sequenceiq/zedapp repository overview

I wish I get 1 dollar each time I install vi in a docker container ... I wanted an easier way to edit files in a running docker container. First of all try to avoid editing files at all, as it is against the container philosophy (see the last paragraph).

But if you have a valid reason, here comes the how-to.

⁠Why Zedapp

Most of the time I use either vi or Atom⁠, but a few months ago I stumbled upon Zedapp⁠ an opinionated editor. It aims to reduce cognitive load while editing, by simplifying things, like deliberately not using tabs.

It stands out with its first-class support of remote editing let it be a remote server, or even directly editing github repositories.

Zedapp just reached version 1.0 and if you like it, consider help Zef Hemmel at gratipay⁠, who was brave enough to quit his regular job, and work full time on an open-source project!

⁠Install Zedapp

You can use zedapp as a chrome plugin or a standalone app. Downloads are available at: zedapp.org⁠. I recommend to go for the standalone version.

⁠Install zedrem

For remote editing⁠, you need zedrem, a small process serving files to be edited in Zedapp. Zedrem is packaged into a docker image: sequenceiq/zedapp⁠

To start a local zed-server, and zed-client in the target container, there is a helper script: zed

To install the docker image and the shell script run this:

docker run --rm \
  -v /usr/local/bin:/target \
  -v /usr/local/bin/docker:/usr/local/bin/docker \
  -v /var/run/docker.sock:/var/run/docker.sock \
  sequenceiq/zedapp

Actually there is only a single binary called zedrem, i just use the terminology⁠: zed-server and zed-client to distinguish when you use it with or without the --server option.

Now you are ready to start a zedrem session, to edit files in Zedapp which are inside of a Docker container's directory.

⁠Start a zedrem session

To start a zedrem client in a container

zed <container> <directory>

This will:

• start a zedrem-server if not already running.
• copy and start zedrem-client into the selected container and print out the zedrem session's remote-url.

Navigate to the project list window by: Command-Shift-O/Ctrl-Shift-O. Select Remote Folder, enter the remote-url into Zedrem URL input field and press Open.

Thats all enyoj! All the following paragraphs are for the curious only.

⁠Boot2docker helper function

The Install zedrem step should have detected that you are using Boot2docker, and instructed you to create a helper function, but in case you missed it, or for reference:

zed() { boot2docker ssh "sudo zed $@" ; }

This is needed as the helper script called zed is installed inside of Boot2docker, so you need the ususal boot2docker ssh workaround.

after that you can issue directly on OSX:

zed <container> <directory>

⁠Local zedrem server.

By default when you want to use Zedapp for remote editing, you need two other components then Zedapp:

• zedrem-server Zedapp gets file content, and sends edit commands on webservices protocol. It maintains sessions with zedrem-clients.
• zedrem-client a small process serving files from a specified directory.

When you use zedrem-client via the official server, all the editing commands/content travel around the blobe:

Compare it with the dockerized local server setup, which is more quick and secure:

⁠nsenter

You might wonder about the step: copy zedrem into the container. How is it possible? Docker's cp command only supportts the other direction: copy from a container into a local dir.

There is an open issue⁠, so it will be fixed soon, but meanwhile you can use nsenter to the rescue. Jérôme Petazzoni prepared us a canned nsenter⁠ with the helper script: docker-enter. We can missuse docker-enter to copy a file from local fs into the container by:

cat local-file | docker-enter $container sh -c 'cat>/zedrem'

btw: docker exec is already merged into the master branch, so it will replace nsenter completely.

⁠Don't do this at all

Let's make it clear, that most of the time you don't need this. First of all editing files in a container, other than development or debug considered bad practice.

You find yourself editing nginx config files? Don't do it, use the great generic nginx appliance⁠ from Jeff Lindsay.

If you really need to edit files in a docker container, just use volumes.

This process comes handy if you've already started a container, and the file in question doesn't sits on a volume.