[RFC] Flags for customizing service creation and links

[josegonzalez]

Rather than have a bunch of semi-related issues open, I'll open a single issue to track the various flags we want to add:

Creation Flags

• Cleaner mongo:create with image, version and options dokku-mongo#37
• Set postgres image/version with postgres:create option dokku-postgres#61
• Enabled ES version as create and delete params dokku-elasticsearch#28

We currently allow some values to be configured via environment variables. This doesn't work as well when users are running commands over ssh. We should instead allow users to specify any of these initial values during the creation step.

• service:create: Add the ability to specify a flag --config-options "OPTS" to define any extra options.
  • Mongo specific
• service:create: Add the ability to specify a flag --custom-env "USER=alpha;HOST=beta" to define the custom env.
• service:create: Add the ability to specify a flag --image IMAGE to define the image name.
• service:create: Add the ability to specify a flag --image-version IMAGE_VERSION to define the image version.
• service:create: Add the ability to specify a flag --password PASSWORD to define the password.
  • Should include a warning that doing this may not be as secure as our random password.
• service:create: Add the ability to specify a flag --root-password PASSWORD to define the root password.
  • Should include a warning that doing this may not be as secure as our random password.

Clone Flags

• dokku postgres:clone ignores POSTGRES_IMAGE_VERSION #105

Upgrading/Downgrading is now impossible since dokku/dokku-postgres@6a86efc, and we should allow folks to easily override the environment variables via flags.

• service:clone: Add the ability to specify a flag --image IMAGE to define the image name.
• service:clone: Add the ability to specify a flag --image-version IMAGE_VERSION to define the image version.

Link Aliases

• can't link or promote 2 redis into same app #52
• mongo:link infinite loop dokku-mongo#44

We have a finite number of services that can be linked at once to an application, limited by a hardcoded list of colors. When that list is depleted, we'll have an infinite loop where we cannot link a service to an app. Users may also wish to specify the exact alias being used for the link so that it is easy to predict what the url for a service will be.

• service:link: Fail hard when the max number of automatic alias names is reached.
• service:link: Add the ability to specify a flag --alias ALIAS for the purposes of defining the exact link alias.
  • The link value should not be prefixed or suffixed with either the name of the plugin or _URL.

Memcached Memory Limit

• How to specify the cache size? dokku-memcached#21

Memcached is currently limited to 64 megabytes. This is probably good for most of our users - people use Dokku on memory-limited servers - but there are cases where they may wish to use more memory.

• service:create: Add the ability to specify a flag --memory MB for the purposes of defining the memory in use.
  • Default to 64, and write this value to disk. This should be used anytime the container is recreated.

Export Options

• Locking tables dokku-mariadb#56

• service:export: Add the ability to specify a flag --export-options "OPTS" to define any extra options.

  • Mariadb/MySQL specific
  • Ignore for the backup automation commands for now.

Querystring Values

• set database connection pool in URL dokku-postgres#56

Some frameworks use querystring values as a way to specify conditions for the connection. For instance, you might set the connection collation or pool size.

• service:link: Add the ability to specify a flag --querystring "key=value&key=value".
  • Validate that the querystring does not begin with a ?. Chop it off it is is there.
  • Do not perform any other validation on this value. If people want to screw it up, not much we can do.
  • Just append it to the end of the url if it is non-zero in length, after a ?.

Single Container Usage

• one service with multiples databases dokku-mariadb#35
• is it possible to link multiple apps to single mysql container with separate database per app? dokku-mysql#44
• single container? dokku-postgres#49

Users on smaller VPSs will want to save memory by not running many containers for a database service. This will allow us to mark all community service plugins as deprecated.

• service:create-database <service> <database-name>: Create this command.
  • Store the list of databases in /var/lib/dokku/services/postgres/SERVICE/databases/NAME, where each file is simply the name of a database.
• service:create: Store the user/pass info on disk in a new format:
  • Store the user/pass info in a set of files located in /var/lib/dokku/services/postgres/SERVICE/auth/USERNAME, where the username is the name of the user, and the contents are the password. Note that we will need to migrate all the old auth stuff over, including any root users.
  • Users will have access to everything in the service. If a developer needs to lockdown a specific user, that's on them to coordinate later.
• service:create-user <service> <username> <password>: Create this command.
• service:link: Add the ability to specify a flag --user USERNAME to specify the user that will be set for a specific link.
• service:link: Add the ability to specify a flag --database DATABASE to specify the database that will be set for a specific link.

[josegonzalez]

Useful stackoverflow comment on argparsing. Repost follows:

---

As other people explained, getopts doesn't parse long options. You can use getopt, but it's not portable (and it is broken on some platform...)

As a workaround, you can implement a shell loop. Here an example that transforms long options to short ones before using the standard getopts command (it's simpler in my opinion):

# Transform long options to short ones
for arg in "$@"; do
  shift
  case "$arg" in
    "--help") set -- "$@" "-h" ;;
    "--rest") set -- "$@" "-r" ;;
    "--ws")   set -- "$@" "-w" ;;
    *)        set -- "$@" "$arg"
  esac
done

# Default behavior
rest=false; ws=false

# Parse short options
OPTIND=1
while getopts "hrw" opt
do
  case "$opt" in
    "h") print_usage; exit 0 ;;
    "r") rest=true ;;
    "w") ws=true ;;
    "?") print_usage >&2; exit 1 ;;
  esac
done
shift $(expr $OPTIND - 1) # remove options from positional parameters

[MichaelSp]

Is there an ETA for the "Single Container"-Feature?

[josegonzalez]

Whenever I get to it. Dokku doesn't pay the bills, so if you want to help change that, let me know and I can get you an ETA.

[javierav]

@josegonzalez I am interested in the "Single Container" feature, how can I help with this issue?

[decentral1se]

🎉 🎉 🎉

[Alir3z4]

Could postgresql container memory limit get included in that list ?

Ref dokku/dokku-postgres#188