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Site profile

The site-env-15, site-env-17, and site-env-orioledb-17 package sets are deployed to /nix/var/nix/profiles/site. They hold supautils, and activate.

Publish

ami-release-nix.yml uploads each store path as a string to the shared artifacts bucket, which is private, in the object nix-catalog/<sha>/<system>/site-env-<major>. Release branches also upload the git sha as a string to nix-catalog/latest/<system>/site-env-<major>. The AMI bake installs the store path passed in as site_env_path and runs activate.

Update

nix-env --profile /nix/var/nix/profiles/site --set <store path>
/nix/var/nix/profiles/site/bin/activate

--set downloads the closure from the binary cache if it is missing. It then creates the generation link site-<N>-link to the store path and repoints the site symlink at that link. If it fails, nix-env exits with 1 and the profile is unchanged. This holds when the path can't be fetched, isn't a store path, or the profile directory isn't writable.

activate runs after the switch. It prints the library settings configured in postgresql.conf, and is idempotent. If it fails, the new generation stays active. Run activate again, or roll back.

New sessions load supautils from the new profile. Open sessions keep the copy they loaded until they reconnect. Postgres does not restart. A restart applies the change to every session at once. The same holds after a rollback.

Roll back

nix-env --profile /nix/var/nix/profiles/site --rollback
/nix/var/nix/profiles/site/bin/activate

Rollback switches to the previous generation. activate then runs from that generation and makes the machine match it. There is no separate rollback script.

To go further back than the previous generation, install an older version by path.

Install any version by path

nix-env --profile /nix/var/nix/profiles/site --set <older store path>
/nix/var/nix/profiles/site/bin/activate

This is the way to roll back past the one kept generation. It is the same as an update with an older path.

activate safety

activate must be idempotent, and the previous generation's activate must be able to converge the machine back. Safety shall be ensured by comparing snapshots in tests before and after an update and a rollback.

Test

nix build .#checks.<system>.site -L

The site VM test covers loading supautils from the site profile, the $libdir fallthrough, and activate.