Logstash not starting properly

For some strange reason, starting logstash manually seems to work like,

bin/logstash -f proj.conf

It doesn't start if I run,

systemctl start logstash

Nothing on the logs since the 25th as shown below,

[2021-03-25T20:17:50,046][INFO ][logstash.inputs.s3       ][main][f10fa5471c0f44015b616b23842ea73af76b0a1a83675d0b3bc9fd1333169dbb] Using default generated file for the sincedb {:filename=>"/var/lib/logstash/plugins/inputs/s3/sincedb_8c1e66466ad2be304379fa32b88e6d81"}
[2021-03-25T20:21:17,544][INFO ][logstash.runner          ] Starting Logstash {"logstash.version"=>"7.11.2", "jruby.version"=>"jruby 9.2.13.0 (2.5.7) 2020-08-03 9a89c94bcc OpenJDK 64-Bit Server VM 11.0.8+10 on 11.0.8+10 +indy +jit [linux-x86_64]"}

Here is the status though,

● logstash.service - logstash
   Loaded: loaded (/etc/systemd/system/logstash.service; disabled; vendor preset: disabled)
   Active: active (running) since Sat 2021-03-27 02:22:29 UTC; 11s ago
 Main PID: 6903 (java)
   CGroup: /system.slice/logstash.service
           └─6903 /usr/share/logstash/jdk/bin/java -Xms4g -Xmx4g -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -Djava.awt.headless=true -Dfile.encoding=UTF-8 -Djruby.compile.invokedynamic=true -Djruby.jit.threshold=0 -Djruby.regexp.interruptible=true -XX:+HeapDumpOnOutOfMemoryError -Djava.security.egd=file:/dev/urandom -Dlog4j2.isThreadContextMapInheritable=true -cp /usr/share/logstash/logstash-core/lib/jars/animal-sniffer-annotations-1.14.jar:/usr/share/logstash/logstash-core/lib/jars/checker-compat-qual-2.0.0.jar:/usr/share/logstash/logstash-core/lib/jars/commons-codec-1.14.jar:/usr/share/logstash/logstash-core/lib/jars/commons-compiler-3.1.0.jar:/usr/share/logstash/logstash-core/lib/jars/commons-logging-1.2.jar:/usr/share/logstash/logstash-core/lib/jars/error_prone_annotations-2.1.3.jar:/usr/share/logstash/logstash-core/lib/jars/google-java-format-1.1.jar:/usr/share/logstash/logstash-core/lib/jars/gradle-license-report-0.7.1.jar:/usr/share/logstash/logstash-core/lib/jars/guava-24.1.1-jre.jar:/usr/share/logstash/logstash-core/lib/jars/j2objc-annotations-1.1.jar:/usr/share/logstash/logstash-core/lib/jars/jackson-annotations-2.9.10.jar:/usr/share/logstash/logstash-core/lib/jars/jackson-core-2.9.10.jar:/usr/share/logstash/logstash-core/lib/jars/jackson-databind-2.9.10.8.jar:/usr/share/logstash/logstash-core/lib/jars/jackson-dataformat-cbor-2.9.10.jar:/usr/share/logstash/logstash-core/lib/jars/janino-3.1.0.jar:/usr/share/logstash/logstash-core/lib/jars/javassist-3.26.0-GA.jar:/usr/share/logstash/logstash-core/lib/jars/jruby-complete-9.2.13.0.jar:/usr/share/logstash/logstash-core/lib/jars/jsr305-1.3.9.jar:/usr/share/logstash/logstash-core/lib/jars/log4j-api-2.13.3.jar:/usr/share/logstash/logstash-core/lib/jars/log4j-core-2.13.3.jar:/usr/share/logstash/logstash-core/lib/jars/log4j-jcl-2.13.3.jar:/usr/share/logstash/logstash-core/lib/jars/log4j-slf4j-impl-2.13.3.jar:/usr/share/logstash/logstash-core/lib/jars/logstash-core.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.core.commands-3.6.0.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.core.contenttype-3.4.100.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.core.expressions-3.4.300.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.core.filesystem-1.3.100.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.core.jobs-3.5.100.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.core.resources-3.7.100.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.core.runtime-3.7.0.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.equinox.app-1.3.100.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.equinox.common-3.6.0.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.equinox.preferences-3.4.1.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.equinox.registry-3.5.101.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.jdt.core-3.10.0.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.osgi-3.7.1.jar:/usr/share/logstash/logstash-core/lib/jars/org.eclipse.text-3.5.101.jar:/usr/share/logstash/logstash-core/lib/jars/reflections-0.9.11.jar:/usr/share/logstash/logstash-core/lib/jars/slf4j-api-1.7.25.jar org.logstash.Logstash --path.settings /etc/logstash

Mar 27 02:22:29 mon-01.ahrq.local systemd[1]: Started logstash.
Mar 27 02:22:29 mon-01.ahrq.local systemd[1]: Starting logstash...
Mar 27 02:22:29 mon-01.ahrq.local logstash[6903]: Using bundled JDK: /usr/share/logstash/jdk

Help?

This could happen due to several reasons leading to this behaviour. can you post logstash logs to understand this issue.

PS - If logstash is not generating logs in the specified log directory, use the following command
journalctl -u logstash.service

Thank you @anandd4 and much appreciated! Logstash was not generating logs but the journalctl helped.

ERROR: Failed to parse YAML file "/etc/logstash/logstash.yml". Please confirm if the YAML structure is valid

On the logstash.yml there was a space before

log.level: info

Correcting that and restarting logstash has made the world normal again!