placeholder README

README.md

@@ -0,0 +1,24 @@
+# Grafana SMS alert
+
+Send Grafana alerts via SMS to a mobile phone, using a GSM modem  that
+understands AT commads, such as the Huawei E3131 broadband USB dongle.
+Fancy SaaS alerting services are great, but what if you want to know
+that the internet is down?
+
+This runs as a service on `localhost:8201`: once you've started it,
+create a "Webhook" type contact point in your Grafana instance
+with the url `http://localhost:8201`.
+
+See Grafana [alerticing contact points](https://grafana.com/docs/grafana/latest/alerting/contact-points/) documentation for background
+
+
+## Installation (Nix)
+
+TBD
+
+## Testing
+
+You can simulate the Grafana webhook invocation check it's operational
+with the sample-alert.json in this repo:
+
+    curl -v --data @sample-alert.json http://localhost:8201

handler.fnl

@@ -1,12 +1,18 @@
 (local json (require :dkjson))
 (local unistd (require :posix.unistd))
 
-(local sms (require :sms))
+(local sms
+       ((. (require :sms) :new)
+        {
+         :smsc "+447958879879"
+         :device "/dev/serial/by-id/usb-HUAWEI_HUAWEI_HiLink-if00-port0"
+         :verbose true
+         }))
 
 (fn send-sms [body]
   (print :send-sms body)
-  (sms.send "+447000123456" body)
-  "OK")
+  (sms:send "447000123456" body)
+  "Sent")
 
 (fn handle [s]
   (let [(m pos err) (json.decode s 1 nil)]

sample-alert.json

@@ -0,0 +1 @@
+{"receiver":"","status":"firing","alerts":[{"status":"firing","labels":{"alertname":"TestAlert","instance":"Grafana"},"annotations":{"summary":"Notification test"},"startsAt":"2022-09-13T21:14:29.77765882+01:00","endsAt":"0001-01-01T00:00:00Z","generatorURL":"","fingerprint":"57c6d9296de2ad39","silenceURL":"http://garf.telent.net:3002/alerting/silence/new?alertmanager=grafana\u0026matcher=alertname%3DTestAlert\u0026matcher=instance%3DGrafana","dashboardURL":"","panelURL":"","valueString":"[ metric='foo' labels={instance=bar} value=10 ]"}],"groupLabels":{},"commonLabels":{"alertname":"TestAlert","instance":"Grafana"},"commonAnnotations":{"summary":"Notification test"},"externalURL":"http://garf.telent.net:3002/","version":"1","groupKey":"{alertname=\"TestAlert\", instance=\"Grafana\"}2022-09-13 21:14:29.77765882 +0100 BST m=+644632.184951212","truncatedAlerts":0,"orgId":1,"title":"[FIRING:1]  (TestAlert Grafana)","state":"alerting","message":"**Firing**\n\nValue: [ metric='foo' labels={instance=bar} value=10 ]\nLabels:\n - alertname = TestAlert\n - instance = Grafana\nAnnotations:\n - summary = Notification test\nSilence: http://garf.telent.net:3002/alerting/silence/new?alertmanager=grafana\u0026matcher=alertname%3DTestAlert\u0026matcher=instance%3DGrafana\n"}

sms.fnl

@@ -11,12 +11,24 @@
 
 (local gsm-char (require :unicode-to-gsm))
 
-(fn escape-for-logging [s]
-  (s:gsub "%c" (fn [x] (.. "{" (string.byte x) "}"))))
+(macro test= [expr expected]
+  `(let [a# ,expr
+         e# ,expected]
+     (if (not (= a# e#))
+         (assert false (.. "expected " ,(view expr) " = " e#
+                           ", actual " a#)))))
+
+(fn escape-readably [s]
+  (s:gsub "%c" (fn [x] (string.format "\\u{%.3x}"  (string.byte x)))))
+
+(fn log-xfer [direction message]
+  (when _G.modem-spew
+    (_G.modem-spew:write direction " " (escape-readably message) "\n"))
+  message)
 
 (fn tx [fd s]
   (write fd s)
-  (print (.. ">>> " (escape-for-logging s)))
+  (log-xfer :>>> s)
   (nanosleep {:tv_sec 0 :tv_nsec (* 10 1000 1000)}))
 
 (fn chars [i]
@@ -29,21 +41,21 @@
 (fn unicode->gsm [s]
   (s:gsub "." (fn [c] (chars (. gsm-char (string.byte c))))))
 
-;(print (escape-for-logging (unicode-to-gsm "hello")))
-;(print (escape-for-logging (unicode-to-gsm "{he@llo}€")))
+(test= (unicode->gsm "abc123") "abc123")
+(test= (unicode->gsm "abc{123}") "abc\x1b(123\x1b)")
 
 (fn expect [fd pattern fail-pattern]
   (let [b (read fd 1024)]
     (if (> (# b) 0)
-        (do
-          (print (.. "<<< " (escape-for-logging b)))
-          (if (string.find b pattern)
-              (do (print "found" pattern) true)
-              (and fail-pattern (string.find b fail-pattern))
-              (error (.. "Expected " pattern ", got " (escape-for-logging b)))
-              (expect fd pattern)))
+        (if (string.find (log-xfer :<<< b) pattern)
+            (log-xfer :!!! pattern)
+            (and fail-pattern (string.find b fail-pattern))
+            (error (.. "Expected " pattern ", got " (escape-readably b)))
+            (expect fd pattern fail-pattern))
         nil)))
 
+
+
 (fn even? [x]
   (= (% x 2) 0))
 
@@ -51,8 +63,8 @@
   (let [n (if (even? (# number)) number (.. number "F"))]
     (n:gsub ".." (fn [s] (.. (s:sub 2 2) (s:sub 1 1))))))
 
-(assert (=  (phone-number->hex "447000123456") "440700214365"))
-(assert (=  (phone-number->hex "85291234567") "5892214365F7"))
+(test= (phone-number->hex "85291234567") "5892214365F7")
+(test= (phone-number->hex "447785016005") "447758100650")
 
 (fn mask [start end]
   (let [width (+ 1 (- end start))]
@@ -123,15 +135,25 @@
 
 ;; per worked example at https://www.developershome.com/sms/cmgsCommand4.asp
 
-(assert (= (message->pdu "85291234567" "It is easy to send text messages.") "01000B915892214365F7000021493A283D0795C3F33C88FE06CDCB6E32885EC6D341EDF27C1E3E97E72E"))
+(test= (message->pdu "85291234567" "It is easy to send text messages.") "01000B915892214365F7000021493A283D0795C3F33C88FE06CDCB6E32885EC6D341EDF27C1E3E97E72E")
 
 
 (fn command [fd s]
   (tx fd (.. s "\r\n"))
   (expect fd "OK" "ERROR"))
 
-(fn send-sms [number body]
-  (let [fd (fcntl.open "/dev/serial/by-id/usb-HUAWEI_HUAWEI_HiLink-if00-port0" posix.O_RDWR)
+(fn send-message [{: fd} number body]
+  (let [pdu (message->pdu number (unicode->gsm body))
+        payload (.. "00" pdu)]
+    (doto fd
+      (tx (.. "AT+CMGS=" (string.format "%d" (/ (# pdu) 2)) "\r\n"))
+      (expect ">" "ERROR")
+      (tx payload)
+      (tx "\026\r\n")
+      (expect "OK"))))
+
+(fn new-sender [{: device : smsc : verbose}]
+  (let [fd (fcntl.open device posix.O_RDWR)
         termios (tcgetattr fd)]
     (tset termios :cflag (bor termios.cflag CLOCAL CREAD))
     (tset termios :lflag (band termios.lflag
@@ -140,26 +162,17 @@
                                (bnot ECHOE)
                                (bnot ISIG)))
     (tset termios :oflag (band termios.oflag ( bnot OPOST)))
-    (tcsetattr fd 0 termios)
+    (doto fd
+      (tcsetattr  0 termios)
+      (tcdrain)
 
-    (tcdrain fd)
+      (command "AT")
+      (command "AT&F")                  ; revert to defaults
+      (command "ATE0")                  ; disable command echo
+      (command "AT+CMEE=1")              ;print CME errors
+      (command (.. "AT+CSCA=\"" smsc "\",145\r\n")) ;set SMSC
+      (command "AT+CMGF=0"))              ;SMS  PDU mode
 
-    (let [pdu (message->pdu number (unicode->gsm body))
-          payload (.. "00" pdu)]
-      (doto fd
-        (command "AT")
-        (command "AT&F")                  ; revert to defaults
-        (command "ATE0")                  ; disable command echo
-        (command "AT+CMEE=1")              ;print CME errors
-        (command "AT+CSCA=\"+447958879879\",145\r\n") ;set SMSC
-        (command "AT+CMGF=0")              ;SMS  PDU mode
+    {:send send-message :device device :smsc smsc :fd fd}))
 
-        (tx (.. "AT+CMGS=" (string.format "%d" (/ (# pdu) 2)) "\r\n"))
-        (expect ">" "ERROR")
-        (tx payload)
-        (tx "\026\r\n")
-        (expect "OK")))))
-
-;(send-sms "447000123456" "It is never {easy} to [send] text messages.")
-
-{  :send send-sms }
+{ :new new-sender :verbose false }