I'm looking for a way to see the contents of the requests the Docker CLI makes to the Docker Daemon for image creation, container creation etc. Is this possible to see, and if so, how?
You can run the docker daemon with debugging enabled which will show the URL being requested, but not the contents of the request. In /etc/docker/daemon.json, you can configure debugging with:
{ "debug": true }
Then restart the service. On systemd based systems, you can see the logs with journalctl -u docker.
Related
This is a question relating to configuring Docker on Linux to ensure the best performance. I'm wondering what settings / command-line flags need to be passed to a docker run command to ensure that the container runs as closely as possible to its equivalent on systemd ?
Would this simply be --privileged and --net host ? How would these settings passed to a Docker container compare (in terms of performance) to the same service running on systemd ?
Thank you!
If the application fails in the docker container you would not be able to troubleshoot what happened. Please propose a solution to that
docker ps -a
This will list all the containers including those who have already existed (for whatever reason)
Then you can copy the process id of the container of your interest and:
docker logs <pid of container that has failed>
Another interesting command is:
docker inspect <pid of container that has failed>
It returns a big json - you can check some sections there, like memory settings, "State" (if the process was OOM killed and so forth)
I am using an image from docker hub and it uses cron to perform some actions after some interval. I have registered and pushed it as described in documentation as a worker process (not a web). It also requires several environment variables.
I've run it from command line, e.g. docker run -t -e E_VAR1=VAL1 registry.heroku.com/image_name/worker and it worked for few days, then suddenly stopped and I had to run the command again.
Questions:
Is this a correct way to run a docker (as worker process) in Heroku?
Why might it stop running after few days? Is there any logs to check?
Is there a way to restart the process automatically?
How properly set environment variables for the docker in Heroku?
Thanks!
If you want to have this run in the background, you should use the -d flag to disconnect stdin and stdout, and not -t.
To check logs, user docker logs [container name or id]. You can find out the container's name and id using docker ps -a. That should give you an idea as to why the container stopped.
To have the container restart automatically add the --restart always flag when you run it. Alternatively, use --restart on-failure to only restart when it exited with a nonzero exit code.
The way you set environment variables seems fine.
I'm very new to kubernetes and trying to conceptualize it as well as set it up locally in order to try developing something on it.
There's a confound though that I am running on a windows machine.
Their "getting started" documentation in github says you have to run Linux to use kubernetes.
As docker runs on windows, I was wondering if it was possible to create a kubernetes instance as a container in windows docker and use it to manage the rest of the cluster in the same windows docker instance.
From reading the setup instructions, it seems like docker, kubernetes, and something called etcd all have to run "in parallel" on a single host operating system... But part of me thinks it might be possible to
Start docker, boot 'default' machine.
Create kubernetes container - configure to communicate with the existing docker 'default' machine
Use kubernetes to manage existing docker.
Pipe dream? Wrongheaded foolishness? I see there are some options around running it in a vagrant instance. Does that mean docker, etcd, & kubernetes together in a single VM (which in turn creates a cluster of virtual machines inside it?)
I feel like I need to draw a picture of what this all looks like in terms of physical hardware and "memory boxes" to really wrap my head around this.
With Windows, you need docker-machine and boot2docker VMs to run anything docker related.
There is no (not yet) "docker for Windows".
Note that issue 7428 mentioned "Can't run kubernetes within boot2docker".
So even when you follow instructions (from a default VM created with docker-machine), you might still get errors:
➜ workspace docker run --net=host -d -v /var/run/docker.sock:/var/run/docker.sock gcr.io/google_containers/hyperkube:v0.14.2 /hyperkube kubelet --api_servers=http://localhost:8080 --v=2 --address=0.0.0.0 --enable_server --hostname_override=127.0.0.1 --config=/etc/kubernetes/manifests
ee0b490f74f6bc9b70c1336115487b38d124bdcebf09b248cec91832e0e9af1d
➜ workspace docker logs -f ee0b490f74f6bc9b70c1336115487b38d124bdcebf09b248cec91832e0e9af1d
W0428 09:09:41.479862 1 server.go:249] Could not load kubernetes auth path: stat : no such file or directory. Continuing with defaults.
I0428 09:09:41.479989 1 server.go:168] Using root directory: /var/lib/kubelet
The alternative would be to try on a full-fledge Linux VM (like the latest Ubuntu), instead of a boot2docker-like VM (based on a TinyCore distro).
All k8s components can be raised up with hyperkube, which helps you bring up a containerized one.
If you're able to run docker on windows, it would probably work. I haven't tried it on windows personally.
I am trying to push some image to my registry, but when i tried to do:
sudo docker push myreg:5000\image
i got some error that told me that i need to start docker daemon with
docker -d --insecure-registry myreg:5000
So i stopped the docker service, and started it using the command above, once i do that the current shell window(ssh) is stuck with docker output, and if i close it the docker service is stopped.
I know this is an easy one, and i searched for hours and couldn't find anything.
Thank you
The problem is that when i run the command, i get all the docker output to the shell, and if i close it, the docker service stopped, usually the -d should take care of it, but it wont work
I think there's a confusion here; the top-level -d (docker -d) flag starts docker in daemon mode, in the foreground. This is different from the docker run -d <image> flag, which means "start a container from <image>, in detached mode". What you're seeing on your screen, is the daemon output / logs, waiting for connections from a docker client.
Back to your original issue;
The instructions to run docker -d --insecure-registry myreg:5000 could be clearer, but they illustrate that you should change the daemon options of your docker service to include the --insecure-registry myreg:5000 option.
Depending on the process manager your system users (e.g., upstart or systemd), this means you'll have to edit the /etc/default/docker file (see the documentation), or adding a "drop-in" file to override the default systemd service options; see SystemD custom daemon options
Some notes;
The top-level -d option is deprecated in docker 1.8 in favor of the new docker daemon command
Using --insecure-registry is discouraged for security reasons as it allows both unencrypted and untrustworthy communication with the registry. It's preferable to add your CA to the trusted list of your system.