Extension: ccache-remote

Enables ccache with remote Redis storage for sharing compilation cache across build hosts

Author: iav

extensions/ccache-remote.sh

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+# Extension: ccache-remote
+# Enables ccache with remote Redis storage for sharing compilation cache across build hosts
+#
+# Documentation: https://ccache.dev/howto/redis-storage.html
+# See also: https://ccache.dev/manual/4.10.html#config_remote_storage
+#
+# Usage:
+#   # With Avahi/mDNS auto-discovery:
+#   ./compile.sh ENABLE_EXTENSIONS=ccache-remote BOARD=...
+#
+#   # With explicit Redis server (no Avahi needed):
+#   ./compile.sh ENABLE_EXTENSIONS=ccache-remote CCACHE_REMOTE_STORAGE="redis://192.168.1.65:6379" BOARD=...
+#
+# Automatically sets USE_CCACHE=yes
+#
+# CCACHE_REMOTE_STORAGE format (ccache 4.4+):
+#   redis://HOST[:PORT][|attribute=value...]
+#   Common attributes:
+#     connect-timeout=N   - connection timeout in milliseconds (default: 100)
+#     operation-timeout=N - operation timeout in milliseconds (default: 10000)
+#   Example: "redis://192.168.1.65:6379|connect-timeout=500"
+#
+# Avahi/mDNS auto-discovery:
+#   This extension tries to resolve 'ccache.local' hostname via mDNS.
+#   To publish this hostname on Redis server, run:
+#     avahi-publish-address -R ccache.local <SERVER_IP>
+#   Or create a systemd service (see below).
+#
+#   Server setup example:
+#     1. Install: apt install redis-server avahi-daemon avahi-utils
+#     2. Configure Redis (/etc/redis/redis.conf):
+#          bind 0.0.0.0 ::
+#          protected-mode no
+#          maxmemory 4G
+#          maxmemory-policy allkeys-lru
+#        WARNING: This configuration is INSECURE - Redis is open without authentication.
+#        Use ONLY in a fully trusted private network with no internet access.
+#        For secure setup (password, TLS, ACL), see: https://redis.io/docs/management/security/
+#     3. Publish hostname (replace IP_ADDRESS with actual IP):
+#          avahi-publish-address -R ccache.local IP_ADDRESS
+#        Or as systemd service /etc/systemd/system/ccache-hostname.service:
+#          [Unit]
+#          Description=Publish ccache.local hostname via Avahi
+#          After=avahi-daemon.service redis-server.service
+#          BindsTo=redis-server.service
+#          [Service]
+#          Type=simple
+#          ExecStart=/usr/bin/avahi-publish-address -R ccache.local IP_ADDRESS
+#          Restart=on-failure
+#          [Install]
+#          WantedBy=redis-server.service
+#
+#   Client requirements for mDNS:
+#     - systemd-resolved (modern systems), or
+#     - libnss-mdns package with /etc/nsswitch.conf containing "mdns" in hosts line
+#
+# Fallback behavior:
+#   If CCACHE_REMOTE_STORAGE is not set and ccache.local is not resolvable,
+#   extension silently falls back to local ccache only.
+
+# Query Redis stats (keys count and memory usage)
+function get_redis_stats() {
+	local ip="$1"
+	local port="${2:-6379}"
+	local stats=""
+
+	if command -v redis-cli &>/dev/null; then
+		local keys mem
+		keys=$(timeout 2 redis-cli -h "$ip" -p "$port" DBSIZE 2>/dev/null | grep -oE '[0-9]+')
+		mem=$(timeout 2 redis-cli -h "$ip" -p "$port" INFO memory 2>/dev/null | grep "used_memory_human" | cut -d: -f2 | tr -d '[:space:]')
+		if [[ -n "$keys" ]]; then
+			stats="keys=${keys:-0}, mem=${mem:-?}"
+		fi
+	else
+		# Fallback: try netcat for basic connectivity check
+		if nc -z -w 2 "$ip" "$port" 2>/dev/null; then
+			stats="reachable (redis-cli not installed for detailed stats)"
+		fi
+	fi
+	echo "$stats"
+}
+
+# This runs on the HOST before Docker is launched.
+# Resolves 'ccache.local' via mDNS (requires Avahi on server publishing this hostname
+# with: avahi-publish-address -R ccache.local <IP>) and passes the resolved IP
+# to Docker container via CCACHE_REMOTE_STORAGE environment variable.
+# mDNS resolution doesn't work inside Docker, so we must resolve on host.
+function add_host_dependencies__setup_remote_ccache_for_docker() {
+	# Skip if already configured explicitly
+	if [[ -n "${CCACHE_REMOTE_STORAGE}" ]]; then
+		display_alert "Remote ccache pre-configured" "${CCACHE_REMOTE_STORAGE}" "info"
+		declare -g -a DOCKER_EXTRA_ARGS+=("--env" "CCACHE_REMOTE_STORAGE=${CCACHE_REMOTE_STORAGE}")
+		return 0
+	fi
+
+	# Try to resolve ccache.local via mDNS on the host
+	local ccache_ip
+	ccache_ip=$(getent hosts ccache.local 2>/dev/null | awk '{print $1; exit}')
+
+	if [[ -n "${ccache_ip}" ]]; then
+		display_alert "Remote ccache discovered on host" "redis://${ccache_ip}:6379" "info"
+
+		# Show Redis stats
+		local stats
+		stats=$(get_redis_stats "${ccache_ip}" 6379)
+		if [[ -n "$stats" ]]; then
+			display_alert "Remote ccache stats" "${stats}" "info"
+		fi
+
+		# Pass to Docker via DOCKER_EXTRA_ARGS
+		declare -g -a DOCKER_EXTRA_ARGS+=("--env" "CCACHE_REMOTE_STORAGE=redis://${ccache_ip}:6379|connect-timeout=500")
+	else
+		display_alert "Remote ccache not found on host" "ccache.local not resolvable via mDNS" "debug"
+	fi
+}
+
+# This runs inside Docker (or native build) during configuration
+function extension_prepare_config__setup_remote_ccache() {
+	# Enable ccache automatically
+	declare -g USE_CCACHE=yes
+
+	# If CCACHE_REMOTE_STORAGE was passed from host (via Docker env), it's already set
+	if [[ -n "${CCACHE_REMOTE_STORAGE}" ]]; then
+		display_alert "Remote ccache configured" "${CCACHE_REMOTE_STORAGE}" "info"
+		return 0
+	fi
+
+	# For native (non-Docker) builds, try to resolve here
+	local ccache_ip
+	ccache_ip=$(getent hosts ccache.local 2>/dev/null | awk '{print $1; exit}')
+
+	if [[ -n "${ccache_ip}" ]]; then
+		export CCACHE_REMOTE_STORAGE="redis://${ccache_ip}:6379|connect-timeout=500"
+		display_alert "Remote ccache discovered" "${CCACHE_REMOTE_STORAGE}" "info"
+	else
+		display_alert "Remote ccache not available" "using local cache only" "debug"
+	fi
+
+	return 0
+}
+
+# This hook runs right before kernel make - add CCACHE_REMOTE_STORAGE to make environment.
+# Required because kernel build uses 'env -i' which clears all environment variables.
+function kernel_make_config__add_ccache_remote_storage() {
+	if [[ -n "${CCACHE_REMOTE_STORAGE}" ]]; then
+		common_make_envs+=("CCACHE_REMOTE_STORAGE='${CCACHE_REMOTE_STORAGE}'")
+		display_alert "Kernel make: added remote ccache" "${CCACHE_REMOTE_STORAGE}" "debug"
+	fi
+}