# Commands to check various states of Kafka

> NOTE: Code blocks indicate input on prompt with a '$'. Everything else is output


## Create a new topic
```
$ /opt/kafka/bin/kafka-topics.sh --topic my_topic --zookeeper localhost:2181 --create --partitions 1 --replication-factor 1
Created topic "my_topic".
```

## List all topics
```
$ /opt/kafka/bin/kafka-topics.sh --list --zookeeper localhost:2181__consumer_offsets
bro_raw
my_topic
```

## List topic details
```
$ /opt/kafka/bin/kafka-topics.sh --topic my_topic --zookeeper localhost:2181 --describe
Topic:my_topic	PartitionCount:1	ReplicationFactor:1	Configs:
	Topic: my_topic	Partition: 0	Leader: 0	Replicas: 0	Isr: 0
```

## Change number of partitions
```
$ /opt/kafka/bin/kafka-topics.sh --topic my_topic --zookeeper localhost:2181 --alter --partitions 4
WARNING: If partitions are increased for a topic that has a key, the partition logic or ordering of the messages will be affected
Adding partitions succeeded!

$ /opt/kafka/bin/kafka-topics.sh --topic my_topic --zookeeper localhost:2181 --describe
Topic:my_topic	PartitionCount:4	ReplicationFactor:1	Configs:
	Topic: my_topic	Partition: 0	Leader: 0	Replicas: 0	Isr: 0
	Topic: my_topic	Partition: 1	Leader: 0	Replicas: 0	Isr: 0
	Topic: my_topic	Partition: 2	Leader: 0	Replicas: 0	Isr: 0
	Topic: my_topic	Partition: 3	Leader: 0	Replicas: 0	Isr: 0
```

## Check topic offsets

Ideally the lag is 0 or close to it. The `Offset` field indicates the last record that the consumer read (in this case, logstash). The `logSize` indicates how many total records are in the topic partition. The `lag` indicates the difference between the two and should approach 0.

```
$ /opt/kafka/bin/kafka-consumer-offset-checker.sh --zookeeper 127.0.0.1:2181 --topic bro_raw --group logstash
Group           Topic                          Pid Offset          logSize         Lag             Owner
logstash        bro_raw                        0   2642920         2642920         0               logstash_lab003.ds.mocyber.org-1448462427435-5d63162f-0
logstash        bro_raw                        1   221536          221536          0               logstash_lab003.ds.mocyber.org-1448462427435-5d63162f-0
logstash        bro_raw                        2   86              86              0               logstash_lab003.ds.mocyber.org-1448462427435-5d63162f-0
logstash        bro_raw                        3   438             438             0               logstash_lab003.ds.mocyber.org-1448462427435-5d63162f-0
logstash        bro_raw                        4   0               0               0               logstash_lab003.ds.mocyber.org-1448462427435-5d63162f-0
logstash        bro_raw                        5   0               0               0               logstash_lab003.ds.mocyber.org-1448462427435-5d63162f-0
```