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This commit adds a new experimental package gitrepo, which serves read-only checkouts of git commits over NFSv4.1 using github.com/tailscale/nfsv4. It is for ephemeral workloads like CI VMs that know which commits they need before they start. A long-lived Manager keeps one bare repository per configured remote, under a root directory. The first checkout of a repository runs "git init --bare", and each checkout of a commit that is not yet in the repository fetches it by SHA into refs/gomodfs/<sha>. NewFS serves a fixed set of checkouts at /repos/<owner>/<repo> as a nodefs filesystem, which the caller serves with its own nfsv4.Server. Each view needs its own server, so jobs on one host cannot see each other's checkouts and we don't need to include the SHA-1 as part of the checkout path. Each repository reads objects with one long-running "git cat-file --batch" process for fast content reads. All contents are immutable, so every object grants read delegations. Each checkout has a read-only .git directory, so that read-only Git commands and Go's VCS stamping work. It contains HEAD, a shallow file, an index generated from the tree, and the loose objects of the commit and no other commit. cmd/gomodfs gets -repo, -commit, and -repo-nfs flags to serve one checkout next to the module cache as a demo, and CI mounts that checkout on Linux and macOS. Updates tailscale/corp#47555 Signed-off-by: Tom Proctor <tomhjp@users.noreply.github.com>
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This commit adds a new experimental package gitrepo, which serves read-only checkouts of git commits over NFSv4.1 using github.com/tailscale/nfsv4. It is for ephemeral workloads like CI VMs that know which commits they need before they start.
A long-lived Manager keeps one bare repository per configured remote, under a root directory. The first checkout of a repository runs "git init --bare", and each checkout of a commit that is not yet in the repository fetches it by SHA into refs/gomodfs/.
NewFS serves a fixed set of checkouts at /repos// as a nodefs filesystem, which the caller serves with its own nfsv4.Server. Each view needs its own server, so jobs on one host cannot see each other's checkouts and we don't need to include the SHA-1 as part of the checkout path. Each repository reads objects with one long-running "git cat-file --batch" process for fast content reads. All contents are immutable, so every object grants read delegations.
Each checkout has a read-only .git directory, so that read-only Git commands and Go's VCS stamping work. It contains HEAD, a shallow file, an index generated from the tree, and the loose objects of the commit and no other commit.
cmd/gomodfs gets -repo, -commit, and -repo-nfs flags to serve one checkout next to the module cache as a demo, and CI mounts that checkout on Linux and macOS.
Updates tailscale/corp#47555