Question

在尝试将r-shiny应用程序泊坞化时，Docker缓存失效使我遇到了问题。更改/app中的文件似乎仅在docker-compose build输出中启用缓存，这根本不反映文件完全不变的容器内部。在build命令的输出下面：

Building app
Step 1/13 : FROM rocker/shiny:latestBuilding app
Step 1/13 : FROM rocker/shiny:latest
 ---> f184f6aaa052
Step 2/13 : RUN apt-get update && apt-get install libssl-dev -y     nano     libxml2-dev     libsodium-dev     libmariadbclient-dev     libhiredis-dev
 ---> Using cache
 ---> 03a28c35ec29
Step 3/13 : COPY install_packages.R  /tmp/install_packages.R
 ---> Using cache
 ---> f0f98562976d
Step 4/13 : RUN Rscript /tmp/install_packages.R
 ---> Using cache
 ---> 1f66021a00f5
Step 5/13 : RUN R -e "install.packages('devtools', dependencies = TRUE, repos = 'http://cran.rstudio.com/')"
 ---> Using cache
 ---> c65054a0b033
Step 6/13 : RUN R -e "devtools::install_github('PaulC91/shinyauthr', dependencies = TRUE)"
 ---> Using cache
 ---> 29135386a24f
Step 7/13 : ARG CACHEPOP=1
 ---> Using cache
 ---> 2916da43a88f
Step 8/13 : ADD shiny-server.conf /etc/shiny-server/shiny-server.conf
 ---> Using cache
 ---> f1289d6aba53
Step 9/13 : ADD shiny-server.sh /usr/bin/shiny-server.sh
 ---> Using cache
 ---> 87f462480ada
Step 10/13 : COPY app /srv/shiny-server/app
 ---> d89ae8e7fa85
Step 11/13 : RUN ["chmod", "+x", "/usr/bin/shiny-server.sh"]
 ---> Running in 27c53685d6ad
Removing intermediate container 27c53685d6ad
 ---> 6cb6baf130af
Step 12/13 : EXPOSE 3838
 ---> Running in 4425302562bb
Removing intermediate container 4425302562bb
 ---> e6c4fc565195
Step 13/13 : CMD ["usr/bin/shiny-server.sh"]
 ---> Running in 7723d0219648
Removing intermediate container 7723d0219648
 ---> 742d77a0a30e
Successfully built 742d77a0a30e
Successfully tagged redis-test:latest

 ---> f184f6aaa052
Step 2/13 : RUN apt-get update && apt-get install libssl-dev -y     nano     libxml2-dev     libsodium-dev     libmariadbclient-dev     libhiredis-dev
 ---> Using cache
 ---> 03a28c35ec29
Step 3/13 : COPY install_packages.R  /tmp/install_packages.R
 ---> Using cache
 ---> f0f98562976d
Step 4/13 : RUN Rscript /tmp/install_packages.R
 ---> Using cache
 ---> 1f66021a00f5
Step 5/13 : RUN R -e "install.packages('devtools', dependencies = TRUE, repos = 'http://cran.rstudio.com/')"
 ---> Using cache
 ---> c65054a0b033
Step 6/13 : RUN R -e "devtools::install_github('PaulC91/shinyauthr', dependencies = TRUE)"
 ---> Using cache
 ---> 29135386a24f
Step 7/13 : ARG CACHEPOP=1
 ---> Using cache
 ---> 2916da43a88f
Step 8/13 : ADD shiny-server.conf /etc/shiny-server/shiny-server.conf
 ---> Using cache
 ---> f1289d6aba53
Step 9/13 : ADD shiny-server.sh /usr/bin/shiny-server.sh
 ---> Using cache
 ---> 87f462480ada
Step 10/13 : COPY app /srv/shiny-server/app
 ---> d89ae8e7fa85
Step 11/13 : RUN ["chmod", "+x", "/usr/bin/shiny-server.sh"]
 ---> Running in 27c53685d6ad
Removing intermediate container 27c53685d6ad
 ---> 6cb6baf130af
Step 12/13 : EXPOSE 3838
 ---> Running in 4425302562bb
Removing intermediate container 4425302562bbBuilding app
Step 1/13 : FROM rocker/shiny:latest
 ---> f184f6aaa052
Step 2/13 : RUN apt-get update && apt-get install libssl-dev -y     nano     libxml2-dev     libsodium-dev     libmariadbclient-dev     libhiredis-dev
 ---> Using cache
 ---> 03a28c35ec29
Step 3/13 : COPY install_packages.R  /tmp/install_packages.R
 ---> Using cache
 ---> f0f98562976d
Step 4/13 : RUN Rscript /tmp/install_packages.R
 ---> Using cache
 ---> 1f66021a00f5
Step 5/13 : RUN R -e "install.packages('devtools', dependencies = TRUE, repos = 'http://cran.rstudio.com/')"
 ---> Using cache
 ---> c65054a0b033
Step 6/13 : RUN R -e "devtools::install_github('PaulC91/shinyauthr', dependencies = TRUE)"
 ---> Using cache
 ---> 29135386a24f
Step 7/13 : ARG CACHEPOP=1
 ---> Using cache
 ---> 2916da43a88f
Step 8/13 : ADD shiny-server.conf /etc/shiny-server/shiny-server.conf
 ---> Using cache
 ---> f1289d6aba53
Step 9/13 : ADD shiny-server.sh /usr/bin/shiny-server.sh
 ---> Using cache
 ---> 87f462480ada
Step 10/13 : COPY app /srv/shiny-server/app
 ---> d89ae8e7fa85
Step 11/13 : RUN ["chmod", "+x", "/usr/bin/shiny-server.sh"]
 ---> Running in 27c53685d6ad
Removing intermediate container 27c53685d6ad
 ---> 6cb6baf130afBuilding app
Step 1/13 : FROM rocker/shiny:latest
 ---> f184f6aaa052
Step 2/13 : RUN apt-get update && apt-get install libssl-dev -y     nano     libxml2-dev     libsodium-dev     libmariadbclient-dev     libhiredis-dev
 ---> Using cache
 ---> 03a28c35ec29
Step 3/13 : COPY install_packages.R  /tmp/install_packages.R
 ---> Using cache
 ---> f0f98562976d
Step 4/13 : RUN Rscript /tmp/install_packages.R
 ---> Using cache
 ---> 1f66021a00f5
Step 5/13 : RUN R -e "install.packages('devtools', dependencies = TRUE, repos = 'http://cran.rstudio.com/')"
 ---> Using cache
 ---> c65054a0b033
Step 6/13 : RUN R -e "devtools::install_github('PaulC91/shinyauthr', dependencies = TRUE)"
 ---> Using cache
 ---> 29135386a24f
Step 7/13 : ARG CACHEPOP=1
 ---> Using cache
 ---> 2916da43a88f
Step 8/13 : ADD shiny-server.conf /etc/shiny-server/shiny-server.conf
 ---> Using cache
 ---> f1289d6aba53
Step 9/13 : ADD shiny-server.sh /usr/bin/shiny-server.sh
 ---> Using cache
 ---> 87f462480ada
Step 10/13 : COPY app /srv/shiny-server/app
 ---> d89ae8e7fa85
Step 11/13 : RUN ["chmod", "+x", "/usr/bin/shiny-server.sh"]
 ---> Running in 27c53685d6ad
Removing intermediate container 27c53685d6ad
 ---> 6cb6baf130af
Step 12/13 : EXPOSE 3838
 ---> Running in 4425302562bb
Removing intermediate container 4425302562bb
 ---> e6c4fc565195
Step 13/13 : CMD ["usr/bin/shiny-server.sh"]
 ---> Running in 7723d0219648
Removing intermediate container 7723d0219648
 ---> 742d77a0a30e
Successfully built 742d77a0a30e
Successfully tagged redis-test:latest

Step 12/13 : EXPOSE 3838
 ---> Running in 4425302562bb
Removing intermediate container 4425302562bb
 ---> e6c4fc565195
Step 13/13 : CMD ["usr/bin/shiny-server.sh"]
 ---> Running in 7723d0219648
Removing intermediate container 7723d0219648
 ---> 742d77a0a30e
Successfully built 742d77a0a30e
Successfully tagged redis-test:latest

 ---> e6c4fc565195
Step 13/13 : CMD ["usr/bin/shiny-server.sh"]
 ---> Running in 7723d0219648
Removing intermediate container 7723d0219648
 ---> 742d77a0a30e
Successfully built 742d77a0a30e
Successfully tagged redis-test:latest

如您所见，在步骤 10/13 中，缓存确实无效，但这并没有反映在容器中，在该容器中我仍然看到旧文件（未添加新文件）。 ADD和COPY产生相同的行为。

这是正常行为还是我没有看到任何东西？

出于彻底的考虑，文件夹结构和Dockerfile：

.
├── app
│   ├── global.R
│   ├── mock_users.R
│   ├── server.R
│   ├── test.txt
│   └── ui.R
├── docker-compose.yml
├── Dockerfile
├── install_packages.R
├── readme.md
├── redis_cache_test.Rproj
├── shiny-server.conf
└── shiny-server.sh

FROM rocker/shiny:latest

# install openssl
# libsodium for shinyauthr
RUN apt-get update && apt-get install libssl-dev -y \
    nano \
    libxml2-dev \
    libsodium-dev \
    libmariadbclient-dev \
    libhiredis-dev

# install packages and remove downloaded files
COPY install_packages.R  /tmp/install_packages.R
RUN Rscript /tmp/install_packages.R

# install shiny authr package
RUN R -e "install.packages('devtools', dependencies = TRUE, repos = 'http://cran.rstudio.com/')"
RUN R -e "devtools::install_github('PaulC91/shinyauthr', dependencies = TRUE)"

# copy config files
ARG CACHEPOP=1
ADD shiny-server.conf /etc/shiny-server/shiny-server.conf
ADD shiny-server.sh /usr/bin/shiny-server.sh

# copy app
COPY app /srv/shiny-server/app

## allow permissions
RUN ["chmod", "+x", "/usr/bin/shiny-server.sh"]

# expose port
EXPOSE 3838

CMD ["usr/bin/shiny-server.sh"]

Answer 1

正如您所观察到的那样，从构建输出中，缓存确实无效，并且您使用目录的新内容构建了一个新映像。但是，根据注释，然后使用卷/app:/srv/shiny-server运行此容器，该卷将把对/srv/shiny-server中的容器内此目录的访问映射到/app上的主机。请注意，此路径是绝对路径，而不是相对路径，因此文件位于主机/app上，而不是位于./app的构建目录中。

根据您的用例，有各种解决方案。首先，在compose文件中，您可以访问相对路径，因此，如果要在本地进行测试（装入卷的典型原因），则通常需要使用./app:/srv/shiny-server之类的相对路径来装入卷。结果是容器使用此目录的内容运行，而无需重建映像，这通常对于更快的开发周期是首选。

如果您不希望挂载卷，例如如果这是在生产中，并且不需要从容器外部访问文件，则最好从撰写文件中删除卷挂载。

最后，如果需要外部访问这些文件，但又希望通过映像的内容对其进行更新，则通常需要将卷的内容保存在安全的地方，并使用入口点脚本。在我的docker-base repo中，我使用save-volume和load-volume脚本执行此操作，一个脚本在映像构建期间运行，另一个脚本在运行容器时在入口点运行。

子文件夹中文件的更改不会使缓存无效（ADD或COPY）

1 个答案: