git-annex/doc/todo/git-annex_proxies.mdwn
Joey Hess 07e899c9d3
git-annex-shell: proxy nodes located beyond remote cluster gateways
Walking a tightrope between security and convenience here, because
git-annex-shell needs to only proxy for things when there has been
an explicit, local action to configure them.

In this case, the user has to have run `git-annex extendcluster`,
which now sets annex-cluster-gateway on the remote.

Note that any repositories that the gateway is recorded to
proxy for will be proxied onward. This is not limited to cluster nodes,
because checking the node log would not add any security; someone could
add any uuid to it. The gateway of course then does its own
checking to determine if it will allow proxying for the remote.
2024-06-26 12:56:16 -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.
* 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 VIA extension to P2P protocol to avoid cycles.
Current status: Distributed cluster nodes are visible,
and can be accessed directly, but trying to GET from a cluster
fails when the content is located behind a remote gateway.
And PUT only sends to the immediate nodes
of the cluster, not on to other gateways.
* 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.
* 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>
* Encryption and chunking. See design for issues.
* 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)