Dockerfile commands to implement

[priyawadhwa]

FROM

• Add support for ARG with FROM

RUN

• Run command in shell form -- RUN , default prefixed by "sh -c"
• Run command in exec form
• Change default shell for RUN command with the SHELL command

CMD

• CMD in exec form
• CMD as default parameters to entrypoint
• CMD in shell form, default prefixed by "sh -c"
• If multiple CMD calls in Dockerfile, only the last should be run

LABEL

• Adds metadata to image (labels are inherited by parent/base images)

EXPOSE

• Expose a port

ENV

• Set environment variables as <key>:<value> pairs in image

ADD
Add has two forms:

• ADD [--chown=<user>:<group>] <src>... <dest>

• ADD [--chown=<user>:<group>] ["<src>",... "<dest>"]

• Copy new files, directories, or remote URLs from <src> to the <dest>

• Multiple sources may be specified, their paths are interpreted as relative to the context of the build

• Support for any <src> to contain wildcards

• <dest> is absolute path, or relative to WORKDIR command

• Specify UID/GID with --chown flag

• If <src> is local tar archive, it is unpacked to destination directory

COPY
COPY has two forms:
-COPY [--chown=<user>:<group>] <src>... <dest>
-COPY [--chown=<user>:<group>] ["<src>",... "<dest>"]

• Allow copy from multiple sources to destination
• Add support for wildcards in <src>
• Specify UID/GID with --chown flag
• Set source location to previous build stage with --from flag

ENTRYPOINT

• Set entrypoint in exec and shell form

VOLUME

• Create a mount point and mark it as holding externally mounted volumes

USER

• Set UID/GID

WORKDIR

• Set working directory

ARG

• Implement ARG

ONBUILD

• Add trigger to metadata of the image, under the key OnBuild

STOPSIGNAL

• Implement stopsignal

HEALTHCHECK

• Implement healthcheck

SHELL

• Override default shell, can effect RUN/CMD/ENTRYPOINT commands