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Alter Column Type for Mysql without downtime

We did this by using pt-online-schema-change 1. Since we are using RDS with Read Replica, and the tool require log_bin_trust_function_creators = 1, we did a failover to Read Replica, modifying parameter group of Master, reboot Master, then failback to Master and repeat this for Read Replica. If you have SUPER privilege of the DB, skip this step. 2. Prepare a…

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Letsencrypt failed to renew

We were getting this letsencrypt renewal error on some Ubuntu 16.04 machines: OSError: Command /opt/eff.org/certbot/venv/bin/python2.7 – setuptools pkg_resources pip wheel failed with error code 1 Googling around, hit a few walls and finally found the solution, just need to run this in Ubuntu: export LC_ALL=”en_US.UTF-8″ export LC_CTYPE=”en_US.UTF-8″ Then continue on with the letsencrypt-auto script will do.

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Scaling PHP CMS in AWS

There’s two major challenge when scaling a traditional CMS like Prestashop / Drupal: – Centralized session – File storage synchronized – Isolate Backend traffic to a single instance Let’s dive into details for each of them:   Centralized Session This is the easiest one to be taken care of, we will use Redis as the session backend, in AWS, the…

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