Creating a vanilla centos6 image using Docker

[Dirk Louwers]

Hi,

I am new to using Vagrant with Docker and ran into the following issue:

Given the following block:

config.vm.provider "docker" do |d|
  d.image = "centos:6"
end

and the following command:

vagrant up --provider=docker

I get the following error:

Error response from daemon: No command specified

Since the machine is down asking for logs through vagrant docker-logs crashes so I have no clue how to debug this.

Hope someone can shed some light on this. Googling hasn't helped me much so far.

Best,

Dirk

[Alvaro Miranda Aguilera]

Hello,

Docker is a cool new tech, but they do many things in a docker way that is different than a virtual machine.

Basically what you are doing in the vagrantfile is download a docker image, but the name is wrong from what I see. plus the message is telling you that you are not doing anything (no commands)

index.docker.io have the boxes

checking this:

https://registry.hub.docker.com/_/centos/tags/manage/

seems the name is like:

centos:centos6

and you need to add a command, docker will run a command, imagine a new vm boots out of nothing and 1 command run, there is no boot like a normal OS.

so if you run a web server, that will be the only process running inside docker.

I would suggest you play a bit with docker outside vagrant first if you haven't done, as that will make things go clear.

Alvaro.

--
You received this message because you are subscribed to the Google Groups "Vagrant" group.
To unsubscribe from this group and stop receiving emails from it, send an email to vagrant-up+...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Dirk Louwers]

Hi,

Yes, I have now tried it with centos:centos6. Documentation incorrectly mentions centos:6. That still yields that error response. So how would I add a command and what command? The vagrant docs don't mention this. I was planning to provision the box with ansible. Does anyone know of an example of this?

Best,

Dirk

--
You received this message because you are subscribed to a topic in the Google Groups "Vagrant" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/vagrant-up/VqXBSaEXBdU/unsubscribe.
To unsubscribe from this group and all its topics, send an email to vagrant-up+...@googlegroups.com.

[Alvaro Miranda Aguilera]

Hello

I will insist on you should do some docker test outside vagrant to see what docker does,

https://www.docker.com/tryit/

you back? cool, welcome back. 

imagine docker create a vm that does nothing, since that is what docker is, a 100% isolated enviroment.

Is more similar to what chroot is, uml (user mode linux), openVz, solaris containers.. if you have had used any of those, docker is  bit ieasier to get.

if you havent, then i can tell you that docker is not a virtualmachine.

Docker will create a OS filesystem, and run 1 or more commands and that is what that docker container will run

example, lets say you want to run a web browser, docker require a image to pull down, and some commands to run and some ports to expose.

are seral ways to do it, that's why is good to play and make your won way to doit.

The ideal way for someone new:

 - pull a docker image that does everything!

this docker image will have already setup some commands to run and some ports to expose

but that is not the docker way.

Docker way goes something like this.

- define a docker image to pull

- command to run (to setup the image)

- ports to expose

- command to run (to start the image)

without those, what you are doing is this:

- pull a docker image

done, you have an isolated filesystem and no process running from here.

from here you can:

- docker build, that allow you create a new docker image based on a Dockerfile, that is a set of instructions

- docker run, execute commands on these images (base or new one)

the images are handled by an ID, but you can tag them for convenience.

Alvaro

[Dirk Louwers]

Hi,

I have previously already done the try it simulation on their website. To answer my own question:

A docker provided box will complain if you don’t send a command to it. This command can be as simple as “cd .”. Since this command would return directly Vagrant will think something bad happened to it. To remedy that you need to set d.remains_running to false. See complete block here:

config.vm.provider “docker” do |d|

  d.image                    = “centos:centos6"

  d.cmd                       = ["ls"]

  d.remains_running   = false

end

Now you can start provisioning. BUT note that most images do not support ssh which is a prerequisite for running ansible. There are some images available that do, like tutum/centos.  In order to get this to work you still have some configuration to do. I will investigate and check back once I have it running.

Best,

Dirk

[Alvaro Miranda Aguilera]

Try a Dockerfile like this:

FROM kikitux/oracle6:latest

MAINTAINER Alvaro Miranda kik...@gmail.com      

RUN sed -i -e 's/session\s*required\s*pam_loginuid.so$/session optional\tpam_loginuid.so/' /etc/pam.d/sshd    && \

    cp /etc/ssh/sshd_config /etc/ssh/sshd_config.ori  && \

    sed -i -e '/#UseDNS yes/a UseDNS no' /etc/ssh/sshd_config && \

    cp /etc/sudoers /etc/sudoers.orig && \

    sed -i -e 's/Defaults\\s*requiretty$/#Defaults\trequiretty/' /etc/sudoers && \

    sed -i -e '/# %wheel\tALL=(ALL)\tNOPASSWD: ALL/a %wheel\tALL=(ALL)\tNOPASSWD: ALL' /etc/sudoers      

RUN useradd vagrant && \

    mkdir ~vagrant/.ssh && \

    chmod 700 ~vagrant/.ssh && \

    echo 'ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA6NF8iallvQVp22WDkTkyrtvp9eWW6A8YVr+kz4TjGYe7gHzIw+niNltGEFHzD8+v1I2YJ6oXevct1YeS0o9HZyN1Q9qgCgzUFtdOKLv6IedplqoPkcmF0aYet2PkEDo3MlTBckFXPITAMzF8dJSIFo9D8HfdOV0IAdx4O7PtixWKn5y2hMNG0zQPyUecp4pzC6kivAIhyfHilFR61RGL+GPXQ2MWZWFYbAGjyiYJnAmCP3NOTd0jMZEnDkbUvxhMmBYSdETk1rRgm+R4LOzFUGaHqHDLKLX+FIPKcF96hrucXzcWyLbIbEgE98OHlnVYCzRdK8jlqm8tehUc9c9WhQ== vagrant insecure public key' | tee -a ~vagrant/.ssh/authorized_keys && \

    chmod 600 ~vagrant/.ssh/authorized_keys && \

    chown -R vagrant: ~vagrant/.ssh && \

    sed -i -e '/# %wheel\tALL=(ALL)\tNOPASSWD: ALL/a vagrant\tALL=(ALL)\tNOPASSWD: ALL' /etc/sudoers

That is all you require to enable ssh to work inside a docker and get vagrant user plus ssh key

Then you can have 

EXPOSE 22

CMD /usr/sbin/sshd -D

if you want to test 

test  kikitux/oracle6-consul:latest

and as command use

/usr/sbin/sshd -D