markdown 在数字海洋上运行Dokku的注意事项。

Posted 2021-05-06

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These may be a bit outdated: Since I originally wrote them, I've reinstalled on a newer Dokku and may not have updated every section below.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](https://github.com/SebastianSzturo/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 (from: https://github.com/progrium/dokku/issues/1297)
    docker ps -q | xargs docker stats
    # Compare to the names you see here
    docker ps
     
    # 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 [e-mail]:my-app
    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](https://github.com/progrium/dokku/issues/519)

## Setup

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

[Create a swapfile](http://dev.housetrip.com/2014/07/06/deploy-rails-and-postgresql-app-to-dokku/) 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](http://askubuntu.com/a/846048/443378):

```
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 [e-mail]: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](https://github.com/Flink/dokku-psql-single-container#providing-an-alternative-docker-image-for-postgresql). 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](https://gist.github.com/henrik/5ebff4ba7d18df85144520e20210a178) or [for dokku-psql-single-container](https://gist.github.com/henrik/1043fecdd0937034cd62)) in `/root/database_backups.sh`, run `chmod +x /root/database_backups.sh`.

Then add something like this to crontab:

``` cron
# 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](https://healthchecks.io/docs/#crontab) to the cron job.

## Static sites alongside Dokku

See [this blog post](https://thepugautomatic.com/2016/01/static-sites-alongside-dokku-on-digital-ocean/).

## Resources

* [Dokku docs](http://progrium.viewdocs.io/dokku/installation/)
* [Dokku plugins](http://progrium.viewdocs.io/dokku/plugins/)
* [Copying a Heroku DB to dokku-psql-single-container](https://gist.github.com/henrik/e6817dd10d9c9a36c22a)