In a multistage Dockerfile, how can you copy a binary from one stage to another?

In a multistage Dockerfile, how can you copy a binary from one stage to another?

• A. By using the COPY directive with the --from flag
• B. By using the RUN directive in a previous stage
• C. By using the ADD directive with --from flag
• D. By using the COPY directive without --from

Answer: (A)

In a multistage build, you move artifacts between stages by copying from a previous stage using the COPY instruction with the --from flag. This selects the source stage (either by name or by index) and copies the specified file(s) into the current stage’s filesystem. For example, build the binary in a builder stage, then in the final stage do COPY --from=builder /path/to/binary /usr/local/bin/binary. This keeps the final image small and only includes what you need. Note that just running commands in an earlier stage doesn’t transfer files to later stages. ADD can also use --from, but COPY is the standard choice for straightforward file copies between stages.

In a multistage build, you move artifacts between stages by copying from a previous stage using the COPY instruction with the --from flag. This selects the source stage (either by name or by index) and copies the specified file(s) into the current stage’s filesystem. For example, build the binary in a builder stage, then in the final stage do COPY --from=builder /path/to/binary /usr/local/bin/binary. This keeps the final image small and only includes what you need. Note that just running commands in an earlier stage doesn’t transfer files to later stages. ADD can also use --from, but COPY is the standard choice for straightforward file copies between stages.