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Questions tagged [containers]

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0
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0answers
16 views

Sending mail from Docker container

I want to send mails from my docker container . We have an SMTP relay host in our network which forwards mail traffic to the SMTP server . I manually installed postfix in our docker container and ...
1
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1answer
71 views

Invalid arguments when mounting with MS_SHARED

I am trying to mount the ext4 file system on /mnt into mount_dir which is a temporary directory I created using mkdtemp(2) with MS_SHARED then a remount with MS_PRIVATE, The idea is creating a mount ...
0
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1answer
84 views

How does Docker run GUIs?

I wrote some Java desktop applications and thought I'd run them with Docker to learn about containers. I got the Java applications into a Docker container with an ubuntu image. And that's when I ...
0
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1answer
37 views

What other `namespace` oriented linux commands are there?

By other I mean to say that I ran into the command: nsenter and have been thinking that there might be other tools/commands geared to working with and debugging namespaces. Are there? Keep in mind I'...
3
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1answer
28 views

Should I set the time in a container?

I have a few containers (systemd-nspawn based) and I am wondering whether I should set up the time (via systemd-timesyncd) or is it maintained by the host?
1
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2answers
201 views

How to create a chroot from which root cannot escape using chdir(“..”) on Linux, inside a filesystem?

I have a directory /var/mychoot on the same filesystem as /, and I've started the program /var/mychroot/prog as sudo chroot /var/mychroot /prog, so the program is running as EUID 0. If the program ...
2
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0answers
142 views

systemd-nspawn: how to allow access to all devices?

I'm trying to create a rough equivalent of Docker's --privileged in a systemd container, but I've got no idea how to allow the container to access all of the devices available on the host (without ...
2
votes
1answer
304 views

How can I inspect a docker container's filesystem that cannot run?

I recently was trying to inspect how this container works, and so I wanted to do what I'd typically do for a running container, mainly: $ docker exec -it <container SHA> /bin/bash However in ...
2
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1answer
751 views

Performance of Linux Apps on Chrome OS [closed]

The support for linux applications makes Chrome OS very interesting to me. But I would like to know more about their actual performance. Apparently, the applications are executed in KVM. The google ...
0
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1answer
338 views

Why could a call to `getaddrinfo()` fail with `EAI_SYSTEM` and errno set to `EBUSY` (“Device or resource busy”)?

I'm seeing this error when running apt update in containers, if that is useful information. apt spits out: System error resolving 'archive.ubuntu.com:80' - getaddrinfo (16: Device or resource busy) ...
2
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1answer
57 views

Are containers transparent to POSIX parent-child process relationships?

Imagine a hypothetical shell that launches all commands in ad-hoc containers with some isolation and resource controls depending on function of each command: cat foo.txt | sed ... | xargs some-...
0
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1answer
124 views

LXD Container/What's the Preferred Way of Accessing Files from Host

I can access files inside a LXD container by running lxc from the host: root@Host# lxc exec Container_Name bash root@Container_Name# touch /tmp/hello Or by accessing the files directly from the host ...
3
votes
1answer
2k views

How can I check if cgroups are available on my Linux host?

Is there a command to check if the container services are running on a Linux system? Someone suggested unshare but I am not sure if that is the best way to do it.
1
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2answers
44 views

Give application instances their own IPs? Extremely lightweight containerization?

About two years ago I received a note with a method, but I was not able to find the note or the method right now. Anyone know the easiest way to achieve this? J.E.B.
2
votes
1answer
852 views

Why does the nspawn of an ubuntu image fail?

I would like to systemd-nspawn an Ubuntu image (yakkety, the host is on yakkety as well). This used to work without problems, so I guess something changed in the last ~6 months. I created an image ...
1
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0answers
569 views

How do I move and run a linux container on a new host?

What is the correct procedure to move a Linux container to a new host? Here is what I have done without success: Compress directory containing linux container: sudo tar -cjf sample_container.tar....
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0answers
26 views

Rendering a screenshot of onely one selected application in a (docker) containter

In this there is for me three questions : How to render a graphical application -ex firefox, in command line ? Without the entire screen. How to render a console output -ie, only text ? I see ...
0
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1answer
30 views

Trimming systemd components in containers

I am working with container on a systemd platform. While I create a container using lxc commands, I see that all the systemd components are present inside this container as well. I am planning to ...
4
votes
1answer
2k views

How to achieve processor affinity in containers?

I see with kubernetes it's possible to set node affinity for certain workloads. I'm wondering if there are any facilities in the various container technologies, such as docker, rocket etc that allow ...
0
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1answer
224 views

Why Docker official images are using an Operating System

Docker containers does not need an operating system and a hypervisor because they use the host kernel. So why all of the official images like: php, nginx, .. whatever are using an operating system in ...
3
votes
1answer
1k views

How to start a program in a container as a service using systemd-nspawn, systemd-run?

How do I run a listening program (specifically unoconv as a listener) inside a container using systemd-nspawn, so that it can run in the background (without a console) and be reached by other ...
2
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0answers
763 views

Nginx with dnsmasq 'could not be resolved (5: Operation refused)'

I'm trying to set up a django site using docker, nginx and uwsgi: I have a nginx docker container working as a reverse proxy (called ceca-nginx-proxy) and another nginx (ceca-nginx) container that ...
0
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0answers
552 views

Disk usage for a mounted drive shows up completely between the host and a container

When comparing the disk usage for a mounted harddrive the usage is completely different when compared between the host and the container. I am running Ubuntu 14.04 on the host and in the lxc container....
6
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1answer
743 views

Sharing unix sockets across unprivileged lxcontainers

I have two unprivileged containers and I'd like to share a unix socket between them. Each container has its own user on the host, complete with separate subuid and subguid mappings. I've tried ...
6
votes
2answers
8k views

How to configure logging inside a Docker container?

I was trying to dockerize (into Debian 8.2) an OpenVPN server (yes, I do know, there already are such containers) but something went wrong inside the container and the server failed to start. I ...
3
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2answers
819 views

Is it possible to mount a device in a process' namespace after unshare()

Say I have a process with an isolated MOUNT namespace pid 1200 the process called unshare() to isolate its namespace from the parent process. I then want to mount a device only accessible outside pid ...
2
votes
1answer
1k views

does/could something like a realtime Linux container exist?

Is there some way to configure a Linux container (ie. cgroups/namespace-isolated process tree) to have realtime characteristics - ideally to the point to be suitable for industrial machine control / ...
6
votes
2answers
4k views

How to run a command inside a running systemd container

I have a systemd container running, and I can login into it with machinectl login <container>. How can I execute a command inside the container directly, i.e. without first logging in, executing ...
3
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2answers
4k views

OverlayFS doesn't work with unprivileged user namespace

OverlayFS mount works weird when accessed from within the unprivileged user namespace. Best to be explained in example: ~# uname -a Linux host 4.1.0-1-amd64 #1 SMP Debian 4.1.3-1 (2015-08-03) x86_64 ...
1
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0answers
32 views

making containers use a different set a block devices

Is it possible to make some Linux processes see a different set of block devices with containers (i.e. no virtualization such as KVM or Xen)? For example, at boot time the system recognizes sda, sdb ...
1
vote
1answer
81 views

What is the correct way to start a container with a given command?

I want to create a set of containers for simulating network traffic. Inside each of the containers, I would like to set a different network delay. Right now I am doing it manually using this command, ...
2
votes
1answer
663 views

How can I detect if a system is running inside a systemd-nspawn container?

Quite recently I started using systemd-nspawn to set up other OS instances on my Arch box. One thing I'd like to do is detect if I'm inside a container, and if so, add the distro name (from ...
5
votes
2answers
2k views

Why is systemd-nspawn not appropriate for production deployments?

While reading about systemd-nspawn, it is mentioned that it should not be used in a production environment. The reason seems to be the lack of management and deployment infrastructure. Is practicality ...
6
votes
3answers
17k views

Docker container not able to ping host

I am following this tutorial https://docs.docker.com/articles/networking/#between-containers I have used following commands $ sudo brctl addbr bridge0 $ sudo ip addr add 192.168.0.160/24 dev ...
10
votes
2answers
4k views

What is a Linux container and a Linux hypervisor?

I looked at the stackexchange site but couldn't find anything. I looked at the wikipedia entry on Linux container https://en.wikipedia.org/wiki/LXC and as well as hypervisor https://en.wikipedia.org/...
1
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0answers
543 views

Bridging lxc vs virtualbox

Something that is confusing me is the difference between "bridging" with a Virtualbox VM, and an lxc container. When you start a start a VM, the VM creates a bridge ( apparently ) as a user. ...
0
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1answer
189 views

Containers for sandboxing

I'm trying to find a container stack for sandboxing and and would like to know which stacks do that particular job well. By sandboxing I mean running applications so that security flaws are confined ...