Some of the common instructions in Dockerfile are as follows:
- FROM: We use FROM to set the base image for subsequent instructions. In every valid Dockerfile, FROM is the first instruction.
- LABEL: We use LABEL to organize our images as per project, module, licensing etc. We can also use LABEL to help in automation.
In LABEL we specify a key value pair that can be later used for programmatically handling the Dockerfile.
- RUN: We use RUN command to execute any instructions in a new layer on top of the current image. With each RUN command we add something on top of the image and use it in subsequent steps in Dockerfile.
- CMD: We use CMD command to provide default values of an executing container. In a Dockerfile, if we include multiple CMD commands, then only the last instruction is used.