Monthly Archives: December 2021

Create a ‘kind’ Kubernetes cluster and deploy an App using a GitLab pipeline

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[This is part 8/8 on GitLab Continuous Integration series]

Objective

In testing microservices I imagine three incremental scenarios:

  1. The first runs in a developer’s machine, mostly unit tests with mock-ups that can run from shell or IDE.
  2. Next one adds a few services like a database. It might be local (developer machine).
  3. Finally, a full app test with deployment to QA servers or Kubernetes cluster.

This post is about scenario #2. We will use a NodeJS app that runs in a web server. The steps to automate are:

  • When the App changes (git push) the GitLab Server will build a image.
  • It will upload it to our local (GitLab) repository.
  • It will create a ‘kind’ Kubernetes cluster in the local PC. I use KIND but there is also Minikube, k3d or MicroK8s.
  • Deploy the application and configure an Ingress controller so we can access it on localhost port 80.

Notes:

  • The scenario #3 can be implemented using the previous IaC post and tags in the pipeline for a deployment branch. There are lots of tutorials, check the reference section at the end. And the two last post of this series.
  • You’ll need in your PC: Python 3 (anaconda), Ansible, kind and a GitLab runner.

I. Prepare your PC

The preferred method that Ansible uses to access the computers is SSH. We need it in our PC.

Install OpenSSH:

  1. Open a terminal and:
# Install
$ sudo apt-get install openssh-server

# Enable service
$ sudo systemctl enable ssh
  1. Make sure you complete the login process into your PC to generate the credential’s files:
$ ssh your-username@your.local.ip

II. Project Set Up

We’ll perform two steps in our GitLab Server (or the code repository of your preference). For our GitLab Server the steps are:

Step 2.1 Create the repository

  1. Access our GitLab Server. I have shown examples our set up using:
    http://example.gitlab.com
    log in as devguy/Clave123
  2. Click create project (plus sight at top). Select ‘blank project’.
    I’m naming mine CICDtest with public access.
    Click create
  3. Get the url to access the project. In our case the string can be copied from the page:
    http://devguy:Clave123@gitlab.example.com/devguy/CICDtest.git

Step 2.2 Create Server variables

We will use a few CI/CD variables for our Ansible scripts. To create them:

  • Access our GitLab Server
  • Go to Project > CICDtest
    then Settings > CI/CD
    expand Variables
  • Enter the values below
  • Note: Some variable can’t be masked because it does not meet the regular expression requirements (see GitLab’s documentation about masked variables).
  • Click ‘Add Variable’ button.

The variables used in our script will hold values we already know or you’ll get from a console terminal in your PC:

  1. Create two variables with the Gitlab project’s login ‘user’ and ‘password’ (replace your values):
  • Key: USERNAME
    Value: devguy
    Type: Variable
    Environment scope: All (default)
    Protect variable: Checked
    Mask variable: Unchecked
  • key: USERPASSWORD
    value: Clave123
    Environment scope: All
    Protect: uncheck Mask: uncheck
  1. Create a variable for your user and IP in the PC. Get the IP from the command ifconfig
  • key: SERVER_USER
    value: <your user name>
    Environment scope: All
    Protect: uncheck
    Mask: uncheck
  • key: SERVER_IP
    value: <your.ip.value>
    Environment scope: All
    Protect: uncheck
    Mask: uncheck
  1. For the SSH login
    You are going to store the SSH private key in a GitLab CI/CD file variable, so that the pipeline can make use of the key to log in to the server. To get the SSH private key use:
$ cat ~/.ssh/id_rsa

Copy the complete output to your clipboard:

-----BEGIN RSA PRIVATE KEY-----
...
-----END RSA PRIVATE KEY-----
  • Key: ID_RSA Value: Paste your SSH private key from your clipboard (including a line break at the end). Environment Scope: All Type: File (it can also be ???) Protect variable: Checked Mask variable: Uncheck
    If you select ‘File’, a file containing the private key will be created on the runner for each CI/CD job and its path will be stored in the $ID_RSA environment variable.

The next one is a big string as it is the values of the server you have ssh into:

  • Key: SSH_KNOWN_HOSTS Value: can be the output of:
# 1. content of the file
$ cat ~/.ssh/known_hosts
# 2. the command ssh-keyscan
$ ssh-keyscan <IPs to log into>
<<output>>

Environment Scope: All Protect variable: Checked Mask variable: Uncheck

III. Get a copy of the code

Four steps are needed to get the code ready

Step 3.1 Get a copy of the example

Create a folder the PC (use your own PATH, it doesn’t affect the setup, just substitute it in a couple of commands):

$ mkdir ~/Desarrollo/ci_cd/Ansible/106_Complete_CI-CD

Get the ‘CICDtest.zip‘ file into that folder and untar/ungzip it.

Step 3.2 Make it into a local repository

Get into the working folder

$ cd ~/Desarrollo/ci_cd/Ansible/106_Complete_CI-CD/CICDtest

and initialize it as a git repository

$ git init
$ git add .

If you, like me (still in december 2021) get a ‘master’ branch from git initialization, then you might want it to rename to a more sensible ‘main’ with:

# Check the brach name
$ git branch -a
* master

# You can rename it with
$ git branch -m master main

# Chech the name again
$ git branch -a
* main

$ git status On branch
On branch main
nothing to commit, working tree clean

Set the remote GitLab repository credentials. I write here my URL (from step 2.1 with the user and password), with ‘devguy’ and ‘devguy@gitlab.example.com‘

$ git remote add origin http://devguy:Clave123@gitlab.example.com/devguy/CICDtest.git
$ git config --global user.name "devguy"
$ git config --global user.email "devguy@gitlab.example.com"

Step 3.3 Modify values according [in your PC]

  1. Update your ‘IP’ and ‘username’ with: vi hosts.ini
192.168.1.120    ansible_user=fjmartinez
  1. In the Kubernetes deployment: Might need to modify ./files/deployment_cluster.yaml as it makes reference to the repository name.

IV. Review the Code

About organization

  • App: The app is just a single file. Its a NodeJS that starts a server and listens in port 8080, if a request is received at ‘/’ and port 80, it prints os.hostname
  • files: Contains the yml Ansible files, yaml files for the cluster deployment (Kubernetes deployment files) and kind cluster config.

The overview of the pipeline is explained in 3 parts, as they were tested. Then they were united and some improvements were made.

Part 4.1. Build the container

The first part of the script is the ‘build stage’, the corresponding part of the pipeline involves using the services of a docker container that will allow us to build a container with the complete tag that includes our GitLab project path.

After successful build we want push the image to the GitLab repository. For that we need to provide the credentials en a ‘before_script’ command. Notice the use of our first variable ($USERPASSWORD) so we avoid writing it in the script that will be in the logs.

.gitlab-ci.yml [Part 1]

stages:
  - build

variables:
  DOCKER_HOST: tcp://docker:2375/
  DOCKER_DRIVER: overlay2
  DOCKER_TLS_CERTDIR: ""

build:
  stage: build
  image: docker:latest
  services:
    - docker:dind
    - name: docker:dind
      alias: docker
  before_script:
    - echo $USERPASSWORD | docker login registry.example.com:5050 -u $USERNAME --password-stdin
  script:
    - docker build -t registry.example.com:5050/devguy/cicdtest/javatest:v1 app
    - docker push registry.example.com:5050/devguy/cicdtest/javatest:v1

Dockerfile

FROM node:7
ADD app.js /app.js
ENTRYPOINT ["node", "app.js"]

Part 4.2. Create the cluster

The next step in the pipeline is the ‘test’ stage. We need a Kubernetes cluster. In some examples it exist as it takes time to create one. If you can have one running all the time, remove this job (part 1 of the step). But I choose to illustrate IaC so we will create one.

But testing in our PC ended up to be more complicated that setting up in other machines:

  • Caveat #1: Local SSH Access
    Running Ansible from a Docker runner works using a local connection. But by executing the .barsh setup script on a no-login sign-in results in exiting and no PATH is set so any software (kind, ansible-playbook, python) is found.
    To provide that information we copy the ssh data needed for the runner to ssh into the PC in the ‘before_script’. Tip: Check your machine’s apps path with the command which kind, which python3, etc.
    The part that is not cool of this approach is that the YML configuration file for the cluster is read from the PC, not the repository. I tried different configuration of inventory/users/connection but to no avail. One option that should work is using a service with an image that contains the software that we need. I’ll update this.
  • Caveat #2: Repository authorization
    Kubernetes can provide credentials to access a private repository or our GitLab repository using a ‘docker-secret’ and referencing it in the deployment spec as ‘imagePullSecrets:’.
    But I am using an ‘insecure’ Server (that has proven to be more complicated than a secure one) that contains our project’s repository. The Kubernetes approach wont work in kind. We need to modify the create ‘kind’ command to enable a plugin. From this:
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
…

To this (in the ./files/kind-config.yaml file)

kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
containerdConfigPatches:
- |-
  [plugins."io.containerd.grpc.v1.cri".registry.mirrors."registry.example.com:5050"]
    endpoint = ["http://registry.example.com:5050"]
...

If you are using minikube, k3s similar configuration can be made.

The part of the script that creates the KinD cluster is:

.gitlab-ci.yml [Part 2]

stages:
  - test
  
before_script:
  - 'which ssh-agent || ( apt-get update -y && apt-get install openssh-client git -y )'
  - eval $(ssh-agent -s)
  - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
  - mkdir -p ~/.ssh
  - chmod 700 ~/.ssh
  - echo "$SSH_KNOWN_HOSTS" >> ~/.ssh/known_hosts
  - chmod 644 ~/.ssh/known_hosts

cluster:
  stage: test
  script:
    - ssh $SERVER_USER@$SERVER_IP 'export PATH="$HOME/go:$HOME/go/bin/:/usr/local/go/bin:$HOME/anaconda3/bin:$PATH"; ~/anaconda3/bin/ansible-playbook -i localhost, ~/Desarrollo/ci_cd/Ansible/106_Complete_CI-CD/CICDtest/files/create_kind_cluster.yml'

Note: You can see that the ‘localhost,’ notation as a name list (use of the coma) here.

Part 4.3. Deploy the App

The next step would be the deployment of the app using the Ansible Kubernetes collection. Using a standard kubectl deployment file we will: create a namespace (is mandatory for the collection), start an Ingress controller, start the App deployment (yaml to start a pod and a service), wait until the Ingress controller is ready to serve requests, and lastly deploy the routing rule. Note that if you change the App, you might just need to update the ‘deployment_cluster.yaml’ .

This is the complete file:

deployment_in_kind.yaml

---
# This playbook deploys an App from a local repository into a Kubernetes cluster

- name: Ansible App Deployment
  hosts: localhost
  collections:
    - kubernetes.core
    
  tasks:
  - name: Create a namespace (requirement for the collection)
    k8s:
      name: testing
      api_version: v1
      kind: Namespace
      state: present

  - name: Deploy the Ingress controller
    k8s:
      state: present
      kubeconfig: "~/.kube/config"
      src: "nginx-deployment.yaml"
      
  - name: Deploy the App
    k8s:
      state: present
      kubeconfig: "~/.kube/config"
      src: "deployment_cluster.yaml"        

  - name: Wait until Ingress conroller is ready to serve requests
    k8s_info:
      kind: Pod
      wait: yes
      wait_timeout: 500
      wait_condition:
        type: Ready
        status: "True"
      namespace: ingress-nginx
      label_selectors:
        app.kubernetes.io/component=controller

  - name: Deploy the routing rule
    k8s:
      state: present
      kubeconfig: "~/.kube/config"
      src: "using_ingress.yaml"

And the third part of the pipeline code is:

.gitlab-ci.yml [Part 3]

stages:
  - deploy

deploy_app:
  stage: deploy

  before_script:
  - 'which ssh-agent || ( apt-get update -y && apt-get install openssh-client git -y )'
  - eval $(ssh-agent -s)
  - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
  - mkdir -p ~/.ssh
  - chmod 700 ~/.ssh
  - echo "$SSH_KNOWN_HOSTS" >> ~/.ssh/known_hosts
  - chmod 644 ~/.ssh/known_hosts

  script:
  - ssh $SERVER_USER@$SERVER_IP 'export PATH="$HOME/go:$HOME/go/bin/:/usr/local/go/bin:$HOME/anaconda3/bin:$PATH"; cd ~/Desarrollo/ci_cd/Ansible/106_Complete_CI-CD/CICDtest/; ~/anaconda3/bin/ansible-playbook -i hosts.ini ./files/deployment_in_kind.yml'

Note: If you want detail logging from ansible then add the -v, -vv or -vvv parameter, like this: ansible-playbook -vvv -i hosts, . If you want logging from the script use CI_DEBUG_TRACE: "true"

In this command the inventory file does reference a hosts.ini file as it list an IP, user and vars:

192.168.1.120    ansible_user=fjmartinez

[vars]
ansible_python_interpreter=/usr/bin/python3.8
ansible_connection=local

The Complete Pipeline

If we assemble the script, the complete .gitlab-ci.yml is:

stages:
  - build
  - test

variables:
  DOCKER_HOST: tcp://docker:2375/
  DOCKER_DRIVER: overlay2
  DOCKER_TLS_CERTDIR: ""

build:
  stage: build
  image: docker:latest
  services:
    - docker:dind
    - name: docker:dind
      alias: docker
  before_script:
    - echo $USERPASSWORD | docker login registry.example.com:5050 -u devguy --password-stdin
  script:
    - docker build -t registry.example.com:5050/devguy/cicdtest/javatest:v1 app
    - docker push registry.example.com:5050/devguy/cicdtest/javatest:v1

cluster:
  stage: test
  before_script:
    - 'which ssh-agent || ( apt-get update -y && apt-get install openssh-client git -y )'
    - eval $(ssh-agent -s)
    - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
    - mkdir -p ~/.ssh
    - chmod 700 ~/.ssh
    - echo "$SSH_KNOWN_HOSTS" >> ~/.ssh/known_hosts
    - chmod 644 ~/.ssh/known_hosts
  script:
    - ssh $SERVER_USER@$SERVER_IP 'export PATH="$HOME/go:$HOME/go/bin/:/usr/local/go/bin:$HOME/anaconda3/bin:$PATH"; ~/anaconda3/bin/ansible-playbook -i localhost, ~/Desarrollo/ci_cd/Ansible/106_Complete_CI-CD/CICDtest/files/create_kind_cluster.yml'
    - ssh $SERVER_USER@$SERVER_IP 'export PATH="$HOME/go:$HOME/go/bin/:/usr/local/go/bin:$HOME/anaconda3/bin:$PATH"; cd ~/Desarrollo/ci_cd/Ansible/106_Complete_CI-CD/CICDtest/; ~/anaconda3/bin/ansible-playbook -i hosts.ini ./files/deployment_in_kind.yml'

V. Update the Code in the remote repository

You have made modifications to several files, so save them and then push them into our GitLab code repository:

$ git commit -a -m "GitLab CI CD test 1.0"
$ git push origin main

an automatic start of the pipeline will be triggered.

VI. Result

Step 6.1 Pipeline

The pipeline page (CI/CD -> Pipelines) shows the result of the two ‘stages’ in our script with the icon and tooltip: Passed

Clicking on them, if you want to read the logs generated by the runner and Ansible.

Step 6.2 Execution

Open a browser to see our app and type:

http://localhost

That will generate a request to ‘/’ and the app will show a text similar to this:

That it!.

The next steps to upgrade this script would be add a ‘task’ to check if the cluster already exist (it fails as is it) and in that case just clean the objects. Or add a ‘job’, part of the stage ‘test’, to execute a test suite/script (like selenium) and at the end of the pipeline delete the cluster.

VII. Clean Up

To clean the cluster you can eliminate the objects in the cluster with:

$ kubectl delete -f ./files/using_ingress.yaml &&
  kubectl delete -f ./files/nginx-deployment.yaml &&
  kubectl delete -f ./files/deployment_cluster.yaml &&
  kubectl delete -f ./files/namespace testing

Or just delete the cluster

$ kind delete cluster --name "ci-cluster"

References

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