I am confused about whether .
means that it\'s a shortened abbreviation of the current directory of the image or if it\'s the current working directory on the l
The .
simply means "current working directory"
In the context of the docker build
command, you are using it to signal that the build context for docker build
is the current working directory. Like so:
docker build -t mytag:0.1 .
Let's say that you have this structure:
/home/me/myapp/
├── Dockerfile
├── theapp.py
And you invoke the docker build
command from /home/me/myapp
- you will pass the current working directory as the build context. This means that docker will see the following filestructure when building:
/
├── Dockerfile
├── theapp.py
In the context of a Dockerfile
, it means that same. Both inside and outside the image.
Take this COPY
instruction for example:
COPY . /app
Here the .
means the current working directory, where the docker build
command is executed. This will be relative the to build context that is passed to the docker build
command.
For this COPY
instruction:
COPY theapp.py .
It means, take the file theapp.py
and copy it to the working directory of the docker image that is being built. This directory can be set at build time with the WORKDIR
instruction, so that:
WORKDIR /app
COPY theapp.py .
Would leave you with the file /app/theapp.py
inside the resulting docker image.
Finally, this COPY
instruction:
COPY . .
Means take everything from the working directory where the docker build command is issued, relative to the build context that is passed to it. And copy it to the current working directory of the docker image.
I saw 3 .
characters on your question, so let me expand one by one.
The first, as you imagine, the .
character means the current directory.
COPY . .
The second dot represented the current location on your virtual machine. Whenever you run cd
command in the Dockerfile. That may be easy to understand.
The first dot more unintelligible a little. The first dot character represented the current location on your host machine. The location you input after docker build
command like that:"docker build [options] <location>
".
The dot character means the current directory whenever you call your docker build
command. For example:
[~]$ docker build .
The dot character represented for default home directory of this user on your real machine.
.(dot) means current working directory.
It depends on the context. In your COPY somecode.java .
it's the image. In COPY . .
it's both. The first dot is in the local machine and the second dot is the image.
In the docker build
command, it tells Docker to take files for the newly built image from the working directory on your local machine.
As others said, it's basically just means "current working directory". But when building a Docker image, there are two of those. One in your local machine where you're building the image. The second one is the file system that's built in the image.