pilgrim2go

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

pilgrim2go

# This is just a cheat sheet:

# On production
sudo -u postgres pg_dump database | gzip -9 > database.sql.gz

# On local
scp -C production:~/database.sql.gz
dropdb database && createdb database
gunzip < database.sql.gz | psql database

pilgrim2go

#!/bin/bash

# get all running docker container names
containers=$(sudo docker ps | awk '{if(NR>1) print $NF}')
host=$(hostname)

# loop through all containers
for container in $containers
do
  echo "Container: $container"

pilgrim2go

def format_filename(s):
    """Take a string and return a valid filename constructed from the string.
Uses a whitelist approach: any characters not present in valid_chars are
removed. Also spaces are replaced with underscores.
 
Note: this method may produce invalid filenames such as ``, `.` or `..`
When I use this method I prepend a date string like '2009_01_15_19_46_32_'
and append a file extension like '.txt', so I avoid the potential of using
an invalid filename.
 

pilgrim2go

import subprocess
import select
from logging import DEBUG, ERROR


def call(popenargs, logger, stdout_log_level=DEBUG, stderr_log_level=ERROR, **kwargs):
    """
    Variant of subprocess.call that accepts a logger instead of stdout/stderr,
    and logs stdout messages via logger.debug and stderr messages via
    logger.error.

pilgrim2go

What exactly is "iowait"?

To summarize it in one sentence, 'iowait' is the percentage
of time the CPU is idle AND there is at least one I/O
in progress.

Each CPU can be in one of four states: user, sys, idle, iowait.
Performance tools such as vmstat, iostat, sar, etc. print
out these four states as a percentage.  The sar tool can
print out the states on a per CPU basis (-P flag) but most

pilgrim2go

Setting up a SSL Cert from Comodo

I use Namecheap.com as a registrar, and they resale SSL Certs from a number of other companies, including Comodo.

These are the steps I went through to set up an SSL cert.

Purchase the cert

pilgrim2go

# to generate your dhparam.pem file, run in the terminal
openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048

pilgrim2go

How to share a folder with a docker container on OSX

Mounting shared folders between OSX and the docker container is tricky due to the intermediate boot2docker VM. You can't use the usual docker -v option as the docker server knows nothing about the OSX filesystem - it can only mount folders from the boot2docker filesystem. Fortunately, you can work around this using SSHFS.

pilgrim2go

# don't treat any of these as errors, warnings or info
ok /setenv /

# ignore TidyXML warnings
ok /line [0-9]+ column [0-9]+ - Error:/
ok /line [0-9]+ column [0-9]+ - Warning:/
ok /[0-9]+ warning.+ error.+ found!/

# ignore weird warnings about build variables in Info.plist:
# e.g. "warning: ignoring operator ':rfc1034Identifier' on 'RSWebClientCore' for macro 'PRODUCT_NAME'"