Tools: unitc Docker mode.

Introduces a new remote host scheme docker:// that specifies a local
container ID. By default, the control socket is assumed to be in the default
location, as per the Docker Official Images for Unit. If not, the path to
the control socket can be appended to the container ID.

2 files changed, 43 insertions, 21 deletions

diff --git a/tools/README.md b/tools/README.md
index 0bb80985..883bc107 100644
--- a/tools/README.md
+++ b/tools/README.md
@@ -55,10 +55,9 @@ The error log is monitored; when changes occur, new log entries are shown.
 |---------|-|
 | `-l` \| `--nolog` | Do not monitor the error log after configuration changes.
 
-#### Examples
+#### Local Examples
 ```shell
 unitc /config
-unitc /control/applications/my_app/restart
 unitc /config < unitconf.json
 echo '{"*:8080": {"pass": "routes"}}' | unitc /config/listeners
 unitc /config/applications/my_app DELETE
@@ -68,10 +67,12 @@ unitc /certificates/bundle cert.pem key.pem
 ### Remote Configuration
 For remote instances of NGINX Unit, the control socket on the remote host can
 be set with the `$UNIT_CTRL` environment variable. The remote control socket
-can be accessed over TCP or SSH, depending on the type of control socket:
+can be accessed over TCP, SSH, or Docker containers on the host, depending on
+the type of control socket:
 
  * `ssh://[user@]remote_host[:ssh_port]/path/to/control.socket`
  * `http://remote_host:unit_control_port`
+ * `docker://container_ID[/path/to/control.socket]`
 
 > **Note:** SSH is recommended for remote confguration. Consider the
 > [security implications](https://unit.nginx.org/howto/security/#secure-socket-and-state)
@@ -81,8 +82,9 @@ can be accessed over TCP or SSH, depending on the type of control socket:
 |---------|-|
 | `ssh://…` | Specify the remote Unix control socket on the command line.
 | `http://…`*URI* | For remote TCP control sockets, the URI may include the protocol, hostname, and port.
+| `docker://…` | Specify the local container ID/name. The default Unix control socket can be overridden.
 
-#### Examples
+#### Remote Examples
 ```shell
 unitc http://192.168.0.1:8080/status
 UNIT_CTRL=http://192.168.0.1:8080 unitc /status
@@ -93,4 +95,12 @@ cat catchall_route.json | unitc POST /config/routes
 echo '{"match":{"uri":"/wp-admin/*"},"action":{"return":403}}' | unitc INSERT /config/routes
 ```
 
+#### Docker Examples
+```shell
+unitc docker://d43251184c54 /config
+echo '{"http": {"log_route": true}}' | unitc docker://d43251184c54 /settings
+unitc docker://f4f3d9e918e6/root/unit.sock /control/applications/my_app/restart
+UNIT_CTRL=docker://4d0431488982 unitc /status/requests/total
+```
+
 ---
diff --git a/tools/unitc b/tools/unitc
index e0e725ec..e671f384 100755
--- a/tools/unitc
+++ b/tools/unitc
@@ -12,7 +12,7 @@ NOLOG=0
 QUIET=0
 CONVERT=0
 URI=""
-SSH_CMD=""
+RPC_CMD=""
 METHOD=PUT
 CONF_FILES=()
 
@@ -82,6 +82,9 @@ while [ $# -gt 0 ]; do
 			elif [ "${1:0:6}" = "ssh://" ]; then
 				UNIT_CTRL=$1
 				shift
+			elif [ "${1:0:9}" = "docker://" ]; then
+				UNIT_CTRL=$1
+				shift
 			else
 				echo "${0##*/}: ERROR: Invalid option ($1)"
 				exit 1
@@ -115,9 +118,10 @@ Local options
 Remote options
   ssh://[user@]remote_host[:port]/path/to/control.socket  # Remote Unix socket
   http://remote_host:port/URI                             # Remote TCP socket
+  docker://container_ID[/non-default/control.socket]      # Container on host
 
- A remote Unit control socket may also be defined with the \$UNIT_CTRL
- environment variable as http://remote_host:port  -OR-  ssh://… (as above)
+ A remote Unit instance may also be defined with the \$UNIT_CTRL environment
+ variable as http://remote_host:port  or  ssh://…  or  docker://…  (as above).
 
 __EOF__
 	exit 1
@@ -133,8 +137,16 @@ if [ "$UNIT_CTRL" = "" ]; then
 	fi
 elif [ "${UNIT_CTRL:0:6}" = "ssh://" ]; then
 	REMOTE=1
-	SSH_CMD="ssh $(echo $UNIT_CTRL | cut -f1-3 -d/)"
+	RPC_CMD="ssh $(echo $UNIT_CTRL | cut -f1-3 -d/)"
 	UNIT_CTRL="--unix-socket /$(echo $UNIT_CTRL | cut -f4- -d/) _"
+elif [ "${UNIT_CTRL:0:9}" = "docker://" ]; then
+	RPC_CMD="docker exec -i $(echo $UNIT_CTRL | cut -f3 -d/)"
+	DOCKSOCK=/$(echo "$UNIT_CTRL" | cut -f4- -d/)
+	if [ "$DOCKSOCK" = "/" ]; then
+		DOCKSOCK="/var/run/control.unit.sock" # Use default location if no path
+	fi
+	UNIT_CTRL="--unix-socket $DOCKSOCK _"
+	REMOTE=1
 elif [ "${URI:0:1}" = "/" ]; then
 	REMOTE=1
 fi
@@ -241,11 +253,11 @@ fi
 #
 if [ -t 0 ] && [ ${#CONF_FILES[@]} -eq 0 ]; then
 	if [ "$METHOD" = "DELETE" ]; then
-		$SSH_CMD curl -X $METHOD $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+		$RPC_CMD curl -X $METHOD $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 	elif [ "$METHOD" = "EDIT" ]; then
 		EDITOR=$(test "$EDITOR" && printf '%s' "$EDITOR" || command -v editor || command -v vim || echo vi)
 		EDIT_FILENAME=/tmp/${0##*/}.$$${URI//\//_}
-		$SSH_CMD curl -fsS $UNIT_CTRL$URI > $EDIT_FILENAME || exit 2
+		$RPC_CMD curl -fsS $UNIT_CTRL$URI > $EDIT_FILENAME || exit 2
 		if [ "${URI:0:12}" = "/js_modules/" ]; then
 			if ! hash jq 2> /dev/null; then
 				echo "${0##*/}: ERROR: jq(1) is required to edit JavaScript modules; install at <https://stedolan.github.io/jq/>"
@@ -255,23 +267,23 @@ if [ -t 0 ] && [ ${#CONF_FILES[@]} -eq 0 ]; then
 			EDIT_FILE=$EDIT_FILENAME.js
 			$EDITOR $EDIT_FILENAME.js || exit 2
 			# Remove the references, delete old config, push new config+reference
-			$SSH_CMD curl -fsS $UNIT_CTRL/config/settings/js_module > /tmp/${0##*/}.$$_js_module && \
-			$SSH_CMD curl -X DELETE $UNIT_CTRL/config/settings/js_module && \
-			$SSH_CMD curl -fsSX DELETE $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
-			printf "%s" "$(< $EDIT_FILENAME.js)" | $SSH_CMD curl -fX PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
-			$SSH_CMD curl -X PUT --data-binary @/tmp/${0##*/}.$$_js_module $UNIT_CTRL/config/settings/js_module 2> /tmp/${0##*/}.$$
+			$RPC_CMD curl -fsS $UNIT_CTRL/config/settings/js_module > /tmp/${0##*/}.$$_js_module && \
+			$RPC_CMD curl -X DELETE $UNIT_CTRL/config/settings/js_module && \
+			$RPC_CMD curl -fsSX DELETE $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
+			printf "%s" "$(< $EDIT_FILENAME.js)" | $RPC_CMD curl -fX PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ && \
+			$RPC_CMD curl -X PUT --data-binary @/tmp/${0##*/}.$$_js_module $UNIT_CTRL/config/settings/js_module 2> /tmp/${0##*/}.$$
 		elif [ $CONVERT -eq 1 ]; then
 			$CONVERT_FROM_JSON < $EDIT_FILENAME > $EDIT_FILENAME.yaml
 			$EDITOR $EDIT_FILENAME.yaml || exit 2
-			$CONVERT_TO_JSON < $EDIT_FILENAME.yaml | $SSH_CMD curl -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+			$CONVERT_TO_JSON < $EDIT_FILENAME.yaml | $RPC_CMD curl -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 		else
 			tr -d '\r' < $EDIT_FILENAME > $EDIT_FILENAME.json # Remove carriage-return from newlines
 			$EDITOR $EDIT_FILENAME.json || exit 2
-			$SSH_CMD curl -X PUT --data-binary @$EDIT_FILENAME.json $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+			$RPC_CMD curl -X PUT --data-binary @$EDIT_FILENAME.json $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 		fi
 	else
 		SHOW_LOG=$(echo $URI | grep -c ^/control/)
-		$SSH_CMD curl $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+		$RPC_CMD curl $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 	fi
 else
 	if [ "$METHOD" = "INSERT" ]; then
@@ -281,9 +293,9 @@ else
 		fi
 		NEW_ELEMENT=$(cat ${CONF_FILES[@]})
 		echo $NEW_ELEMENT | jq > /dev/null || exit $? # Test the input is valid JSON before proceeding
-		OLD_ARRAY=$($SSH_CMD curl -s $UNIT_CTRL$URI)
+		OLD_ARRAY=$($RPC_CMD curl -s $UNIT_CTRL$URI)
 		if [ "$(echo $OLD_ARRAY | jq -r type)" = "array" ]; then
-			echo $OLD_ARRAY | jq ". |= [$NEW_ELEMENT] + ." | $SSH_CMD curl -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+			echo $OLD_ARRAY | jq ". |= [$NEW_ELEMENT] + ." | $RPC_CMD curl -X PUT --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 		else
 			echo "${0##*/}: ERROR: the INSERT method expects an array"
 			exit 3
@@ -293,7 +305,7 @@ else
 			cat ${CONF_FILES[@]} | $CONVERT_TO_JSON > /tmp/${0##*/}.$$_json
 			CONF_FILES=(/tmp/${0##*/}.$$_json)
 		fi
-		cat ${CONF_FILES[@]} | $SSH_CMD curl -X $METHOD --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
+		cat ${CONF_FILES[@]} | $RPC_CMD curl -X $METHOD --data-binary @- $UNIT_CTRL$URI 2> /tmp/${0##*/}.$$ | $OUTPUT
 	fi
 fi