docker: merge config from example on boot

docker-entrypoint.sh

@@ -9,6 +9,7 @@ BUNDLED_EXAMPLE_PATH="${INSTALL_DIR}/config.yaml.example"
 RUNTIME_USER="${USER:-repeater}"
 RUNTIME_UID="${PUID:-unknown}"
 RUNTIME_GID="${PGID:-unknown}"
+YQ_CMD="${YQ_CMD:-/usr/local/bin/yq}"
 
 mkdir -p "${CONFIG_DIR}"
 
@@ -22,6 +23,52 @@ copy_or_die() {
     fi
 }
 
+merge_config_from_example() {
+    config_path="$1"
+
+    if [ ! -f "${config_path}" ] || [ ! -f "${EXAMPLE_PATH}" ]; then
+        return 0
+    fi
+
+    if [ ! -x "${YQ_CMD}" ] || ! "${YQ_CMD}" --version 2>&1 | grep -q "mikefarah/yq"; then
+        echo "Skipping config merge: mikefarah yq is not available at ${YQ_CMD}." >&2
+        return 0
+    fi
+
+    tmpdir="$(mktemp -d)"
+    stripped_user="${tmpdir}/config.stripped.yaml"
+    merged_config="${tmpdir}/config.merged.yaml"
+
+    cleanup_merge() {
+        rm -rf "${tmpdir}"
+    }
+    trap cleanup_merge EXIT HUP INT TERM
+
+    # Keep only the example's comments to avoid comment duplication across upgrades.
+    "${YQ_CMD}" eval '... comments=""' "${config_path}" > "${stripped_user}" 2>/dev/null || cp "${config_path}" "${stripped_user}"
+
+    if ! "${YQ_CMD}" eval-all '. as $item ireduce ({}; . * $item)' "${EXAMPLE_PATH}" "${stripped_user}" > "${merged_config}" 2>/dev/null; then
+        echo "Failed to merge ${config_path} with ${EXAMPLE_PATH}; keeping the existing config." >&2
+        cleanup_merge
+        trap - EXIT HUP INT TERM
+        return 0
+    fi
+
+    if ! "${YQ_CMD}" eval '.' "${merged_config}" >/dev/null 2>&1; then
+        echo "Merged config for ${config_path} is invalid; keeping the existing config." >&2
+        cleanup_merge
+        trap - EXIT HUP INT TERM
+        return 0
+    fi
+
+    if ! cmp -s "${config_path}" "${merged_config}"; then
+        copy_or_die "${merged_config}" "${config_path}"
+    fi
+
+    cleanup_merge
+    trap - EXIT HUP INT TERM
+}
+
 if [ ! -f "${EXAMPLE_PATH}" ] && [ -f "${BUNDLED_EXAMPLE_PATH}" ]; then
     copy_or_die "${BUNDLED_EXAMPLE_PATH}" "${EXAMPLE_PATH}"
 fi
@@ -35,4 +82,6 @@ elif [ ! -s "${CONFIG_PATH}" ] && [ -f "${EXAMPLE_PATH}" ]; then
     copy_or_die "${EXAMPLE_PATH}" "${CONFIG_PATH}"
 fi
 
+merge_config_from_example "${CONFIG_PATH}"
+
 exec python3 -m repeater.main --config "${CONFIG_PATH}"

dockerfile

@@ -5,6 +5,8 @@ ARG USER=repeater
 ARG GROUP=repeater
 ARG PUID=15888
 ARG PGID=15888
+ARG TARGETARCH
+ARG YQ_VERSION=v4.40.5
 
 ENV INSTALL_DIR=/opt/pymc_repeater \
     CONFIG_DIR=/etc/pymc_repeater \
@@ -29,6 +31,17 @@ RUN DEBIAN_FRONTEND=noninteractive apt-get update && apt-get install -y \
     python3-dev \
     && rm -rf /var/lib/apt/lists/*
 
+RUN arch="${TARGETARCH:-}" \
+    && if [ -z "${arch}" ]; then arch="$(uname -m)"; fi \
+    && case "${arch}" in \
+        amd64|x86_64) YQ_BINARY="yq_linux_amd64" ;; \
+        arm64|aarch64) YQ_BINARY="yq_linux_arm64" ;; \
+        arm|armv7|armv7l) YQ_BINARY="yq_linux_arm" ;; \
+        *) echo "Unsupported architecture for yq: ${arch}" >&2; exit 1 ;; \
+    esac \
+    && wget -qO /usr/local/bin/yq "https://github.com/mikefarah/yq/releases/download/${YQ_VERSION}/${YQ_BINARY}" \
+    && chmod +x /usr/local/bin/yq
+
 # Create the group and user in order to run without root privileges
 RUN groupadd --gid "$PGID" "$GROUP" \
     && useradd --uid "$PUID" --gid "$PGID" --home-dir "$HOME_DIR" --create-home --shell /usr/bin/bash "$USER"