About Jenkins + Docker + ASP.NET Core automated deployment issues (avoid pitfalls)

I didn't intend to write this blog, but during the actual operation, one is that I was overwhelmed by network problems (I really feel that the network can drive people crazy. Others can download packages and images in seconds, but I feel so miserable looking at my few KB small pipe), and the other is that there are still some pitfalls here. I wrote it down to prevent others from repeating the pitfalls.

A few points to note:

• Most of the shell commands below require administrator privileges, so if the user you are using is not root, you must add sudo
• For more complex commands, I provide both commented and uncommented versions. The uncommented version is for your convenience in copying.

Preparation

• CentOS 7.x
• Docker
• Jenkins
• A Docker-supported ASP.NET Core application code, you can use mine directly: https://github.com/xiaoxiaotank/MyAspNetCoreApp

Install Docker

Official documentation: https://docs.docker.com/engine/install/centos/

1. If you choose a new system, it is recommended to update yum and system kernel first

yum update

2. Make sure to uninstall the old version of docker

• Images, containers, volumes, and networks under /var/lib/docker/ are retained
• In the old version, Docker was named docker or docker-engine . Now it is named docker-ce

yum remove docker \
           docker-client \
           docker-client-latest \
           docker-common \
           docker-latest \
           docker-latest-logrotate \
           docker-logrotate \
           docker-engine

3. Install yum-utils (which provides yum-config-manager, which will be used below)

yum install -y yum-utils

4. Configure yum Alibaba Cloud Docker Repository Docker Official Repository: https://download.docker.com/linux/centos/docker-ce.repo

yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

5. Install Docker

yum install -y docker-ce docker-ce-cli containerd.io

6. Configure Docker image accelerator to obtain accelerator

Address: https://cr.console.aliyun.com/cn-hangzhou/instances/mirrors

sudo mkdir -p /etc/docker
sudo tee /etc/docker/daemon.json <<-'EOF'
{
  "registry-mirrors": ["Fill in your accelerator URL here"]
}
EOF
sudo systemctl daemon-reload
sudo systemctl restart docker

7. View docker information

docker info

8.hello-world test

docker run hello-world

Install and initialize Jenkins

Official documentation: https://www.jenkins.io/doc/book/installing/docker/

First of all, let me say that the official documentation uses the image docker:dind to execute docker commands and run program containers. I feel that it is completely unnecessary, and introducing this thing will bring a lot of additional problems, so I didn’t use it.

If you want to learn more about dind, please visit here and this blog

Install Jenkins

1. Create a Dockerfile

vim Dockerfile

2. Fill in the following content in the Dockerfile file

• Tag reference: https://hub.docker.com/r/jenkins/jenkins
• Note: Do not use the outdated image jenkins , but use the image jenkins/jenkins

FROM jenkins/jenkins:lts-jdk11
USER root
RUN apt-get update && apt-get install -y apt-transport-https \
       ca-certificates curl gnupg2 \
       software-properties-common
RUN curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -
RUN apt-key fingerprint 0EBFCD88
RUN add-apt-repository \
       "deb [arch=amd64] https://download.docker.com/linux/debian \
       $(lsb_release -cs) stable"

# Install docker-ce-cli to send docker commands to docker daemon in jenkins
RUN apt-get update && apt-get install -y docker-ce-cli

3. Build the image

docker build . -t myjenkins

If a warning appears: [Warning] IPv4 forwarding is disabled. Networking will not work.

In fact, it means that your Linux does not have the IPv4 packet forwarding function enabled.

You can try to restart Docker first

systemctl restart docker

If invalid, then

# 1. Open sysctl.conf
vim /etc/sysctl.conf

# 2. Add the following line net.ipv4.ip_forward=1

# 3. Restart network and docker
systemctl restart network && systemctl restart docker

4. Run the Jenkins comment version

docker run \
  --name jenkins \ # Give the container a name, called jenkins
  --detach \ # Run in background detached mode --publish 8080:8080 \ # Map host port 8080 to container port 8080 --publish 50000:50000 \ # Map host port 50000 to container port 50000 --volume jenkins-data:/var/jenkins_home \ # Volume jenkins-data maps container path /var/jenkins_home, so that you can modify jenkins configuration directly on the host --volume /var/run/docker.sock:/var/run/docker.sock \ # The docker sock on the host maps the docker sock of the container, so that the docker commands in the container are sent to the docker on the host to execute myjenkins # Use the image myjenkins just built to run the container

Unannotated version

docker run \
  --name jenkins \
  --detach \
  --publish 8080:8080 \
  --publish 50000:50000 \
  --volume jenkins-data:/var/jenkins_home \
  --volume /var/run/docker.sock:/var/run/docker.sock \
  myjenkins

5. Change the Jenkins plugin source

Earlier we mapped the path /var/jenkins_home in the container to the volume jenkins-data , and all docker volumes are stored in the directory /var/lib/docker/volumes/

Open hudson.model.UpdateCenter.xml

vim /var/lib/docker/volumes/jenkins-data/_data/hudson.model.UpdateCenter.xml

Change the URL in the file to the official mirror of Tsinghua University:

https://mirrors.tuna.tsinghua.edu.cn/jenkins/updates/update-center.json

Right now:

<?xml version='1.1' encoding='UTF-8'?>
<sites>
  <site>
    <id>default</id>
    <!--Original URL: https://updates.jenkins.io/update-center.json -->
    <url>https://mirrors.tuna.tsinghua.edu.cn/jenkins/updates/update-center.json</url>
  </site>
</sites>

Restart Jenkins:

docker restart jenkins

Initialize Jenkins

Visit: http://<host-ip>:8080 Enter the administrator's initial password to view the administrator's initial password:

cat /var/lib/docker/volumes/jenkins-data/_data/secrets/initialAdminPassword 

Select "Install recommended plugins"

After a long wait, due to network environment and dependency issues, some plug-ins may fail to install. However, let's click "Continue" and go in to fix it.

Next, create your own administrator account and confirm the jenkins url

After entering, the main page of Jenkins looks like this

Let's first fix the plugin that failed to install

Click "Manage Jenkins" in the left menu bar to upgrade Jenkins to the latest version

On the Update Center page, remember to check the box at the bottom that says "Restart Jenkins after installation completes (when idle)"

Automated configuration and deployment

Click the first "New Task" in the menu on the left side of the Jenkins page, fill in the task name, and select Free Style

Fill in the following configuration information and save it

The shell command is as follows:

image_tag=`date +%Y%m%d%H%M%S`;
echo $image_tag;

# Build the image and tag it
docker build -t myapp:$image_tag .;
docker images;

# Stop and delete the old version of myapp container
CID=$(docker ps | grep "myapp" | awk '{print $1}')
echo $CID
if [ "$CID" != "" ];then
  docker stop $CID
  docker rm $CID
fi

# Run the image just built docker run -p 5000:80 --name myapp -d myapp:$image_tag;
docker ps -a;
docker logs myapp;

Click "Build Now" on the left menu to deploy our AspNetCoreApp and check the "Console Output". When "Finished: SUCCESS" appears, it means the deployment is successful.

Visit: http://<host-ip>:5000/hello (note the addition of hello)

2021-05-12T15:28:43.9032704+00:00: Hello !

Now check the running container in Docker:

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
e167a135f7a0 myapp:20210512152453 "dotnet MyAspNetCore…" 2 minutes ago Up 2 minutes 0.0.0.0:5000->80/tcp, :::5000->80/tcp myapp
e83a2570c334 myjenkins "/sbin/tini -- /usr/…" About an hour ago Up About an hour ago 0.0.0.0:8080->8080/tcp, :::8080->8080/tcp, 0.0.0.0:50000->50000/tcp, :::50000->50000/tcp jenkins

Precautions

1. About the download and installation of jenkins blueocean and other plug-ins

If Jenkins wants to install plugins such as bluocean, do not follow the official website and put the installation command in the Dockerfile. Even if you add the parameter --jenkins-update-center to specify the acceleration source, it is not recommended to do so. Because I also wanted to automate it as much as possible at the beginning, but due to network problems, the plugin failed to download and install, which caused the image to fail to build, wasting two or three hours of my time (really painful)

In addition, you can also directly use the image jenkinsci/blueocean when installing Jenkins, which contains the relevant plug-ins of blueocean.

2. About myapp container port mapping 5000:80

Because the port exposed to the outside in my Dockerfile is 80, I mapped the container port 80 with the host's port 5000. You need to make changes here according to your actual situation.

3. If you are interested in dind (docker in docker)

If you want to learn more about dind, please visit here and this blog

The above is the details about the issue of automated deployment of Jenkins + Docker + ASP.NET Core. For more information about automated deployment of Jenkins + Docker + ASP.NET Core, please pay attention to other related articles on 123WORDPRESS.COM!