majackson

Django Migrations without Downtime

The following instructions describe a set of processes allowing you to run Django database migrations against a production database without having to bring the web service down.

Note that in the below instructions, migrations are all run manually at explicit points, and are not an automatic part of the deployment process.

Adding Fields or Tables

Adding a (nullable) field or a new table

1. Make the model or column addition in your code.

tommyip

# Based on https://gist.github.com/bastibe/c0950e463ffdfdfada7adf149ae77c6f
# Changes:
# * Instead of overriding cd, we detect directory change. This allows the script to work
#   for other means of cd, such as z.
# * Update syntax to work with new versions of fish.
# * Handle virtualenvs that are not located in the root of a git directory.

function __auto_source_venv --on-variable PWD --description "Activate/Deactivate virtualenv on directory change"
  status --is-command-substitution; and return

appeltel

import asyncio
import random


class Hub():

    def __init__(self):
        self.subscriptions = set()

    def publish(self, message):

vsajip

#
# Copyright (C) 2013-2020 Vinay Sajip. New BSD License.
#
import os
import os.path
from subprocess import Popen, PIPE
import sys
from threading import Thread
from urllib.parse import urlparse
from urllib.request import urlretrieve

r3m0t

# coding: utf-8
"""Cause git to detect a merge conflict when two branches have migrations."""
# myapp/management/commands/makemigrations.py
# you'll need myapp/management/commands/__init__.py and myapp/management/__init__.py in PY2, see Django docs
from __future__ import absolute_import, unicode_literals

import io

import os
import six

alanhamlett

import uuid
import wtforms_json
from sqlalchemy import not_
from sqlalchemy.dialects.postgresql import UUID
from wtforms import Form
from wtforms.fields import FormField, FieldList
from wtforms.validators import Length

from flask import current_app as app
from flask import request, json, jsonify, abort

davialexandre

{
  "background" : "#282828",
  "black" : "#282828",
  "blue" : "#458588",
  "brightBlack" : "#928374",
  "brightBlue" : "#83A598",
  "brightCyan" : "#8EC07C",
  "brightGreen" : "#B8BB26",
  "brightPurple" : "#D3869B",
  "brightRed" : "#FB4934",

robin-a-meade

Unofficial Bash Strict Mode

Sometimes a programming language has a "strict mode" to restrict unsafe constructs. E.g., Perl has use strict, Javascript has "use strict", and Visual Basic has Option Strict. But what about bash? Well, bash doesn't have a strict mode as such, but it does have an unofficial strict mode:

set -euo pipefail

set -e

kachayev

Channels Are Not Enough

... or Why Pipelining Is Not That Easy

Golang Concurrency Patterns for brave and smart.

By @kachayev

Intro

klange

Since this is on Hacker News and reddit...

• No, I don't distribute my résumé like this. A friend of mine made a joke about me being the kind of person who would do this, so I did (the link on that page was added later). My actual résumé is a good bit crazier.
• I apologize for the use of _t in my types. I spend a lot of time at a level where I can do that; "reserved for system libraries? I am the system libraries".
• Since people kept complaining, I've fixed the assignments of string literals to non-const char *s.
• My use of type * name, however, is entirely intentional.
• If you're using an older compiler, you might have trouble with the anonymous unions and the designated initializers - I think gcc 4.4 requires some extra braces to get them working together. Anything reasonably recent should work fine. Clang and gcc (newer than 4.4, at le