A quick overview of the Dockerfile's syntax
In this section, we will explain the syntax or the format of Dockerfile
. A Dockerfile
is made up of instructions, comments, and empty lines, as shown here:
# Comment INSTRUCTION arguments
The instruction line of Dockerfile
is made up of two components, where the instruction line begins with the instruction itself, which is followed by the arguments for the instruction. The instruction could be written in any case, in other words, it is case-insensitive. However, the standard practice or convention is to use uppercase in order to differentiate it from the arguments. Let's take another look at the content of Dockerfile
in our previous example:
FROM busybox:latest CMD echo Hello World!!
Here, FROM
is an instruction which has taken busybox:latest
as an argument, and CMD
is an instruction which has taken echo Hello World!!
as an argument.
The comment line in Dockerfile
must begin with the #
symbol. The #
symbol after an instruction is considered as an argument...