Referencing a loop object - kubernetes

Question

i am currently checking out tanka + jsonnet. But evertime i think i understand it... sth. new irritates me. Can somebody help me understand how to do a loop-reference? (Or general better solution?)
Trying to create multiple deployments with a corresponding configmapVolumeMount and i am not sure how to reference to the according configmap object here?
(using a configVolumeMount it works since it refers to the name, not the object).
deployment: [
deploy.new(
name='demo-' + instance.name,
],
)
+ deploy.configMapVolumeMount('config-' + instance.name, '/config.yml', k.core.v1.volumeMount.withSubPath('config.yml'))
for instance in $._config.demo.instances
],
configMap: [
configMap.new('config-' + instance.name, {
'config.yml': (importstr 'files/config.yml') % {
name: instance.name,
....
},
}),
for instance in $._config.demo.instances
]
regards

Answer 1

Great to read that you're making progress with tanka, it's an awesome tool (once you learned how to ride it heh).
Find below a possible answer, see inline comments in the code, in particular how we ab-use tanka layout flexibility, to "populate" deploys: [...] array with jsonnet objects containing each paired deploy+configMap.
config.jsonnet
{
demo: {
instances: ['foo', 'bar'],
image: 'nginx', // just as example
},
}
main.jsonnet
local config = import 'config.jsonnet';
local k = import 'github.com/grafana/jsonnet-libs/ksonnet-util/kausal.libsonnet';
{
local deployment = k.apps.v1.deployment,
local configMap = k.core.v1.configMap,
_config:: import 'config.jsonnet',
// my_deploy(name) will return name-d deploy+configMap object
my_deploy(name):: {
local this = self,
deployment:
deployment.new(
name='deploy-%s' % name,
replicas=1,
containers=[
k.core.v1.container.new('demo-%s' % name, $._config.demo.image),
],
)
+ deployment.configMapVolumeMount(
this.configMap,
'/config.yml',
k.core.v1.volumeMount.withSubPath('config.yml')
),
configMap:
configMap.new('config-%s' % name)
+ configMap.withData({
// NB: replacing `importstr 'files/config.yml';` by
// a simple YAML multi-line string, just for the sake of having
// a simple yet complete/usable example.
'config.yml': |||
name: %(name)s
other: value
||| % { name: name }, //
}),
},
// Tanka is pretty flexible with the "layout" of the Kubernetes objects
// in the Environment (can be arrays, objects, etc), below using an array
// for simplicity (built via a loop/comprehension)
deploys: [$.my_deploy(name) for name in $._config.demo.instances],
}
output
$ tk init
[...]
## NOTE: using https://kind.sigs.k8s.io/ local Kubernetes cluster
$ tk env set --server-from-context kind-kind environments/default
[... save main.jsonnet, config.jsonnet to ./environments/default/]
$ tk apply --dry-run=server environments/default
[...]
configmap/config-bar created (server dry run)
configmap/config-foo created (server dry run)
deployment.apps/deploy-bar created (server dry run)
deployment.apps/deploy-foo created (server dry run)