How to pass Pulumi's Output<T> to the container definition of a task within ecs? - json

Question

A containerDefinition within a Task Definition needs to be provided as a single valid JSON document. I'm creating a generic ECS service that should handle dynamic data. Here is the code:
genericClientService(environment: string, targetGroupArn: Output<string>) {
return new aws.ecs.Service(`${this.domainName}-client-service-${environment}`, {
cluster: this.clientCluster.id,
taskDefinition: new aws.ecs.TaskDefinition(`${this.domainName}-client-${environment}`, {
family: `${this.domainName}-client-${environment}`,
containerDefinitions: JSON.stringify(
clientTemplate(
this.defaultRegion,
this.domainName,
this.taskEnvVars?.filter((object: { ENVIRONMENT: string }) => object.ENVIRONMENT === environment),
this.ecrRepositories
)
),
cpu: "256",
executionRoleArn: taskDefinitionRole.arn,
memory: "512",
networkMode: "awsvpc",
requiresCompatibilities: ["FARGATE"],
}).arn,
desiredCount: 1,
...
There is a need of information from an already built resource this.ecrRepositories which represents a list of ECR repositories needed. The problem here is that let's say you want to retrieve the repository URL and apply the necessary 'apply()' method, it will return an Output<string>. This would be fine normally, but since containerDefinitions needs to be a valid JSON document, Pulumi can't handle it since JSON on an Output<T> is not supported;
Calling [toJSON] on an [Output<T>] is not supported. To get the value of an Output as a JSON value or JSON string consider either: 1: o.apply(v => v.toJSON()) 2: o.apply(v => JSON.stringify(v)) See https://pulumi.io/help/outputs for more details. This function may throw in a future version of #pulumi/pulumi.
Blockquote
Neither of the suggested considerations above will work as the dynamicly passed variables are wrapped within a toJSON function callback. Because of this it won't matter how you pass resource information since it will always be an Output<T>.
Is there a way how to deal with this issue?

Answer 1

Assuming clientTemplate works correctly and the error happens in the snippet that you shared, you should be able to solve it with
containerDefinitions: pulumi.all(
clientTemplate(
this.defaultRegion,
this.domainName,
this.taskEnvVars?.filter((object: { ENVIRONMENT: string }) => object.ENVIRONMENT === environment),
this.ecrRepositories
)).apply(JSON.stringify),