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This article is about how to use dockerfile to build a nginx image, the editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

Docker's method of building an image: commit, dockerfile

1. Use commit to build an image:

Commit is an image based on the original image. The purpose of using this method to build an image is to save some configuration information and modified information in the image. Equivalent to a mirrored snapshot.

2. Use dockerfile to build an image:

Dockerfile is the required (custom) image for a quick build.

Dockerfile's instructions:

FROM: specify the base image (FROM is a required instruction and must be the first instruction).

RUN: used to execute command line commands. Its basic format:

Shell format: RUN, enter the command in the bash environment, a dockerfile allows you to use RUN no more than 127th layers, so use RUN once, use'\ 'line feeds, and use' & &'to execute the next command. This format is generally used

Exec format: RUN, which is like the format in a function call

COPY: copy the file. Its basic format:

Format 1:COPY...

Format 2:COPY [",."]

ADD: a more advanced way to copy files. Some functions have been added to COPY. If you copy a compressed package, it will be decompressed directly, without the need for RUN decompression.

CMD: container startup command. Its basic format:

Shell format: CMD

Exec format: CMD ["executable", "parameter 1", "parameter 2".]

Parameter list format: CMD ["Parameter 1", "Parameter 2"...]. After specifying the ENTRYPOINT instruction, specify the specific parameters with CMD.

ENTRYPOINT: entry point. Its basic format is divided into exec and shell.

The purpose of ENTRYPOINT, like CMD, is to start the program and parameters in the specified container. ENTRYPOINT can be replaced in operation, but it is more tedious than CMD and needs to be specified by the parameter entrypoint of docker run. When ENTRYPOINT is specified, the meaning of CMD changes. Instead of running its command directly, it passes the contents of the CMD as an argument to the ENTRYPOINT instruction. When it is executed, it becomes: "

ENV: sets the environment variable. (you can use the variables used here) its basic format:

Format 1:ENV

Format 2:ENV = =...

ARG: build parameters. The effect of build parameters is the same as that of ENV, which sets environment variables, except that the environment variables built by ARG do not exist in the future container runtime. Its basic format:

Format 1: ARG [=]

Format 2: this default value can be overridden with-- build-arg = in the build command docker build

VOLUME: defines anonymous volumes. Its basic format:

Format 1: VOLUME ["", "...]

Format 2: VOLUME

EXPOSE: expose the port. The EXPOSE directive declares the port provided by the runtime container, and the port is not opened because of this declaration when the container is started. Its basic format:

Format 1: EXPOSE [...]

WORKDIR: specify the working directory. Its basic format:

Format 1: WORKDIR

USER: specifies the current user. USER is to help you switch to the specified user. Its basic format:

Format 1: USER

HEALTCHECK: health check to determine whether the container is in a normal state. Its basic format:

Format 1: HEALTCHECK [options] CMD: set commands to check the health of containers

Format 2: HEALTCHECK NONE: if the basic image has a health check instruction, use this format to block its health check instruction

Build a nginx image:

Create a directory and write dockerfile in that directory:

[root@docker ~] # mkdir mynginx [root@docker ~] # cd mynginx/ [root@docker mynginx] # pwd/root/mynginx [root@docker mynginx] #

Download the nginx source package to the directory you created (under the mynginx directory):

[root@docker] # wget-P / root/mynginx/ http://nginx.org/download/nginx-1.15.2.tar.gz

Write a Dockerfile:

[root@docker mynginx] # vi Dockerfile

Its contents are as follows:

FROM centosRUN ping-c 1 www.baidu.comRUN yum-y install gcc make pcre-devel zlib-devel tar zlibADD nginx-1.15.2.tar.gz / usr/src/RUN cd / usr/src/nginx-1.15.2\ & mkdir / usr/local/nginx\ & &. / configure-- prefix=/usr/local/nginx & & make & & make install\ & & ln-s / usr/local/nginx/sbin/nginx / usr/local/sbin/\ & & nginxRUN Rm-rf / usr/src/nginx-1.15.2EXPOSE 80

Run the docker command to build the image:

[root@docker mynginx] # docker build-t nginx:v3 .Sending build context to Docker daemon 1.029MBStep 1 5182e96772bfStep 7: FROM centos-- > 5182e96772bfStep 2 www.baidu.com 7: RUN ping-c 1 www.baidu.com-- > Using cache-- > 2f70f8abaf2aStep 3 y install gcc make pcre-devel zlib-devel tar zlib- 7: RUN yum-y install gcc make pcre-devel zlib-devel tar zlib- > Using cache-- > dbdda4b7ae6fStep 4 Using cache 7: ADD nginx-1.15.2.tar.gz / usr/src/-- > Using cache-- -> 18ace6285668Step 5ln 7: RUN cd / usr/src/nginx-1.15.2 & & mkdir / usr/local/nginx & &. / configure-- prefix=/usr/local/nginx & & make & & make install & & ln-s / usr/local/nginx/sbin/nginx / usr/local/sbin/ & & nginx- > Using cache-- > 99629488ede9Step 6 nginx- 7: RUN rm-rf / usr/src/nginx-1.15.2-- > Using cache- -- > 869fbad71879Step 7 869fbad71879Step 7: EXPOSE 80-> Using cache-> 384bed72ea6fSuccessfully built 384bed72ea6fSuccessfully tagged nginx:v3

The output of two Successfully means that the construction is successful!

Start the custom image:

Use docker images to view the built image:

Start a custom image:

[root@docker ~] # docker run-dit-p 80:80-- name nginx nginx:v3ecaafe1190447878b98dfb0198e92439db60ff7dab57a1674e0e9e7282a9c858 [root@docker ~] # docker ps-aCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMESecaafe119044 nginx:v3 "/ bin/bash" 3 seconds ago Up 2 seconds 0.0.0.0 dit 80-> 80/tcp nginx

Note: at this point, no matter how you start the container, it is still in the exited state.

After all kinds of solutions, we finally know where the problem lies. When the original container starts, it starts with a thread in the background. It has already started when it starts, but after it executes the command, it exits and is not running in the background, so use the-dit parameter to make it run in the background.

[root@docker ~] # docker run-dit-p 80:80-- name nginx nginx:v3ecaafe1190447878b98dfb0198e92439db60ff7dab57a1674e0e9e7282a9c858 [root@docker ~] # docker ps-aCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMESecaafe119044 nginx:v3 "/ bin/bash" 3 seconds ago Up 2 seconds 0.0.0.0 dit 80-> 80/tcp nginx

However.

At this time, there is a problem, although it is up, but the nginx web web page interface can not be accessed, showing that the connection is rejected!

[root@docker ~] # curl 192.168.100.22curl: (7) Failed connect to 192.168.100.22 Failed connect to 80; refuse to connect [root@docker ~] # elinks-- dump 192.168.100.22ELinks: reject a connection

Then, after asking Baidu and FQ to see Google, I finally found out where the problem lies. It turns out that all you have to do is to use exec to enter the container and start nginx.

[root@docker ~] # docker exec-it nginx bash [root@ecaafe119044 /] # nginx [root@ecaafe119044 /] # exitexit [root@docker ~] # curl 192.168.100.22Welcome to nginx! Body {width: 35eme; margin: 0 auto; font-family: Tahoma, Verdana, Arial, sans-serif;} Welcome to nginx!

If you see this page, the nginx web server is successfully installed andworking. Further configuration is required.

For online documentation and support please refer tonginx.org.Commercial support is available atnginx.com.

Thank you for using nginx.

The above is how to use dockerfile to build a nginx image. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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