False
+  failed_when: False
+  register: kubernetes_dashboard_service
+  when: kubernetes_enable_web_ui
+
+- name: Enable the Kubernetes Web Dashboard UI (if configured).
+  command: "kubectl create -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard.yaml"
+  when:
+    - kubernetes_enable_web_ui
+    - kubernetes_dashboard_service is failed

tasks/node-setup.yml

@@ -0,0 +1,5 @@
+---
+- name: Join node to Kubernetes master
+  shell: >
+    {{ kubernetes_join_command.stdout }}
+    creates=/etc/kubernetes/kubelet.conf