I'm having issues sending logs from a file to a destination using logstash - logstash

Question

I'm very new to logstash configuration. Below is my logstash pipeline configuration that I'm using to send a log file to Coralogix without success.
input {
file {
path => "/etc/logstash/conf.d/CSE-Candidate-Exercise-LOG.log"
type => "log" # a type to identify those logs (will need this later)
start_position => "beginning"
sincedb_path => "NUL"
}
}
output {
http {
url => "https://api.coralogix.com/logs/rest/singles "
http_method => "post"
headers => ["private_key", "xxxxxxxx-cccc-7777-ffff-000000000000"]
format => "json_batch"
codec => "line"
mapping => {
"applicationName" => "%{[#metadata][application]}"
"subsystemName" => "%{[#metadata][subsystem]}"
"computerName" => "%{host}"
"text" => "%{[#metadata][event]}"
}
http_compression => true
automatic_retries => 5
retry_non_idempotent => true
connect_timeout => 30
keepalive => false
}
}
The input should be ok but I think my issue is with the output. I'm not sure what "codec" plugin to use, do I need the "format" field?
Each time I run logstash to send the log in the file specified in the path, all I get is the below log snippet:
[INFO ] 2022-08-02 13:25:02.659 [Api Webserver] agent - Successfully started Logstash API endpoint {:port=>9600, :ssl_enabled=>false}
[INFO ] 2022-08-02 13:25:03.588 [Converge PipelineAction::Create<main>] Reflections - Reflections took 135 ms to scan 1 urls, producing 124 keys and 408 values
[INFO ] 2022-08-02 13:25:04.158 [Converge PipelineAction::Create<main>] javapipeline - Pipeline `main` is configured with `pipeline.ecs_compatibility: v8` setting. All plugins in this pipeline will default to `ecs_compatibility => v8` unless explicitly configured otherwise.
[INFO ] 2022-08-02 13:25:04.278 [[main]-pipeline-manager] javapipeline - Starting pipeline {:pipeline_id=>"main", "pipeline.workers"=>4, "pipeline.batch.size"=>125, "pipeline.batch.delay"=>50, "pipeline.max_inflight"=>500, "pipeline.sources"=>["/etc/logstash/conf.d/logstash-config.conf"], :thread=>"#<Thread:0x5a5e32c1 run>"}
[INFO ] 2022-08-02 13:25:05.154 [[main]-pipeline-manager] javapipeline - Pipeline Java execution initialization time {"seconds"=>0.87}
[INFO ] 2022-08-02 13:25:05.235 [[main]-pipeline-manager] javapipeline - Pipeline started {"pipeline.id"=>"main"}
[INFO ] 2022-08-02 13:25:05.316 [[main]<file] observingtail - START, creating Discoverer, Watch with file and sincedb collections
[INFO ] 2022-08-02 13:25:05.344 [Agent thread] agent - Pipelines running {:count=>1, :running_pipelines=>[:main], :non_running_pipelines=>[]}
I see no log in Coralogix platform. I simply want to send the raw log in the file without any filtering or manipulations to the destination. Any help would be appreciated.