什么是Dockerfile以及如何创建Docker镜像（） _Docker镜像

本文概述

什么是Dockerfile？
基本命令
如何使用Dockerfile创建Docker镜像？
运行一个Dockerfile

在处理Docker项目时, 大多数情况下, 现有的Docker映像无法满足你的要求。
这就是Dockerfile出现的地方；它将帮助你创建自定义Docker映像。因此, 了解Dockerfile是必不可少的。
什么是Dockerfile？它是带有一组命令或指令的简单文本文件。这些命令/指令将依次执行以对基本映像执行操作以创建新的docker映像。
注释和命令+参数是Dockerfile语法中的两种主线块
注释语法

#Line blocks used for commentingcommand argument argument1 …..

命令+参数示例

#Line blocks used for commentingcommand argument argument1 …..

以下是你的工作流程外观。

创建一个Dockerfile并提及创建你的Docker映像的说明
运行docker build命令将构建一个docker镜像
现在可以使用docker映像了, 使用docker run命令创建容器

文章图片
基本命令 FROM –定义要使用的基本映像并开始构建过程。
RUN –使用命令及其参数从映像运行它。
CMD –与RUN命令类似的功能, 但仅在实例化容器后才执行。
ENTRYPOINT –创建容器时, 它将在图像中定位默认应用程序。
ADD –将文件从源复制到目标(在容器内部)。
ENV –设置环境变量。
如何使用Dockerfile创建Docker镜像？首先, 让我们创建一个Dockerfile。

[email protected]:~$ gedit Dockerfile

将以下命令/说明放入其中并保存。

# Set the base image to UbuntuFROM ubuntu# Update the repository sources list and install gnupg2RUN apt-get update & & apt-get install -y gnupg2# Add the package verification keyRUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10# Add MongoDB to the repository sources listRUN echo 'deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen' > tee /etc/apt/sources.list.d/mongodb.list# Update the repository sources listRUN apt-get update# Install MongoDB package (.deb)RUN apt-get install -y mongodb# Create the default data directoryRUN mkdir -p /data/db# Expose the default portEXPOSE 27017# Default port to execute the entrypoint (MongoDB)CMD ["--port 27017"]# Set default container commandENTRYPOINT usr/bin/mongodb

在此Dockerfile中, 将ubuntu设置为基本映像。然后提到安装MongoDB所需的命令和参数。端口27017通过默认容器命令usr / bin / mongodb暴露给MongoDB
接下来, 我将运行它来创建一个docker镜像。
运行一个Dockerfile 成功执行后, 以下命令将创建一个名为geekflare_mongodb的Docker映像。

[email protected]:~$ docker build -t geekflare_mongodb .Sending build context to Docker daemon 667.2MBStep 1/9 : FROM ubuntulatest: Pulling from library/ubuntu7413c47ba209: Pull complete0fe7e7cbb2e8: Pull complete1d425c982345: Pull complete344da5c95cec: Pull completeDigest: sha256:c303f19cfe9ee92badbbbd7567bc1ca47789f79303ddcef56f77687d4744cd7aStatus: Downloaded newer image for ubuntu:latest---> 3556258649b2Step 2/10 : RUN apt-get update & & apt-get install -y gnupg2---> Running in de3706328761Get:1 http://security.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB]Get:2 http://archive.ubuntu.com/ubuntu bionic InRelease [242 kB]Fetched 16.9 MB in 38s (445 kB/s)Reading package lists...Reading package lists...Building dependency tree...Reading state information...Need to get 5187 kB of archives.After this operation, 15.8 MB of additional disk space will be used.Get:1 http://archive.ubuntu.com/ubuntu bionic/main amd64 readline-common all 7.0-3 [52.9 kB]Get:2 http://archive.ubuntu.com/ubuntu bionic/main amd64 libreadline7 amd64 7.0-3 [124 kB]Get:3 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 libsqlite3-0 amd64 3.22.0-1ubuntu0.1 [497 kB]Get:4 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 libssl1.1 amd64 1.1.1-1ubuntu2.1~18.04.4 [1300 kB]debconf: delaying package configuration, since apt-utils is not installedFetched 5187 kB in 12s (416 kB/s)Selecting previously unselected package readline-common.(Reading database ... 4040 files and directories currently installed.)Preparing to unpack .../00-readline-common_7.0-3_all.deb ...Unpacking readline-common (7.0-3) ...Selecting previously unselected package libreadline7:amd64.Preparing to unpack .../01-libreadline7_7.0-3_amd64.deb ...Selecting previously unselected package dirmngr.Setting up libnpth0:amd64 (1.5-3) ...Setting up libksba8:amd64 (1.3.5-2) ...Setting up gnupg-l10n (2.2.4-1ubuntu1.2) ...Processing triggers for libc-bin (2.27-3ubuntu1) ...Removing intermediate container de3706328761---> a32533894ed1Step 3/10 : RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10---> Running in 69c4dba38983Warning: apt-key output should not be parsed (stdout is not a terminal)Executing: /tmp/apt-key-gpghome.MuT5BDWwKZ/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10gpg: key 5F8F93707F0CEB10: public key "Totally Legit Signing Key < [email protected]> " importedgpg: key 9ECBEC467F0CEB10: 1 signature not checked due to a missing keygpg: key 9ECBEC467F0CEB10: public key "Richard Kreuter < [email protected]> " importedgpg: Total number processed: 2gpg: imported: 2Removing intermediate container 69c4dba38983---> cffbe06c1b50Step 4/10 : RUN echo 'deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen' > tee /etc/apt/sources.list.d/mongodb.list---> Running in 40630fd7b0a9Removing intermediate container 40630fd7b0a9---> a1bd9d8d7e51Step 5/10 : RUN apt-get update---> Running in 750717d9c0eaHit:1 http://archive.ubuntu.com/ubuntu bionic InReleaseHit:2 http://archive.ubuntu.com/ubuntu bionic-updates InReleaseHit:3 http://security.ubuntu.com/ubuntu bionic-security InReleaseHit:4 http://archive.ubuntu.com/ubuntu bionic-backports InReleaseReading package lists...Removing intermediate container 750717d9c0ea---> 397d6501db58Step 6/10 : RUN apt-get install -y mongodb---> Running in 88609c005e73Reading package lists...Building dependency tree...Reading state information...The following NEW packages will be installed:libboost-filesystem1.65.1 libboost-iostreams1.65.1libboost-program-options1.65.1 libboost-system1.65.1 libgoogle-perftools4libpcap0.8 libpcrecpp0v5 libsnappy1v5 libstemmer0d libtcmalloc-minimal4libunwind8 libyaml-cpp0.5v5 mongo-tools mongodb mongodb-clientsmongodb-server mongodb-server-core0 upgraded, 17 newly installed, 0 to remove and 0 not upgraded.Need to get 53.7 MB of archives.After this operation, 218 MB of additional disk space will be used.Get:1 http://archive.ubuntu.com/ubuntu bionic-updates/universe amd64 mongodb-clients amd64 1:3.6.3-0ubuntu1.1 [20.2 MB]Get:2 http://archive.ubuntu.com/ubuntu bionic-updates/universe amd64 mongodb-server-core amd64 1:3.6.3-0ubuntu1.1 [20.3 MB]Get:3 http://archive.ubuntu.com/ubuntu bionic-updates/universe amd64 mongodb-server all 1:3.6.3-0ubuntu1.1 [12.6 kB]Get:4 http://archive.ubuntu.com/ubuntu bionic-updates/universe amd64 mongodb amd64 1:3.6.3-0ubuntu1.1 [9968 B]Fetched 53.7 MB in 10s (5485 kB/s)Selecting previously unselected package libpcap0.8:amd64.(Reading database ... 4390 files and directories currently installed.)Selecting previously unselected package mongodb-clients.Preparing to unpack .../13-mongodb-clients_1%3a3.6.3-0ubuntu1.1_amd64.deb ...Unpacking mongodb-clients (1:3.6.3-0ubuntu1.1) ...Selecting previously unselected package mongodb-server-core.Preparing to unpack .../14-mongodb-server-core_1%3a3.6.3-0ubuntu1.1_amd64.deb ...Unpacking mongodb-server-core (1:3.6.3-0ubuntu1.1) ...Selecting previously unselected package mongodb-server.Preparing to unpack .../15-mongodb-server_1%3a3.6.3-0ubuntu1.1_all.deb ...Unpacking mongodb-server (1:3.6.3-0ubuntu1.1) ...Selecting previously unselected package mongodb.Preparing to unpack .../16-mongodb_1%3a3.6.3-0ubuntu1.1_amd64.deb ...Unpacking mongodb (1:3.6.3-0ubuntu1.1) ...Setting up mongodb-server-core (1:3.6.3-0ubuntu1.1) ...Setting up mongo-tools (3.6.3-0ubuntu1) ...Setting up mongodb-clients (1:3.6.3-0ubuntu1.1) ...Setting up mongodb-server (1:3.6.3-0ubuntu1.1) ...invoke-rc.d: could not determine current runlevelinvoke-rc.d: policy-rc.d denied execution of start.Setting up mongodb (1:3.6.3-0ubuntu1.1) ...Processing triggers for libc-bin (2.27-3ubuntu1) ...Removing intermediate container 88609c005e73---> d9c072cb1f84Step 7/10 : RUN mkdir -p /data/db---> Running in f817778f69abRemoving intermediate container f817778f69ab---> a3fbdb3def5cStep 8/10 : EXPOSE 27017---> Running in 8d070e2a1e07Removing intermediate container 8d070e2a1e07---> f770776a538cStep 9/10 : CMD ["--port 27017"]---> Running in ab612410df77Removing intermediate container ab612410df77---> e5830b80934fStep 10/10 : ENTRYPOINT usr/bin/mongod---> Running in 95f574727aabRemoving intermediate container 95f574727aab---> 095d17727ca0Successfully built 095d17727ca0Successfully tagged geekflare_mongodb:latest

让我们检查是否使用名称geekflare_mongodb创建了docker映像。

[email protected]:~$ docker imagesREPOSITORY TAG IMAGE ID CREATED SIZEgeekflare_mongodb latest 095d17727ca0 3 minutes ago 325MBubuntu latest 3556258649b2 4 days ago 64.2MBmean_express latest 35dcb3df9806 6 days ago 923MBmean_angular latest 9f8d61db600c 6 days ago 1.29GB

在容器mongo_container中运行docker映像geekflare_mongodb。

[email protected]:~$ docker run --name mongo_container -i -t geekflare_mongodb2019-07-27T19:38:23.734+0000 I CONTROL [initandlisten] MongoDB starting : pid=6 port=27017 dbpath=/data/db 64-bit host=b0095c1e55362019-07-27T19:38:23.735+0000 I CONTROL [initandlisten] db version v3.6.32019-07-27T19:38:23.735+0000 I CONTROL [initandlisten] git version: 9586e557d54ef70f9ca4b43c26892cd55257e1a52019-07-27T19:38:23.736+0000 I CONTROL [initandlisten] OpenSSL version: OpenSSL 1.1.1 11 Sep 20182019-07-27T19:38:23.739+0000 I CONTROL [initandlisten] allocator: tcmalloc2019-07-27T19:38:23.739+0000 I CONTROL [initandlisten] modules: none2019-07-27T19:38:23.739+0000 I CONTROL [initandlisten] build environment:2019-07-27T19:38:23.739+0000 I CONTROL [initandlisten] distarch: x86_642019-07-27T19:38:23.739+0000 I CONTROL [initandlisten] target_arch: x86_642019-07-27T19:38:23.739+0000 I CONTROL [initandlisten] options: {}2019-07-27T19:38:23.745+0000 I STORAGE [initandlisten] wiredtiger_open config: create, cache_size=2038M, session_max=20000, eviction=(threads_min=4, threads_max=4), config_base=false, statistics=(fast), log=(enabled=true, archive=true, path=journal, compressor=snappy), file_manager=(close_idle_time=100000), statistics_log=(wait=0), verbose=(recovery_progress), 2019-07-27T19:38:24.733+0000 I CONTROL [initandlisten]2019-07-27T19:38:24.734+0000 I CONTROL [initandlisten] ** WARNING: Access control is not enabled for the database.2019-07-27T19:38:24.735+0000 I CONTROL [initandlisten] ** Read and write access to data and configuration is unrestricted.2019-07-27T19:38:24.736+0000 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.2019-07-27T19:38:24.736+0000 I CONTROL [initandlisten]2019-07-27T19:38:24.736+0000 I CONTROL [initandlisten] ** WARNING: This server is bound to localhost.2019-07-27T19:38:24.737+0000 I CONTROL [initandlisten] ** Remote systems will be unable to connect to this server.2019-07-27T19:38:24.737+0000 I CONTROL [initandlisten] ** Start the server with --bind_ip < address> to specify which IP2019-07-27T19:38:24.737+0000 I CONTROL [initandlisten] ** addresses it should serve responses from, or with --bind_ip_all to2019-07-27T19:38:24.737+0000 I CONTROL [initandlisten] ** bind to all interfaces. If this behavior is desired, start the2019-07-27T19:38:24.738+0000 I CONTROL [initandlisten] ** server with --bind_ip 127.0.0.1 to disable this warning.2019-07-27T19:38:24.738+0000 I CONTROL [initandlisten]2019-07-27T19:38:24.739+0000 I STORAGE [initandlisten] createCollection: admin.system.version with provided UUID: 4b8b509d-633a-46c1-a302-cb8c82b0d5d32019-07-27T19:38:24.788+0000 I COMMAND [initandlisten] setting featureCompatibilityVersion to 3.62019-07-27T19:38:24.818+0000 I STORAGE [initandlisten] createCollection: local.startup_log with generated UUID: 6c1c0366-4b1b-4b92-9fcd-d18acc1260722019-07-27T19:38:24.862+0000 I FTDC [initandlisten] Initializing full-time diagnostic data capture with directory '/data/db/diagnostic.data'2019-07-27T19:38:24.866+0000 I NETWORK [initandlisten] waiting for connections on port 27017

打开一个新终端, 然后检查mongo_container是否正在运行。

[email protected]:~$ docker psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMESb0095c1e5536 geekflare_mongodb "/bin/sh -c usr/bin/…" 35 seconds ago Up 33 seconds 27017/tcp mongo_container

如你所见, 从geekflare_mongodb映像创建的容器已启动并正在运行。
【什么是Dockerfile以及如何创建Docker镜像（）】我希望这能使你对dockerfile及其好处有所了解。你还可以查看有关Dockerfile最佳实践的文档以了解更多信息。