Docker, install postgresql in a container contain “ubuntu:14.04”, lost when out of the container

问题

I tried to install postgresql-9.3 in the container contains images "ubuntu: 14:04"

The first step, which I did make images "ubuntu: 14:04"

 $ sudo Docker pull ubuntu:14.04

The second step, I create a container with the command

 $ sudo docker run -t -i ubuntu:14.04 /bin/bash

The third step, I install postgresql-9.3 in a container contain "ubuntu:14.04" (in a container containing ubuntu)

I tried to get in postgresql could, then I tried to get out containers, straight out with the command

 # exit

I tried to log back in, the container postgresql I install missing, whether it can do and helped explain why?

Docker itself, whether running in the kernel?

Hardware> OS> Docker.

Docker concept:

Docker = images> Container

回答1:

You should not install anything in a bash session.
Since docker uses UnionFS (union filesystem service), as soon as you exit your bash session, any modification is lost when the container is removed.

You could try a docker commit of your "Exited" container, but that is not how you build a new image.

What you do is create a text file named Dockerfile, in which you follow similar steps as the official postgres image Dockerfile (except you want to start from ubuntu).

It includes:

RUN apt-get update \
    && apt-get install -y postgresql-common \
    && sed -ri 's/#(create_main_cluster) .*$/\1 = false/' /etc/postgresql-common/createcluster.conf \
    && apt-get install -y \
        postgresql-$PG_MAJOR=$PG_VERSION \
        postgresql-contrib-$PG_MAJOR=$PG_VERSION \
    && rm -rf /var/lib/apt/lists/*

You the run docker build -t mypostgres .: that will build a new image which will contain postgres.

In other words, the Dockerfile is there to persists the installation steps in a declarative text file, from which you can build an image at any time.

回答2:

If you find easier to install all with bash and not with Dockerfile and build command you could do exactly as you wrote for first and second steps but after as third step quit bash with

CONTROL + P followed by CONTROL + Q

that's will exit container leaving it running and after use

docker commit mycurrentcontainer mynewimagewithpostgrestobeuseinfuture

回答3:

This has fixed the issue. These steps are followed

Step1: Docker builds -t Mohan. step2: Docker run -it Mohan bash Mohan is your container name

This is my Dockerfile:

FROM Ubuntu: 18.04

FROM postgres: 9.6

RUN apt-get update && apt-get install -q -y postgresql-9.6 postgresql-client-9.6 postgresql-contrib-9.6 postgresql-client-common postgresql-common RUN echo postgres:postgres | chpasswd

RUN pg_createcluster 9.6 main --start

CMD /etc/init.d/postgresql start

CMD su -c "psql -c \"ALTER USER postgres PASSWORD 'postgres';\"" postgres

来源：https://stackoverflow.com/questions/33913474/docker-install-postgresql-in-a-container-contain-ubuntu14-04-lost-when-out

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postgresql

Ubuntu

Docker

containers