All Posts - Filipe Felisbinohttps://felisbino.dev/posts/All Posts | Filipe FelisbinoHugo -- gohugo.ioenSat, 10 Sep 2016 00:00:00 +0000Docker: Service discovery for docker containers on AWShttps://felisbino.dev/posts/docker-service-discovery-on-aws/Sat, 10 Sep 2016 00:00:00 +0000Filipe Felisbinohttps://felisbino.dev/posts/docker-service-discovery-on-aws/<p>These days we see lots of fancy ways to do service discovery with docker. You see examples of people using etcd, zookeeper, consul and so on. I recently had a project to migrate some solr clusters to docker and I started looking at some of those tools and how they would fit that our current infrastructure.</p> <p>After some researching I found that the KISS way of doing service discovery on our environment was to use route53. The main reasons for this decision were:</p>Ansible: Data structure handling and transformationhttps://felisbino.dev/posts/ansible-data-structures/Fri, 02 Sep 2016 00:00:00 +0000Filipe Felisbinohttps://felisbino.dev/posts/ansible-data-structures/From time to time I had some dificulties with handling data structures with ansible. Things like converting a list of dicts to a list of values ( inside a dict ) or even filtering a list aren’t always trivial.

Because of that, I’ve written a small filter plugin called json_query, that allows you to do some cool transformations with ansible. The filter uses jmespath ( http://jmespath.org/ ) a query language for json data. The plugin is already merged to devel branch and will be released on 2.2 version of ansible.

]]>AWS custom-crafted load balancer with haproxyhttps://felisbino.dev/posts/aws-load-balancer/Sat, 06 Aug 2016 00:00:00 +0000Filipe Felisbinohttps://felisbino.dev/posts/aws-load-balancer/Today’s tip is on how to launch a custom-crafted load balancer on AWS as a replacement for ELBs.

Motivation

First of all I need to say that I love AWS’ ELB. It is cost-effective and works just fine for most of the cases.

So why would I create a custom-crafted ELB? Well, there are some features that AWS’ ELB just don’t support. Things like:

  • A static IP or elastic IP entry point
  • UDP load balancing
  • Customized balancing strategy
  • Custom backend routing
  • One load balancer for multiple backends
  • SNI resolution(SSL routing)

So if the ELB is not suited for your use case, do it yourself :-)

]]>Ansible: Using with_nested to merge a list with a dicthttps://felisbino.dev/posts/ansible-nested-example/Wed, 20 Jan 2016 00:00:00 +0000Filipe Felisbinohttps://felisbino.dev/posts/ansible-nested-example/I make heavy use of Ansible for AWS infrastructure provisioning. From creating VPCs, subnets, EC2 instances, security groups and so on.

Because we have a central point where we define per-environment networks, I recently got stuck with having to convert a list of subnets (just strings) to a list of dicts to be used by the ec2_group module. My list of subnets was something like:

internal_networks:
  - 10.100.32.0/20
  - 10.100.128.0/20
  - 10.100.144.0/20
  - 10.50.128.0/20
  - 10.50.144.0/20

While the ec2_group expects its rules to be something like:

]]>Bash: Simple network ip/mask calculations with bashhttps://felisbino.dev/posts/bash-calculating-ip-addresses/Sun, 06 Dec 2015 00:00:00 +0000Filipe Felisbinohttps://felisbino.dev/posts/bash-calculating-ip-addresses/Here is quick-and-dirty network subnet calculator for bash:

#converts an int to a netmask as 24 -> 255.255.255.0
netmask()
{
    local mask=$((0xffffffff << (32 - $1))); shift
    local ip n
    for n in 1 2 3 4; do
        ip=$((mask & 0xff))${ip:+.}$ip
        mask=$((mask >> 8))
    done
    echo $ip
}

#receives a ip/mask parameter and returns the nth ip in that range:
get_nth_ip()
{
    IFS=". /" read -r i1 i2 i3 i4 mask <<< $1
    IFS=" ." read -r m1 m2 m3 m4 <<< $(netmask $mask)
    printf "%d.%d.%d.%d\n" "$((i1 & m1))" "$((i2 & m2))" "$((i3 & m3))" "$(($2 + (i4 & m4)))"
}

To find the 10th ip in a subnet you just need to:

]]>Ansible: Flattening a list of dicts to a single dicthttps://felisbino.dev/posts/ansible-flattening-list-of-dicts/Thu, 03 Dec 2015 00:00:00 +0000Filipe Felisbinohttps://felisbino.dev/posts/ansible-flattening-list-of-dicts/Ansible is a great tool for automation. It has lots of modules that makes our lives easier. As a heavy-user of ansible for infrastructure provisioning on AWS, I sometimes get frustrated to have to deal with different data structures used by modules.

One example I had to deal with recently was the tags attribute of ec2_asg and ec2_tag. You cannot just pass the same value for both of them because ec2_asg tags attribute expects a list of dicts, while ec2_tag expects just a dict. That difference is because ec2_asg’s dicts have an optional attribute called propagate_at_launch.

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