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README.md

IPFS fs-repo version 1 Spec

Author[s]: Juan Benet

Reviewer[s]:

The Spec for the fs-repo IPFS repository.

This spec defines fs-repo version 1, its formats, and semantics. The repo interface is defined here.

Definition

fs-repo is a filesystem implementation of the IPFS repo.

Contents

.ipfs/
├── api             <--- running daemon api addr
├── blocks/         <--- objects stored directly on disk
│   └── aa          <--- prefix namespacing like git
│       └── aa      <--- N tiers
├── config          <--- config file (json or toml)
├── hooks/          <--- hook scripts
├── keys/           <--- cryptographic keys
│   ├── id.pri      <--- identity private key
│   └── id.pub      <--- identity public key
├── datastore/      <--- datastore
├── logs/           <--- 1 or more files (log rotate)
│   └── events.log  <--- can be tailed
├── repo.lock       <--- mutex for repo
└── version         <--- version file

api

api is a file that exists only if there is currently a live api listening for requests. This is used when the repo.lock prevents access. Clients may opt to use the api service, or wait untill the process holding repo.lock exits. The file's content is the api multiaddr

> cat .ipfs/api
/ip4/127.0.0.1/tcp/5001

Notes:

  • The API server must remove the api file before releasing the repo.lock.
  • It is not enough to use the config file, as the API addr of a daemon may have been overridden via ENV or flag.

blocks/

The block/ component contains the raw data representing all IPFS objects stored locally, whether pinned or cached. This component is controlled by the datastore. For example, it may be stored within a leveldb instance in datastore/, or it may be stored entirely with independent files, like git.

In the default case, the user uses fs-datastore for all /blocks so the objects are stored in individual files. In other cases, /blocks may even be stored remotely

config

The config file is a JSON or TOML file that contains the tree of configuration variables. It MUST only be changed while holding the repo.lock, or potentially lose edits.

hooks/

The hooks directory contains exectuable scripts to be called on specific events to alter ipfs node behavior.

Currently available hooks:

none

keys/

The keys directory holds all the keys the node has access to. The keys are named with their hash, and an extension describing what type of key they are. The only specially-named key is id.{pub, sec}

<key>.pub is a public key
<key>.pri is a private key
<key>.sym is a symmetric secret key

datastore/

The datastore directory contains the data for a leveldb instance used to store operation data for the IPFS node. If the user uses a boltdb datastore instead, the directory will be named boltdb. Thus the data files of each database will not clash.

TODO: consider whether all should just be named leveldb/

logs/

IPFS implementations put event log files inside the logs/ directory. The latest log file is logs/events. Others, rotated out may exist, with a timestamp of their creation. For example:

repo.lock

repo.lock prevents concurrent access to the repo. Its content is the PID of the process currently holding the lock. This allows clients to detect a failed lock cleanup.

> cat .ipfs/repo.lock
42
> ps | grep "ipfs daemon"
42 ttys000   79:05.83 ipfs daemon

version

The version file contains the repo implementation name and version

> cat version
fs-repo: 1

Any fs-repo implementation of any versions MUST be able to read the version file. It MUST NOT change between versions.

Datastore

Both the /blocks and /datastore directories are controlled by the datastore component of the repo.

Notes

Location

The fs-repo can be located anywhere on the filesystem. By default clients should search for a repo in:

~/.ipfs

Users can tell IPFS programs to look elsewhere with the env var:

IPFS_PATH=/path/to/repo

blocks/ with an fs-datastore

Each object is stored in its own file. The filename is the hash of the object. The files are nested in directories whose names are prefixes of the hash, as in .git/objects.

For example:

# multihashes
1220fe389b55ea958590769f9046b0f7268bca90a92e4a9f45cbb30930f4bf89269d # sha2
1114f623e0ec7f8719fb14a18838d2a3ef4e550b5e53 # sha1

# locations of the blocks
.ipfs/blocks/1114/f6/23/e0ec7f8719fb14a18838d2a3ef4e550b5e53
.ipfs/blocks/1220/fe/38/9b55ea958590769f9046b0f7268bca90a92e4a9f45cbb30930f4bf89269d

Important Notes:

  • the hashes are encoded in hex, not the usual base58, because some filesystems are case insensitive.
  • the multihash prefix is two bytes, which would waste two directory levels, thus these are combined into one.
  • the git idx and pack file could be used to coalesce objects

Reading without the repo.lock

Programs MUST hold the repo.lock while reading and writing most files in the repo. The only two exceptions are:

  • repo.lock - so clients may check for it
  • api - so clients may use the API