[av_dropcap1]H[/av_dropcap1]eroku (and Dokku) make for an awesome development environment- the most well-known feature being the use of “git push” to deploy changes to a server. For simple projects, I’ve found that the deployment time is as fast as compilation times on JVM based projects, except that at the end you have a working environment.
Knowing you can deploy an environment at any time during a project means you can spin up as many environments as you want later, and it forces you to think through migrations in your checkins.
The downside of Heroku is that you are somewhat locked in, and if you want to build many small applications as a hobbyist, it adds up ($7/mo to keep one app running – the free ones shut down all the time). On the other hand, you could just set up a VM to run several apps, which guarantees many wasted hours on dependency hell problems (every time you update a shared library, you risk breaking what you have previously built).
[av_dropcap1]C[/av_dropcap1]onceptually this setup is not that complex, but there are a lot of moving parts to get right, and it isn’t that satisfying to work on vs. actually building things.
To build a system like Heroku where you can push from git, you’d start by checking a script into the repository that runs when code is pushed to one of the remote repositories (a post-commit hook). This would kick off the deployment.
Heroku also has you check in a script to the root of your repository that defines what you want to run (a bash script with something like “node index.js” and any arguments). This lets them control the deployment, and lets the developer control what actually runs.
[av_dropcap1]V[/av_dropcap1]irtualization at the operating system-level saves you from dependency issues (called “Linux Containers” or “LXC”), without having to build and secure a VM for every app. Linux containers seem pretty complex and I would assume there are some good ways to screw this up from a security perspective. It is new enough that tools and best practices aren’t as mature and clear as the older generation, so it’s easy to get mired in all the options (the few hours I spent trying to get Docker working have yet to pay off)
There is an open-source script called Dokku (a Star Wars reference, perhaps?), which ties all these pieces together for you, and tries to act as much like Heroku as possible. Consequently you can use a cheap virtual machine, and then upgrade it when you need real infrastructure. The marketing materials for Dokku seem quite slick, so I suspect that one or more companies is sponsoring it (probably someone like Digital Ocean), although I haven’t been able to find evidence of this.
[av_dropcap1]D[/av_dropcap1]igital Ocean has a pre-built Dokku image you can use at $5/mo. While they’ve had some growing pains, they typically give out credits when they have issues. If you follow them on Facebook and subscribe to their give out a lot of coupons as well, which has made the $5 VMs basically free – clearly a loss leader for them (feel free to use my referral link – you get $10 off to start, and I get another $25)
Regardless of who you use, if you set up a Dokku image, there is a page where you upload your SSH public key:
This lets it accepts your “git push.”
If you want to use subdomains for each app like Heroku does, you’ll need to add them to your DNS manually. I put Cloudflare on any site I can, if only because it has the best DNS management UI I’ve ever seen (and they don’t do referral links, unfortunately!):
Once you set these two things up, ssh into the VM.
You can run create commands for each app you want to configure:
dokku apps:create editor dokku apps:create meeting dokku apps:create gmail-search dokku apps:create document-search
This will let your VM receive pushes.
Then, to push changes, you need to set up the remote:
git remote add dokku firstname.lastname@example.org:generic-search-ui
If you add this to an existing app, you can push to both Heroku and Dokku simultaneously by doing this:
git push heroku master git push dokku master
You will see the same sort of commit log on the remote that you see with Heroku:
gary@gary-PC MINGW64 /d/projects/heroku/editor (master) $ git push dokku master Counting objects: 451, done. Delta compression using up to 8 threads. Compressing objects: 100% (350/350), done. Writing objects: 100% (451/451), 47.84 KiB | 0 bytes/s, done. Total 451 (delta 305), reused 138 (delta 91) -----> Cleaning up... -----> Building editor from herokuish... -----> Setting config vars CURL_CONNECT_TIMEOUT: 5 -----> Setting config vars CURL_TIMEOUT: 30 -----> Adding BUILD_ENV to build environment... -----> Node.js app detected -----> Creating runtime environment NPM_CONFIG_LOGLEVEL=error NPM_CONFIG_PRODUCTION=true NODE_ENV=production NODE_MODULES_CACHE=true -----> Installing binaries engines.node (package.json): 5.5.0 engines.npm (package.json): unspecified (use default) Downloading and installing node 5.5.0... Using default npm version: 3.3.12 -----> Restoring cache Skipping cache restore (new runtime signature) -----> Building dependencies Pruning any extraneous modules Installing node modules (package.json) email@example.com /tmp/build +-- firstname.lastname@example.org ... -----> Caching build Clearing previous node cache Saving 2 cacheDirectories (default): - node_modules - bower_components (nothing to cache) -----> Build succeeded! +-- email@example.com +-- firstname.lastname@example.org +-- email@example.com +-- firstname.lastname@example.org +-- email@example.com +-- firstname.lastname@example.org +-- email@example.com +-- firstname.lastname@example.org +-- email@example.com `-- firstname.lastname@example.org -----> Discovering process types Procfile declares types -> web -----> Releasing editor (dokku/editor:latest)... -----> Deploying editor (dokku/editor:latest)... -----> DOKKU_SCALE file not found in app image. Generating one based on Procfile... -----> New DOKKU_SCALE file generated =====> web=1 -----> Running pre-flight checks For more efficient zero downtime deployments, create a file CHECKS. See http://dokku.viewdocs.io/dokku/checks-examples.md for examples CHECKS file not found in container: Running simple container check... -----> Waiting for 10 seconds ... -----> Default container check successful! =====> editor container output: Node app is running on port 5000 =====> end editor container output -----> Running post-deploy =====> renaming container (3735de61fe0a) suspicious_euclid to editor.web.1 -----> Creating new /home/dokku/editor/VHOST... -----> Setting config vars DOKKU_NGINX_PORT: 80 -----> Configuring editor.garysieling.com... (using /var/lib/dokku/plugins/available/ nginx-vhosts/templates/nginx.conf.template) -----> Creating http nginx.conf -----> Running nginx-pre-reload Reloading nginx -----> Setting config vars DOKKU_APP_RESTORE: 1 =====> Application deployed: http://editor.garysieling.com To email@example.com:editor * [new branch] master -> master
Then, if you need a database, you can install this as well:
sudo dokku plugin:install https://github.com/dokku/dokku-postgres.git dokku postgres:link editor editor
I name my database and my apps the same, which makes the above command a little unclear.
Dokku supports the same concept of environment configuration variables that Heroku does (i.e. your database connection string, API keys, etc should never be checked in). When you run the above commands, you will get log entries like this:
no config vars for generic-search-ui -----> Setting config vars DATABASE_URL: postgres://postgres:baf4@dokku-editor:5432/editor -----> Restarting app generic-search-ui App generic-search-ui has not been deployed
If you are migrating an application and change the DNS, you will need to update any references in external services – e.g. typekit, the twitter developer API, Google Developer keys, etc.
Once you’ve set this up, there are some useful troubleshooting commands. E.g. list installed apps:
dokku apps root@ubuntu-512mb-nyc2-01:~# dokku apps =====> My Apps editor generic-search generic-search-ui
Viewing logs is a little more complex – you need to list the running processes, and get them using docker:
root@ubuntu-512mb-nyc2-01:~# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES fcc5604164c9 dokku/generic-search-ui:latest "/start web" About a minute ago Up About a minute generic-search-ui.web.1 e4e42ace32f2 postgres:9.5.0 "/docker-entrypoint.s" About an hour ago Up About an hour 5432/tcp dokku.postgres.generic-search-ui 697e11c55807 dokku/editor:latest "/start web" 2 days ago Up 2 days editor.web.1 docker attach fcc5604164c9
And there you have it- your own PaaS, with limited dependencies on external companies for hosting.
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