初识Dockerfile

系统管理员 2022-08-22 04:48 139阅读 0赞

原文链接: [点击打开链接][Link 1]

Docker通过从 Dockerfile读取指令来自动编译images, Dockerfile包含生成一个image所需要的所有命令集合,它是一个文档,使用 docker build用户可以持续执行一些命令行指令.

The [`docker build`][docker build] command builds an image from a`Dockerfile` and a context.

The build’s context is the files at a specified location `PATH` or `URL`.

--The `PATH` is a directory on your local filesystem.

--The `URL` is a the location of a Git repository.

Warning: Do not use your root directory, `/`, as the`PATH` as it causes the build to transfer the entire contents of your hard drive to the Docker daemon.

the `Dockerfile` is called `Dockerfile`and located in the root of the context. You use the `-f`flag with `docker build` to point to a Dockerfile anywhere in your file system.

$ docker build -f /path/to/a/Dockerfile .

Image在编译好后的保存操作

>指定一个 image的保存路径

You can specify a repository and tag at which to save the new image if the build succeeds:

$ docker build -t shykes/myapp .

>tag多个image

To tag the image into multiple repositories after the build, add multiple `-t` parameters when you run the `build`command:

$ docker build -t shykes/myapp:1.0.2 -t shykes/myapp:latest .

加速Docker编译

Whenever possible, Docker will re-use the intermediate images (cache), to accelerate the `docker build`process significantly. This is indicated by the`Using cache` message in the console output. (For more information, see the [Build cache section][]) in the`Dockerfile` best practices guide:

Docker runs the instructions in a `Dockerfile` in order.The first instruction must be \`FROM\` in order to specify the [Base Image][] from which you are building.

**"\#" 是注释符**

**转义符( \\ ) :**

Escaping is possible by adding a `\` before the variable:`\$foo` or `\${foo}`, for example, will translate to`$foo` and `${foo}` literals respectively.

[Link 1]: https://docs.docker.com/engine/reference/builder/
[docker build]: https://docs.docker.com/engine/reference/commandline/build/
[Build cache section]: https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/#build-cache
[Base Image]: https://docs.docker.com/engine/reference/glossary/#base-image