# question about the docker module **URL:** \ **Category:** Ansible Project\ **Created:** [April 16, 2014, 9:41pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036 "2014-04-16T21:41:04Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Patrick\_Galbraith](https://avatars.discourse-cdn.com/v4/letter/p/48db29/32.png) [@Patrick\_Galbraith](https://forum.ansible.com/u/Patrick_Galbraith)\ **Post date:** [April 16, 2014, 9:41pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/1 "2014-04-16T21:41:04Z")
Hi all! I have what I think is a simple question. It pertains to what is visible/available in the “docker\_containers” dictionary when running a run book. Ok, so, what’s throwing me off is whether to use one of the following: - name launch containers docker: image=df02bd73464a count={{ start\_containers\_count }} Or - name launch containers docker: image=df02bd73464a name=somename\_{{item}} with\_sequence: count={{ start\_containers\_count }} It is the first snippet that works for doing this next task: - name: print container info debug: msg=“{{item[‘NetworkSettings’][‘IPAddress’]}}” with\_items: docker\_containers Why? Because the latter results in “docker\_containers” only having the last container’s information (last container launched), whereas the former gives me all of them. It’s probably something really simple… ---
**Author:** ![Paul\_Durivage](https://avatars.discourse-cdn.com/v4/letter/p/94ad74/32.png) [@Paul\_Durivage](https://forum.ansible.com/u/Paul_Durivage)\ **Post date:** [April 16, 2014, 11:41pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/2 "2014-04-16T23:41:36Z")
I’ll venture a guess as to what is happening here, but I don’t know for sure. I guess I could look at the source. 😉 I think what’s happening here is that with\_sequence is actually invoking a new module build/upload/run for every item in the with\_sequence, and thereby overwriting the docker\_containers variable with the facts from the last docker module run. So, it’s a guess, but you could probably verify that by running with some extra verbosity (I think you need at least -vv). This is definitely not happening in the first container launch, because it’s passing those values directly to the module, running only once. If you don’t give it a shot, I’ll probably take a look at it in the morning. Let me know what you find! ---
**Author:** ![Patrick\_Galbraith](https://avatars.discourse-cdn.com/v4/letter/p/48db29/32.png) [@Patrick\_Galbraith](https://forum.ansible.com/u/Patrick_Galbraith)\ **Post date:** [April 17, 2014, 2:09am UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/3 "2014-04-17T02:09:54Z")
Thanks! I could actually tinker with this. I’m comfortable with ansible source now, having a pull-request in for the nova\_compute module (ahem 🙂 What you describe seems to be the case and in fact I was running with -vvvv and noticed this. ---
**Author:** ![Michael\_DeHaan1](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michael\_DeHaan1](https://forum.ansible.com/u/Michael_DeHaan1)\ **Post date:** [April 17, 2014, 2:13am UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/4 "2014-04-17T02:13:16Z")
Yep yep! Paul nailed it. Ideally every cloud module would support an exact\_count like was done for Rackspace and EC2, where it makes that number of containers exist. Though I’m a little unclear why you’d want multiple docker containers on the same host, the way that sucker runs (i.e. it’s not a cloud API so those images get all on the same box). –Michael ---
**Author:** ![Patrick\_Galbraith](https://avatars.discourse-cdn.com/v4/letter/p/48db29/32.png) [@Patrick\_Galbraith](https://forum.ansible.com/u/Patrick_Galbraith)\ **Post date:** [April 17, 2014, 3:28pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/5 "2014-04-17T15:28:49Z")
Hi Paul, When are you around in IRC? I wouldn’t mind going over this with you. I was looking at the code, poking around and had some questions. I’m EDT. ---
**Author:** ![Paul\_Durivage](https://avatars.discourse-cdn.com/v4/letter/p/94ad74/32.png) [@Paul\_Durivage](https://forum.ansible.com/u/Paul_Durivage)\ **Post date:** [April 17, 2014, 3:37pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/6 "2014-04-17T15:37:06Z")
I’m in the channel as angstwad. I’m not very good at paying attention to my IRC, but I’ll keep an eye on it. 🙂 ---
**Author:** ![Patrick\_Galbraith](https://avatars.discourse-cdn.com/v4/letter/p/48db29/32.png) [@Patrick\_Galbraith](https://forum.ansible.com/u/Patrick_Galbraith)\ **Post date:** [April 17, 2014, 4:22pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/7 "2014-04-17T16:22:18Z")
Michael, With containers (versus VMs), you ideally can run a LOT of them on a single host. RedHat did a demo with 1000s of them running: [Red Hat bets on 'Project Atomic' for its container-loaded server future • The Register](http://www.theregister.co.uk/2014/04/15/red_hat_project_atomic_docker/) Maybe I’m not understanding what you are saying, and apologies in advance 😉 So, I was looking at the code but having a _heck_ of a time figuring out how to do some in-depth debugging. I want to print out a dictionary (“containers” in this case) def get\_deployed\_containers(self): # determine which images/commands are running already containers = self.client.containers(all=True) image = self.module.params.get(‘image’) command = self.module.params.get(‘command’) if command: command = command.strip() name = self.module.params.get(‘name’) if name and not name.startswith(‘/’): name = ‘/’ + name deployed = I’m new to Ansible, I will admit, and using my tried-and-true “print” statement debugging tool breaks an ansible run. I’d like to know the trick to being able to debug Python code that runs ansible. Regards, Patrick ---
**Author:** ![Paul\_Durivage](https://avatars.discourse-cdn.com/v4/letter/p/94ad74/32.png) [@Paul\_Durivage](https://forum.ansible.com/u/Paul_Durivage)\ **Post date:** [April 17, 2014, 4:59pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/8 "2014-04-17T16:59:17Z")
Hey Patrick, I typically use “raise Exception(message)” when debugging in modules, since Ansible captures this output and prints it to the console. ---
**Author:** ![louis\_gueye](https://avatars.discourse-cdn.com/v4/letter/l/838e76/32.png) [@louis\_gueye](https://forum.ansible.com/u/louis_gueye)\ **Post date:** [November 18, 2014, 11:41pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/9 "2014-11-18T23:41:04Z")
Hi Patrick, Actually i don’t know if it has anything to do with the “with\_sequences” clause. I have the following code docker: name=“cluster-data” hostname=“{{ data\_hostname }}” image=“lgueye/cluster-data” state=present . . . docker: name=“cluster-index” hostname=“{{ index\_hostname }}” image=“lgueye/cluster-index” state=present When I loop over the **docker\_containers** dict, seeking for IP adresses, I only get one IP adress. I dumped the dict and It contains information only about the last running container. I’m just providing information, unfortunately I I’m totally unable to provide a fix right now. Sorry. ---
**Author:** ![Toshio\_Kuratomi](https://avatars.discourse-cdn.com/v4/letter/t/41988e/32.png) [@Toshio\_Kuratomi](https://forum.ansible.com/u/Toshio_Kuratomi)\ **Post date:** [November 19, 2014, 1:22am UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/10 "2014-11-19T01:22:48Z")
This has to do with the way that new facts are returned from ansible modules. Anytime a task is run, the module that is run by that task has an opportunity to return new facts in an \_ansible\_facts entry. This is usually a mapping of names to values that were determined during the module's run. Ansible on the controlling machine reads the data in \_ansible\_facts and adds the new facts to the global facts dictionary that is available to subsequent tasks. Ansible does not provide any automatic namespacing for the facts returned by tasks. That means that if two tasks return dicts that use some of the same keys in \_ansible\_facts then the values from the latest task to be run will overwrite the earlier ones. So to take three examples we have: tasks:   - docker: name="cluster-data" hostname="{{ data\_hostname }}" image="lgueye/cluster-data" state=present   - docker: name="cluster-data" hostname="{{ index\_hostname }}" image="lgueye/cluster-data" state=present In this example, we have two tasks calling the same module to do the same thing to different hostnames. The module is almost certainly going to return the same \_ansible\_facts dictionary entries for both calls which means only the latest one will be seen by subsequent tasks. tasks:   - docker: image=df02bd73464a name=somename\_{{item}}     with\_sequence: count={{ start\_containers\_count }} In this example, we are looping start\_containers\_count times and invoking the docker module each time with a slightly different name parameter. So even though it's not as apparent, it's doing the same thing as the above example. tasks:   - docker: image=df02bd73464a count={{ start\_containers\_count }} Only in this example are we actually executing the docker module only a single time. We're telling the module that it is responsible for starting up start\_countainr\_count instances on its own. Since the module has all the information in its one invocation to start all of hte containers, it is able to return information about all of the containers that it started in its one run to the ansible controller so the facts are set so that you can see all of the ip and host information. Hope that explanation is helpful! -Toshio ---
**Author:** ![louis\_gueye](https://avatars.discourse-cdn.com/v4/letter/l/838e76/32.png) [@louis\_gueye](https://forum.ansible.com/u/louis_gueye)\ **Post date:** [November 19, 2014, 9:27am UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/11 "2014-11-19T09:27:02Z")
Thank you very much for your answer. Now I get it fully. Is there a way to append the docker\_containers result in a dict after each execution: I need all containers {IP,name} couple later in the execution? ---
**Author:** ![Brian\_Coca](https://avatars.discourse-cdn.com/v4/letter/b/6de8d8/32.png) [@Brian\_Coca](https://forum.ansible.com/u/Brian_Coca)\ **Post date:** [November 19, 2014, 2:45pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/12 "2014-11-19T14:45:09Z")
you can use a add\_host or set\_fact task after each docker task. ---
**Author:** ![louis\_gueye](https://avatars.discourse-cdn.com/v4/letter/l/838e76/32.png) [@louis\_gueye](https://forum.ansible.com/u/louis_gueye)\ **Post date:** [November 19, 2014, 6:43pm UTC](https://forum.ansible.com/t/question-about-the-docker-module/15036/13 "2014-11-19T18:43:44Z")
I did not know about set\_fact. I'll give it a try. Also, I will review my understanding of add\_host. I could not save both name and IP. Anyway thank you all for your answers. This community is one of the most active and helpful. Regards, Louis