Menu
I'm new to Docker, using Boot2Docker on OSX. After booting it, this message is given:
To connect the Docker client to the Docker daemon, please set export DOCKER_HOST=tcp://192.168.59.103:2375 Yet even without it, basic Docker commands (eg, docker run hello-world) work fine.
The install instructions aren't very informative:
Note: If you see a message in the terminal that looks something like this: To connect the Docker client to the Docker daemon, please set: export DOCKER_HOST=tcp://192.168.59.103:2375 you can safely set the evironment variable as instructed. Knowing that it's "safe" doesn't say why it's useful.
What I'm not clear on:
270
The Docker CLI uses the DOCKER_HOST environment variable to determine the host to connect to. The local daemon's Unix socket will be used when the variable isn't set. This will start a new container from the httpd:latest image using the Docker engine at 192.168.
docker_host. string. Default: "unix://var/run/docker.sock" The URL or Unix socket path used to connect to the Docker API.
Overview. Environment variables are a convenient way to externalize application configuration. Therefore they are also useful for building Docker containers. However, passing and using them in the Dockerfile is not as easy as it might be.
Fetch Using docker exec Command Here, we are executing the /usr/bin/env utility inside the Docker container. Using this utility, you can view all the environment variables set inside Docker containers.
Ok, I think I got it.
The client is the docker command installed into OS X.
The host is the Boot2Docker VM.
The daemon is a background service running inside Boot2Docker.
This variable tells the client how to connect to the daemon.
When starting Boot2Docker, the terminal window that pops up already has DOCKER_HOST set, so that's why docker commands work. However, to run Docker commands in other terminal windows, you need to set this variable in those windows.
Failing to set it gives a message like this:
$ docker run hello-world 2014/08/11 11:41:42 Post http:///var/run/docker.sock/v1.13/containers/create: dial unix /var/run/docker.sock: no such file or directory One way to fix that would be to simply do this:
$ export DOCKER_HOST=tcp://192.168.59.103:2375 But, as pointed out by others, it's better to do this:
$ $(boot2docker shellinit) $ docker run hello-world Hello from Docker. [...] To spell out this possibly non-intuitive Bash command, running boot2docker shellinit returns a set of Bash commands that set environment variables:
export DOCKER_HOST=tcp://192.168.59.103:2376 export DOCKER_CERT_PATH=/Users/ddavison/.boot2docker/certs/boot2docker-vm export DOCKER_TLS_VERIFY=1 Hence running $(boot2docker shellinit) generates those commands, and then runs them.
94
Upon investigation, it's also worth noting that when you want to start using docker in a new terminal window, the correct command is:
$(boot2docker shellinit) I had tested these commands:
>> docker info Get http:///var/run/docker.sock/v1.15/info: dial unix /var/run/docker.sock: no such file or directory >> boot2docker shellinit Writing /Users/ddavison/.boot2docker/certs/boot2docker-vm/ca.pem Writing /Users/ddavison/.boot2docker/certs/boot2docker-vm/cert.pem Writing /Users/ddavison/.boot2docker/certs/boot2docker-vm/key.pem export DOCKER_HOST=tcp://192.168.59.103:2376 export DOCKER_CERT_PATH=/Users/ddavison/.boot2docker/certs/boot2docker-vm export DOCKER_TLS_VERIFY=1 >> docker info Get http:///var/run/docker.sock/v1.15/info: dial unix /var/run/docker.sock: no such file or directory Notice that docker info returned that same error. however.. when using $(boot2docker shellinit)...
>> $(boot2docker init) Writing /Users/ddavison/.boot2docker/certs/boot2docker-vm/ca.pem Writing /Users/ddavison/.boot2docker/certs/boot2docker-vm/cert.pem Writing /Users/ddavison/.boot2docker/certs/boot2docker-vm/key.pem >> docker info Containers: 3 ... If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
