Docker learning: Coreos + Docker + rancher is really convenient and simple

Docker learning: Coreos + Docker + rancher is really convenient and simple
1. docker is really convenient

The advantage of using Docker is that it can save server costs, Fast deployment, and fast expansion. The advantage of using rancher is to simplify docker operations and use web to manage docker. The advantage of using coreos is that the linux system is simplified, and the startup speed is fast and consumes less resources.

2. quickly create eight tomcat servers

On your virtualbox virtual machine, click a few clicks to configure six tomcat servers.

It is easy to start and stop tomcat.

Resource Saving. My VM has 1 cup 2 GB memory, including docker and rancher services.
In fact, the rancher service is also a tomcat. Then start seven tomcat servers.
Some suitable for 7th tomcat cannot be started. The memory is insufficient.
At this time, the load is more than 50 after startup, and more than 100 at startup.

3. Created Application

Many docker catalog applications can be directly downloaded and used.

These are all rancher images. After downloading the images, You Can Package Multiple docker images into one stack for download, deployment, and external services.
You can also directly enter a name to create the instance.
For example, create a Jenkins, gogs:

Just click two.

Gogs is started successfully. Go to the installation page and do not install it.
I have previously written a detailed installation process:

4. Build a Server Load balancer instance

There is only one docker server, which is a standalone environment and finds the Server Load balancer.
Wait for the Intranet to get a few more machines to study, and then you can easily do the website architecture.
View the architecture diagram:

Gogs calls the mysq service.

5. About host files

After several docker sprees, we found that the disk consumption was high.
After searching for half a day, I found the largest folder in the directory:
/Var/lib/docker/overlay

All the files during docker running are saved here.
Including the deleted container files.
Use docker logs to view logs stored in:
/Var/lib/docker/containers/{container_id}. log
A total of 6 GB disks. After running a few more times, the results will soon be full.

4. Summary

Coreos + docker + rancher is really super convenient. You can use the web interface to create a docker application.
Containers make online development and deployment more convenient, and the efficiency of system deployment and launch is higher.
At the same time, the system becomes transparent and can be better scaled horizontally.
At the same time, system monitoring and alarms are all unified, making it easier to do so.
When a server is split into multiple tomcat servers, the ports remain the same, and the ports that provide external services are different.
This makes monitoring much easier. O & M costs are also reduced.
At the same time, when a host is split into multiple virtual machines, each virtual machine does not have to follow the CentOS operating system, as long as one coreos can be followed, and the rest is handed over to the image.

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