git-annex/doc/todo/git-annex_proxies.mdwn
2024-06-27 12:57:08 -04:00

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This is a summary todo covering several subprojects, which would extend
git-annex to be able to use proxies which sit in front of a cluster of
repositories.
1. [[design/passthrough_proxy]]
2. [[design/p2p_protocol_over_http]]
3. [[design/balanced_preferred_content]]
4. [[todo/track_free_space_in_repos_via_git-annex_branch]]
5. [[todo/proving_preferred_content_behavior]]
Joey has received funding to work on this.
Planned schedule of work:
* June: git-annex proxy
* July, part 1: git-annex proxy support for exporttree
* July, part 2: p2p protocol over http
* August: balanced preferred content
* September: streaming through proxy to special remotes (especially S3)
* October: proving behavior of balanced preferred content with proxies
[[!tag projects/openneuro]]
# work notes
In development on the `proxy` branch.
For June's work on [[design/passthrough_proxy]], remaining todos:
* Since proxying to special remotes is not supported yet, and won't be for
the first release, make it fail in a reasonable way.
* Proxying for special remotes.
* Encryption and chunking. See design for issues.
* Getting a key from a cluster currently always selects the lowest cost
remote, and always the same remote if cost is the same. Should
round-robin amoung remotes, and prefer to avoid using remotes that
other git-annex processes are currently using.
* When a cluster has multiple gateways, and a key is uploaded via one
gateway, that gateway learns about every node where the key is stored.
But other gateways do not, they only learn about nodes reached via them
where the key is stored. This means that another user, syncing with
the other gateway, won't know how many copies exist, or necessarily
that the key is in the cluster at all. Should gateways broadcast
location change messages to other gateways?
* Optimise proxy speed. See design for ideas.
* Use `sendfile()` to avoid data copying overhead when
`receiveBytes` is being fed right into `sendBytes`.
Library to use:
<https://hackage.haskell.org/package/hsyscall-0.4/docs/System-Syscall.html>
* Indirect uploads (to be considered). See design.
* Support using a proxy when its url is a P2P address.
(Eg tor-annex remotes.)
* `viconfig` support for setting preferred content, group,
and description of clusters
# completed items for June's work on [[design/passthrough_proxy]]:
* UUID discovery via git-annex branch. Add a log file listing UUIDs
accessible via proxy UUIDs. It also will contain the names
of the remotes that the proxy is a proxy for,
from the perspective of the proxy. (done)
* Add `git-annex updateproxy` command (done)
* Remote instantiation for proxies. (done)
* Implement git-annex-shell proxying to git remotes. (done)
* Proxy should update location tracking information for proxied remotes,
so it is available to other users who sync with it. (done)
* Implement `git-annex updatecluster` command (done)
* Implement cluster UUID insertation on location log load, and removal
on location log store. (done)
* Omit cluster UUIDs when constructing drop proofs, since lockcontent will
always fail on a cluster. (done)
* Don't count cluster UUID as a copy in numcopies checking etc. (done)
* Tab complete proxied remotes and clusters in eg --from option. (done)
* Getting a key from a cluster should proxy from one of the nodes that has
it. (done)
* Implement upload with fanout to multiple cluster nodes and reporting back
additional UUIDs over P2P protocol. (done)
* Implement cluster drops, trying to remove from all nodes, and returning
which UUIDs it was dropped from. (done)
* `git-annex testremote` works against proxied remote and cluster. (done)
* Avoid `git-annex sync --content` etc from operating on cluster nodes by
default since syncing with a cluster implicitly syncs with its nodes. (done)
* On upload to cluster, send to nodes where its preferred content, and not
to other nodes. (done)
* Support annex.jobs for clusters. (done)
* Add `git-annex extendcluster` command and extend `git-annex updatecluster`
to support clusters with multiple gateways. (done)
* Support proxying for a remote that is proxied by another gateway of
a cluster. (done)
* Support distributed clusters: Make a proxy for a cluster repeat
protocol messages on to any remotes that have the same UUID as
the cluster. Needs extension to P2P protocol to avoid cycles.
(done)