mars(mnemosyne): fix review blockers — relative plugin symlink, wipe-and-rebuild venv, PyYAML config cue, drop root-executes-luna-tree

This commit is contained in:
2026-09-18 23:48:32 +00:00
parent a8e5c200dc
commit 694317acbb
2 changed files with 155 additions and 70 deletions
+110 -70
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@@ -76,15 +76,24 @@ let
# Mnemosyne memory provider (local SQLite, third-party plugin — not bundled
# with Hermes). Requirements pins live in ./mnemosyne/requirements.txt; see
# the provisioning unit near the bottom of this file for the layout mapped
# into hermesHome. The symlink target below must be the SAME path the
# side venv was built with (hermesHome/mnemosyne-venv) — Hermes resolves
# plugin modules through it, so relative traversal after the bind mount
# still resolves inside the container identically.
# the provisioning unit near the bottom of this file. The venv lives at
# ${hermesHome}/mnemosyne-venv and the plugin discovery symlink
# (${hermesHome}/plugins/mnemosyne) is made RELATIVE — ../mnemosyne-venv/…
# — so it resolves identically on the host and inside the container, where
# /opt/data is a bind mount of hermesHome and hosts/containers see
# different mountpoint prefixes for the same tree.
mnemosyneReqs = pkgs.writeText "mnemosyne-requirements.txt" (
builtins.readFile ./mnemosyne/requirements.txt
);
# config.yaml provider-cue setter (PyYAML, preserves all other keys) — run
# host-side by the provisioning unit against the just-built, still
# root-owned venv's interpreter, BEFORE that venv is chowned to the
# container uid (root never executes from a luna-writable tree).
mnemosyneSetProvider = pkgs.writeText "mnemosyne-set-provider.py" (
builtins.readFile ./mnemosyne/set-provider.py
);
# Wire event names (X-GitHub-Event) each route accepts — NOT the
# subscription names the gitea hooks in services/dev/gitea.nix use. The two
# namespaces collide; see the long comment on the route unit below.
@@ -435,110 +444,141 @@ in
# bundled with the official image. Two pieces must exist before the gateway
# starts for memory.provider = mnemosyne to activate:
#
# 1. ${hermesHome}/plugins/mnemosyne — a symlink to the plugin package
# inside the side venv. Hermes discovers providers by scanning
# $HERMES_HOME/plugins (see its plugins/memory discovery code), reads
# __init__.py/. For it to IMPORT cleanly the plugin's sibling
# `mnemosyne` core package must be importable too — which is exactly
# why the plugin code lives inside the side venv's site-packages
# rather than as a bare writable copy.
# 1. ${hermesHome}/plugins/mnemosyne — a RELATIVE symlink to the plugin
# package inside the side venv (../mnemosyne-venv/lib/…/site-packages/
# hermes_memory_provider). Hermes discovers providers by scanning
# $HERMES_HOME/plugins; resolve() keeps the traversal inside the
# bind-mounted tree, so it lands on the same files whether read
# host-side (/var/lib/hermes/…) or container-side (/opt/data/…).
#
# 2. The side venv itself (${hermesHome}/mnemosyne-venv), built with the
# pinned pins in ./mnemosyne/requirements.txt. Inside hermesHome so
# it lands inside HERMES_WRITE_SAFE_ROOT=/opt/data (visible to the
# container at /opt/data/mnemosyne-venv) and survives image rebuilds.
# 2. The side venv (${hermesHome}/mnemosyne-venv), built with the pinned
# pins in ./mnemosyne/requirements.txt. Inside hermesHome so it lives
# under the container's HERMES_WRITE_SAFE_ROOT and survives image
# rebuilds.
#
# The venv's absolute paths embed ${hermesHome}: uv venv records the
# creation prefix, which is by construction identical inside and outside
# the container thanks to /opt/data being a bind mount of hermesHome.
# Import mechanics (verified against the plugin, not assumed): Hermes's own
# interpreter imports hermes_memory_provider OFF THE SYMLINK; that module's
# __init__.py itself inserts Path(__file__).resolve().parent.parent — the
# venv's site-packages — into sys.path before importing `mnemosyne.*`. So
# nothing needs to EXECUTE the venv's interpreter inside the container: the
# interpreter is only used host-side, by this unit, at provisioning time.
#
# Idempotent: marked done by a stamp file keyed by the hash of the
# requirements text, so a changed pin re-provisions. Never deletes —
# removing memory.provider from config is what retires it.
# requirements text; the console script is verified before the stamp is
# written, so a half-install (venv present but install died) re-provisions
# rather than exiting on a stale stamp. A pin change also re-provisions.
#
# Re-provisioning always wipes and recreates the venv (`uv venv --clear`,
# plus an explicit rm -f for a leftover non-directory): `uv venv` refuses
# to reuse an existing dir, and a wipe-and-rebuild is precisely what a
# changed stamp is supposed to mean. Working under root against a
# luna-writable ${hermesHome} means Python must never be made to IMPORT
# from a tree she has written to — that's why siteDir is composed here
# (python3.13 is pinned in the uv venv path) instead of executing
# $venv/bin/python to ask it, and why the rm -f/ln -sfn pair cannot leave
# stale venv content behind. Deleting first is what guarantees the new
# venv is hermetic to root, not incremental.
#
# Ordering: before podman-hermes-agent (the gateway needs the plugin at
# import time), after network (uv may fetch wheels on first provision),
# with a bounded timeout so a broken proxy cannot hang boot.
# import time), after network (uv fetches wheels on first provision,
# ~largest payload is onnxruntime), with a bounded timeout so a broken
# proxy cannot hang boot.
#
# Deliberately NOT Required= / requiredBy: a failed provision leaves the
# container running as before, without mnemosyne (RETAINED on purpose —
# hermes-webhook-routes and the gateway keep working, and config.yaml
# stays untouched, so a plain retry after fixing the network/mirror is
# enough). If mnemosyne activation itself should hard-fail boot, that
# needs an explicit decision from darman — the default here errs toward
# "don't take memory down along with everything else".
#
# No RequiresMountsFor: this unit only touches ${stateDir}, which is on
# the local filesystem (not a mount) on mars.
systemd.services.hermes-agent-mnemosyne-provision = {
description = "Provision Mnemosyne memory provider (side venv + plugin symlink)";
before = [ "podman-hermes-agent.service" ];
wantedBy = [ "podman-hermes-agent.service" ];
wants = [ "network-online.target" ];
after = [ "network-online.target" ];
unitConfig.RequiresMountsFor = [ "/mnt/jupiter" ];
path = [ pkgs.python3 pkgs.uv pkgs.coreutils ];
path = [ pkgs.uv pkgs.coreutils ];
serviceConfig = {
Type = "oneshot";
TimeoutStartSec = 600;
};
environment = {
UV_PYTHON_INSTALL_DIR = "${hermesHome}/mnemosyne-uv/python";
UV_CACHE_DIR = "${hermesHome}/mnemosyne-uv/cache";
UV_COMPILE_BYTECODE = "1";
};
script = ''
set -euo pipefail
venv=${hermesHome}/mnemosyne-venv
pluginDir=${hermesHome}/plugins/mnemosyne
pluginsDir=${hermesHome}/plugins
pluginDir=$pluginsDir/mnemosyne
stampFile=${hermesHome}/mnemosyne-provision.stamp
reqHash=$(sha256sum ${mnemosyneReqs} | cut -d" " -f1)
if [ -x "$venv/bin/python" ] && [ -f "$stampFile" ] \
if [ -x "$venv/bin/mnemosyne-hermes" ] && [ -f "$stampFile" ] \
&& [ "$(cat "$stampFile")" = "$reqHash" ] \
&& [ -e "$pluginDir" ] \
&& [ -x "$venv/bin/mnemosyne-hermes" ]; then
&& [ -e "$pluginDir" ]; then
exit 0
fi
mkdir -p ${hermesHome}/plugins ${hermesHome}/mnemosyne
uv venv "$venv" --python ${pkgs.python313}/bin/python3 --quiet
UV_VENV="$venv" uv pip install \
mkdir -p "$pluginsDir"
# Recreate from scratch so she cannot place anything into it that
# provisioning would then execute or trust (root/luna trust boundary:
# root only ever IMPORTS from a venv IT just built).
rm -rf "$venv"
uv venv "$venv" --python ${pkgs.python313}/bin/python3 --quiet --clear
uv pip install \
--python "$venv/bin/python" \
--requirement ${mnemosyneReqs} --quiet
# The plugin wrapper lands as hermes_memory_provider inside site-packages;
# uv installs the exact entry point scripts shown below. Symlink the
# discovered package dir (never a fixed guess find it by marker).
siteDir=$("$venv/bin/python" -c 'import site; print(site.getsitepackages()[0])')
target="$siteDir/hermes_memory_provider"
[ -d "$target" ] || { echo "mnemosyne plugin package not found in venv" >&2; exit 1; }
# Console script EXISTENCE is the success marker verified before the
# stamp, so a half-install cannot be trusted on the next run.
[ -x "$venv/bin/mnemosyne-hermes" ] || {
echo "mnemosyne-hermes console script missing after install" >&2; exit 1;
}
install -d -m 0755 -o ${hermesUid} -g ${hermesGid} \
"$(dirname "$pluginDir")"
# The plugin package dir name hermes_memory_provider is fixed by the
# upstream wheel; catching a rename here costs one ls per provision
# and is cheaper than importing from a mid-name drift.
siteDir="$venv/lib/python3.13/site-packages"
target="hermes_memory_provider"
[ -d "$siteDir/$target" ] || {
echo "mnemosyne plugin package not found in venv" >&2; exit 1;
}
# RELATIVE symlink: unambiguous across the bind mount (host prefix
# /var/lib/hermes vs container prefix /opt/data point at the same
# tree; build the traversal from plugins/mnemosyne, not from any
# absolute path baked in either direction).
rm -f "$pluginDir"
ln -s "$target" "$pluginDir"
ln -sfn "../mnemosyne-venv/lib/python3.13/site-packages/$target" "$pluginDir"
chmod 0755 "$(dirname "$pluginDir")" "$pluginsDir"
chown ${hermesUid}:${hermesGid} "$(dirname "$pluginDir")"
# Config cue FIRST the venv is still root-owned here, so root is
# executing its own freshly built interpreter, not a container-uid
# tree (the chown below hands that tree over; nothing executes from
# it after that point).
cfg=${hermesHome}/config.yaml
# A pre-existing wrong `provider:` value, `memory: null` / `memory: {}`,
# a missing memory section and a missing config.yaml are all handled
# inside the helper (see its header) never a bare sed on YAML.
if [ -f "$cfg" ]; then
"$venv/bin/python" ${mnemosyneSetProvider} "$cfg"
chown ${hermesUid}:${hermesGid} "$cfg"
else
# Keep the cue out of first-run's way; just logged, not fatal.
echo "WARNING: $cfg not found; skipping provider cue (first-run will seed it)" >&2
fi
printf '%s' "$reqHash" > "$stampFile"
chown -R ${hermesUid}:${hermesGid} \
"$venv" "$(dirname "$pluginDir")" "$stampFile" \
"$venv" "$pluginsDir" "$stampFile" \
${hermesHome}/mnemosyne-uv
# Mirror the "active provider" cue into config.yaml equivalent to
# `hermes config set memory.provider mnemosyne`, but idempotent and
# non-interactive. Only touches the one key, never rewrites the file.
cfg=${hermesHome}/config.yaml
if [ -f "$cfg" ]; then
if ! grep -q '^ provider: mnemosyne' "$cfg"; then
if grep -q '^memory:' "$cfg"; then
sed -i 's/^memory:$/memory:\n provider: mnemosyne/' "$cfg"
else
printf '\nmemory:\n provider: mnemosyne\n' >> "$cfg"
fi
chown ${hermesUid}:${hermesGid} "$cfg"
fi
else
printf 'memory:\n provider: mnemosyne\n' > "$cfg"
chown ${hermesUid}:${hermesGid} "$cfg"
fi
'';
};
# Also assert mnemosyne as the active provider so the container's own
# config.yaml says the same thing statelessly — mirrored from the docs'
# `hermes config set memory.provider mnemosyne`. Done here (not a separate
# unit) so venv and config-cue stay in lockstep; never edits anything else
# in the file. Runs at the tail of the provisioning oneshot, after a
# successful venv, so a half-provision never flips the provider on.
# (system.activationScripts is NOT used — the file must exist first, and
# activation would run before hermesHome's own cont-init has created it.)
}
+45
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@@ -0,0 +1,45 @@
# Set memory.provider = mnemosyne in Hermes's config.yaml, preserving every
# other key, comment-free but value-faithful. Written as a separate file so
# the provisioning unit runs it from the nix store (never inline) and ALWAYS
# before the venv is chowned to the container uid — root must not execute an
# interpreter inside a tree luna can write to.
#
# Behaviour per config.yaml state:
# existing `memory:` mapping (incl. an old `provider:` value) → merge/replace
# `memory: null` or `memory: {}` or key missing → create mapping
# top-level not a mapping → abort loudly
# file missing → SKIP: Hermes's
# first-run seeding must create it; a one-key stub would stop that.
import sys
import yaml
def set_provider(path: str) -> int:
try:
with open(path) as f:
data = yaml.safe_load(f) or {}
except FileNotFoundError:
print(
f"WARNING: {path} not found; skipping provider cue (first-run will seed it)",
file=sys.stderr,
)
return 0
if not isinstance(data, dict):
print(
f"ERROR: {path} is a {type(data).__name__}, not a mapping; not touched",
file=sys.stderr,
)
return 1
mem = data.get("memory")
if isinstance(mem, dict):
mem["provider"] = "mnemosyne"
else:
data["memory"] = {"provider": "mnemosyne"}
with open(path, "w") as f:
yaml.safe_dump(data, f, sort_keys=False)
return 0
if __name__ == "__main__":
sys.exit(set_provider(sys.argv[1]))