Hi, I'm Roger Stringer. also known as @freekrai. I'm a DevOps engineer, generalist software engineer, author, speaker and founder of Flybase. I write, travel to conferences and work from anywhere, bootstrap companies and tell it like it is. Follow this blog to learn more about DevOps and related.

Your toolbelt

Every profession has a toolbelt, that set of tools they need to do their job and that has to be within reach at all times: writers have their pen and paper, chefs have their knives, carpenters have their actual tools.

And if you do DevOps, then your tools are usually on your computer, tablet, smart phone and sometimes your smart watch.

Our tools vary but all serve the purpose of keeping the servers running, keeping the developers happy, and even more importantly, keeping the clients happy.

Here’s a list of tools I use in my day to day DevOps work:

  • Operating Systems
    • Linux (RHEL, CentOS, Ubuntu, Debian)
    • Unix (Solaris, AIX, HP/UX, etc.)
    • Windows
    • Mac OS X
  • Infrastructure as a Service
    • Amazon Web Services
    • Rackspace
    • Digital Ocean
    • Azure
    • Heroku
  • Virtualization Platforms
    • VMware
    • KVM
    • VirtualBox
    • Vagrant
  • Containerization Tools
    • LXC
    • Docker
  • Linux OS Installation
    • Kickstart
    • Cobbler
  • Configuration Management
    • Ansible
    • Puppet
    • Chef
  • Test, Build and Deployment Systems
    • Travis CI
    • Circle CI
    • Jenkins
  • Web Servers
    • nginx
    • Apache
  • Databases
    • MongoDB
    • MySQL
    • PostgresSQL
    • Cassandra
    • Redis
  • Monitoring, Alerting, and Trending
    • New Relic
    • Nagios
    • Zabbix
    • Uptime Robot
    • PagerDuty
    • Push Over
  • Logging
    • PaperTrail
    • Loggly
    • Rtail

This list will probably grow every other week, DevOps means staying on top of this growing stack of tools and using which ever tools help you get the job done more efficiently.

•••

Load Testing Apache with AB (Apache Bench)

The only productive way to load test web site is to test a real-world page that itself performs –

  • Loading and processing of multiple PHP files.
  • Establishment of multiple MySQL connections, and performing multiple table reads.

This is the minimum, because the test of an almost empty and static page (used by most examples) tells us nothing about how the different parts of a web-server hold up under stress, nor how that web-server setup will handle real-world concurrent connections to websites running on web-apps such as WordPress.

  • Ideally, this test would also:
  1. perform GETs of all page assets (css, js, images) and
  2. simulate traffic of which 10% is DB writes (we’ll skip this because its more complicated to set up).

Using AB

Luckily, this type of test is very easy to do in a quick (and somewhat dirty) way by using Apache’s ab (Apache Bench) application (that’s included with each Apache version in its \bin directory).

This ab test won’t be the most extensive test, and it comes with its own caveats, but it will quickly show you –

  • If there is an immediate problem with the setup (this problem will manifest itself in Apache crashing).
  • How far you can push the Apache, PHP, and MySQL web-server (with concurrent connections and page request load).
  • And what Apache and PHP settings you should modify to get better performance and eliminate the crashes.

AB Issues

There are some problems with ab to be aware of –

  • ab will not parse HTML to get the additional assets of each page (css, images, etc).
  • ab can start to error out, breaking the test, as the number of requests to perform is increased, more connections are established but not returned, and as the load increases and more time passes (see ab -h for explanation of -r switch).
  • ab is an HTTP/1.0 client, not a HTTP/1.1 client, and “Connection: KeepAlive” (ab -k switch) requests of dynamic pages will not work (dynamic pages don’t have a predetermined “Content-Length: value“, and using “Transfer-Encoding: chunked” is not possible with HTTP/1.0 clients).

More on AB and the KeepAlive issue –

KeepAlive – Apache Directive

A Keep-Alive connection with an HTTP/1.0 client can only be used when the length of the content is known in advance. This implies that dynamic content will generally not use Keep-Alive connections to HTTP/1.0 clients.

Compatibility with HTTP/1.0 Persistent Connections – Hypertext Transfer Protocol HTTP/1.1 Standard

A persistent connection with an HTTP/1.0 client cannot make use of the chunked transfer-coding, and therefore MUST use a Content-Length for marking the ending boundary of each message.

Chunked transfer encoding – Wikipedia

Chunked transfer encoding allows a server to maintain an HTTP persistent connection for dynamically generated content. In this case the HTTP Content-Length header cannot be used to delimit the content and the next HTTP request/response, as the content size is as yet unknown.

Request Floods

ab will flood the Apache server with requests – as fast as it can generate them (not unlike in a DDoS attack). AB has no option to set a delay between these requests.

And given that these requests are generated from the same local system they are going to (i.e., the network layer is bypassed), this will create a peak level of requests that will cause Apache to stop responding and the OS to start blocking/dropping additional requests. Especially if the requested page is a simple PHP file that can be processed within a millisecond.

In this context, with ab, the bigger the -c (concurrent number of requests to do at the same time) is, the lower your -n (total number of requests to perform) should be… Even with a -c of 5, -n should not be more than 200.

Expect the behavior of the ab tests to be very non-deterministic under higher concurrent loads, they will fail and succeed randomly. Even a -c of 2 will cause issues.

These are the error messages displayed by ab

apr_socket_recv: An existing connection was forcibly closed by the remote host. (730054)
apr_pollset_add(): Not enough space (12)

When this happens (a message is displayed that Apache has crashed), just ignore it (Apache is still running), and keep repeating the test until “Failed requests:” is reported as “0”, AND “Percentage of the requests served within a certain time (ms)” is about 2-20x between the 50% and 99% mark (and not 200x). Otherwise, the test is not reliable due to the issues that present themselves when ab floods Apache on loopback (and due to how the OS responds to that flood).

This is what you should see on a good test of a simple index.php page…

ab -l -r -n 100 -c 10 -k -H "Accept-Encoding: gzip, deflate" http://www.example.com/

Benchmarking www.example.com (be patient).....done

Server Software:        Apache/2.4.10
Server Hostname:        www.example.com
Server Port:            80

Document Path:          /
Document Length:        Variable

Concurrency Level:      10
Time taken for tests:   0.046 seconds
Complete requests:      100
Failed requests:        0
Keep-Alive requests:    100
Total transferred:      198410 bytes
HTML transferred:       167500 bytes
Requests per second:    2173.91 [#/sec] (mean)
Time per request:       4.600 [ms] (mean)
Time per request:       0.460 [ms] (mean, across all concurrent requests)
Transfer rate:          4212.17 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.2      0       2
Processing:     1    4   5.9      3      33
Waiting:        1    4   5.9      3      32
Total:          1    4   6.0      3      33

Percentage of the requests served within a certain time (ms)
50%      3
66%      4
75%      4
80%      5
90%      6
95%     22
98%     32
99%     33
100%     33 (longest request)

Before Performing The Load Test

Make sure that –

  • You’ve rebooted the system and don’t have anything extra open/running (i.e., YouTube videos playing in your Browser).
  • These extra PHP extensions are not loaded: Zend OPcache, APC, nor XDebug.
  • You wait 4 minutes before performing another ab test to avoiding TCP/IP Port Exhaustion (also known as ephemeral port exhaustion).
  • And in a test where KeepAlive works (it doesn’t in ab tests getting dynamic pages), the number of Apache Worker Threads are set to be greater than the number of concurrent users/visitors/connections.
  • If Apache or PHP crashes, you’ve rebooted the computer or VM before performing another test (some things get stuck and continue to persist after Apache and/or mod_fcgid’s PHP processes are restarted).

Start The AB Test

  1. Install WordPress as http://www.example.com/blog

  2. Open the terminal.

  3. Restart Apache and MySQL, and prime the web-server (with 1 request):

ab -n 1 -c 1 -k -H "Accept-Encoding: gzip, deflate" http://www.example.com/blog/
  1. Run the Apache Bench program to simulate –

1 concurrent user doing 100 page hits

This is 100 sequential page loads by a single user:

ab -l -r -n 100 -c 1 -k -H "Accept-Encoding: gzip, deflate" http://www.example.com/blog/

This shows you how well the web-server will handle a simple load of 1 user doing a number of page loads.

5 concurrent users each doing 10 page hits

This is 100 page loads by 5 different concurrent users, each user is doing 10 sequential pages loads.

ab -l -r -n 50 -c 10 -k -H "Accept-Encoding: gzip, deflate" http://www.example.com/blog/

This represents a peak load of a website that gets about 50,000+ hits a month. Congratulations, your website / business / idea has made it (and no doubt is on its way up).

10 concurrent users each doing 10 page hits

This is 100 page loads by 10 different concurrent users, each user is doing 10 sequential pages loads.

ab -l -r -n 100 -c 10 -k -H "Accept-Encoding: gzip, deflate" http://www.example.com/blog/

This is where the load starts to really stress test the web-server, as 10 concurrent (simultaneous) users is a lot of traffic. Most websites will be lucky to see 1 or 2 users (visitors) a minute… So let me say it again, 10 users per second is a lot of traffic!

30 concurrent users each doing 20 page hits

This is 600 page loads by 30 different concurrent users, each user is doing 20 sequential pages loads.

ab -l -r -n 600 -c 30 -k -H "Accept-Encoding: gzip, deflate" http://www.example.com/blog/

This is the edge of what a non-cached WordPress setup will be able to handle without crashing or timing-out the web-server (and/or ab itself). This type of load represents an extremely active website or forum, the top 1%.

90 concurrent users each doing 30 page hits

This is 2700 page loads by 90 different concurrent users, each user is doing 30 sequential pages loads.

ab -n 2700 -c 90 -k -H "Accept-Encoding: gzip, deflate" http://www.example.com/blog/

Only a fully cached (using mod_cache) Apache setup will be able to handle this type of a load. This represents some of the busiest sites on the net, and there is no hope of this not maxing out and crashing (if your settings are not just right) the web-server with a non-cached WordPress setup.

Analyze the AB Results

We only care about 3 things:

  1. How many Requests Per Second are we seeing? The other metrics are not really useful, as they are not representative of anything real in this ab context. * This value will remain somewhat the same regardless of the concurrency level used.

  2. Are there any errors in the website’s or Apache’s (general) error and php logs? * When things stat to choke, PHP memory issues will start coming up. A lot of PHP scripts also begin to crash (and take out Apache + PHP processes) if they are not written with concurrency in mind.

  3. At what concurrency level does Apache crash and/or time-out? * If this is happening at a lower concurrency level, something is wrong and you need to adjust these settings either lower of higher…

Also, in my experience, the switch from 32 bit to 64 bit Apache, PHP, and MySQL versions only provides limited/marginal performance gains (and in some cases it’s even negative).

To sum everything up, 99% of all performance gains will come from utilizing Apache’s caching mechanisms (via mod_cache), using PHP Zend OPcache (extension), and afterwards (once the bottleneck is moved from Apache with PHP to MySQL), improving MySQL performance by tuning my.ini settings, and optimizing/restructuring MySQL queries by utilizing MySQL’s Slow Query log (to see what the problem is).

Having said that, there are also performance robbing issues that can exist on the OS, in the Apache/MySQL/PHP settings, and even the client’s Browser, that are covered here.

•••

3 signs that you might need to move to NoSQL.

####Why NoSQL?

NoSQL databases are a class of databases in which data is NOT stored in tabular relations - Unlike other relational database solutions, and this is why it is called “Not Only SQL”. Data which is stored in other data-structure other than tabular relations are sometimes better for some scenarios which are outlined later in this post.

NoSQL databases are great at doing a bunch of things. For example - storing big data for internet scale applications, scenarios which prefer low latency data-storage, improved performance, and more.

Here are three signs why you should be considering NoSQL databases for your solution:

#####Your data is BIG:

You’re collecting a ton of data over the internet - like web analytics, sensor data from the Internet of Things (IoT), saving a lot of user data (like tweets in twitter), etc and you need a place to store + have an efficient way to do a “distributed read” on all of the data. If this is what you’re looking for - then NoSQL is a perfect fit for you.

#####You have a “schema less” data:

Data which you’re storing in the traditional RDBMS databases like SQL has a pre-defined schema ahead of time. If your schema changes a lot OR if you don’t have a pre-defined schema where you can add a field anytime you like then NoSQL is the good fit for these type of scenarios.

#####Scale out:

There are two things you can do when you want to scale your solution. You can either scale up where you keep adding more memory, processing capacity and storage to a single machine or you can scale out where you can have multiple machines supporting your solution.

NoSQL is a perfect solution when you have a ton of data that doesn’t fit on a single server. Most of the NoSQL databases are horizontally scalable - What I mean by this is you can shard or divide your data into multiple servers and still have efficient access to your data. NoSQL databases are elastic, you can have thousands of nodes / servers and you can scale horizontally well.

####What will you be missing?

#####No relations and joins:

Most NoSQL databases for example MongoDb have no relation support between tables (Graph Databases like Neo4j does, but that’s a completely different type of database to look at) - Which means there’s no support for joins when you query your data. If you have joins between your data you can combine documents together and save them as sub-documents or do a manual join by running two queries over your database.

#####No atomic operations:

Most of the NoSQL databases like MongoDB have no atomic operations or transactions across multiple tables / record. For example, In MongoDB a single write is atomic but if you write multiple records / documents at the same time then as a whole they’re not atomic. If you ever need to have transaction support on your data which is critical for your solution. You should store that piece of data in RDBMS instead.

#####No reporting:

NoSQL has no reporting in general - as you’re used to when you were on RDBMS databases. If you want to generate reports, create graphs, or do something with all of the data in your NoSQL stack, you’ll need to start coding and write what we call - “map-reduce” jobs for the reports you want.

####Where is NoSQL the best fit?

These are few of the sample scenarios where NoSQL is the best fit. Typically these include high-volume / low-latency data-storage scenarios. Few examples of these are:

#####Storing logs / user analytics data:

Servers generate a large number of logs that contain useful information about their operation including errors, warnings, and user behaviour. By default, most servers, store these data in plain text log files on their local file systems.

While plain-text logs are accessible and human-readable, they are difficult to use and analyse. NoSQL Column Oriented database like Cassandra is a perfect databases to store log files. Cassandra can handle huge number of writes which is useful when you store logs or Meta data about where user behaviour on your site.

#####Internet of Things - Storing data from the sensors:

Sensor-enabled devices are pumping out a ton of data, but sensor data is only useful if you can do something with it. With NoSQL databases, you can make sense of sensor data, building applications never before possible.

The Internet of Things is a world where all your physical assets and devices are connected to each other and share information, making life easier and more convenient. To enable this inter-connected world, You need to have all the data these devices are pumping out and making sense of it and this is one of the scenarios where NoSQL is the great fit.

####So, do I migrate?

It depends on your application which you’re building. If your application has a ton of transactional and relational features - You can go ahead with RDBMS, if your application has a scalability issue with your current data infrastructure. Then I think you seriously need to use NoSQL. You can even use both and this is what most companies do.

For piece of data which is related, they tend to go ahead with Relational Database, but for a piece of data which has no relations / or is big data. They use a NoSQL database solution and I think this is the best approach to go forward with.

•••

Continuous Integration with dokku-alt

I recently rolled my own PAAS solution using Dokku, and ran into a couple problems that I think others might run in to, as well. It took just a few hours and I have a very cheap, but efficient CI stack. All things considered, the entire stack is made up of:

  • Docker
  • Circle CI
  • dokku-alt (and Digital Ocean for VM hosting)
  • Github

My main goal was to be able to simply run my test commands, build my Docker container, and deploy the app every time I pushed to Github.

Docker

The first thing that you need to is Docker-ize your app. There are many different tutorials on this, so I will assume that this part has been done.

dokku-alt

dokku is an open source competitor to Heroku. It is gaining a lot of popularity and even Digital Ocean has a premade VM that runs dokku out of the box. While I wanted to go this route, it could not handle Docker containers.

Another open source project based on dokku did, however, called dokku-alt. dokku-alt is essentially dokku but with much more features that made things very simple. The setup is a bit more manual than the Digital Ocean dokku but it is still pretty easy. To set it up, start a new Digital Ocean/Ubuntu VM. I would recommend selecting at least the second “size” Digital Ocean droplet as I tried the $5/month one and was constantly running out of memory for npm installs. I also would recommend including your ssh keys here so that Digital Ocean can add them on creating the droplet and you won’t have to do this later.

If you are new to Digital Ocean, it is highly recommend and if you’d like, you can use my referral link and get $10 towards a droplet (one free month in this case!).

Once the droplet is set up, go to the DNS records and route a new A record to the droplet’s IP that was just created (this is optional but makes things a lot nicer). For this tutorial, I added ci.freekrai and *.ci.freekrai to the IP of the droplet. I will explain why this is nice later in the tutorial.

After everything is setup, ssh [email protected]_IP or ssh [email protected], if you set up the A records, on your local machine. Now, run the script suggested by dokku-alt.

$ sudo bash -c "$(curl -fsSL bit.ly/dokku-alt)"

This will handle the full installation for you, and at the end, will tell you to point to ci.website.com:2000 to finish the setup. I used the pre-set SSH key, as it was mine already, and then changed the IP to be ci.website.com and then enabled virtual hosting. As you can see it allows for different projects to have much better URLs such as app.ci.website.com. This is the reason that I suggested to add the wilcard A record to Digital Ocean.

After you save these settings, ctrl-c the start up script out of the dokku-alt vm. That’s it!

You can now test that this works by adding a new remote origin to your Docker project’s git remotes. To do use this following command, and be sure to change the URL correctly:

$ git remote add deploy [email protected]:app

Also, be sure that you change app to whatever you want app.ci.website.com to be. I made mine dev in this case because it would be the development version of the app. After this is done, run git push dokku master to push the app up to dokku-alt. dokku-alt will recognize the Dockerfile and appropriately start the container. You will know if its working if at the end it says something about visiting app.ci.website.com.

One issue that I had a problem with was exposing the proper port! If dokku-alt does not detect that ports 80, 8080, or 5000 are not EXPOSE‘d using the Dockerfile, it won’t actually launch the site.

CircleCI

CircleCI is a continuous integration service (written in React!!) that integrates well with Github and is very cheap. It is actually free if you are okay with only running one CI at a time. In my case, this was perfectly acceptable as I would never have too many builds going on at once.

To begin sign up with your Github account and link your project. That’s technically it. At this point, Circle recognized that I was running a Node.js app so it read my package.json and built my Docker container. It ran the tests based off my test suite in package.json and simply ended. You may or may not have to do more to get Circle to work with your app specifically. This is where the circle.yml file comes in. The docs are very good if you find that you have to use more configuration.

Add a private ssh key to the Project Settings for this specific project. In my case, I used my own private key but it would definitely be better to create a deploy key for Circle and then configure dokku-alt to receive that deployments (and deployments only) from that key.

For this tutorial, however, we will use the circle.yml file to deploy to our dokku-alt instance at the end of a successful test. It is very simple:

deployment:  
  production:
    branch: master    
    commands:
      - ./deploy.sh

All it says is at the deployment step, in production, on the master branch, run ./deploy.sh. This allows you to have multiple different configurations for production, demo, staging, etc. and can all run different deploy scripts.

Put this circle.yml file in the root of you repository, and then create another new file called deploy.sh. This file is even simpler:

#! /bin/bash

git remote add dokku [email protected]:dev  
git push dokku master  

We just do exactly the same thing we did as before to see if dokku-alt was running correctly! Just push to the dokku branch, as if it were being done manually. Be sure to chmod +x deploy.sh so that Circle can execute the file, and push to master.

At this point you can watch Circle receive the new push, initialize your container, run your tests, and then, on success, run the deploy.sh script.

Conclusion

So far this has been working great, and I hope that if you followed this tutorial, you might avoid some of the mistakes that I made. If you have any questions, please email me or find me on Twitter.

•••

PaaS in under 10 minutes

If you’ve ever used Heroku or Github Pages, you know how easy and convenient it is to be able to deploy a quick static site by pushing to a remote. Being able to type git push origin gh-pages and have your site immediately live on a publicly accessible domain is hugely satisfying and you end up experimenting way more, pushing up micro-sites and project pages because it’s easy.

GitHub pages does have a limitation, though: there is no concept of a server. While you might not notice that on smaller projects or experiments, it is inevitable that you will run into it eventually. Sometimes you just want a server.

Heroku does enables you to have the concept of a server, with a similar work-flow: make something, then push to a remote with git and it’s on the internet. But Heroku costs money. It’s free at first, (as long as you don’t mind your site being down for up to 6 hours a day) but as you scale, it begins to get more expensive fairly quickly. Add a couple more dynos and you’re already up to $70.

Enter Dokku, an open source mini-Heroku.

With Dokku, you can run your own (albeit slightly less feature-rich) Heroku. With a $5 / month Digital Ocean droplet, this DIY solution is pretty inexpensive and easy to set up. Dokku is a Docker powered mini-Heroku.

I’m actually using the Dokku-alt fork, as it includes plugins already to go, so setup is even quicker.

1. Get a Domain Name

I recommend Hover only because I have experience with them and they’re not Godaddy…

2. Create a Digital Ocean Account

Create an account with Digital Ocean: digitalocean.com.

3. Create a Droplet

Make a new droplet in DigitalOcean. Be sure to name the droplet exactly what your domain is. Select the smallest size, and whatever region is closest to you.

In the Select Image section, click the Distributions tab and choose the Ubuntu 14.04 option.

Click Create Droplet.

4. Configure the DNS

To get your domain to point to your new droplet, you need to change the DNS records. Use the following host name and subdomain settings in your name registrar:

HOST NAME IP ADDRESS/URL RECORD TYPE MX PREF TTL
@ your.droplet.ip.address A (Address) n/a 60
www your.droplet.ip.address A (Address) n/a 60
* your.droplet.ip.address A (Address) n/a 60

The * entry for subdomains allows you to make any number of apps on different subdomains.

5. Generate an SSH Key Pair

I’ll describe what these are in more detail below in the Set up SSH Keys section. Don’t worry too much about it right now, just generate a pair like this:

  1. Go into your .ssh directory: cd ~/.ssh
  2. Type: ssh-keygen
  3. When prompted, enter a name for the pair (I used rslab)
  4. If you’d like to password protect it enter a password (I left this blank)
  5. After it’s done, you should have two files: {name} and {name}.pub

6. Install Dokku-alt

Login to your Droplet and install dokku-alt using the handy one line script:

sudo bash -c "$(curl -fsSL bit.ly/dokku-alt)"

Check virtual host naming if you’d like your Dokku apps to be formatted like app-name.your.domain.

Follow the instructions on screen and you’ll be set up.

After a minute or two, it will prompt you to open your browser to configure via a web page, when you do, you should see a screen that has several fields. Add a public ssh key from the previous step (that’s the one that ends in .pub).

Hostname should be your domain name exactly.

Check virtual host naming if you’d like your Dokku apps to be formatted like app-name.your.domain.

Click Finish Setup

7. Set up SSH Keys

To make it so you don’t have to type your password every time you connect to your droplet or push to Dokku, you can set up ssh keys. Basically, there are two files, one that is on your machine, and one that is on the Digital Ocean droplet. The droplet checks to make sure you have the key that matches it’s key, and automatically connects you without a password. We created the keys a few steps back, now let’s use them to connect to our droplet.

Make Sure you Have the Keys

  1. Go into your .ssh directory: cd ~/.ssh
  2. Ensure your keys you generated previously are still there. You should see them listed if you type ls -l.
  3. If they aren’t there, generate a new pair (see above).
  4. Create a Config File

Create a file named config inside your .ssh/ directory so your computer knows to use the new ssh keys for your domain. My config looks like this:

Host rslab rslab.me
Hostname rslab.me
IdentityFile ~/.ssh/rslab

Basically, this is how ssh knows to use that particular key for that host. Obviously change rslab.me to your domain, and .ssh/rslab to whatever you named your ssh keys.

Put the Public Key on your Droplet

To upload the public key to your droplet, just type:

cat ~/.ssh/{name}.pub | ssh [email protected] "cat >> ~/.ssh/authorized_keys"

Replacing the {name} with your key name and your.domain with your domain name.

Connect Without a Password

You should now be able to now connect to your droplet without a password like this: ssh [email protected]

If that worked, you can now (optionally) disable password login to your droplet:

Connect to your droplet: ssh [email protected] Open your config: sudo nano /etc/ssh/sshd_config Find the PermitRootLogin line and edit it so it reads: PermitRootLogin without-password Reload your ssh: reload ssh

8. Deploy your first App

Now you can deploy apps on your Dokku. Let’s deploy the Heroku Node.js sample app. All you have to do is add a remote to name the app. It’s created on-the-fly.

$ git clone https://github.com/heroku/node-js-sample
$ cd node-js-sample
$ git remote add deploy [email protected]:node-js-app
$ git push deploy master
Counting objects: 296, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (254/254), done.
Writing objects: 100% (296/296), 193.59 KiB, done.
Total 296 (delta 25), reused 276 (delta 13)
-----> Building node-js-app ...
       Node.js app detected
-----> Resolving engine versions
... blah blah blah ...
-----> Application deployed:
       http://node-js-app.YOURDOMAIN.com

You’re done!

Right now Buildstep supports buildpacks for Node.js, Ruby, Python, PHP, and more.

It’s not hard to extend the list with your own buildpack. Please check the documentation for your particular build pack as you may need to include configuration files (such as a Dockerfile or Procfile) in your project root.

9. Enable manager

Dokku-alt includes a handy manager that you can use to manage your apps from a web interface, to set this up use:

It’s a web interface to easily manage your dokku-alt instance. To install manager, simply run:

dokku manager:install

You can enable or disable it anytime:

dokku manager:enable
dokku manager:disable

Or even uninstall if you prefer command line access (it will also wipe used database):

dokku manager:uninstall

Once set up, you can access the manager from http://dam.YOURDOMAIN.com

10. Set up SWAP

This bit of preemptive work helps out a lot if you use a box with 512MB of memory, to prevent these messages:

runtime: panic before malloc heap initialized
fatal error: runtime: cannot allocate heap metadata

Run the following (it will create 512MB swap file, you can adjust it for your needs):

dd if=/dev/zero of=/extraswap bs=1M count=512
mkswap /extraswap

Add it to /etc/fstab:

/extraswap         none            swap    sw                0       0

Turn it on:

swapon -a

11. Configuring apps to run on another domain

It’s also pretty easy to use another domain and point it to Dokku.

Let’s say you are building a little site for a domain you own, we’ll call it my-special-domain.com, but you set up Dokku on another domain like dokku-domain.com. When you decide to deploy your site, all you need to do is change the DNS records for my-special-domain. In your DNS registrator, change the @ and CNAME records like this:

HOST NAME IP ADDRESS/URL RECORD TYPE MX PREF TTL
@ your.droplet.ip.address A (Address) n/a 60
www your.domain CNAME n/a 60

Then when you add your remote, you would add it like this:

git remote add dokku [email protected]:my-special-domain.com

Once the domain is pointing to your droplet’s IP and you’ve pushed to your remote, you should see your app on my-special-domain.com.

12. Hosting a static website

If you want to deploy a static website, there are two methods:

Deploying a Static App in a Subfolder

Deploying a static app actually took a bit of hunting around to find, but once I figured it out, it’s dead simple. Essentially you just include an empty .nginx file in the root level of your project, and put all your static content in a www directory and it will be served on an nginx server automatically. For example, if I had a simple index.html file and a style.css file I wanted to serve statically, my project would look something like this:

.nginx
www
  - index.html
  - style.css

That’s it! You can have as many folders and files inside the www directory as you need and it will serve it up statically for you. This is really useful if you use a static site generator to produce a folder of html as you can just set it to build to /www and your site will automatically work.

Deploying a Static App From the Root Folder

If you have no need for a subfolder, you can deploy a static app from the root of your project by adding an empty .htaccess file. The folder structure would look something like this:

.htaccess
index.html
style.css

Dokku should automagically understand that you’re writing an app that uses Apache and give you a simple static site after you push.

13. Deleting an App

If you want to remove an app, first, connect with ssh:

ssh [email protected]

If you set up ssh keys, this should work without a password. Then simply run:

dokku delete app_name

Where app_name is the name of the app you’d like to delete.

If you set up the manager then you can also delete an app from the manager itself.

Finishing up

That’s it, you’ve now built your own mini Heroku using Dokku.

I’ve got my main Dokku server running PHP, Node.js, Static and a Jekyll site and they all run nicely together.

Amazon EC2 works well with this as well, actually any server running Ubuntu will work well, but I specifically used Digital Ocean in this post due to being a Digital Ocean user.

Originally published on my personal blog