In this chapter, we will create a new basic Go app. It will get some new functionality with each new chapter, eventually resembling the real-life app that incorporates the best practices for organizing applications and CI/CD with werf.
Preparing the environment
If you haven’t prepared your environment during previous steps, please, do it using the instructions provided in the “Preparing the environment” chapter.
If your environment has stopped working or instructions in this chapter don’t work, please, refer to these hints:
Let’s launch Docker Desktop. It takes some time for this application to start Docker. If there are no errors during the startup process, check that Docker is running and is properly configured:
docker run hello-world
You will see the following output if the command completes successfully:
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
Should you have any problems, please refer to the Docker documentation.
Let’s launch the Docker Desktop application. It takes some time for the application to start Docker. If there are no errors during the startup process, then check that Docker is running and is properly configured:
docker run hello-world
You will see the following output if the command completes successfully:
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
Should you have any problems, please refer to the Docker documentation.
Start Docker:
sudo systemctl restart docker
Make sure that Docker is running:
sudo systemctl status docker
If the Docker start is successful, you will see the following output:
● docker.service - Docker Application Container Engine
Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2021-06-24 13:05:17 MSK; 13s ago
TriggeredBy: ● docker.socket
Docs: https://docs.docker.com
Main PID: 2013888 (dockerd)
Tasks: 36
Memory: 100.3M
CGroup: /system.slice/docker.service
└─2013888 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
dockerd[2013888]: time="2021-06-24T13:05:16.936197880+03:00" level=warning msg="Your kernel does not support CPU realtime scheduler"
dockerd[2013888]: time="2021-06-24T13:05:16.936219851+03:00" level=warning msg="Your kernel does not support cgroup blkio weight"
dockerd[2013888]: time="2021-06-24T13:05:16.936224976+03:00" level=warning msg="Your kernel does not support cgroup blkio weight_device"
dockerd[2013888]: time="2021-06-24T13:05:16.936311001+03:00" level=info msg="Loading containers: start."
dockerd[2013888]: time="2021-06-24T13:05:17.119938367+03:00" level=info msg="Loading containers: done."
dockerd[2013888]: time="2021-06-24T13:05:17.134054120+03:00" level=info msg="Daemon has completed initialization"
systemd[1]: Started Docker Application Container Engine.
dockerd[2013888]: time="2021-06-24T13:05:17.148493957+03:00" level=info msg="API listen on /run/docker.sock"
Now let’s check if Docker is available and its configuration is correct:
docker run hello-world
You will see the following output if the command completes successfully:
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
b8dfde127a29: Pull complete
Digest: sha256:9f6ad537c5132bcce57f7a0a20e317228d382c3cd61edae14650eec68b2b345c
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
Should you have any problems, please refer to the Docker documentation.
Let’s start the minikube cluster we have already configured in the “Preparing the environment” chapter:
minikube start
Set the default Namespace so that you don’t have to specify it every time you invoke kubectl:
kubectl config set-context minikube --namespace=werf-guide-app
You will see the following output if the command completes successfully:
😄 minikube v1.20.0 on Ubuntu 20.04
✨ Using the docker driver based on existing profile
👍 Starting control plane node minikube in cluster minikube
🚜 Pulling base image ...
🎉 minikube 1.21.0 is available! Download it: https://github.com/kubernetes/minikube/releases/tag/v1.21.0
💡 To disable this notice, run: 'minikube config set WantUpdateNotification false'
🔄 Restarting existing docker container for "minikube" ...
🐳 Preparing Kubernetes v1.20.2 on Docker 20.10.6 ...
🔎 Verifying Kubernetes components...
▪ Using image gcr.io/google_containers/kube-registry-proxy:0.4
▪ Using image k8s.gcr.io/ingress-nginx/controller:v0.44.0
▪ Using image registry:2.7.1
▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🔎 Verifying registry addon...
🔎 Verifying ingress addon...
🌟 Enabled addons: storage-provisioner, registry, default-storageclass, ingress
🏄 Done! kubectl is now configured to use "minikube" cluster and "werf-guide-app" namespace by default
Make sure that the command output contains the following line:
Restarting existing docker container for "minikube"
Its absence means that a new minikube cluster was created instead of using the old one. In this case, repeat all the steps required to install the environment using minikube.
Now run the command in the background PowerShell terminal (do not close its window):
minikube tunnel --cleanup=true
Let’s start the minikube cluster we have already configured in the “Preparing the environment” chapter:
minikube start --namespace werf-guide-app
Set the default Namespace so that you don’t have to specify it every time you invoke kubectl:
kubectl config set-context minikube --namespace=werf-guide-app
You will see the following output if the command completes successfully:
😄 minikube v1.20.0 on Ubuntu 20.04
✨ Using the docker driver based on existing profile
👍 Starting control plane node minikube in cluster minikube
🚜 Pulling base image ...
🎉 minikube 1.21.0 is available! Download it: https://github.com/kubernetes/minikube/releases/tag/v1.21.0
💡 To disable this notice, run: 'minikube config set WantUpdateNotification false'
🔄 Restarting existing docker container for "minikube" ...
🐳 Preparing Kubernetes v1.20.2 on Docker 20.10.6 ...
🔎 Verifying Kubernetes components...
▪ Using image gcr.io/google_containers/kube-registry-proxy:0.4
▪ Using image k8s.gcr.io/ingress-nginx/controller:v0.44.0
▪ Using image registry:2.7.1
▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
▪ Using image docker.io/jettech/kube-webhook-certgen:v1.5.1
▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🔎 Verifying registry addon...
🔎 Verifying ingress addon...
🌟 Enabled addons: storage-provisioner, registry, default-storageclass, ingress
🏄 Done! kubectl is now configured to use "minikube" cluster and "werf-guide-app" namespace by default
Make sure that the command output contains the following line:
Restarting existing docker container for "minikube"
Its absence means that a new minikube cluster was created instead of using the old one. In this case, repeat all the steps required to install the environment from scratch using minikube.
If you have inadvertently deleted Namespace of the application, you must run the following commands to proceed with the guide:
kubectl create namespace werf-guide-app
kubectl create secret docker-registry registrysecret \
--docker-server='https://index.docker.io/v1/' \
--docker-username='<Docker Hub username>' \
--docker-password='<Docker Hub password>'
You will see the following output if the command completes successfully:
namespace/werf-guide-app created
secret/registrysecret created
If nothing worked, repeat all the steps described in the “Preparing the environment” chapter and create a new environment from scratch. If creating an environment from scratch did not help either, please, tell us about your problem in our Telegram chat or create an issue on GitHub. We will be happy to help you!
Preparing the repository
Update the existing repository containing the application:
Run the following commands in PowerShell:
cd ~/werf-guide/app
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -Recurse -Force ~/werf-guide/guides/examples/golang/010_basic_app/* .
git add .
git commit -m WIP
# Enter the command below to show the files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
Run the following commands in Bash:
cd ~/werf-guide/app
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -rf ~/werf-guide/guides/examples/golang/010_basic_app/. .
git add .
git commit -m WIP
# Enter the command below to show files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
Doesn’t work? Try the instructions on the “I am just starting from this chapter” tab above.
Prepare a new repository with the application:
Run the following commands in PowerShell:
# Clone the example repository to ~/werf-guide/guides (if you have not cloned it yet).
if (-not (Test-Path ~/werf-guide/guides)) {
git clone https://github.com/werf/website $env:HOMEPATH/werf-guide/guides
}
# Copy the (unchanged) application files to ~/werf-guide/app.
rm -Recurse -Force ~/werf-guide/app
cp -Recurse -Force ~/werf-guide/guides/examples/basic/004_modify_app ~/werf-guide/app
# Make the ~/werf-guide/app directory a git repository.
cd ~/werf-guide/app
git init
git add .
git commit -m initial
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -Recurse -Force ~/werf-guide/guides/examples/golang/010_basic_app/* .
git add .
git commit -m WIP
# Enter the command below to show the files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
Run the following commands in Bash:
# Clone the example repository to ~/werf-guide/guides (if you have not cloned it yet).
test -e ~/werf-guide/guides || git clone https://github.com/werf/website ~/werf-guide/guides
# Copy the (unchanged) application files to ~/werf-guide/app.
rm -rf ~/werf-guide/app
cp -rf ~/werf-guide/guides/examples/basic/004_modify_app ~/werf-guide/app
# Make the ~/werf-guide/app directory a git repository.
cd ~/werf-guide/app
git init
git add .
git commit -m initial
# To see what changes we will make later in this chapter, let's replace all the application files
# in the repository with new, modified files containing the changes described below.
git rm -r .
cp -rf ~/werf-guide/guides/examples/golang/010_basic_app/. .
git add .
git commit -m WIP
# Enter the command below to show files we are going to change.
git show --stat
# Enter the command below to show the changes that will be made.
git show
A new Go application
In this chapter, we will use a new basic Go application with the same feature set as the application from the previous section.
We got it like this - generated the directory structure for our Go:
.
├── app
│ └── main.go
├── go.mod
├── go.sum
└── internal
└── app
└── app.go
Please Note! The commands in the current section are for illustrative purposes only. They show how a basic application was generated. Only the commands in the “Deploying a new application” section are intended to be executed.
This application doesn’t have any functionality that is not needed at this stage. The only thing left is the configuration for the production environment.
Then, a new /ping route has been added to the API:
Then, a new /ping route that returns pong has been added to the API:
package app
import (
"net/http"
"github.com/gin-gonic/gin"
)
func Run() {
route := gin.Default()
route.GET("/ping", func(context *gin.Context) {
context.String(http.StatusOK, "pong\n")
})
err := route.Run()
if err != nil {
return
}
}
The ping method of the standard controller will handle this route (and return the pong string):
As for the building and CI/CD, the most significant changes affected the image build process:
# Here, a multi-stage build is used to assemble the image
# The image to build the project
FROM golang:1.18-alpine AS build
# Copy the source code of the application.
COPY . /app
WORKDIR /app
# Запускаем загрузку нужных пакетов.
RUN go mod download
# Запускаем сборку приложения.
RUN go build -o /goapp cmd/main.go
# The image to deploy to the cluster.
FROM alpine:latest
WORKDIR /
# Copy the project executable from the build image.
COPY --from=build /goapp /goapp
EXPOSE 8080
ENTRYPOINT ["/goapp"]
… while CI/CD changes were minimal. For example, here is the Deployment of the new application:
apiVersion: apps/v1
kind: Deployment
metadata:
name: werf-guide-app
spec:
replicas: 1
selector:
matchLabels:
app: werf-guide-app
template:
metadata:
labels:
app: werf-guide-app
spec:
imagePullSecrets:
- name: registrysecret
containers:
- name: app
image: {{ .Values.werf.image.app }}
# Задаем переменную окружения, переводящую Gin в Release Mode.
env:
- name: GIN_MODE
value: "release"
ports:
- containerPort: 8080
Our current application is stateless and does not need a database to run. We will show you how to turn it into a stateful application and deploy a dedicated database in the following chapters.
Deploying a new application
Let’s check if the new application is running fine by deploying it to the Kubernetes cluster:
werf converge --repo <DOCKER HUB USERNAME>/werf-guide-app
You should see the following output:
...
│ │ app/dockerfile Successfully built b4db644c6b58
│ │ app/dockerfile Successfully tagged 61fa7ef9-7959-4017-b77c-6d352dcd0f0e:latest
│ │ ┌ Store stage into <DOCKER HUB USERNAME>/werf-guide-app
│ │ └ Store stage into <DOCKER HUB USERNAME>/werf-guide-app (9.19 seconds)
│ ├ Info
│ │ name: <DOCKER HUB USERNAME>/werf-guide-app:14979813b9457ce28c8f06fa24c57975a14f537d6f6c1a3805b2ffc3-1686828883957
│ │ id: b4db644c6b58
│ │ created: 2023-06-15 14:34:42 +0300 MSK
│ │ size: 8.8 MiB
│ └ Building stage app/dockerfile (54.72 seconds)
└ ⛵ image app (55.40 seconds)
┌ Waiting for resources to become ready
│ ┌ Status progress
│ │ DEPLOYMENT REPLICAS AVAILABLE UP-TO-DATE
│ │ werf-guide-app 1/1 1 1
│ │ │ POD READY RESTARTS STATUS
│ │ ├── guide-app-6658d99959-5nfrg 1/1 0 Terminating
│ │ └── guide-app-8456cd6679-8dbd4 1/1 0 Running
│ │ RESOURCE NAMESPACE CONDITION: CURRENT (DESIRED)
│ │ Service/werf-guide-app werf-guide-app -
│ │ Ingress/werf-guide-app werf-guide-app -
│ └ Status progress
└ Waiting for resources to become ready (4.64 seconds)
Release "werf-guide-app" has been upgraded. Happy Helming!
NAME: werf-guide-app
LAST DEPLOYED: Thu Jun 15 14:34:55 2023
LAST PHASE: rollout
LAST STAGE: 0
NAMESPACE: werf-guide-app
STATUS: deployed
REVISION: 3
TEST SUITE: None
Running time 64.24 seconds
Let’s check whether our application works:
curl http://werf-guide-app.test/ping
You should see the following response:
pong
