How To Run Tahoe-LAFS

Introduction

This is how to run a Tahoe-LAFS client or a complete Tahoe-LAFS grid. First you have to install the Tahoe-LAFS software, as documented in Installing Tahoe-LAFS.

The tahoe program in your virtualenv’s bin directory is used to create, start, and stop nodes. Each node lives in a separate base directory, in which there is a configuration file named tahoe.cfg. Nodes read and write files within this base directory.

A grid consists of a set of storage nodes and client nodes running the Tahoe-LAFS code. There is also an introducer node that is responsible for getting the other nodes talking to each other.

If you’re getting started we recommend you try connecting to the public test grid as you only need to create a client node. When you want to create your own grid you’ll need to create the introducer and several initial storage nodes (see the note about small grids below).

Being Introduced to a Grid

A collection of Tahoe servers is called a Grid and usually has 1 Introducer (but sometimes more, and it’s possible to run with zero). The Introducer announces which storage servers constitute the Grid and how to contact them. There is a secret “fURL” you need to know to talk to the Introducer.

One way to get this secret is using traditional tools such as encrypted email, encrypted instant-messaging, etcetera. It is important to transmit this fURL secretly as knowing it gives you access to the Grid.

An additional way to share the fURL securely is via magic wormhole. This uses a weak one-time password and a server on the internet (at wormhole.tahoe-lafs.org) to open a secure channel between two computers. In Tahoe-LAFS this functions via the commands tahoe invite and tahoe create-client –join. A person who already has access to a Grid can use tahoe invite to create one end of the magic wormhole and then transmits some JSON (including the Introducer’s secret fURL) to the other end. tahoe invite will print a one-time secret code; you must then communicate this code to the person who will join the Grid.

The other end of the magic wormhole in this case is tahoe create-client –join <one-time code>, where the person being invited types in the code they were given. Ideally, this code would be transmitted securely. It is, however, only useful exactly once. Also, it is much easier to transcribe by a human. Codes look like 7-surrender-tunnel (a short number and two words).

Running a Client

To construct a client node, run “tahoe create-client”, which will create ~/.tahoe to be the node’s base directory. Acquire the introducer.furl (see below if you are running your own introducer, or use the one from the TestGrid page), and paste it after introducer.furl = in the [client] section of ~/.tahoe/tahoe.cfg. Then use “tahoe run ~/.tahoe”. After that, the node should be off and running. The first thing it will do is connect to the introducer and get itself connected to all other nodes on the grid.

Some Grids use “magic wormhole” one-time codes to configure the basic options. In such a case you use tahoe create-client --join <one-time-code> and do not have to do any of the tahoe.cfg editing mentioned above.

By default, “tahoe create-client” creates a client-only node, that does not offer its disk space to other nodes. To configure other behavior, use “tahoe create-node” or see Configuring a Tahoe-LAFS node.

The “tahoe run” command above will run the node in the foreground. On Unix, you can run it in the background instead by using the “tahoe start” command. To stop a node started in this way, use “tahoe stop”. tahoe --help gives a summary of all commands.

Running a Server or Introducer

To build either a storage server node, or an introducer node, you’ll need a way for clients to connect to it. The simplest case is when the computer is on the public internet (e.g. a “VPS” virtual private server, with a public IP address and a DNS hostname like example.net). See How To Configure A Server for help with more complex scenarios, using the --port and --location arguments.

To construct an introducer, create a new base directory for it (the name of the directory is up to you), cd into it, and run “tahoe create-introducer --hostname=example.net .” (but using the hostname of your VPS). Now run the introducer using “tahoe start .”. After it starts, it will write a file named introducer.furl into the private/ subdirectory of that base directory. This file contains the URL the other nodes must use in order to connect to this introducer. (Note that “tahoe run .” doesn’t work for introducers, this is a known issue: #937.)

You can distribute your Introducer fURL securely to new clients by using the tahoe invite command. This will prepare some JSON to send to the other side, request a magic wormhole code from wormhole.tahoe-lafs.org and print it out to the terminal. This one-time code should be transmitted to the user of the client, who can then run tahoe create-client --join <one-time-code>.

Storage servers are created the same way: tahoe create-node --hostname=HOSTNAME . from a new directory. You’ll need to provide the introducer FURL (either as a --introducer= argument, or by editing the tahoe.cfg configuration file afterwards) to connect to the introducer of your choice.

See Configuring a Tahoe-LAFS node for more details about how to configure Tahoe-LAFS.

A note about small grids

By default, Tahoe-LAFS ships with the configuration parameter shares.happy set to 7. If you are using Tahoe-LAFS on a grid with fewer than 7 storage nodes, this won’t work well for you — none of your uploads will succeed. To fix this, see Configuring a Tahoe-LAFS node to learn how to set shares.happy to a more suitable value for your grid.

Do Stuff With It

This is how to use your Tahoe-LAFS node.

The WUI

Point your web browser to http://127.0.0.1:3456 — which is the URL of the gateway running on your own local computer — to use your newly created node.

Create a new directory (with the button labelled “create a directory”). Your web browser will load the new directory. Now if you want to be able to come back to this directory later, you have to bookmark it, or otherwise save a copy of the URL. If you lose the URL to this directory, then you can never again come back to this directory.

The CLI

Prefer the command-line? Run “tahoe --help” (the same command-line tool that is used to start and stop nodes serves to navigate and use the decentralized file store). To get started, create a new directory and mark it as the ‘tahoe:’ alias by running “tahoe create-alias tahoe”. Once you’ve done that, you can do “tahoe ls tahoe:” and “tahoe cp LOCALFILE tahoe:foo.txt” to work with your file store. The Tahoe-LAFS CLI uses similar syntax to the well-known scp and rsync tools. See The Tahoe-LAFS CLI commands for more details.

To backup a directory full of files and subdirectories, run “tahoe backup LOCALDIRECTORY tahoe:”. This will create a new LAFS subdirectory inside the “tahoe” LAFS directory named “Archive”, and inside “Archive”, it will create a new subdirectory whose name is the current date and time. That newly created subdirectory will be populated with a snapshot copy of all files and directories currently reachable from LOCALDIRECTORY. Then tahoe backup will make a link to that snapshot directory from the “tahoe” LAFS directory, and name the link “Latest”.

tahoe backup cleverly avoids uploading any files or directories that haven’t changed, and it also cleverly deduplicates any files or directories that have identical contents to other files or directories that it has previously backed-up. This means that running tahoe backup is a nice incremental operation that backs up your files and directories efficiently, and if it gets interrupted (for example by a network outage, or by you rebooting your computer during the backup, or so on), it will resume right where it left off the next time you run tahoe backup.

See The Tahoe-LAFS CLI commands for more information about the tahoe backup command, as well as other commands.

As with the WUI (and with all current interfaces to Tahoe-LAFS), you are responsible for remembering directory capabilities yourself. If you create a new directory and lose the capability to it, then you cannot access that directory ever again.

The SFTP and FTP frontends

You can access your Tahoe-LAFS grid via any SFTP or FTP client. See Tahoe-LAFS SFTP and FTP Frontends for how to set this up. On most Unix platforms, you can also use SFTP to plug Tahoe-LAFS into your computer’s local filesystem via sshfs, but see the FAQ about performance problems.

The SftpFrontend page on the wiki has more information about using SFTP with Tahoe-LAFS.

The WAPI

Want to program your Tahoe-LAFS node to do your bidding? Easy! See The Tahoe REST-ful Web API.

Socialize

You can chat with other users of and hackers of this software on the #tahoe-lafs IRC channel at irc.freenode.net, or on the tahoe-dev mailing list.

Complain

Bugs can be filed on the Tahoe-LAFS “Trac” instance, at https://tahoe-lafs.org/trac/ .

You can also “fork” the repo and submit Pull Requests on Github: https://github.com/tahoe-lafs/tahoe-lafs .