如何在 Docker 容器内运行命令

Question

I'm new to Docker and I'm trying to understand the following setup.

I want to debug my docker container to see if it is receiving AWS credentials when running as a task in Fargate . It is suggested that I run the command:

curl 169.254.170.2$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI

But I'm not sure how to do so.

The setup uses Gitlab CI to build and push the docker container to AWS ECR .

Here is the dockerfile:

FROM rocker/tidyverse:3.6.3

RUN apt-get update && \
    apt-get install -y openjdk-11-jdk && \
    apt-get install -y liblzma-dev && \
    apt-get install -y libbz2-dev && \
    apt-get install -y libnetcdf-dev

COPY ./packrat/packrat.lock /home/project/packrat/

COPY initiate.R /home/project/

COPY hello.Rmd /home/project/

RUN install2.r packrat

RUN which nc-config

RUN Rscript -e 'packrat::restore(project = "/home/project/")'

RUN echo '.libPaths("/home/project/packrat/lib/x86_64-pc-linux-gnu/3.6.3")' >> /usr/local/lib/R/etc/Rprofile.site

WORKDIR /home/project/

CMD Rscript initiate.R

Here is the gitlab-ci.yml file:

image: docker:stable

variables:
 ECR_PATH: XXXXX.dkr.ecr.eu-west-2.amazonaws.com/
 DOCKER_DRIVER: overlay2
 DOCKER_TLS_CERTDIR: ""

services:
   - docker:dind

stages:
  - build
  - deploy

before_script:
   - docker info
   - apk add --no-cache curl jq py-pip
   - pip install awscli
   - chmod +x ./build_and_push.sh

build-rmarkdown-task:
   stage: build
   script:
    - export REPO_NAME=edelta/rmarkdown_report
    - export BUILD_DIR=rmarkdown_report
    - export REPOSITORY_URL=$ECR_PATH$REPO_NAME
    - ./build_and_push.sh
   when: manual

Here is the build and push script:

#!/bin/sh

$(aws ecr get-login --no-include-email --region eu-west-2)
docker pull $REPOSITORY_URL || true
docker build --cache-from $REPOSITORY_URL -t $REPOSITORY_URL ./$BUILD_DIR/
docker push $REPOSITORY_URL

I'd like to run this command on my docker container:

curl 169.254.170.2$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI

How I run this command on container startup in fargate?

Answer 1

For running a command inside docker container you need to be inside the docker container.

Step 1: Find the container ID / Container Name that you want to debug

docker ps A list of containers will be displayed, pick one of them

Step 2 run following command docker exec -it <containerName/ConatinerId> bash and then enter wait for few seconds and you will be inside the docker container with interactive mode Bash

for more info read https://docs.docker.com/engine/reference/commandline/exec/

Answer 2

Short answer, just replace the CMD

CMD ["sh", "-c", " curl 169.254.170.2$AWS_CONTAINER_CREDENTIALS_RELATIVE_UR && Rscript initiate.R"]

Long answer, You need to replace the CMD of the DockerFile, as currently running only Rscript .

you have two option add entrypoint or change CMD , for CMD check above

create entrypoint.sh and run run only when you want to debug.

#!/bin/sh

if [ "${IS_DEBUG}" == true ];then

   echo "Container running in debug mode"
   curl 169.254.170.2$AWS_CONTAINER_CREDENTIALS_RELATIVE_URI
   # uncomment below section if you still want to execute R script.
   # exec "$@"
else
   exec "$@"
fi

Changes that will required on Dockerfile side

WORKDIR /home/project/
ENV IS_DEBUG=true
COPY entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh
entrypoint ["/entrypoint.sh"]
CMD Rscript initiate.R