pservice: initial version

The can be convenient for running commands or services as procd services
without needing to separately write initscripts, just uci configuration.

The package was imported from [1].

 [1] 0a85f5c75f/pservice

Ref: https://github.com/yousong/waller/issues/1
Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

utils/pservice/Makefile

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+# Copyright (C) 2017 Yousong Zhou
+
+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=pservice
+PKG_VERSION:=2017-08-29
+PKG_RELEASE=1
+
+PKG_MAINTAINER:=Yousong Zhou <yszhou4tech@gmail.com>
+
+include $(INCLUDE_DIR)/package.mk
+
+define Package/pservice
+  SECTION:=utils
+  CATEGORY:=Utilities
+  TITLE:=Wrap commands as procd services
+endef
+
+define Build/Compile
+endef
+
+define Package/pservice/install
+	$(INSTALL_DIR) $(1)/usr/bin $(1)/etc/init.d $(1)/etc/config
+	$(INSTALL_BIN) ./files/pservice.init $(1)/etc/init.d/pservice
+	$(INSTALL_DATA) ./files/pservice.config $(1)/etc/config/pservice
+endef
+
+$(eval $(call BuildPackage,pservice))

utils/pservice/README.md

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+# uci
+
+`disabled`, bool, default `0`
+
+`name`, string, name of the service instance
+
+`command`, file, the service instance executable
+
+`args`, list of args
+
+`stderr`, bool, default `0`, log stderr output of the service instance
+
+`stdout`, bool, default `0`, log stdout output of the service instance
+
+`env`, list of environment variable settings of the form `var=val`
+
+`file`, list of file names.  Service instances will be restarted if content of
+these files have changed on service reload event.
+
+`respawn_threshold`, uinteger, default `3600`, time in seconds the instances
+have to be in running state to be considered a valid run
+
+`respawn_timeout`, uinteger, default `5`, time in seconds the instance should
+be delayed to start again after the last crash
+
+`respawn_maxfail`, uinteger, default `5`, maximum times the instances can
+crash/fail in a row and procd will not try to bring it up again after this
+limit has been reached
+
+# notes and faq
+
+Initial environment variables presented to service instances may be different
+from what was observed on the interactive terminal.  E.g. `HOME=/` may affect
+reading `~/.ssh/known_hosts` of dropbear ssh instance.
+
+	PATH=/usr/sbin:/usr/bin:/sbin:/bin PWD=/ HOME=/
+
+If `list args xxx` seems to be too long causing pain, consider using `/bin/sh`
+as the `command`.  It is also worth noting that uci supports multi-line option
+value.
+
+Child processes will keep running when their parent process was killed.  This
+is especially the case and should be taken into account with option `command`
+being `/bin/sh` and it is recommended to use `exec` as the last shell command.

utils/pservice/files/pservice.config

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+config pservice
+	option disabled 1
+	option name 'demo0'
+	option command /bin/sh
+	option respawn_maxfail 0
+	list args -c
+	list args 'env | logger -t $name; exec sleep $time'
+	list env 'v0=0'
+	list env 'v1=val with space'
+	list env 'name=demo0'
+	list env 'time=1799'
+	list file /tmp/sleep.conf
+
+config pservice
+	option disabled 1
+	option name 8021x
+	option command /usr/sbin/wpa_supplicant
+	option stdout 1
+	list args -i
+	list args eth0.1
+	list args -D
+	list args wired
+	list args -c
+	list args /etc/wpa_supplicant-eth0.1.conf

utils/pservice/files/pservice.init

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+#!/bin/sh /etc/rc.common
+# Copyright (C) 2017 Yousong Zhou
+
+START=99
+
+USE_PROCD=1
+
+pservice_list_cb() {
+	local val="$1"; shift
+	local param="$1"; shift
+
+	procd_append_param "$param" "$val"
+}
+
+pservice() {
+	local cfg="$1"
+
+	eval "$(validate_pservice_section "$cfg" pservice_validate_mklocal)"
+	validate_pservice_section "$cfg" || return 1
+	[ "$disabled" = 0 ] || return 0
+	[ -x "$command" ] || return 1
+
+	procd_open_instance "$name"
+	procd_set_param command "$command"
+	procd_set_param stderr "$stderr"
+	procd_set_param stdout "$stdout"
+	procd_set_param respawn "$respawn_threshold" "$respawn_timeout" "$respawn_maxfail"
+	[ -z "$args" ] || config_list_foreach "$cfg" args pservice_list_cb command
+	if [ -n "$env" ]; then
+		procd_set_param env
+		config_list_foreach "$cfg" env pservice_list_cb env
+	fi
+	if [ -n "$file" ]; then
+		procd_set_param file
+		config_list_foreach "$cfg" file pservice_list_cb file
+	fi
+	procd_close_instance
+}
+
+start_service() {
+	config_load 'pservice'
+	config_foreach pservice pservice
+}
+
+stop_service() {
+	true
+}
+
+service_triggers() {
+	procd_open_validate
+	validate_pservice_section
+	procd_close_validate
+}
+
+pservice_validate_mklocal() {
+	local tuple opts
+
+	shift 2
+	for tuple in "$@"; do
+		opts="${tuple%%:*} $opts"
+	done
+	[ -z "$opts" ] || echo "local $opts"
+}
+
+pservice_validate() {
+	uci_validate_section pservice "$@"
+}
+
+validate_pservice_section() {
+	local cfg="$1"; shift
+	local func="$1"; shift
+
+	"${func:-pservice_validate}" pservice "$cfg" \
+		"disabled:bool:0" \
+		"name:string" \
+		"env:regex('^[a-zA-Z_][a-zA-Z0-9_]*=.*$')" \
+		"command:file" \
+		"args:list(string)" \
+		"stderr:bool:0" \
+		"stdout:bool:0" \
+		"respawn_threshold:uinteger:3600" \
+		"respawn_timeout:uinteger:5" \
+		"respawn_maxfail:uinteger:5" \
+		"file:string"
+}