SSHFS synced folder implementation for Vagrant.
Ruby Cucumber Shell
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README.adoc

vagrant-sshfs

Considerations

The benefits of this approach:

  • Works on any host platform and hypervisor type

    • Windows, Linux, Mac OS X

    • Virtualbox, Libvirt, Hyper-V, VMWare

  • Seamlessly works on remote Vagrant solutions

    • Works with vagrant aws/openstack/etc.. plugins

The drawbacks with this approach:

  • Performance is worse than an implementation like NFS

  • There must be sftp-server software on the Vagrant host

sftp-server is usually provided by SSH server software so it already exists on Linux/Mac. On windows you only need to install openssh via cygwin and you will get sftp-server.

History

The inspiration for this plugin came from Fabio Kreusch and his code for the original vagrant-sshfs Vagrant plugin. The goal of this plugin (as opposed to the old implementation) is to implement SSHFS as a synced folder plugin just like the other synced folder plugins (NFS/RSYNC/SMB/VirtualBox).

This plugin was developed mainly by copying the code from the NFS synced folder plugin from the Vagrant core code and molding it to fit SSHFS.

Modes of Operation

Sharing Vagrant Host Directory to Vagrant Guest - 94% of users

This plugin uses SSHFS slave mounts (see link) to mount a directory from the Vagrant Host into the Vagrant Guest. It uses the sftp-server software that exists on the host and sshfs running in slave mode within the guest to create a connection using the existing authentication over SSH that vagrant sets up for you.

Sharing Arbitrary Host Directory to Vagrant Guest - 1% of users

This plugin allows you to share a folder from an arbitrary host to the Vagrant Guest. This would allow you to do a folder mount to some other host that may have files that you need. To do this the plugin will run an SSHFS command from the Guest and connect to the arbitrary host that must have an SSH daemon running. You must provide the ssh_host option in the Vagrantfile to get this to work. You can use ssh key forwarding or username/password for authentication for this.

See Options and Appendix A for more information.

Sharing Vagrant Guest Directory to Vagrant Host - 5% of users

NOTE: This option is dangerous as data will be destroyed upon vagrant destroy

This plugin allows you to share a folder from a Vagrant guest into the host. If you have workloads where there are a lot of disk intensive operations (such as compilation) it may be ideal to have the files live in the guest where the disk intensive operations would occur. For discussion see Issue #7.

See Options for more information on how to enable this type of mount.

Getting Started

In order to use this synced folder implementation perform the following steps:

Install Plugin

In order to install the plugin simply run the following command:

# vagrant plugin install vagrant-sshfs

Add SSHFS Synced Folder in Vagrantfile

Edit your Vagrantfile to specify a folder to mount from the host into the guest:

config.vm.synced_folder "/path/on/host", "/path/on/guest", type: "sshfs"

Now you can simply vagrant up and your folder should be mounted in the guest. For more options that you can add see the Options section.

Executing the vagrant sshfs Command

The Vagrant SSHFS plugin also supports execution of the vagrant sshfs command from the command line. Executing this command with the --mount option will iterate through the Vagrant file and attempt to mount (via SSHFS) any folders that aren’t already mounted in the Vagrant guest. Executing with the --unmount option will unmount any mounted folders.

vagrant sshfs [--mount|--unmount] [vm-name]

Options

The SSHFS synced folder plugin supports a few options that can be provided in the Vagrantfile. The following sections describe the options in more detail.

Generic Options

The SSHFS synced folder plugin supports a few options that can be provided in the Vagrantfile. They are described below:

  • disabled

    • If set to 'true', ignore this folder and don’t mount it.

  • ssh_opts_append

    • Add some options for the ssh connection that will be established.

    • See the ssh man page for more details on possible options.

  • sshfs_opts_append

    • Add some options for the sshfs fuse mount that will made

    • See the sshfs man page for more details on possible options.

An example snippet from a Vagrantfile:

config.vm.synced_folder "/path/on/host", "/path/on/guest",
    ssh_opts_append: "-o Compression=yes -o CompressionLevel=5",
    sshfs_opts_append: "-o auto_cache -o cache_timeout=115200",
    disabled: false, type: "sshfs"

Options Specific to Arbitrary Host Mounting

The following options are only to be used when sharing an arbitrary host directory with the guest. They will be ignored otherwise:

  • ssh_host

    • The host to connect to via SSH. If not provided this will be detected as the Vagrant host that is running the Vagrant guest.

  • ssh_port

    • The port to use when connecting. Defaults to port 22.

  • ssh_username

    • The username to use when connecting. If not provided it is detected as the current user who is interacting with Vagrant.

  • ssh_password

    • The password to use when connecting. If not provided and the user is not using SSH keys, then the user will be prompted for the password. Please use SSH keys and don’t use this option!

  • prompt_for_password

    • The user can force Vagrant to interactively prompt the user for a password by setting this to 'true'. Alternatively the user can deny Vagrant from ever prompting for the password by setting this to 'false'.

An example snippet from a Vagrantfile:

config.vm.synced_folder "/path/on/host", "/path/on/guest",
    ssh_host: "somehost.com", ssh_username: "fedora",
    ssh_opts_append: "-o Compression=yes -o CompressionLevel=5",
    sshfs_opts_append: "-o auto_cache -o cache_timeout=115200",
    disabled: false, type: "sshfs"

Options Specific to Reverse Mounting (Guest→Host Mount)

If your host has the sshfs software installed then the following options enable mounting a folder from a Vagrant Guest into the Vagrant Host:

  • reverse

    • This can be set to 'true' to enable reverse mounting a guest folder into the Vagrant host.

An example snippet from a Vagrantfile where we want to mount /data on the guest into /guest/data on the host:

config.vm.synced_folder "/guest/data", "/data", type: 'sshfs', reverse: true

FAQ

Here are some answers to some frequently asked questions:

Why do new files take time to appear inside the guest?

Sometimes it can take time for files to appear on the other end of the sshfs mount. An example would be I create a file on my host system and then it doesn’t show up inside the guest mount for 10 to 20 seconds. This is because of caching that SSHFS does to improve performance. Performance vs accuracy is always going to be a trade-off. If you’d like to disable caching completely you can disable caching completely by appending the cache=no SSHFS option to the synced folder definition in the Vagrantfile like so:

config.vm.synced_folder "/path/on/host", "/path/on/guest",
    type: "sshfs", sshfs_opts_append: "-o cache=no"

All caching options that are available to sshfs can be added/modified in this same manner.

Appendix A: Using Keys and Forwarding SSH Agent

When sharing an arbitrary host directory you may want a completely non-interactive experience. You can either hard code your password in the Vagrantfile or you can use SSH keys. A few guides for setting up ssh keys and key forwarding are on Github:

The idea is that if key1 is a key that is authorized to log in to the Vagrant host ,meaning there is an entry for key1 in the ~/.ssh/authorized_keys file, then you should be able to do the following to have a non-interactive experience with SSH keys and agent forwarding:

Modify the Vagrantfile to forward your SSH agent:

config.ssh.forward_agent = 'true'

Now set up your agent and add your key to the agent:

# eval $(ssh-agent)
# ssh-add /path/to/key1

And finally bring up your Vagrant guest:

# vagrant up

Appendix B: Development

For local development of this plugin here is an example of how to build, test and install this plugin on your local machine:

# Install development dependencies
$ gem install bundler && bundle install

# List available Rake tasks
$ bundle exec rake -T

# Run Cucumber tests
$ bundle exec rake featuretests

# Build the gem (gets generated in the 'pkg' directory
$ bundle exec rake build

# Run Vagrant in the context of the plugin
$ bundle exec vagrant <command>

# Install built gem into global Vagrant installation (run outside of git checkout!)
$ vagrant plugin install <path to gem in pkg directory>