Let's assume for a moment that, for some strange reason, the "directory
watching" strategy won't work here. Does anyone have any other suggestions?
I am thinking there must be a simple way to setup Jenkins and Supervisord
to run these apps, but what I'm doing keeps getting more and more complex,
which is typically a warning sign that I'm on the wrong track.
On Saturday, August 8, 2015 at 5:24:28 PM UTC-4, Lawrence Krubner wrote:
>
> I feel stupid, but I have not been able to track this down.
>
> The background is that I have Jenkins running on the server, and when
> triggered it pulls code from Github, compiles it, and then moves the final
> uberjar to the directory where I keep all the uberjars that run on this
> server. Then I have an app that should kill all currently running
> instances. Then Supervisord should step in and restart the instances, using
> the new uberjars for the new instances.
>
> All of this works, but I have been doing one bit by hand: "kill all
> currently running instances". I log in as root and run a script that kills
> the old instances. But just today I wrote a quick Clojure app to automate
> this for me (the whole app is 50 lines of code, so this is a very small
> app).
>
> To trigger the main action, I thought the app should set a watcher on the
> final directory where Jenkins moves the uberjars to. When Jenkins moves a
> new uberjar to the directory, the watch would be triggered and then it
> could run the "kill all currently running instances" script. However, I
> assumed that the ""kill all currently running instances"" script would be
> triggered once each time the uberjar was updated, but instead it seems to
> be triggered infinitely. Does a JVM app, or a Clojure app, change the dir
> its in, on launch? Or is the problem in my own code? I'm using Chris
> Zheng's excellent Hara library for the Watch. This is the main function of
> my app, which is called on startup:
>
> (defn establish-watchers []
> "The config contains a hashmap which has a 'watchers' key, which
> contains a vector that holds hashmaps with 2 keys, one pointing to the
> directory that should be watched and the other pointing to the command that
> should be run when the watch is triggered."
> (let [config (read-string (slurp "/etc/fiit.edn"))
> watchers (:watchers config)]
> (doseq [w watchers]
> (common-watch/add (clojure.java.io/file (:dir-to-watch w)) (keyword
> (:dir-to-watch w))
> (fn [f k _ [cmd file]]
> (pprint/pprint (:out (sh/sh (:action-to-do w)))))
> {:types #{:create :modify}
> :recursive false
> :async false}))))
>
> So if I log in as root and start the app like this:
>
> /usr/bin/java -jar /home/jenkins/fiit/fiit-1-standalone.jar
>
> Then at the terminal I see this, which I expect:
>
> [/home/jenkins/sarr]
> [/home/jenkins/food_for_all]
>
> Those are the 2 directories that it is watching.
>
> Then if I trigger Jenkins for the sarr app, Jenkins will pull the sarr
> code from Github, rebuild the sarr uberjar, and move the uberjar to
> /home/jenkins/sarr.
>
> All of that works just great. And then my app sees there has been a change
> in /home/jenkins/sarr, and so it calls the command to kill all existing
> instances of the sarr app. However, instead of doing this once, it starts
> doing so an infinite number of times. At the terminal I see:
>
> (sarr is a Java app, not a Clojure app)
>
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \nroot 25593 0.0 0.1 5813460 19452 ?
> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
> com.candle.sarr.Main\nroot 25595 0.0 0.1 5813460 19564 ? Sl
> 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
> com.candle.sarr.Main\n25593\n25595\n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n25694\n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \nroot 26239 0.0 0.1 5813460 19452 ?
> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
> com.candle.sarr.Main\n26239\n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \nroot 26319 0.0 0.1 5811252 15484 ?
> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
> com.candle.sarr.Main\n26319\n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
> "We will kill these processes: \n"
>
>
> I have Supervisord set to run 3 instances of the sarr app, so you can see
> at first it it is killing these PIDs:
>
> 25593
> 25595
> 25694
>
> Supervisord restarts these almost instantly, so you can see these
> processes are launched and instantly killed, all on the same line of
> output:
>
> "We will kill these processes: \nroot 26239 0.0 0.1 5813460 19452 ?
> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
> com.candle.sarr.Main\n26239\n"
>
> "We will kill these processes: \nroot 26319 0.0 0.1 5811252 15484 ?
> Sl 20:28 0:00 /usr/bin/java -cp /home/jenkins/sarr/sarr.jar
> com.candle.sarr.Main\n26319\n"
>
> This goes on for as long as I allow it (it takes Supervisord a long time
> to quit, because when I am developing new software, I set startretries=500,
> in Supervisord, exactly so I can experiment like this).
>
> I looked here to try to figure out what was going on:
>
>
> https://github.com/zcaudate/hara/blob/55b4eda688a4e616f03bf3740419a69b5c5dd658/src/hara/io/watch.clj
>
> As near as I can tell, the main action happens here:
>
> (defn run-watcher [watcher]
> (let [^java.nio.file.WatchKey wkey
> (.take ^java.nio.file.WatchService (:service watcher))]
> (doseq [^java.nio.file.WatchEvent event (.pollEvents wkey)
> :when (not= (.kind event)
> StandardWatchEventKinds/OVERFLOW)]
> (let [kind (.kind event)
> ^java.nio.file.Path path (.watchable wkey)
> ^java.nio.file.Path context (.context event)
> ^java.nio.file.Path res-path (.resolve path context)
> ^java.io.File file (.toFile res-path)]
> (if (and (= kind StandardWatchEventKinds/ENTRY_CREATE)
> (.isDirectory file)
> (-> watcher :options :recursive))
> (register-sub-directory watcher (.getPath file)))
> (if (.isFile file)
> (process-event watcher kind file))))
> (.reset wkey)
> (recur watcher)))
>
>
> Again, maybe I am being stupid, but it looks to me like the callback is
> called once per event triggered on that directory. So why would the
> callback seem to be called an infinite number of times? Does starting or
> stopping the app trigger a change in the directory (thus triggering the
> callback again)?
>
>
>
>
>
>
>
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