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Category: System Administration

How we manage WordPress website with Terraform, Chef and GitHub

water drop falling

Our website twindb.com is built on WordPress software and has always been. A while ago we decided the website needs a better look. But not only that. Managing our old website was quite laborious and manual process which goes strongly against our culture at TwinDB to do things right. Few weeks ago we migrated to […]

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Show Differences Found by Pt-Table-Checksum

Louvre Museum

First of all,pt-table-checksum is perfect for checking if the master and its slaves are in-sync. It answers the question “Are the slaves consistent with the master?”. However, if they’re not, pt-table-checksum doesn’t actually tell you what exactly is wrong.

Frompt-table-checksum to pt-table-sync Nevertheless, pt-table-sync may give you a partial answer. It can print SQL statements to sync the replication […]

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Working with CloudFlare DNS in python

stones

Last week I wrote about aDNS discovery feature in Etcd. As a step in the whole process we need to create DNS records in twindb.com zone. CloudFlare provides rich API to work with it. We wrapped it into a Python module twindb_cloudflare and opensourced it: Source code: https://github.com/twindb/twindb_cloudflare Documentation: https://twindb-cloudflare.readthedocs.io PyPi package: https://pypi.python.org/pypi/twindb_cloudflare In the […]

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Setting Up Etcd Cluster With DNS Discovery

сelestial fireworks

Setting up an Etcd cluster with DNS discovery may be challenging. First of all, there are several building blocks: Etcd – a distributed key value store Amazon EC2 – a cloud computing provider Cloudflare – a DNS provider Chef – for configuring individual nodes Each of them has its pitfalls, but we will guide you through whole […]

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Data Loss After MySQL Restart

equipment

Not so long ago, I had a customer who experienced data loss after a MySQL restart. It was really puzzling. MySQL was up & running for many months, but after the customer restarted the MySQL server all tables have gone. The tables were still visible in the SHOW TABLES output, but they were not readable:

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Encrypting MySQL Backups

Encryption is an important component of secure environments. While being intangible, property security doesn’t get enough attention when it comes to describing various systems. “Encryption support” is often as detailed as it gets, if you ask how secure the system is. Other important facts are often omitted, but, as we know, the devil is in […]

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Xtrabackup And MySQL 5.6 On an Amazon Instance

Have you ever tried to install Xtrabackup on an Amazon EC2 instance with Oracle’s MySQL 5.6? Dependencies hell breaks loose when you ask for something as simple as running the GA version of MySQL and backing it up with the most popular open-source tool, XtraBackup. From this post you will learn how to resolve conflicts […]

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Setting Up Authentication En Masse

Managing many hosts is a quite challenging task. There are many tools to solve the problem. My favorite is pdsh. Running a command across a set of hosts is as simple as following:

Together with dshbak (which is a part of pdsh package) you can do even cooler things. Like, check which systems have […]

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A Real Example Of Nagios Monitoring

It’s now time to setup proper monitoring to avoid unpleasant surprises in future. There are two major problems the monitoring solves: alerting and trending. Alerting is to notify the person in charge about a major event like service failing to work. Trending is to track the change of something over time – disk or memory […]

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