Use a Global Static List¶

Warning

Requires permissions to modify the global cluster configurations located under:

/etc/ood/config/clusters.d/

You can take advantage of the Cluster Configuration files for defining a common static queue/partition list that can be used across all properly configured Interactive Apps. This is accomplished by:

Modify Cluster Configuration
Add Custom Attribute to Form
Handle Custom Attribute in Job Submission

Modify Cluster Configuration¶

Danger

This assumes you have walked through Add Cluster Configuration Files for the cluster you intend on submitting the Interactive App to.

We will add a custom: field to our cluster configuration file if it doesn’t already exist and then introduce a custom field (named anything your heart desires) with a list of available queues/partitions:

# /etc/ood/config/clusters.d/my_cluster.yml
---
v2:
  metadata:
    title: "My Cluster"
  login:
    host: "my_cluster.my_center.edu"
  job:
    # ... resource manager specific options here ...
  custom:
    queues: # this can be named anything your heart desires
      - "queue1"
      - "queue2"

Warning

Be sure to click “Restart Web Server” on the Dashboard everytime you edit the Cluster Configuration file for changes to take effect within the app.

Add Custom Attribute to Form¶

We want to replace the bc_queue form attribute with a custom HTML <select> element (a drop-down list of options) built up of queue/partition options read from the corresponding cluster configuration file.

Note

You can read more about customizing attributes in the form.yml file for Interactive Apps under the Customizing Attributes section.

First we rename the form.yml for the Jupyter Interactive App to form.yml.erb:
```
mv ~/ondemand/dev/jupyter/form.yml ~/ondemand/dev/jupyter/form.yml.erb
```
This will cause the YAML file to be processed using the eRuby (embedded Ruby) templating system, which allows us to embed Ruby code into the YAML configuration file for flow control, variable substitution, and more.

Next we remove the bc_queue field from our form.yml for the Jupyter Interactive App by removing the following line from this file:

# ~/ondemand/dev/jupyter/form.yml.erb
---
cluster: "my_cluster"
attributes:
  modules: "python"
  extra_jupyter_args: ""
form:
  - modules
  - extra_jupyter_args
  - bc_account
  - bc_queue
  - bc_num_hours
  - bc_num_slots
  - bc_email_on_started

We remove the following line from this file:
```
- bc_account
- bc_queue
- bc_num_hours
```
Now when we refresh the web page for our sandbox Jupyter App we won’t see the “Queue” form element anymore.
We now add in code that reads in the list of available queues/partitions from the cluster configuration file and generates a custom drop-down attribute with this list of queues/partitions:
```
# ~/ondemand/dev/jupyter/form.yml.erb
<%-
  queues = OodAppkit.clusters[:my_cluster].custom_config[:queues]
-%>
---
cluster: "my_cluster"
attributes:
  modules: "python"
  extra_jupyter_args: ""
  custom_queue:
    label: Queue
    help: Please select a queue from the drop-down.
    widget: select
    options:
    <%- queues.each do |q| -%>
      - [ "<%= q %>", "<%= q %>" ]
    <%- end -%>
form:
  - modules
  - extra_jupyter_args
  - bc_account
  - custom_queue
  - bc_num_hours
  - bc_num_slots
  - bc_email_on_started
```
At the top we have an execution tag that sets a local variable queues from a line of Ruby code that should read in the list of queues you defined under custom: and queues: for the corresponding cluster configuration file.
Warning

The cluster defined in OodAppkit.clusters[:my_cluster] must correspond to a cluster with a cluster configuration file. Also it should match the cluster defined on the line:
```
cluster: "my_cluster"
```
in the form.yml.erb file above.
Later in the YAML file we have another execution tag that loops through this list of queues/partitions in the local variable queues. It uses a pair of expression tags to output a YAML pair list (see the note below).

Now when we refresh the web page for our sandbox Jupyter App we will see a “Queue” form element with a drop-down that lists “queue1” and “queue2”. Underneath this will be our custom help message defined above.
Note

An attribute with the field widget: select expects an options: field with an array of pairs. The first string in the pair is the option text and the second string in the pair is the option value.

For example:
```
widget: select
options:
  - [ "Volvo", "volvo" ]
  - [ "Ford", "ford" ]
  - [ "Toyota", "toyota" ]
```
The user will see a list of options: “Volvo”, “Ford”, and “Toyota” to choose from in the HTML form, but the backend will process a value of either “volvo”, “ford”, or “toyota” depending on what the user chose.

Handle Custom Attribute in Job Submission¶

Now that we have our custom form attribute called custom_queue, we need to tell our app how to handle it when submitting the job. As of right now our app has no idea what to do with this value when the user clicks “Launch” after filling out the form.

Note

You can read more about customizing submission arguments in the submit.yml.erb file for Interactive Apps under the Job Submission section.

We first start with the default submit.yml.erb for the Jupyter Interactive App:

# ~/ondemand/dev/jupyter/submit.yml.erb
---
batch_connect:
  template: "basic"

We now create a script: section if it doesn’t already exist and handle the value of the custom_queue attribute submitted by the user:
```
# ~/ondemand/dev/jupyter/submit.yml.erb
---
batch_connect:
  template: "basic"
script:
  queue_name: <%= custom_queue %>
```
Where we take advantage of the generic OodCore::Job::Script#queue_name method to supply a queue/partition that is resource manager (e.g., Slurm, Torque, …) agnostic.

Note

For the queue/partition we do not need to use the native: field which must be customized for the specific resource manager you are leveraging.

You can find a list of generic fields that are resource manager agnostic under the OodCore::Job::Script documentation.