huynhbaoan

#!/bin/bash

set -u
set -e

set -o pipefail

export PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

cat <<'EOF' > /etc/modprobe.d/blacklist-ipv6.conf

huynhbaoan

### Handling error example 

import sys
import traceback

try:
    f = open('myfile.txt')
    s = f.readline()
    i = int(s.strip())
except OSError as err:

huynhbaoan

AWS S3 bucket and IAM policy recipes

• Anonymous GET access
• Anonymous GET access - match HTTP referrer
• Full access for specific IAM user/role
• GET/PUT/DELETE access to specific path within a bucket
• Restricted LIST & PUT/DELETE access to specific path within a bucket
• Full access (and S3 console) for specific IAM users
• Reference

Anonymous GET access

huynhbaoan

acm.amazonaws.com
apigateway.amazonaws.com
athena.amazonaws.com
autoscaling.amazonaws.com
clouddirectory.amazonaws.com
cloudformation.amazonaws.com
cloudfront.amazonaws.com
cloudsearch.amazonaws.com
cloudtrail.amazonaws.com
codecommit.amazonaws.com

huynhbaoan

#
# Acts as a nginx HTTPS proxy server
# enabling CORS only to domains matched by regex 
# /https?://.*\.mckinsey\.com(:[0-9]+)?)/
#
# Based on: 
# * http://blog.themillhousegroup.com/2013/05/nginx-as-cors-enabled-https-proxy.html
# * http://enable-cors.org/server_nginx.html
#
server {

huynhbaoan

Recently, I use JMXterm to collect info about Java JVM via JMX and MBeans. Here is a short note.

- Download JMXterm
https://sourceforge.net/projects/cyclops-group/files/jmxterm/1.0.0/jmxterm-1.0.0-uber.jar/download

- Run JMXterm
java -jar jmxterm-1.0.0-uber.jar --url localhost:<jmx listen port>

- All MBeans from java.lang
$>domain java.lang

huynhbaoan

#
# Config file for collectd(1).
# Please read collectd.conf(5) for a list of options.
# http://collectd.org/
#

##################
# Global settings
##################

huynhbaoan

A few show tricks to find slow queries in mongodb

Enable profiling

First, you have to enable profiling

> db.setProfilingLevel(1)

Now let it run for a while. It collects the slow queries ( > 100ms) into a capped collections, so queries go in and if it's full, old queries go out, so don't be surprised that it's a moving target...