Reference
Inheritance
FROM ruby:2.2.2
Variables
ENV APP_HOME /myapp
RUN mkdir $APP_HOME
ARG APP_HOME=""
RUN mkdir $APP_HOME
Initialization
RUN bundle install
WORKDIR /myapp
VOLUME ["/data"]
# Specification for mount point
ADD file.xyz /file.xyz
COPY --chown=user:group host_file.xyz /path/container_file.xyz
Run commands in strict shell
ENV my_var
SHELL ["/bin/bash", "-euo", "pipefail", "-c"]
# With strict mode:
RUN false # fails build like using &&
RUN echo "$myvar" # will throw error due to typo
RUN true | false # will bail out of pipe
Using shell will turn on strict mode for shell commands.
Onbuild
ONBUILD RUN bundle install
# when used with another file
Commands
EXPOSE 5900
CMD ["bundle", "exec", "rails", "server"]
Entrypoint
ENTRYPOINT ["executable", "param1", "param2"]
ENTRYPOINT command param1 param2
Configures a container that will run as an executable.
ENTRYPOINT exec top -b
This will use shell processing to substitute shell variables, and will ignore any CMD or docker run command line arguments.
Metadata
LABEL version="1.0"
LABEL "com.example.vendor"="ACME Incorporated"
LABEL com.example.label-with-value="foo"
LABEL description="This text illustrates \
that label-values can span multiple lines."
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