# Kafka output plugin is not picking up value from @metadata field
**URL:** https://discuss.elastic.co/t/kafka-output-plugin-is-not-picking-up-value-from-metadata-field/194825
**Category:** Logstash
**Created:** [August 12, 2019, 10:04am UTC](https://discuss.elastic.co/t/kafka-output-plugin-is-not-picking-up-value-from-metadata-field/194825 "2019-08-12T10:04:34Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@amrutadale](https://discuss.elastic.co/u/amrutadale)
#### Post date: [August 12, 2019, 10:04am UTC](https://discuss.elastic.co/t/kafka-output-plugin-is-not-picking-up-value-from-metadata-field/194825/1 "2019-08-12T10:04:35Z")
Hello Team,
I have http endpoint as input. Based on the value received in header tag for application , I need to generate the jass configuration at run time for kafka output topic.
input {
http {
host =\> "127.0.0.1" # default: 0.0.0.0
port =\> "9600" # default: 8080
}
}
filter {
if [headers][app] == "cop" {
mutate { add\_field =\> { "[@metadata][topic]" =\> "data\_cop\_test\_topic" } }
mutate { add\_field =\> { "@[metadata][jass]" =\> "C:\kafka\_kerberos\jass1.conf" } }
mutate { add\_field =\> { "@[metadata][kerberos\_config]" =\> "C:\kafka\_kerberos\krb5.conf" } }
}
}
output {
kafka {
bootstrap\_servers =\> "xxx"
topic\_id =\> "%{[@metadata][topic]}"
jaas\_path =\> "%{[@metadata][jass]}"
kerberos\_config =\>%{[@metadata][kerberos\_config]}"
sasl\_kerberos\_service\_name =\> "kafka"
security\_protocol =\> "SASL\_PLAINTEXT"
sasl\_mechanism =\> "GSSAPI"
}
}
This picked up topic name correctly , but throws below error for jass path and kerberos config
Invalid setting for kafka output plugin:
output {
kafka {
# This setting must be a path
# File does not exist or cannot be opened %{[@metadata][kerberos\_config]}
kerberos\_config =\> "%{[@metadata][kerberos\_config]}"
...
}
}
[2019-08-12T15:32:59,506][ERROR][logstash.outputs.kafka] Invalid setting for kafka output plugin:
output {
kafka {
# This setting must be a path
# File does not exist or cannot be opened %{[@metadata][jass]}
jaas\_path =\> "%{[@metadata][jass]}"
...
}
Can someone please suggest how can we provide jass config at runtime? I am using logstash 7.1
---
### Author:  [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [August 12, 2019, 12:37pm UTC](https://discuss.elastic.co/t/kafka-output-plugin-is-not-picking-up-value-from-metadata-field/194825/2 "2019-08-12T12:37:07Z")
> [@amrutadale](#):
>
> Can someone please suggest how can we provide jass config at runtime?
jaas\_path and kerberos\_config are [passed straight through](https://github.com/logstash-plugins/logstash-output-kafka/blob/b99d69d7abc9e6e55df8c2e6b1b0b943f9a69189/lib/logstash/outputs/kafka.rb#L372) to the environment, so no sprintf substitutions are done. It cannot be a runtime variable.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [September 9, 2019, 12:37pm UTC](https://discuss.elastic.co/t/kafka-output-plugin-is-not-picking-up-value-from-metadata-field/194825/3 "2019-09-09T12:37:14Z")
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