我了解层、Copy-on-Write (COW) 和 UnionFS 等基本概念。我一直听到这样的说法
every line in a Dockerfile creates a new layer
所以我做了一些实验。这是我的 Dockerfile:
FROM davidjfelix/python3.5
RUN mkdir -p /code/server
ADD app.py /code
ADD ./server /code/server
ADD requirements.txt /code/
WORKDIR /code
RUN pip3 install -r requirements.txt
VOLUME /stuff
EXPOSE 7000
CMD ["/usr/local/bin/python", "-u", "app.py"]
我基于 Python 3.5 镜像创建了一个新镜像。使用 dockerspect 检查两个镜像后，我发现与 Python 3.5 镜像相比，新镜像仅具有 5 个附加层:
"RootFS": {
"Type": "layers",
"Layers": [
"sha256:6c3eb4525275f7040b8e3fbc846425ef934e1d44412d01cb37dc907d7d16e468",
"sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef",
"sha256:19f5e5ea72d6119ff25fb7bd45974cc108ae0bdc42bdeef1d805e1114502fe70",
"sha256:cd55733e01aec60a4e2c644f5bbf14b4c543cc1bce38f1757e8dda457d19de28",
"sha256:b8d8fe2d495aefca232e1a5b683b5ba3dce0661da29adc97e492274f31d9f4b6",
"sha256:258951e4bcc601a96055b0bf6e230a298f27c44bd9838ab9fbe4fb4824f3f1ca",
"sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef",
"sha256:b421868bee11843b136d6051d5f497c6d47fa67d2d5895853c6055ef5c75ef5a",
"sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef",
"sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef",
"sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef",
"sha256:26f874482e486b9989aba19b50a9b8308cb29a8dc6d3d8da00d05373cb0bad1e",
"sha256:4a3ef76df24253c3034313384494e3f8136c2580d2ddf423aaeed9297f83b22d",
"sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef"
]
}
最佳答案
此处显示的层是文件系统层。
Dockerfile 指令，例如 WORKDIR、VOLUME、EXPOSE、CMD 不会更改 FS .
一个docker history会显示这些命令，但不会显示 docker inspect .
请参阅“Show Layers of Docker Image”
关于docker - Dockerfile 中的每一行都会创建一个新层吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39325279/