Docker For Mac 2018
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Docker Desktop for Mac provides several networking features to make iteasier to use.
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Features
VPN Passthrough
Docker Desktop for Mac’s networking can work when attached to a VPN. To do this,Docker Desktop for Mac intercepts traffic from the containers and injects it intoMac as if it originated from the Docker application.
Port Mapping
When you run a container with the -p argument, for example:
Docker Desktop for Mac makes whatever is running on port 80 in the container (inthis case, nginx) available on port 80 of localhost. In this example, thehost and container ports are the same. What if you need to specify a differenthost port? If, for example, you already have something running on port 80 ofyour host machine, you can connect the container to a different port:
Now, connections to localhost:8000 are sent to port 80 in the container. Thesyntax for -p is HOST_PORT:CLIENT_PORT.
HTTP/HTTPS Proxy Support
See Proxies.
Known limitations, use cases, and workarounds
Following is a summary of current limitations on the Docker Desktop for Macnetworking stack, along with some ideas for workarounds.
There is no docker0 bridge on macOS
Because of the way networking is implemented in Docker Desktop for Mac, you cannot see adocker0 interface on the host. This interface is actually within the virtualmachine.
I cannot ping my containers
Docker Desktop for Mac can’t route traffic to containers.
Per-container IP addressing is not possible
The docker (Linux) bridge network is not reachable from the macOS host.
Use cases and workarounds
There are two scenarios that the above limitations affect:
I want to connect from a container to a service on the host
The host has a changing IP address (or none if you have no network access). We recommend that you connect to the special DNS namehost.docker.internal which resolves to the internal IP address used by thehost. This is for development purpose and will not work in a production environment outside of Docker Desktop for Mac.
You can also reach the gateway using gateway.docker.internal.
If you have installed Python on your machine, use the following instructions as an example to connect from a container to a service on the host:
Run the following command to start a simple HTTP server on port 8000.
python -m http.server 8000If you have installed Python 2.x, run
python -m SimpleHTTPServer 8000.Now, run a container, install
curl, and try to connect to the host using the following commands:
I want to connect to a container from the Mac
Port forwarding works for localhost; --publish, -p, or -P all work.Ports exposed from Linux are forwarded to the host.
Our current recommendation is to publish a port, or to connect from anothercontainer. This is what you need to do even on Linux if the container is on anoverlay network, not a bridge network, as these are not routed.
The command to run the nginx webserver shown in Getting Startedis an example of this.
To clarify the syntax, the following two commands both expose port 80 on thecontainer to port 8000 on the host:
To expose all ports, use the -P flag. For example, the following commandstarts a container (in detached mode) and the -P exposes all ports on thecontainer to random ports on the host.
See the run command for more details onpublish options used with docker run.
We heavily use Docker for Mac for the internal development of our products. It allows us to closely replicate the internal, automated testing, user acceptance testing and production platforms.
There is just one problem, that I'm sure you've also found... The performance of the file system when using volume mounts.
macOS (OSX) Catalina. This article has been recently updated, please see the amendments at the bottom.
Before Docker, came Vagrant, before Vagrant, came MAMP stacks. As developers we have been through a few different development environments in our time. Moving from Vagrant to Docker was a blessing, although one thing that hit us hard was the performance of Docker on Mac, specifically the file system performance.
When developing on macOS you would typically mount your local project folder volume to the /app directory within your container. If you made a change in your IDE, it would be replicated into the container (somehow), and you could then serve the updated content through your application.
This is fairly simple to set-up, i.e. you could start your docker container like this:
or if you are using docker-compose (tip: you should), then you might have an block of config in your docker-compose.yml file looking like this:
By default this will create a consistent link between the host and docker file system, this is extremely slow.
i.e. if you perform anything with extensive file I/O in either the docker container or the host file system, such as $ bin/console cache:clear, you can expect a long wait.
In Docker for Mac 17.04 CE, the option to use a delegated link became available, this is pretty much the same speed as consistent in terms of transferring information between host and container, but with one important difference - it did not block the container when performing I/O inside the container. This meant that the host file system was the last to know about the changes, but this was a good thing (generally) as it meant your application would run fairly smoothly inside the container.
There is much more about the subject here:https://docs.docker.com/docker-for-mac/osxfs-caching/
However the long and short of it is you can add a :delegated flag to the volume mount to enable this, such as:
or in your docker-compose.yml file:
Look why this is such a problem
I should point out these were tested very unscientifically, on a Mac Book Pro 2018 with a typical Symfony project and your mileage may vary.
Running on host file system
Running in the docker container in consistent (default) mode
Running in the docker container in delegated mode
Enter NFS
NFS is a popular mechanism that volumes were mounted when using Vagrant and it's performance has been pretty consistent in the past, it's been a stretch to bring it to docker as there have been a number of challenges to overcome, however if you create a volume in your docker-compose.yml config file to point to NFS such as:
... then modify your volume mount in docker-compose.yml as such:
... then run a nice little script I found from https://gist.github.com/seanhandleyGitHub Link
It will set up a NFS link between your $PWD (current working directory) and the containers /app directory, and finally when you run a cache:clear again:
Running in the docker container in NFS mode
Verdict
While I hope sincerely you have already been using delegated mode before finding this labs post, NFS is much nicer as it removes a lot of the CPU overhead between host and container. Now, I/O peformance is not the only element of the overall app performance, but I'll take this performance improvement over delegated anyday.
Docker For Mac 2018 Download
Go forth and NFS things!
OSX Catalina had changed the volume for various paths, including your user folder, this is a simple fix to move the NFS path to the new location. The above scripts/config must be changed so that
LINE='/Users -alldirs -mapall=$U:$G localhost'
Docker For Mac Getting Started
changes to
LINE='/System/Volumes/Data -alldirs -mapall=$U:$G localhost'
and also
device: ':$PWD'
changes to
device: ':/System/Volumes/Data/${PWD}'
Be sure to re-run the script and also remove/recreate any Docker volumes, you can list your Docker volumes with:
docker volume ls
Docker For Macbook
and then delete the relevant volumes created in a past Docker session with:
docker volume rm <YOUR_VOLUME_NAME>
Docker For Mac 2018-19-
Credit goes to:https://www.firehydrant.io/blog/nfs-with-docker-on-macos-catalina/