docker 多阶段构建

docker 多阶段构建

FROM alpine as b1

RUN echo "b1xxx" >> /b1

FROM alpine as b2

RUN echo "b2bbb" >> /b2

FROM alpine 

COPY --from=b1 /b1 /b1
COPY --from=b2 /b2 /b2

WORKDIR /
RUN cat b1 b2

CMD [ "cat","b1","b2" ]

$ docker build  -t mt:0.0.1 .

$ docker run --rm mt:0.0.1
b1xxx
b2bbb

---

验证是否是并行构建

FROM alpine as b1

RUN echo "b1xxx" >> /b1
RUN sleep 3 # sleep 3s

FROM alpine as b2

RUN echo "b2bbb" >> /b2
RUN sleep 5 # sleep 5s

FROM alpine 

COPY --from=b1 /b1 /b1
COPY --from=b2 /b2 /b2

WORKDIR /
RUN cat b1 b2

CMD [ "cat","b1","b2" ]

最后使用时间5.4s，并不是 8s；所以是并行构建的

结论：多阶段构建是并行构建，并且一个 dockerfile 中可以加入多个阶段