crazyguitar

When you cancel a Jenkins job

Unfinished draft; do not use until this notice is removed.

We were seeing some unexpected behavior in the processes that Jenkins launches when the Jenkins user clicks "cancel" on their job. Unexpected behaviors like:

• apparently stale lockfiles and pidfiles
• overlapping processes
• jobs apparently ending without performing cleanup tasks
• jobs continuing to run after being reported "aborted"

crazyguitar

Running Docker on two hosts, bridged with Open vSwitch

This Gist shows how to use Open vSwitch to bridge Docker containers on two hosts. It is based on this blog post http://goldmann.pl/blog/2014/01/21/connecting-docker-containers-on-multiple-hosts/.

A similar Gist using Tinc instead of Open vSwitch is available: https://gist.github.com/noteed/11031504.

Setup

crazyguitar

/*
 * A sample program of KCM.
 *
 * $ gcc -lbcc kcm-sample.c
 * $ ./a.out 10000
 */
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>

crazyguitar

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <err.h>

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>

crazyguitar

obj-m += tcp_svr_sample.o
 
all:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
 
clean:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clea

crazyguitar

1. Execute make first. This will result in a netlinkKernel.ko output among many others.
2. Execute $ gcc netlinkUser.c -o netlinkUser
3. Insert kernel module by :$ sudo insmod netlinkKernel.ko      
4. Run ./netlinkUser to see message and run dmesg to see debug messages
5. Remove module by : $ sudo rmmod netlinkKernel          
6. Finally make clean to remove output files.

crazyguitar

package main

import (
	"fmt"
	"net"
	"os"
	"syscall"
)

const (

crazyguitar

# Basics of Elliptic Curve Cryptography implementation on Python
import collections


def inv(n, q):
    """div on PN modulo a/b mod q as a * inv(b, q) mod q
    >>> assert n * inv(n, q) % q == 1
    """
    for i in range(q):
        if (n * i) % q == 1:

crazyguitar

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

crazyguitar

How to setup AWS lambda function to talk to the internet and VPC

I'm going to walk you through the steps for setting up a AWS Lambda to talk to the internet and a VPC. Let's dive in.

So it might be really unintuitive at first but lambda functions have three states.

1. No VPC, where it can talk openly to the web, but can't talk to any of your AWS services.
2. VPC, the default setting where the lambda function can talk to your AWS services but can't talk to the web.
3. VPC with NAT, The best of both worlds, AWS services and web.