snap: hooks: add initial hook implementation

Signed-off-by: Ondrej Kubik <ondrej.kubik@canonical.com>

snap/hooks/configure

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+hook_name=$(basename "${0}")
+logger "avahi.hook.${hook_name}: entering the hook" || true
+
+config_file="avahi-daemon.conf"
+# work on temp file, before commiting changes back, to reduce number of writes
+cp "${SNAP_COMMON}/etc/avahi/${config_file}" "/tmp/"
+
+process_line() {
+  # each line starts with key name and ends with the value
+  local key="${1}"
+  local value="${2}"
+  sed -i 's/.*'"${key}"'.*/'"${key}"'='"${value}"'/g' /tmp/${config_file}
+}
+
+# read key value pairs from snap config line by line
+while read -r line
+do
+  process_line ${line}
+done < <( snapctl get -d avahi-daemon-conf | jq -r '.[] | to_entries[] | "\(.key) \(.value)"')
+
+# we are done, write back config file, only if it has changed
+if ! cmp "/tmp/${config_file}" "${SNAP_COMMON}/etc/avahi/${config_file}"; then
+  logger "avahi.${hook_name}: ${config_file} changed, updating it...."  || true
+  mv "/tmp/${config_file}" "${SNAP_COMMON}/etc/avahi/"
+  snapctl restart "${SNAP_INSTANCE_NAME}.daemon"
+fi
+
+# no need to restart avahi-daemon, it tracks the changes in the config file
+
+logger "avahi.hook.${hook_name}: hook finished successfully" || true

snap/hooks/install

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+hook_name=$(basename "${0}")
+logger "avahi.hook.${hook_name}: entering the hook" || true
+
+mkdir -p "${SNAP_COMMON}/etc" "${SNAP_COMMON}/usr/share"
+
+[ ! -d "${SNAP_COMMON}/etc/avahi/services" ] && cp -r "${SNAP}/etc/avahi/*" "${SNAP_COMMON}/etc/avahi"
+[ ! -d "${SNAP_COMMON}/usr/share/dbus-1" ] && cp -r "${SNAP}/usr/share/dbus-1" "${SNAP_COMMON}/usr/share"
+[ ! -e "${SNAP_COMMON}/usr/share/avahi/avahi-service.dtd" ] && cp -r "${SNAP}/usr/share/avahi/*" "${SNAP_COMMON}/usr/share/avahi"
+
+logger "avahi.hook.${hook_name}: hook finished successfully" || true

snap/hooks/post-refresh

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+hook_name=$(basename "${0}")
+logger "avahi.hook.${hook_name}: entering the hook" || true
+
+mkdir -p "${SNAP_COMMON}/etc" "${SNAP_COMMON}/usr/share"
+
+[ ! -d "${SNAP_COMMON}/etc/avahi/services" ] && cp -r "${SNAP}/etc/avahi/*" "${SNAP_COMMON}/etc/avahi"
+[ ! -d "${SNAP_COMMON}/usr/share/dbus-1" ] && cp -r "${SNAP}/usr/share/dbus-1" "${SNAP_COMMON}/usr/share"
+[ ! -e "${SNAP_COMMON}/usr/share/avahi/avahi-service.dtd" ] && cp -r "${SNAP}/usr/share/avahi/*" "${SNAP_COMMON}/usr/share/avahi"
+
+logger "avahi.hook.${hook_name}: hook finished successfully" || true