deep thoughts

if we run off the end of the events fixture, it didn't work

THOUGHTS.txt

@@ -4137,3 +4137,155 @@ p-clock-init,mfp,allows-mesh-bcast crc32 62f7565f
 [   16.762697] ath10k_pci 0000:00:00.0: pdev param 0 not supported by firmware
 [   23.030622] ath10k_pci 0000:00:00.0: pdev param 0 not supported by firmware
 [
+
+
+Tue Feb 27 23:16:27 GMT 2024
+
+We made it a full week with rotuer running internet chez nous and no
+need for an intervention, so I am happy to call it "production". There are
+still things that need fixing but they're mostly within scope for
+a services refresh
+
+I have embarked on "profiles" by creating a wap.nix
+
+I think we could have a service module for resolvconf
+
+It would be good to build a wap.nix example for the belkin and we
+could start looking at ubifs
+
+I've lost a chunk of notes about using events to drive desired service
+state. There is probably only going to be one udev listener, so
+what if we have udev as a config key thusly
+
+udev.rules = [
+{
+  match = {
+   SUBSYSTEM = "rpmsg";
+    ATTR.name = "DATA5_CNTL";
+  };
+
+  service = longrun {
+    name = "lte-modem";
+    run = "blah blah blah";
+  };
+}
+
+# this one would be provided by the bridge module instead of
+# adding bridge member services to the default target
+
+{
+  match = {
+    SUBSYSTEM="net";
+    ID_PATH="pci-0000:04:00.0";
+    ATTR.operstate = "up";
+  };
+
+  service = oneshot {
+    up = "ip link set dev $dev master $(output ${primary} ifname)";
+    down = "ip link set dev $(output ${member} ifname) nomaster";
+  }
+}
+]
+
+This works for udev/sysfs, but we want a similar architecture(sic) for
+user-generated target state so we could have services that run on e.g.
+"is the ppp0 service healthy" or not. Probably there isn't a top-level
+config key for each service though
+
+services.wan = svc.ppoe.build   { .... };
+services.lte = watcher.build {
+  watching = services.wan;
+  match =  {
+    # an expression matching the outputs of the service
+    # to be watched
+    health = "failing";
+  };
+  service = oneshot {
+    run = "start_lte_blah";
+  };
+}
+
+thing is, we could use this syntax also for sysfs watches, but not vice versa
+
+... but it's not quite the same because here we're doing static matches
+on contents of files, whereas the udev one is a query expression on the
+sysfs database. we might need that flexibiity to implement "mount the
+backup drive no matter _which_ damn sda_n_ device it appears as". I don't
+know if there's the same need for service outputs - postulate the
+existence of a collection of services which are all similar enough that
+some other service can watch them all and do $something when one of
+the changes state. Or a single service with very complicated outputs.
+For example, something could watch the snmp database and update service
+status depending on what it finds. Or something something mqtt...
+
+we find that the "match" needs to be interpreted differently according
+to the thing being watched. perhaps the service being watched needs to
+provide a "watch me" interface somehow which accepts match criteria and
+outputs a true/false. Something else then needs to
+
+
+services.addmember = services.udev.watch {
+  match = {
+    SUBSYSTEM = "net";
+    ID_PATH = "pci-0000:04:00.0";
+    ATTR.operstate = "up";
+  };
+
+  service = oneshot {
+    up = "ip link set dev $dev master $(output ${primary} ifname)";
+    down = "ip link set dev $(output ${member} ifname) nomaster";
+  };
+}
+
+Sat Mar  2 15:37:29 GMT 2024
+
+Simply put, what I think it boils down to is that we want a service
+which acts as an actuator or control switch for another service,
+and will start/stop that controlled service according to some
+criteria.
+
+services.addmember = svc.network.ifwatch.build {
+  interface = config.hardware.networkInterfaces.lan1;
+
+  # this should be part of the definition not the params
+  service = oneshot {
+    name = "member-${bridge}-${interface}";
+    up = "ip link set dev $dev master $(output ${primary} ifname)";
+    down = "ip link set dev $(output ${member} ifname) nomaster";
+  };
+}
+
+we could start by writing this. we need to adapt ifwait
+
+Sun Mar  3 17:09:21 GMT 2024
+
+this is annoyingly hard to test. the tests we'd like to write are
+
+1) when it gets events that don't match the requirement, nothing happens
+2) when it gets an event that should start the service, the
+  service starts
+3) when stop should stop
+4) when start and already started, nothing happens
+5) when stop and already stopped, nothing happens
+
+what do we do if service fails to start? s6-rc will eventually reset it
+to "down", I think: do we need to take action?
+
+Mon Mar  4 20:46:55 GMT 2024
+
+# relevant but not correct for this model: https://www.forked.net/forums/viewtopic.php?f=13&t=3490
+
+# power on port 5
+snmpset -v 1 -c private  192.168.5.14 .1.3.6.1.4.1.318.1.1.4.4.2.1.3.5 integer 1
+
+# power off port 5
+snmpset -v 1 -c private  192.168.5.14 .1.3.6.1.4.1.318.1.1.4.4.2.1.3.5 integer 2
+
+# toggle off/on port 5
+snmpset -v 1 -c private  192.168.5.14 .1.3.6.1.4.1.318.1.1.4.4.2.1.3.5 integer 3
+
+Wed Mar  6 18:24:29 GMT 2024
+
+What happens when we attempt to start the service but it fails?  We
+assume the start was successful so we won't try and restart it again
+next time we get an event that should cause it to start.

pkgs/anoia/init.fnl

@@ -1,3 +1,7 @@
+(fn assoc [tbl k v]
+  (tset tbl k v)
+  tbl)
+
 (fn merge [table1 table2]
   (collect [k v (pairs table2) &into table1]
     k v))
@@ -62,4 +66,4 @@
     (s:sub 1 (- (# s) pad))))
 
 
-{ : merge : split : file-exists? : system : hash : base64url : dup }
+{ : assoc : merge : split : file-exists? : system : hash : base64url : dup }

pkgs/anoia/nl.fnl

@@ -0,0 +1,15 @@
+(local netlink (require :netlink))
+
+(local { : view } (require :fennel))
+
+(fn events [groups]
+  (let [sock (netlink.socket)]
+    (coroutine.wrap
+     (fn []
+       (each [_ e (ipairs (sock:query groups))]
+         (coroutine.yield e))
+       (while (sock:poll)
+         (each [_ e (ipairs (sock:event))]
+           (coroutine.yield e)))))))
+
+{ : events }

pkgs/anoia/test-nl.fnl

@@ -0,0 +1,7 @@
+(local nl (require :anoia.nl))
+(local { : view } (require :fennel))
+
+(let [events (nl.events {:link true})]
+  (each [ev events]
+    (print "got one ")
+    (print (view ev))))

pkgs/fennelrepl/default.nix

@@ -8,12 +8,14 @@
 , writeScriptBin
 , linotify
 , anoia
+, netlink-lua
 , fennel
 }:
 let packages = [
       linotify
       anoia
       fennel
+      netlink-lua
       lua.pkgs.luafilesystem
     ];
     join = ps: builtins.concatStringsSep ";" ps;

pkgs/ifwait/events-fixture

@@ -0,0 +1,195 @@
+{:event "newlink"
+ :hwaddr "00:00:00:00:00:00"
+ :index 1
+ :mtu 65536
+ :name "lo"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "50:3e:aa:08:df:52"
+ :index 2
+ :mtu 1500
+ :name "enp1s0"
+ :running "no"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "1c:1b:0d:9c:39:2d"
+ :index 3
+ :mtu 1500
+ :name "enp0s31f6"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "da:4d:53:c3:54:43"
+ :index 4
+ :mtu 1500
+ :name "vbridge0"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "00:28:f8:69:fa:14"
+ :index 6
+ :mtu 1500
+ :name "wlp4s0"
+ :running "no"
+ :stamp 857161382
+ :up "no"}
+{:event "newlink"
+ :hwaddr "02:42:b1:e6:e5:bd"
+ :index 7
+ :mtu 1500
+ :name "br-7ddfef4820c5"
+ :running "no"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "02:42:8d:d4:36:34"
+ :index 8
+ :mtu 1500
+ :name "br-95da8b40a7cc"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "02:42:bc:cf:a8:5e"
+ :index 9
+ :mtu 1500
+ :name "docker0"
+ :running "no"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "b6:66:50:69:33:a6"
+ :index 11
+ :mtu 1500
+ :name "veth2ff6ec3"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "e6:94:c8:48:f3:97"
+ :index 13
+ :mtu 1500
+ :name "veth0913974"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "9a:87:d8:f2:c6:96"
+ :index 15
+ :mtu 1500
+ :name "veth0e74156"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "5e:d2:92:b9:5f:6d"
+ :index 17
+ :mtu 1500
+ :name "veth89a36b3"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "ca:88:3f:09:bc:51"
+ :index 19
+ :mtu 1500
+ :name "veth73c1e0b"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "b6:7d:5c:38:89:1d"
+ :index 21
+ :mtu 1500
+ :name "dummy0"
+ :running "no"
+ :stamp 857161382
+ :up "no"}
+{:event "newlink"
+ :hwaddr "52:f0:46:da:0c:0c"
+ :index 22
+ :mtu 1500
+ :name "dummy1"
+ :running "yes"
+ :stamp 857161382
+ :up "yes"}
+{:event "newneigh"
+ :hwaddr "00:22:61:3d:f7:54"
+ :index 4
+ :ip "192.168.8.140"
+ :probes 1
+ :stamp 857165355
+ :state "stale"}
+{:event "delneigh"
+ :hwaddr "5c:60:ba:58:34:93"
+ :index 3
+ :stamp 857166891
+ :state "stale"}
+{:event "newneigh"
+ :hwaddr "80:64:6f:9e:15:02"
+ :index 4
+ :ip "192.168.8.161"
+ :probes 1
+ :stamp 857172523
+ :state "stale"}
+{:event "newneigh"
+ :hwaddr "e4:95:6e:42:c2:6c"
+ :index 3
+ :stamp 857174763
+ :state "reachable"}
+{:event "newneigh"
+ :hwaddr "e4:b3:18:76:1b:23"
+ :index 4
+ :ip "2001:8b0:de3a:40de:4708:c700:4de2:9264"
+ :probes 1
+ :stamp 857175595
+ :state "stale"}
+{:event "newneigh"
+ :hwaddr "80:64:6f:9e:10:c6"
+ :index 4
+ :ip "192.168.8.53"
+ :probes 1
+ :stamp 857176619
+ :state "stale"}
+{:event "newneigh"
+ :hwaddr "80:64:6f:9e:15:02"
+ :index 4
+ :ip "192.168.8.161"
+ :probes 1
+ :stamp 857177643
+ :state "probe"}
+{:event "newneigh"
+ :hwaddr "80:64:6f:9e:15:02"
+ :index 4
+ :ip "192.168.8.161"
+ :probes 1
+ :stamp 857177644
+ :state "reachable"}
+{:event "newlink"
+ :hwaddr "b6:7d:5c:38:89:1d"
+ :index 21
+ :mtu 1500
+ :name "dummy0"
+ :running "yes"
+ :stamp 857178258
+ :up "yes"}
+{:event "newlink"
+ :hwaddr "b6:7d:5c:38:89:1d"
+ :index 21
+ :mtu 1500
+ :name "dummy0"
+ :running "no"
+ :stamp 857181661
+ :up "no"}
+{:event "newneigh"
+ :hwaddr "80:64:6f:9e:10:c6"
+ :index 4
+ :ip "192.168.8.53"
+ :probes 1
+ :stamp 857182251
+ :state "probe"}

pkgs/ifwait/ifwait.fnl

@@ -1,52 +1,64 @@
-(local netlink (require :netlink))
-(local sock (netlink.socket))
+(local nl (require :anoia.nl))
+(local { : assoc : system } (require :anoia))
 
 ; (local { : view} (require :fennel))
 
-(fn assoc [tbl k v]
-  (tset tbl k v)
-  tbl)
-
 (fn parse-args [args]
   (match args
     ["-v" & rest]  (assoc (parse-args rest) :verbose true)
     ["-t" timeout & rest] (assoc (parse-args rest) :timeout (tonumber timeout))
+    ["-s" service & rest] (assoc (parse-args rest) :service service)
     [linkname "up"] {:link linkname :expecting "up"}
     [linkname "running"] {:link linkname :expecting "running"}
     [linkname "present"] {:link linkname :expecting "present"}
     [linkname nil] {:link linkname :expecting "present"}
     _  nil))
 
-(local parameters
-       (or
-        (parse-args arg)
-        (assert false (.. "Usage: " (. arg 0) " [-v] ifname [present|up|running]"))))
+(fn event-matches? [params v]
+  (let [got
+        (match v
+          ;; - up: Reflects the administrative state of the interface (IFF_UP)
+          ;; - running: Reflects the operational state (IFF_RUNNING).
+          {:event "newlink" :name params.link :up :yes :running :yes}
+          {:present true :up true :running true}
 
-(fn run-events [evs]
-  (each [_ v (ipairs evs)]
-    (let [got
-          (match v
-            ;; - up: Reflects the administrative state of the interface (IFF_UP)
-            ;; - running: Reflects the operational state (IFF_RUNNING).
-            {:event "newlink" :name parameters.link :up :yes :running :yes}
-            {:present true :up true :running true}
+          {:event "newlink" :name params.link :up :yes}
+          {:present :true :up true}
 
-            {:event "newlink" :name parameters.link :up :yes}
-            {:present :true :up true}
+          {:event "newlink" :name params.link}
+          {:present true }
 
-            {:event "newlink" :name parameters.link}
-            {:present true }
+          _
+          {})]
+    (not (not (. got params.expecting)))))
 
-            _
-            {})]
-      (when (. got parameters.expecting)
-        (os.exit 0)))))
+(var up :unknown)
+(fn toggle-service [service wanted?]
+  (when (not (= up wanted?))
+    (set up
+         (if wanted?
+             (pcall system (.. "s6-rc -u change " service))
+             (not (pcall system (.. "s6-rc -d change " service)))))
+    ))
 
+(fn run [args event-fn]
+  (set up :unknown)
+  (let [parameters
+        (assert (parse-args args)
+                (.. "Usage: ifwait [-v] ifname [present|up|running]"))]
+    (when parameters.verbose
+      (print (.. "ifwait: waiting for "
+                 parameters.link " to be " parameters.expecting)))
 
-(when parameters.verbose
-  (print (.. (. arg 0) ": waiting for "
-             parameters.link " to be " parameters.expecting)))
+    (if parameters.service
+        (each [e (event-fn)]
+          (if (= e.name parameters.link)
+              (toggle-service parameters.service (event-matches? parameters e))))
+        (each [e (event-fn)
+               &until (event-matches? parameters e)]
+          true))))
 
-(run-events (sock:query {:link true}))
+(when (not (= (. arg 0) "test"))
+  (run arg #(nl.events {:link true})))
 
-(while (sock:poll) (run-events (sock:event)))
+{ : run  }

pkgs/ifwait/test-ifwait.fnl

@@ -0,0 +1,119 @@
+(local { : view &as fennel } (require :fennel))
+(local anoia (require :anoia))
+
+(var fake-system (fn [s] (print "executing " s)))
+(tset anoia :system #(fake-system $1))
+
+(macro expect= [actual expected]
+  `(let [ve# (view ,expected)
+         va# (view ,actual)]
+     (when (not (= ve# va#))
+       (assert false
+               (.. "\nexpected " ve# "\ngot " va#)
+               ))))
+
+(fn event-generator [events]
+  (coroutine.wrap
+   (fn []
+     (each [_ e (ipairs events)] (coroutine.yield e)))))
+
+(fn file-events [path]
+  (let [data (with-open [e (io.open path "r")] (e:read "*a"))
+        parse (fennel.parser data)]
+    (icollect [_ ast parse]
+      ast)))
+
+(set _G.arg (doto [] (tset 0 "test")))
+(local ifwait (require :ifwait))
+
+(let [gen (event-generator (file-events "events-fixture"))]
+  (ifwait.run ["dummy0" "up"] #gen)
+  (match (pcall gen)
+    (true _) true
+    (false msg) (error "didn't detect dummy0 up event")))
+
+(var upsies [])
+(set fake-system
+     (fn [s]
+       (if (s:match "-u change addmember")
+           (table.insert upsies :u)
+           (s:match "-d change addmember")
+           (table.insert upsies :d))))
+
+(fn newlink [name up running]
+  {:event "newlink"
+   :hwaddr "b6:7d:5c:38:89:1d"
+   :index (string.unpack ">i2" name)
+   :mtu 1500
+   : name
+   : running
+   :stamp 857161382
+   : up })
+
+"when it gets events that don't match the interface, nothing happens"
+
+(let [gen (-> [(newlink "eth1" "no" "no")] event-generator)]
+  (set upsies [])
+  (ifwait.run [ "-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies []))
+
+"when it gets an event that should start the service, the service starts"
+
+(let [gen (->
+           [(newlink "dummy0" "no" "no")
+            (newlink "dummy0" "yes" "no")
+            (newlink "eth1" "no" "no")]
+           event-generator)]
+  (set upsies [])
+  (ifwait.run ["-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies [:d :u]))
+
+"when it gets an event that should stop the service, the service stops"
+
+(let [gen (->
+           [(newlink "dummy0" "no" "no")
+            (newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "no" "no")
+            ]
+           event-generator)]
+  (set upsies [])
+  (ifwait.run ["-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies [:d :u :d]))
+
+"it does not call s6-rc again if the service is already in required state"
+
+(let [gen (->
+           [(newlink "dummy0" "no" "no")
+            (newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "yes" "yes")
+            (newlink "dummy0" "yes" "yes")
+            (newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "no" "no")
+            ]
+           event-generator)]
+  (set upsies [])
+  (ifwait.run ["-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies [:d :u :d]))
+
+"it handles an error return from s6-rc"
+
+(set fake-system
+     (fn [s]
+       (if (s:match "-u change addmember")
+           (table.insert upsies :u)
+           (s:match "-d change addmember")
+           (table.insert upsies :d))
+       (error "false")
+       ))
+
+(let [gen (->
+           [(newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "yes" "yes")
+            (newlink "dummy0" "yes" "yes")
+            (newlink "dummy0" "yes" "no")
+            (newlink "dummy0" "no" "no")
+            ]
+           event-generator)]
+  (set upsies [])
+  (ifwait.run ["-s" "addmember" "dummy0" "up"] #gen)
+  (expect= upsies [:u :u :u :u]))