health_check | Simple health check of Rails app | Monitoring library

The resource attributes to metrics label conversion is disabled by default. Please update the otel config to following to see the resource attribute is prom UI.

values returns values in alphanumerical order, not in the order you have them defined. Thus, the first value returned will be 28883. Subsequently, var.healthcheck_map["28883"] fails, because var.healthcheck_map has only 8883 key, not the required 28883.

Basically, your values in var.listen_map do not match keys in var.healthcheck_map.

You can use a for expression to iterate through the object of your exported resource and construct a map with all of the target groups and their associated ARNs:

All your apt commands do not have -y flag. Which means that your script will hang for manual confirmation to perform any updates and installations.

There could be other issues, but this one is the most apparent one.

Q1: When to use a CF Application with Sidecar vs when to use a CF Application with Processes

Different process types are helpful when you have well-separated applications. They might talk to each other, they might interact, but it's done through some sort of published interface like a REST API or through a message queue.

A typical example is a work queue. You might have one process that's running your web application & handling traffic, but if a big job comes in then it'll instruct a worker process, running separately, to handle that job. This is often done through a message queue. The advantage is you can scale each individually.

With a sidecar, they are in the same process. This works well for the scenario where you need tight coupling between two or more processes. For example, if you need to share the same file system or if you have proxy process that intercepts traffic.

The two processes are often linked in a way that they are scaled in tandum, i.e. there is a one-to-one relationship between the processes. This relationship is necessary because if you scale up the application instance count, you're scaling up both. You cannot scale them independently.

In an application with multiple processes , if I want to run 2 processes in 2 different technology ( one process on Java another process in Go / anything else), how to do so ?

You're correct. You'd need to rely on multi-buildpack support.

Your application is only staged once and a single droplet is produced. Each process is spun up from the same droplet. Everything you need must be built into that one droplet. Thus you need to push everything all together and you need to run multiple buildpacks.

In your manifest.yml, the buildpacks entry is a list. You can specify the buildpacks you want to run and they will run in that order.

Alternatively, you could pre-compile. If you're using Go. Cross-compilation is often trivial, so you could compile ahead of time and just push the binary you generate with your application.

In this context how can one process call/talk/interact with the other processes within the application. What are the options available here ? I could not find any sample which demonstrate multiple interacting processes within an app, any sample would be really helpful.

I'll split this in two parts:

If you're talking about apps running as a sidecar, it depends on what the sidecar does, but you have options. Basically, anything you can do in a Linux environment, keeping in mind you're running as a non-root user, you can do. Coordinate through a shared file/folder, intercept the network port & proxy to another port, or other ipc.

If you're talking about multiple processes (the CF terminology) such that you have each running in a separate container, then you are more limited. You would need to use some external method to communicate. This could be a service broker, a database (not recommended), or an API (Rest, gRCP or rsocket are all options).

Note that this "external" method of communication doesn't necessarily need to be public, just external to the container. You could use a private service like a broker/DB, or you could use internal routes & container networking.

Q4 : Difference between Multi Target Application vs Multi Process Application

Sorry, I'm not sure about this one. Multi Target apps are not a core concept in CF. I'll leave it for someone else to answer.

Try to increase first_byte_timeout parameter like this:

Rails 7 is using hotwire and turbo instead of Rails/ujs. So link_to have some problems, change link_to to button_to, it should work.

Here is some documentation about Setting up HTTP(S) Load Balancing with Ingress. This tutorial shows how to run a web application behind an external HTTP(S) load balancer by configuring the Ingress resource.

Related to Creating a HTTP Load Balancer on GKE using Ingress, I found two threads where instances created are marked as unhealthy.

In the first one, they mention the necessity to manually enable a firewall rule to allow http load balancer ip range to pass health check.

In the second one, they mention that the Pod’s spec must also include containerPort. Example:

change the file permissions to