Docker image commands- Part-01
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The docker build command builds Docker images from a Dockerfile
$ docker image build --helpTo list the help on any command just execute the above command, followed by the — help option.
Create a Dockerfile with the below content.
FROM nginx:alpineCMD ["nginx", "-g", "daemon off;"]
- Create a docker image
$ docker image build -t myapp:v1.0.0 .
2. Create a docker image with different file locations and a custom dockerfile name
$ docker image build -t myapp:v1.0.0 -f Dockerfile/sample/prod.dockerfile .
3. Build a docker image with memory and CPU limit
$ docker build --cpu-shares=2 --memory=1024m -t myapp:1.0 .
4. Force Docker to build a Docker image without the cache
$ docker build --pull --no-cache --tag myapp:v1 .
--no-cache - This will force rebuilding of layers already available
--pull - This will trigger a pull of the base image referenced using FROM ensuring you got the latest version.
5. Set a build-time variable with — build-arg
FROM alpine:3.9.3#Setting a default value to Argument WELCOME_USER
ARG WELCOME_USER=Bikram
RUN echo "Welcome $WELCOME_USER, to Docker World!" > message.txt
CMD cat message.txt
Building Docker Image with default argument and create a container
$ docker image build -t arg:v1 .
$ docker run arg:v1
Passing the argument(WELCOME_USER) during image build time using –build-arg flag
$ docker image build -t arg:v2 --build-arg WELCOME_USER=Google .
$ docker run arg:v2
6. Docker image history command helps us find all the intermediate layers.
$ docker image history httpd -H
Different Options with history command:
— format string Pretty-print images using a Go template
-H, — human Print sizes and dates in human-readable format (default true)
— no-trunc Don’t truncate output
-q, — quiet Only show image IDs
