Notes from running Dokku on Digital Ocean.

My notes for Dokku on Digital Ocean.

These may be a bit outdated: Since I originally wrote them, I've reinstalled on a newer Dokku and may not have updated every section below.

Commands

Install dokku-cli (gem install dokku-cli) for a more Heroku-like CLI experience (dokku config:set FOO=bar).

# List/run commands when not on Dokku server (assuming a "henroku" ~/.ssh/config alias)
ssh henroku dokku
ssh henroku dokku config:get my-app

# Access the server, list commands, run command
ssh henroku
dokku
dokku config:get my-app

# See memory usage
# Source: https://gist.github.com/SQiShER/5d8cd3f14e4c72c39456#gistcomment-2209487
sudo docker stats $(sudo docker ps --format={{.Names}})
# With highest usage first, not live-updating
# Source: https://stackoverflow.com/a/54230482/6962
sudo docker stats --no-stream --format "table {{.Name}}\t{{.Container}}\t{{.MemUsage}}" | sort -k 3 -h -r
 
# See server stats (memory, disk usage, load) - same as shown on login
landscape-sysinfo

# Interesting dirs
cd /var/lib/dokku/plugins  # plugins
cd ~dokku  # apps

Adding a new app

git remote add dokku [email protected]:my-app  # Note to self: This might actually be "dokku.nyh.name" these days.
git push dokku

ssh henroku dokku domains:add my-app my-app.nyh.name  # and configure DNS

# DB?
ssh henroku dokku psql:create my-app

# memcache?
ssh henroku dokku memcached:create my-app  # MEMCACHE_SERVERS env will be set

Working with an app

# See logs
ssh henroku dokku logs my-app -t

# Conf
ssh henroku dokku config:get my-app
ssh henroku dokku config:set my-app KEY1=val KEY2=val

Removing a plugin

cd /var/lib/dokku/plugins
rm -rf the-plugin

# List containers, remove the ones from the plugin
ssh henroku
sudo docker ps -a
docker rm <the id>

# List images, remove the ones from the plugin
docker images
docker rmi <the id>

How to uninstall a Dokku plugin

Setup

Use Digital Ocean's "Ubuntu with Dokku" image.

Create a swapfile to avoid out-of-memory errors during build/deploy (I got those sometimes even with a 1 GB RAM image):

ssh henroku
dd if=/dev/zero of=/swapfile bs=1024 count=1024000
mkswap /swapfile
swapon /swapfile

Change the default root password to avoid later issues with crontab not working:

sudo -u root passwd

Follow the instructions, specifying a new password as prompted, and store it in e.g. 1Password.

DNS

It's convenient to set up wildcard DNS so e.g. *.henroku.nyh.name points to this server.

With LoopiaDNS, you need to add a CNAME for sub-subdomain wildcards (e.g. *.henroku.nyh.name pointing to henroku.nyh.name).

Plugins

memcached

https://github.com/Flink/dokku-memcached-plugin

This fork seems to be the most up to date, with nice features like autostart on server reboot.

cd /var/lib/dokku/plugins
git clone [email protected]:Flink/dokku-memcached-plugin.git
git clone https://github.com/rlaneve/dokku-link.git link  # dependency
dokku plugins-install

PostgreSQL

https://github.com/Flink/dokku-psql-single-container

Before you install, see the section on getting a newer version of Postgres. At the time of writing, 9.4 has some cool new features over the default 9.3.

After install, run: dokku psql:start

(Got errors from Kloadut/dokku-pg-plugin, and it seems unmaintained.)

DB backups

Put one of these scripts (for dokku-postgres or for dokku-psql-single-container) in /root/database_backups.sh, run chmod +x /root/database_backups.sh.

Then add something like this to crontab:

# m h  dom mon dow   command
  0 0  *   *   *     /root/database_backups.sh

You will get daily backups in /var/backups/postgres. The script keeps a few days and then removes too old ones. Digital Ocean's infrequent server backups will include these dumps.

I recommend also adding a healthcheck to the cron job.

Static sites alongside Dokku

See this blog post.

henrik/dokku_on_digital_ocean.md