Fix fortinet.firewall.mem value to be interpreted as integer (#19335)

Fix fortinet.firewall.mem value to be interpreted as integer. Add convert processor for fortinet.firewall.mem to ingest pipeline.

Closes #19327

Co-authored-by: Andrew Kroh <andrew.kroh@elastic.co>

CHANGELOG.next.asciidoc

@@ -175,6 +175,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 
 *Filebeat*
 
+- Fix mapping of fortinet.firewall.mem as integer. {pull}19335[19335]
 - Ensure all zeek timestamps include millisecond precision. {issue}14599[14599] {pull}16766[16766]
 - Fix s3 input hanging with GetObjectRequest API call by adding context_timeout config. {issue}15502[15502] {pull}15590[15590]
 - Add shared_credential_file to cloudtrail config {issue}15652[15652] {pull}15656[15656]

filebeat/docs/fields.asciidoc

@@ -59147,7 +59147,7 @@ type: integer
 Memory usage system statistics
 
 
-type: keyword
+type: integer
 
 --
 

x-pack/filebeat/module/fortinet/firewall/_meta/fields.yml

@@ -1126,7 +1126,7 @@
  Fabric medium count
 
  - name: mem
- type: keyword
+ type: integer
  description: >
  Memory usage system statistics
 

x-pack/filebeat/module/fortinet/firewall/ingest/event.yml

@@ -218,6 +218,11 @@ processors:
  ignore_failure: true
  ignore_missing: true
  if: "ctx.event?.duration == null"
+- convert:
+ field: fortinet.firewall.mem
+ type: integer
+ ignore_failure: true
+ ignore_missing: true
 - geoip:
  field: source.ip
  target_field: source.geo

x-pack/filebeat/module/fortinet/firewall/test/fortinet.log-expected.json

@@ -973,7 +973,7 @@
  "fortinet.firewall.disklograte": "0",
  "fortinet.firewall.fazlograte": "0",
  "fortinet.firewall.freediskstorage": "331",
- "fortinet.firewall.mem": "10",
+ "fortinet.firewall.mem": 10,
  "fortinet.firewall.setuprate": "0",
  "fortinet.firewall.subtype": "system",
  "fortinet.firewall.sysuptime": "25170",