How to create executable JAR from single Groovy script

Groovy scripts are nice - they allow to use dependencies and write logic in small single file, but Groovy is mostly available on developers machine, but not on servers, so deploying them is a little more tricky. You can package them in uberjar with Gradle, but it requires additional build file and compatible structure, so it is more like project than script already.

To keep things simple, I have created Groovy script that converts other Groovy scripts into executable JARs. It packages all dependencies from Grab and compiles original script into Java main class with same name as script and sets it in manifest. So it is perfectly usable from empty JVM. JAR structure is also compatible with AWS lambda, so it can be launched from there too, just put logic in specific method. To convert your script, just download it from here and run like:

./scriptjar.groovy input.groovy output.jar

Script tries to find groovy libs via GROOVY_HOME, so set it or just hack it for your location, it is just one small Groovy script.

Erlang connection from boot2docker

If you need to connect from outside of Docker into boot2docker instance on MacOS, but nothing happens: First, make sure that all ports are mapped in VirtualBox instance - at minimum it requires 4369 and 20000-20999. Then, for hidden nodes, you may need to ping them explicitly, like:

net_adm:ping('server@127.0.0.1').

Using Clojure dependencies without specifying version number

Clojure has mandatory version number for dependecies, so until you are a real fan of the library, you may need to look it up somewhere. Fortunately, it is possible to specify LATEST instead of version, like:

(leiningen.exec/deps '[[http-kit "LATEST"]])
...

Clojure command line script with dependencies

If you want to use Clojure for command line scripts, the easiest way is by using lein-exec plugin. It compiles clj files on the fly and downloads all necessary dependencies that are declared in same file, similarly to Groovy @Grab annotation.

For example, if you have file named download.clj with

(leiningen.exec/deps '[[http-kit "2.1.16"]])
(require '[org.httpkit.client :as http])

(prn (:body @(http/get "http://www.google.com")))

it is possible to run it by:

lein exec download.clj

My recipe for IntelliJ IDEA distraction free mode

One of the top features in IntelliJ IDEA 14.1 is distraction free mode. I am totally in love with it and not looking back, working 100% of time in it. Biggest concern about it is: loosing tabs. I was happy with tabs before, but it looks like there is a bunch of better options:

• Recent Files (Cmd + E) - basically dropdown with tabs, but you can also do text search in it.
• Switcher (Ctrl + Tab) - same as Recent Files, but opens file once shortcut is released. A little faster, but you are loosing search. This is the closest to original tabs.
• Search Everywhere (Shift + Shift) - acts as Recent Files, but if you type something - also does search for Classes, Files, Symbols, Actions, Preferences. So together with tabs it basically replaces also Cmd + E, Cmd + O, Shift + Cmd + O, Alt + Cmd + O, Shift + Cmd + A.

I chose Search Everywhere as it is most feature rich and is really awesome. I also remapped it to Ctrl + E as it includes Recent Files, but as shortcut Ctrl + E works faster and is easier to reach.

Tabs had another aspect - tabs pinning, I didn't used it a lot, but for occasional use, bookmarks replace them nicely and provide more features as can pin specific line together with file. So use F3 to bookmark and Cmd + F3 to list bookmarks.

Everything else: like splitting, navigation bar, file path, tool windows, etc. is easy accessible via shortcuts or Find Action... (Shift + Cmd + A) if you forgot shortcut.

Changing SSH port for dynamic inventory script in Ansible

If you have to write dynamic inventory script in Ansible, but need to use SSH port which is not 22, there is example output of the script output:

{"databases":{
    "hosts":["127.0.0.1"],
    "vars":{
        "ansible_ssh_port":2222
        }
    }
}

Ansible freezes during start

If Ansible stops for several minutes or so during start without any messages, check if it calls your inventory script, because it might query for additional options using --host parameter and if there are a lot of hosts, it may take some time.

It can be easily fixed by adding this to JSON root:

    "_meta" : {
       "hostvars" : {
       }
    }

More about it here.