Phase 1: CKPool build infrastructure

Forks CKPool-solo at upstream commit cfb0f83b (v1.0) via a multi-stage
Docker build, with an env-driven entrypoint that renders ckpool.conf from
a template. The pinned commit already includes every fix referenced in
Bassin issue #29 (workbase_id double increment, extended low-power
timeouts, configurable dropidle, vardiff burst handling).

No patches are applied yet — the patches/ directory holds the workflow
and build wiring so Kamado-specific patches can be added incrementally.

Build is portable across aarch64/x86_64: yasm is intentionally omitted
so CKPool falls back to its C SHA256, and CFLAGS override drops upstream's
default -march=native. Runtime image ships ckpool and ckpmsg for socket
debugging; share logging (-L) is enabled by default.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ckpool/entrypoint.sh

@@ -0,0 +1,96 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# ckpool-solo entrypoint for Kamado Pool
+#
+# Reads configuration from environment variables, renders the ckpool.conf
+# from the template, and execs ckpool-solo.
+#
+# Required env:
+#   POOL_BTCADDRESS       - Bitcoin address that receives block rewards
+#   BITCOIN_RPC_HOST      - e.g. bitcoind, 127.0.0.1
+#   BITCOIN_RPC_PORT      - e.g. 8332 (mainnet) / 48332 (testnet4)
+#   BITCOIN_RPC_USER      - RPC username
+#   BITCOIN_RPC_PASSWORD  - RPC password
+#
+# Optional env (with defaults):
+#   STRATUM_PORT=3333
+#   POOL_BTCSIG="/Kamado Pool/"
+#   BLOCKPOLL_MS=100
+#   UPDATE_INTERVAL_S=30
+#   MINDIFF=1
+#   STARTDIFF=42
+#   MAXDIFF=0              (0 = unlimited)
+#   DROPIDLE=0             (seconds; 0 = never drop idle clients)
+#   BITCOIN_NOTIFY=true    (use bitcoind blocknotify/walletnotify)
+#   ZMQ_BLOCK=""           (e.g. tcp://bitcoind:28332)
+#   LOGDIR=/var/log/ckpool
+#   SOCKET_DIR=/run/ckpool
+#   SHARE_LOG=1            (1 = enable -L share logging)
+# ----------------------------------------------------------------------------
+set -eu
+
+: "${POOL_BTCADDRESS:?POOL_BTCADDRESS is required}"
+: "${BITCOIN_RPC_HOST:?BITCOIN_RPC_HOST is required}"
+: "${BITCOIN_RPC_PORT:?BITCOIN_RPC_PORT is required}"
+: "${BITCOIN_RPC_USER:?BITCOIN_RPC_USER is required}"
+: "${BITCOIN_RPC_PASSWORD:?BITCOIN_RPC_PASSWORD is required}"
+
+STRATUM_PORT="${STRATUM_PORT:-3333}"
+POOL_BTCSIG="${POOL_BTCSIG:-/Kamado Pool/}"
+BLOCKPOLL_MS="${BLOCKPOLL_MS:-100}"
+UPDATE_INTERVAL_S="${UPDATE_INTERVAL_S:-30}"
+MINDIFF="${MINDIFF:-1}"
+STARTDIFF="${STARTDIFF:-42}"
+MAXDIFF="${MAXDIFF:-0}"
+DROPIDLE="${DROPIDLE:-0}"
+BITCOIN_NOTIFY="${BITCOIN_NOTIFY:-true}"
+ZMQ_BLOCK="${ZMQ_BLOCK:-}"
+LOGDIR="${LOGDIR:-/var/log/ckpool}"
+SOCKET_DIR="${SOCKET_DIR:-/run/ckpool}"
+SHARE_LOG="${SHARE_LOG:-1}"
+
+mkdir -p "$LOGDIR" "$SOCKET_DIR"
+
+TEMPLATE=/etc/ckpool/ckpool.conf.template
+CONF=/etc/ckpool/ckpool.conf
+
+# Simple placeholder substitution (no envsubst dependency).
+# We intentionally don't use eval/printf tricks — sed is safe and predictable.
+sed \
+    -e "s|\${BITCOIN_RPC_HOST}|${BITCOIN_RPC_HOST}|g" \
+    -e "s|\${BITCOIN_RPC_PORT}|${BITCOIN_RPC_PORT}|g" \
+    -e "s|\${BITCOIN_RPC_USER}|${BITCOIN_RPC_USER}|g" \
+    -e "s|\${BITCOIN_RPC_PASSWORD}|${BITCOIN_RPC_PASSWORD}|g" \
+    -e "s|\${BITCOIN_NOTIFY}|${BITCOIN_NOTIFY}|g" \
+    -e "s|\${POOL_BTCADDRESS}|${POOL_BTCADDRESS}|g" \
+    -e "s|\${POOL_BTCSIG}|${POOL_BTCSIG}|g" \
+    -e "s|\${BLOCKPOLL_MS}|${BLOCKPOLL_MS}|g" \
+    -e "s|\${UPDATE_INTERVAL_S}|${UPDATE_INTERVAL_S}|g" \
+    -e "s|\${STRATUM_PORT}|${STRATUM_PORT}|g" \
+    -e "s|\${MINDIFF}|${MINDIFF}|g" \
+    -e "s|\${STARTDIFF}|${STARTDIFF}|g" \
+    -e "s|\${MAXDIFF}|${MAXDIFF}|g" \
+    -e "s|\${DROPIDLE}|${DROPIDLE}|g" \
+    -e "s|\${LOGDIR}|${LOGDIR}|g" \
+    -e "s|\${ZMQ_BLOCK}|${ZMQ_BLOCK}|g" \
+    "$TEMPLATE" > "$CONF"
+
+# If ZMQ is not configured, strip the zmqblock line entirely.
+# The template keeps zmqblock as a non-final key with a trailing comma,
+# so removing the whole line leaves valid JSON.
+if [ -z "$ZMQ_BLOCK" ]; then
+    sed -i '/"zmqblock":/d' "$CONF"
+fi
+
+echo "[kamado] rendered ckpool.conf:"
+sed "s|\"pass\": \".*\"|\"pass\": \"<redacted>\"|" "$CONF"
+echo
+
+# Build command line
+CMD="/usr/local/bin/ckpool --btcsolo --config $CONF --sockdir $SOCKET_DIR"
+if [ "$SHARE_LOG" = "1" ]; then
+    CMD="$CMD --log-shares"
+fi
+
+echo "[kamado] exec: $CMD"
+exec $CMD