Lab 5: Create an image with ENTRYPOINT instruction

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The ENTRYPOINT instruction make your container run as an executable.
ENTRYPOINT can be configured in two forms:

Exec Form
ENTRYPOINT [“executable”, “param1”, “param2”]
Shell Form
ENTRYPOINT command param1 param2

If an image has an ENTRYPOINT if you pass an argument it, while running container it wont override the existing entrypoint, it will append what you passed with the entrypoint.To override the existing ENTRYPOINT you should user –entrypoint flag when running container.

Pre-requisite:

Tested Infrastructure

Platform	Number of Instance	Reading Time
Play with Docker	1	5 min

Pre-requisite

Create an account with DockerHub
Open PWD Platform on your browser
Click on Add New Instance on the left side of the screen to bring up Alpine OS instance on the right side

Assignment:

Create an image with ENTRYPOINT instruction(Exec Form)
ENTRYPOINT instruction in Shell Form
Override the existing ENTRYPOINT

Create an image with ENTRYPOINT instruction(Exec Form)

Dockerfile

FROM alpine:3.5
LABEL maintainer="Collabnix"

ENTRYPOINT ["/bin/echo", "Hi, your ENTRYPOINT instruction in Exec Form !"]

Build Docker Image

$ docker build -t entrypoint:v1 .

Verify the Image

$ docker image ls

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
entrypoint          v1                  1d06f06c2062        2 minutes ago       4MB
alpine              3.5                 f80194ae2e0c        7 months ago        4MB

Create a container

$ docker container run entrypoint:v1
Hi, your ENTRYPOINT instruction in Exec Form !

ENTRYPOINT instruction in Shell Form

Dockerfile

$ cat Dockerfile 
FROM alpine:3.5
LABEL maintainer="Collabnix"

ENTRYPOINT echo "Hi, your ENTRYPOINT instruction in Shell Form !"

Build Docker Image

$ docker build -t entrypoint:v2 .

Verify the Image

$ docker image ls

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
entrypoint          v2                  cde521f13080        2 minutes ago       4MB
entrypoint          v1                  1d06f06c2062        5 minutes ago      4MB
alpine              3.5                 f80194ae2e0c        7 months ago        4MB

Create a container

$ docker container run entrypoint:v2
Hi, your ENTRYPOINT instruction in Shell Form !

Override the existing ENTRYPOINT

$ docker container run --entrypoint "/bin/echo" entrypoint:v2 "Hello, Welocme to Docker Meetup! "
Hello, Welocme to Docker Meetup! 

Lab 5: Create an image with ENTRYPOINT instruction

Pre-requisite:

Tested Infrastructure

Pre-requisite

Assignment:

Create an image with ENTRYPOINT instruction(Exec Form)

Build Docker Image

Verify the Image

Create a container

ENTRYPOINT instruction in Shell Form

Build Docker Image

Verify the Image

Create a container

Override the existing ENTRYPOINT

Lab 5: Create an image with ENTRYPOINT instruction

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