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--- lab:stack_of_nucs:demonstrate_app_on_k8s [2023/05/09 20:41] – [Step 3 - Create a Service] user
+++ lab:stack_of_nucs:demonstrate_app_on_k8s [2024/05/06 02:12] (current) – removed user
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-====== Demonstrate App on k8s ======
-In our previous step we [[Ansible Playbook - install_kubernetes|installed Kubernetes]] (k8s) on our [[start|Stack of NUCs]].
-Now we are going to install a web app and expose it to our internal network.
-Purpose:
-  * Demonstrate a running a web application on Kubernetes
-References
-  * [[https://gitlab.com/doritoes/speedtester]]
-  * [[https://hub.docker.com/repository/docker/doritoes/speedtester/general]]
-  * [[https://docs.ansible.com/ansible/latest/collections/kubernetes/core/k8s_module.html]]
-  * [[https://opensource.com/article/20/9/ansible-modules-kubernetes]]
-====== Step 1 - Connect to the Kubernetes Master node ======
-From [[NUC 1]], log in to the Ansible control node, [[NUC 2]].
-====== Step 2 - Deploy a Distribution ======
-  - Create the YAML file to create the distribution
-    * <file yaml speedtester-deployment.yml>
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  name: speedtester
-  labels:
-    run: speedtester
-  namespace: default
-spec:
-  selector:
-    matchLabels:
-      run: speedtester
-  replicas: 2
-  template:
-    metadata:
-      labels:
-        run: speedtester
-    spec:
-      containers:
-      - name: speedtester
-        image: docker.io/doritoes/speedtester:latest
-        livenessProbe:
-          httpGet:
-            path: /favicon.ico
-            port: 80
-          initialDelaySeconds: 3
-          periodSeconds: 3
-</file>
-  - Apply the definition deployment
-    * ''kubectl apply -f speedtester-deployment.yml''
-  - View distribution information
-    * ''kubectl get pods,deployments''
-    * ''kubectl describe deployments speedtester''
-    * ''kubectl get deployment speedtester -o yaml''
-  - Increase number of replicas
-    *  Edit the file speedtester-deployment.yml to set the number of replicas to the number of Kubernetes worker nodes you have
-    * ''kubectl apply-f speedtester-deployment.yml''
-    * ''kubectl get pods -w''
-    * ''kubectl get deployments''
-    * ''kubectl describe deployments speedtester''
-    * ''kubectl get deployment speedtester -o yaml''
-====== Step 3 - Create a Service ======
-  - Create a service
-    - Using expose
-      * <code bash>kubectl expose deployment speedtester --port=8080 --name=speedtester-service --target-port=80</code>
-      * Removing it
-      * <code bash>
-kubectl get svc
-kubectl delete svc speedtester-service
-</code>
-    - Using a manifest
-      * <file yaml speedtester-service.yml>
-apiVersion: v1
-kind: Service
-metadata:
-  name: speedtester-service
-spec:
-  selector:
-    run: speedtester
-  type: NodePort
-  ports:
-    - protocol: TCP
-      port: 8080
-      targetPort: 80
-      nodePort: 30080
-</file>
-      * ''kubectl apply -f speedtester-service.yml''
-  - ''kubectl get all''
-  - ''kubectl describe svc speedtester-service''
-====== Step 4 - Testing Access ======
-Point your web browser on [[NUC 1]] to the IP address of any node and the port we selected, port 300080
-''http://IPADDRESSWORKER:30080''
-====== Next Step ======
-Congratulations, you have a working Web application on your Kubernetes cluster. Now continue to [[Ansible Playbook - Install HAProxy|Install HAProxy]].
-====== Optional ======
-===== Managing Kubernetes using Ansible =====
-Ansible can be used for managing Kubernetes.
-[[https://docs.ansible.com/ansible/latest/collections/kubernetes/core/k8s_module.html]]
-Run from the Ansible control node, NUC 2, in ''/home/ansible/my-project/k8s/''.
-Install python module kubernetes on all nodes
-<file yaml install-python-kubernetes.yml>
----
-- hosts: all
-  become: true
-  tasks:
-    - name: Install pip
-      apt:
-        name: python-pip
-    - name: Copy kube-config
-      copy:
-      src: /etc/kubernetes/admin.conf
-      dest
-      remote_src: true
-    - name: Install Kubernetes python package
-      ansible.builtin.pip:
-        name: kubernetes
-</file>
-==== Creating Namespaces ====
-This an example use case from the documentation.
-<file yaml namespace.yml>
----
-- hosts: master
-  become_user: ansible
-  tasks:
-    - name: Create namespace
-      k8s:
-        name: my-namespace
-        api_version: v1
-        kind: Namespace
-        state: present
-</file>
-''ansible-playbook namespace.yml''
-==== Deploy with Ansible ====
-This section uses the standard set out at [[https://opensource.com/article/20/9/ansible-modules-kubernetes]].
-Note the alternative approach at [[https://shashwotrisal.medium.com/kubernetes-with-ansible-881f32b8c53e]], where the YAML files are copied and used.
-Example standard deployment file:
-<file yaml>
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  name: speedtester
-  labels:
-    run: speedtester
-spec:
-  selector:
-    matchLabels:
-      run: speedtester
-  replicas: 2
-  template:
-    metadata:
-      labels:
-        run: speedtester
-    spec:
-      containers:
-      - name: speedtester
-        image: docker.io/doritoes/speedtester:latest
-        livenessProbe:
-          httpGet:
-            path: /favicon.ico
-            port: 80
-          initialDelaySeconds: 3
-          periodSeconds: 3
-</file>
-Now we move that YAML into a definition element in your Ansible playbook:
-<file yaml ansible-deployment.yml>
----
-- hosts: master
-  become_user: ansible
-  collections:
-    - kubernetes.core
-  tasks:
-    - name: Deploy speedtester2
-      k8s:
-        state: present
-        definition:
-          api_version: 1
-          kind: Deployment
-          metadata:
-            name: speedtester2
-            labels:
-              run: speedtester2
-          spec:
-            selector:
-              matchLabels:
-                run: speedtester2
-            replicas: 2
-            template:
-              metadata:
-                labels:
-                  run: speedtester2
-              spec:
-                containers:
-                  - name: speedtester2
-                    image: docker.io/doritoes/speedtester:latest
-                    livenessProbe:
-                      httpGet:
-                        path: /favicon.ico
-                        port: 80
-                      initialDelaySeconds: 3
-                      periodSeconds: 3
-</file>
-''ansible-playbook ansible-deployment.yml''
-''kubectl get pods''
-===== Chaos Testing =====
-Chaos engineering exercises the resiliency of a service by means of randomly or continually interrupting service.
-Proper chaos testing:  [[https://opensource.com/article/21/6/chaos-kubernetes-kube-monkey]]
-Some small scale chase testing is outlined below.
-==== Kill Pods ====
-You can watch what's happening a couple of ways:
-  * ''watch kubectl get pods''
-  * ''kubectl get pods -w''
-Killing pods:
-  * watch pods terminating and creating
-Rebooting nodes:
-  * worker nodes show status unknown on pods, then return to running
-  * once in a while the random selection hits the master node
-    * watch to see what happens then
-=== Literally kill the first pod in the list ===
-<code bash>
-kubectl delete pod $(kubectl get pods -l run=speedtester -o jsonpath='{.items[0].metadata.name}')
-</code>
-=== Forever loop to keep killing the first pod on the list ===
-<code bash>
-while true; do
-kubectl delete pod $(kubectl get pods -l run=speedtester -o jsonpath='{.items[0].metadata.name}')
-done
-</code>
-=== Kill all the current pods ===
-This is slow because the loop structure is sequential.
-''ansible-playbook deletepod.yml''
-<file yaml deletepod.yml>
----
-- name: Delete current pods matching speedtester
-  hosts: master
-  become: true
-  become_user: ansible
-  vars:
-    pod_filter:
-      - speedtester # beginning of the pod name
-  gather_facts: false
-  tasks:
-    - name: Get a list of all pods from the namespace
-      command: kubectl get pods --no-headers -o custom-columns=":metadata.name"
-      register: pod_list
-    - name: Print pod names
-      debug:
-        msg: "{{ item }}"
-      loop: "{{ pod_list.stdout_lines }}"
-      when: item is match(pod_filter|join('|'))
-    - name: Delete matching pods
-      command: kubectl delete pod "{{ item }}"
-      loop: "{{ pod_list.stdout_lines }}"
-      when: item is match(pod_filter|join('|'))
-</file>
-Using async we can limit the waiting to see if the command returns.
-''ansible-playbook deletepod-async.yml''
-<file yaml deletepod-async.yml>
----
-- name: Delete current pods matching speedtester
-  hosts: master
-  become: true
-  become_user: ansible
-  vars:
-    pod_filter:
-      - speedtester # beginning of the pod name
-  gather_facts: false
-  tasks:
-    - name: Get a list of all pods from the namespace
-      command: kubectl get pods --no-headers -o custom-columns=":metadata.name"
-      register: pod_list
-    - name: Print pod names
-      debug:
-        msg: "{{ item }}"
-      loop: "{{ pod_list.stdout_lines }}"
-      when: item is match(pod_filter|join('|'))
-    - name: Delete matching pods
-      command: kubectl delete pod "{{ item }}"
-      async: 5 # timeout in seconds
-      poll: 1 # poll every second
-      loop: "{{ pod_list.stdout_lines }}"
-      when: item is match(pod_filter|join('|'))
-</file>
-==== Crash Pods ====
-''ansible-playbook killpod-webservice.yml''
-<file yaml killpod-webservice.yml>
----
-- name: Crash current pods matching speedtester
-  hosts: master
-  become: true
-  become_user: ansible
-  vars:
-    pod_filter:
-      - speedtester # beginning of the pod name
-  gather_facts: false
-  tasks:
-    - name: Get a list of all pods from the namespace
-      command: kubectl get pods --no-headers -o custom-columns=":metadata.name"
-      register: pod_list
-    - name: Print pod names
-      debug:
-        msg: "{{ item }}"
-      loop: "{{ pod_list.stdout_lines }}"
-      when: item is match(pod_filter|join('|'))
-    - name: Crash container by killing supervisord
-      command: kubectl exec "{{ item }}" -- pkill supervisord
-      loop: "{{ pod_list.stdout_lines }}"
-      when: item is match(pod_filter|join('|'))
-</file>
-==== Reboot a Random Ansible Node ====
-<file yaml randomreboot.yml>
----
-- hosts: localhost
-  connection: local
-  gather_facts: no
-  tasks:
-    - add_host:
-        name: "{{ item }}"
-        groups: limited_selection
-      loop: "{{ (groups['all'] | shuffle)[0:1] }}"
-- hosts: limited_selection
-  gather_facts: no
-  tasks:
-    - reboot:
-</file>