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In this chapter, I will explain to you: the second part of Dockerfile:

Dockerfile

FROM instruction

The main function is to specify an image as the base image for building a custom image, and modify and customize it based on it.

This instruction is a necessary instruction in Dockerfile, and it must also be the first instruction.

There are many high-quality official images on Docker Store, which can be directly used as our basic images.

As a service class, such as Nginx Mongo, etc.

For development, such as Python golang

Operating system classes, such as Centos ubuntu

In addition to some existing images, Docker also has a special mirror scratch

This image is virtual and represents a blank image.

FORM scratch

This means that it will not be mirrored on any basis.

Executable binaries can be copied to the image for direct execution, and the container itself shares the Linux kernel with the host.

Many applications developed in the Go language use this way to create images, which is one of the reasons why some people think that Go is a particularly suitable language for container microservice architecture.

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Make your own Hello world

On any Linux machine, install gcc to see if it is installed

[root@localhost hello_qf] # rpm-qa gcc glibc-static

Glibc-static-2.17-222.el7.x86_64

Gcc-4.8.5-11.el7.x86_64

If not, just install it.

[root@localhost hello_qf] # yum install gcc glibc-static

Edit C source code file

[root@localhost docker] # cat hello.c

# include

Int main ()

{

Printf ("Hello, Yangge!\ n")

Return 0

}

Compile source code files into executable binaries

[root@localhost hello_qf] # gcc-- static hello.c-o hello

After compiling, test it.

[root@localhost hello_qf] # ls

Hello hello.c

# hello is the binary file we compiled

# hello.c is the source file of C

[root@localhost hello_qf] #. / hello

Hello Yangge # output result indicates that the compilation is successful

Editing

Edit Dockerfile

Under the file directory with hello binary, compile the Dockerfile file as follows:

[root@localhost hello_qf] # ls

Dockerfile hello hello.c

[root@localhost hello_qf] # cat Dockerfile

FROM scratch

ADD hello /

CMD ["/ hello"]

ADD is to copy the hello document in the current directory to the root directory in the container, CMD executes the hello file in the root directory to build a new image.

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