Fluxer PostgreSQL→Cassandra migration tool

Type-aware migration from Fluxer's PostgreSQL fluxer_kv backend to the
native Apache Cassandra schema, plus scylla-feature image builds and a
full cutover runbook.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

images/Dockerfile.messages.cassandra

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+# SPDX-License-Identifier: AGPL-3.0-or-later
+# Identical to Dockerfile but compiled with --features scylla for Apache Cassandra support.
+# The feature is named "scylla" after the Rust crate — the runtime target is Cassandra.
+
+FROM rust:1-bookworm AS builder
+
+WORKDIR /usr/src/app
+
+COPY . .
+
+RUN cargo build --release -p fluxer-messages --features scylla
+
+FROM debian:bookworm-slim
+
+ARG BUILD_VERSION=""
+
+WORKDIR /usr/local/bin
+
+RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates && \
+	rm -rf /var/lib/apt/lists/*
+
+COPY --from=builder /usr/src/app/target/release/fluxer-messages /usr/local/bin/fluxer-messages
+
+ENV BUILD_VERSION="${BUILD_VERSION}"
+
+USER 65532:65532
+
+EXPOSE 8090
+
+CMD ["/usr/local/bin/fluxer-messages"]

images/Dockerfile.users.cassandra

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+# SPDX-License-Identifier: AGPL-3.0-or-later
+# Identical to Dockerfile but compiled with --features scylla for Apache Cassandra support.
+# The feature is named "scylla" after the Rust crate — the runtime target is Cassandra.
+
+FROM rust:1-bookworm AS builder
+
+WORKDIR /usr/src/app
+
+COPY . .
+
+RUN cargo build --release -p fluxer-users --features scylla
+
+FROM debian:bookworm-slim
+
+ARG BUILD_VERSION=""
+
+WORKDIR /usr/local/bin
+
+RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates && \
+	rm -rf /var/lib/apt/lists/*
+
+COPY --from=builder /usr/src/app/target/release/fluxer-users /usr/local/bin/fluxer-users
+
+ENV BUILD_VERSION="${BUILD_VERSION}"
+
+USER 65532:65532
+
+EXPOSE 8090
+
+CMD ["/usr/local/bin/fluxer-users"]

images/build-cassandra-images.sh

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+#!/usr/bin/env bash
+# Build the two Fluxer Rust shard services WITH the `scylla` feature, which the
+# public ghcr.io images are compiled WITHOUT. Tag them to match your stack's
+# FLUXER_IMAGE_TAG so the custom images never drift out of sync on upgrades.
+#
+# Usage:
+#   ./build-cassandra-images.sh <git-tag> [path-to-fluxer-source]
+# Example:
+#   ./build-cassandra-images.sh v1 ~/fluxer-src
+set -euo pipefail
+
+TAG="${1:?usage: build-cassandra-images.sh <git-tag> [source-dir]}"
+SRC="${2:-$HOME/fluxer-src}"
+HERE="$(cd "$(dirname "$0")" && pwd)"
+
+if [[ ! -f "$SRC/Cargo.toml" ]]; then
+  echo "error: $SRC is not a Fluxer source checkout (no Cargo.toml)." >&2
+  echo "Clone it first:  git clone https://github.com/fluxerapp/fluxer.git $SRC" >&2
+  exit 1
+fi
+
+echo ">> checking out $TAG in $SRC"
+git -C "$SRC" fetch --tags --quiet
+git -C "$SRC" checkout "$TAG"
+
+# Drop the scylla-enabled Dockerfiles into the source tree (build context = repo root).
+cp "$HERE/Dockerfile.messages.cassandra" "$SRC/fluxer_messages/Dockerfile.cassandra"
+cp "$HERE/Dockerfile.users.cassandra"    "$SRC/fluxer_users/Dockerfile.cassandra"
+
+echo ">> building fluxer-messages-cassandra:$TAG"
+docker build -f "$SRC/fluxer_messages/Dockerfile.cassandra" -t "fluxer-messages-cassandra:$TAG" "$SRC"
+
+echo ">> building fluxer-users-cassandra:$TAG"
+docker build -f "$SRC/fluxer_users/Dockerfile.cassandra" -t "fluxer-users-cassandra:$TAG" "$SRC"
+
+echo ">> done. images:"
+docker images | grep -E "fluxer-(messages|users)-cassandra" | grep "$TAG"