Doubt: How is the dockerfile able to generate executable as there is no command that builds it

[AJ-54]

I am not able to understand how the Dockerfile is able to run the command ENTRYPOINT["/otelcol"] as there is no executable. how does the dockerfile instruct to run the main.go file and create an executable out of it?

[mx-psi]

The Makefile task first builds the binary and copies it to the cmd/otelcol folder

opentelemetry-collector/Makefile

Lines 175 to 176 in 3f5c718

	GOOS=linux $(MAKE) $(COMPONENT)
	cp ./bin/$(COMPONENT)_linux_amd64 ./cmd/$(COMPONENT)/$(COMPONENT)

then the Dockerfile copies the binary from the build context folder to the otelcol image

opentelemetry-collector/cmd/otelcol/Dockerfile

Line 5 in 3f5c718

COPY otelcol /

and finally it gets copied to the last stage

opentelemetry-collector/cmd/otelcol/Dockerfile

Line 16 in 3f5c718

COPY --from=otelcol /otelcol /

(this is a multi-stage build)

[AJ-54]

Thank you so much @mx-psi !!!