Lab12

LAB12.md

@@ -0,0 +1,54 @@
+# 12
+
+## K8s ConfigMaps
+
+In this lab you will figure out how to manage non-confidential data in kubernetes.
+
+### 10 points
+
+1. Read about `ConfigMaps` objects:
+    * [ConfigMaps](https://kubernetes.io/docs/concepts/configuration/configmap/)
+
+2. We tried env vars, so let's mount a config file to our container. Create a folder `files` with `config.json`
+file inside. Put some data in json format inside to check your success in the end.
+
+3. Use helm and mount config.json:
+
+    * Create a `configMap` manifest. Get data from your `config.json`, use `.Files.Get`.
+    * Then update your `deployment.yaml`. Add `Volumes` and `VolumeMounts`.
+    > [Example](https://carlos.mendible.com/2019/02/10/kubernetes-mount-file-pod-with-configmap/)
+    * Install your updated helm chart and test the result. Get pods: `kubectl get po`. Use the name of the pod to provide a proof of your success. Check your config map inside pod, example: - `kubectl exec demo-758cc4d7c4-cxnrn -- cat /config.json`.`.Files.Get`.
+
+4. Create 12.md in the k8s folder and provide the output of the commands inside.
+
+5. You need to upgrade your application. For future labs your app must do something persistent. You can follow next steps or suggest any your logic.
+
+    1. Your application must write to a file the time when the root path `/` was accessed by the client.
+    2. It must have a new endpoint with path `/visits`.
+    3. Return the content via new endpoint, like you saw it for `/metrics`, but in any format.
+    4. Test it:
+        1. Update your `docker-compose.yml`.
+        2. Add a new volume for your file.
+        3. Test that it works.
+        4. Update your README.md for your application.
+
+6. Create a PR to the forked repo lab12 branch, ask your teammates to review it and review PRs of your teammates.
+
+7. Create a PR in your own repository from the lab12 branch to the lab11 one. It will help us with grading.
+
+### List of requirements
+
+* `config.json` file in `files` folder
+* `configMap` that takes data from `config.json` using `.Files.Get`
+* `volume`s and `volumeMount`s exist in deployments.yml
+* `12.md` file with results of commands
+
+## Bonus
+
+### 2 points
+
+1. Upgrade your bonus app in the same way, it must do something persistent.
+2. Read about `StatefulSet, Headless service, Persistent Volumes`. Describe how did you understand them, and why do we need them.
+    * https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/
+    * https://kubernetes.io/docs/concepts/services-networking/service/#headless-services
+    * https://kubernetes.io/docs/concepts/storage/persistent-volumes/

app_python/Dockerfile

@@ -9,6 +9,7 @@ COPY --chown=python:python timeweb/requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
 COPY --chown=python:python timeweb/timeweb.py timeweb/wsgi.py /app/
+RUN mkdir /data && chown python:python /data
 
 USER python
 

app_python/docker-compose.yml

@@ -0,0 +1,12 @@
+version: '3.4'
+services:
+  timeweb:
+    image: passkeyra/timeweb:latest
+    restart: unless-stopped
+    ports:
+      - '50000:50000'
+    volumes:
+      - data:/data
+
+volumes:
+  data: {}

app_python/timeweb/requirements.txt

@@ -1,11 +1,5 @@
-click==8.1.3
-Flask==2.2.2
-importlib-metadata==4.12.0
-itsdangerous==2.1.2
-Jinja2==3.1.2
-MarkupSafe==2.1.1
-Werkzeug==2.2.2
-zipp==3.8.1
+setuptools==65.5.1
+Flask
 gunicorn
 pytz
 requests

app_python/timeweb/timeweb.py

@@ -2,13 +2,32 @@
 """This web app shows Moscow time"""
 from datetime import datetime
 import pytz
+import sqlite3
+import json
 from flask import Flask
 
 UTC = pytz.utc
 timez_msk = pytz.timezone('Europe/Moscow')
 
 app = Flask(__name__)
 
+con = sqlite3.connect("/data/visits.db")
+cur = con.cursor()
+cur.execute('CREATE TABLE IF NOT EXISTS visits (visit_time TEXT)')
+con.commit()
+cur.close()
+
+@app.route('/visits')
+def visits():
+    cur = con.cursor()
+    data = cur.execute('SELECT * FROM visits')
+    output = []
+    for d in data.fetchall():
+        output.append(d[0])
+    cur.close()
+    return json.dumps(output)
+
+
 @app.route('/')
 def index():
     """
@@ -19,6 +38,10 @@ def index():
     """
     current_time = datetime.now(timez_msk)
     current_time = current_time.strftime('%H:%M:%S')
+    cur = con.cursor()
+    cur.execute(f'INSERT INTO visits (visit_time) VALUES (\'{current_time}\')')
+    con.commit()
+    cur.close()
     return f'Hello! Current time in Moscow is: {current_time}'
 
 if __name__ == '__main__':

k8s/12.md

@@ -0,0 +1,5 @@
+# K8s ConfigMaps
+
+* Add config and upgrade the helm package
+
+![](https://i.ibb.co/jWryK3L/1.png)

k8s/timeweb/files/config.json

@@ -0,0 +1 @@
+{"mydata":"hereismydata"}

k8s/timeweb/templates/config.yaml

@@ -0,0 +1,9 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: {{ include "timeweb.fullname" . }}-config
+  labels:
+    {{- include "timeweb.labels" . | nindent 4 }}
+data:
+  config.json: |-
+    {{ .Files.Get "files/config.json" }}

k8s/timeweb/templates/deployment.yaml

@@ -53,6 +53,14 @@ spec:
               port: 50000
           resources:
             {{- toYaml .Values.resources | nindent 12 }}
+          volumeMounts:
+            - name: config-volume
+              mountPath: /config.json
+              subPath: config.json
+      volumes:
+        - name: config-volume
+          configMap:
+            name: {{ include "timeweb.fullname" . }}-config
       {{- with .Values.nodeSelector }}
       nodeSelector:
         {{- toYaml . | nindent 8 }}