How to use the Kafka exporter Docker image? - docker

Question

I'm trying to use the Kafka Exporter packaged by Bitnami, https://github.com/bitnami/bitnami-docker-kafka-exporter, together with the Bitnami image for Kafka, https://github.com/bitnami/bitnami-docker-kafka. I'm trying to run the following docker-compose.yml:
version: '2'
networks:
app-tier:
driver: bridge
services:
zookeeper:
image: 'bitnami/zookeeper:latest'
environment:
- 'ALLOW_ANONYMOUS_LOGIN=yes'
networks:
- app-tier
kafka:
image: 'bitnami/kafka:latest'
environment:
- KAFKA_CFG_ZOOKEEPER_CONNECT=zookeeper:2181
- ALLOW_PLAINTEXT_LISTENER=yes
networks:
- app-tier
kafka-exporter:
image: bitnami/kafka-exporter:latest
ports:
- "9308:9308"
command:
- --kafka.server=kafka:9092
However, if I run this with docker-compose up, I get the following error:
bitnami-docker-kafka-kafka-exporter-1 | F0103 17:44:12.545739 1 kafka_exporter.go:865] Error Init Kafka Client: kafka: client has run out of available brokers to talk to (Is your cluster reachable?)
I've tried to use the answer to How to pass arguments to entrypoint in docker-compose.yml to specify a command for the kafka-exporter service which - assuming the entrypoint is defined in exec form - should append additional flags to the invocation of the Docker Exporter binary. However, it seems that either the value of kafka:9092 is not right for the value of the kafka.server flag, or the flag is not getting picked up, or perhaps there is some kind of race condition where the exporter fails and exits before Kafka is up and running. Any ideas on how to get this example to work?

Answer 1

It would appear that this is just caused by a race condition with the Kafka Exporter trying to connect to Kafka before it has started up. If I just run docker-compose up and allow the Kafka Exporter to fail, and then separately run the danielqsh/kafka-exporter container, it works:
> docker run -it -p 9308:9308 --network bitnami-docker-kafka_app-tier danielqsj/kafka-exporter
I0103 18:49:04.694898 1 kafka_exporter.go:774] Starting kafka_exporter (version=1.4.2, branch=HEAD, revision=15e4ad6a9ea8203135d4b974e825f22e31c750e5)
I0103 18:49:04.703058 1 kafka_exporter.go:934] Listening on HTTP :9308
and on http://localhost:9308 I can see metrics:
# HELP go_gc_duration_seconds A summary of the pause duration of garbage collection cycles.
# TYPE go_gc_duration_seconds summary
go_gc_duration_seconds{quantile="0"} 8.82e-05
go_gc_duration_seconds{quantile="0.25"} 8.82e-05
go_gc_duration_seconds{quantile="0.5"} 8.82e-05
go_gc_duration_seconds{quantile="0.75"} 8.82e-05
go_gc_duration_seconds{quantile="1"} 8.82e-05
go_gc_duration_seconds_sum 8.82e-05
go_gc_duration_seconds_count 1
# HELP go_goroutines Number of goroutines that currently exist.
# TYPE go_goroutines gauge
go_goroutines 20
# HELP go_info Information about the Go environment.
# TYPE go_info gauge
go_info{version="go1.17.3"} 1
# HELP go_memstats_alloc_bytes Number of bytes allocated and still in use.
# TYPE go_memstats_alloc_bytes gauge
go_memstats_alloc_bytes 3.546384e+06
# HELP go_memstats_alloc_bytes_total Total number of bytes allocated, even if freed.
# TYPE go_memstats_alloc_bytes_total counter
go_memstats_alloc_bytes_total 4.492048e+06
# HELP go_memstats_buck_hash_sys_bytes Number of bytes used by the profiling bucket hash table.
# TYPE go_memstats_buck_hash_sys_bytes gauge
go_memstats_buck_hash_sys_bytes 1.448119e+06
# HELP go_memstats_frees_total Total number of frees.
# TYPE go_memstats_frees_total counter
go_memstats_frees_total 6512
# HELP go_memstats_gc_cpu_fraction The fraction of this program's available CPU time used by the GC since the program started.
# TYPE go_memstats_gc_cpu_fraction gauge
go_memstats_gc_cpu_fraction 1.6141668631896834e-06
# HELP go_memstats_gc_sys_bytes Number of bytes used for garbage collection system metadata.
# TYPE go_memstats_gc_sys_bytes gauge
go_memstats_gc_sys_bytes 4.835688e+06
# HELP go_memstats_heap_alloc_bytes Number of heap bytes allocated and still in use.
# TYPE go_memstats_heap_alloc_bytes gauge
go_memstats_heap_alloc_bytes 3.546384e+06
# HELP go_memstats_heap_idle_bytes Number of heap bytes waiting to be used.
# TYPE go_memstats_heap_idle_bytes gauge
go_memstats_heap_idle_bytes 2.686976e+06
# HELP go_memstats_heap_inuse_bytes Number of heap bytes that are in use.
# TYPE go_memstats_heap_inuse_bytes gauge
go_memstats_heap_inuse_bytes 5.07904e+06
# HELP go_memstats_heap_objects Number of allocated objects.
# TYPE go_memstats_heap_objects gauge
go_memstats_heap_objects 4687
# HELP go_memstats_heap_released_bytes Number of heap bytes released to OS.
# TYPE go_memstats_heap_released_bytes gauge
go_memstats_heap_released_bytes 1.736704e+06
# HELP go_memstats_heap_sys_bytes Number of heap bytes obtained from system.
# TYPE go_memstats_heap_sys_bytes gauge
go_memstats_heap_sys_bytes 7.766016e+06
# HELP go_memstats_last_gc_time_seconds Number of seconds since 1970 of last garbage collection.
# TYPE go_memstats_last_gc_time_seconds gauge
go_memstats_last_gc_time_seconds 1.6412358823440428e+09
# HELP go_memstats_lookups_total Total number of pointer lookups.
# TYPE go_memstats_lookups_total counter
go_memstats_lookups_total 0
# HELP go_memstats_mallocs_total Total number of mallocs.
# TYPE go_memstats_mallocs_total counter
go_memstats_mallocs_total 11199
# HELP go_memstats_mcache_inuse_bytes Number of bytes in use by mcache structures.
# TYPE go_memstats_mcache_inuse_bytes gauge
go_memstats_mcache_inuse_bytes 9600
# HELP go_memstats_mcache_sys_bytes Number of bytes used for mcache structures obtained from system.
# TYPE go_memstats_mcache_sys_bytes gauge
go_memstats_mcache_sys_bytes 16384
# HELP go_memstats_mspan_inuse_bytes Number of bytes in use by mspan structures.
# TYPE go_memstats_mspan_inuse_bytes gauge
go_memstats_mspan_inuse_bytes 71536
# HELP go_memstats_mspan_sys_bytes Number of bytes used for mspan structures obtained from system.
# TYPE go_memstats_mspan_sys_bytes gauge
go_memstats_mspan_sys_bytes 81920
# HELP go_memstats_next_gc_bytes Number of heap bytes when next garbage collection will take place.
# TYPE go_memstats_next_gc_bytes gauge
go_memstats_next_gc_bytes 5.283728e+06
# HELP go_memstats_other_sys_bytes Number of bytes used for other system allocations.
# TYPE go_memstats_other_sys_bytes gauge
go_memstats_other_sys_bytes 1.499625e+06
# HELP go_memstats_stack_inuse_bytes Number of bytes in use by the stack allocator.
# TYPE go_memstats_stack_inuse_bytes gauge
go_memstats_stack_inuse_bytes 622592
# HELP go_memstats_stack_sys_bytes Number of bytes obtained from system for stack allocator.
# TYPE go_memstats_stack_sys_bytes gauge
go_memstats_stack_sys_bytes 622592
# HELP go_memstats_sys_bytes Number of bytes obtained from system.
# TYPE go_memstats_sys_bytes gauge
go_memstats_sys_bytes 1.6270344e+07
# HELP go_threads Number of OS threads created.
# TYPE go_threads gauge
go_threads 8
# HELP kafka_brokers Number of Brokers in the Kafka Cluster.
# TYPE kafka_brokers gauge
kafka_brokers 1
# HELP kafka_exporter_build_info A metric with a constant '1' value labeled by version, revision, branch, and goversion from which kafka_exporter was built.
# TYPE kafka_exporter_build_info gauge
kafka_exporter_build_info{branch="HEAD",goversion="go1.17.3",revision="15e4ad6a9ea8203135d4b974e825f22e31c750e5",version="1.4.2"} 1
# HELP process_cpu_seconds_total Total user and system CPU time spent in seconds.
# TYPE process_cpu_seconds_total counter
process_cpu_seconds_total 0.11
# HELP process_max_fds Maximum number of open file descriptors.
# TYPE process_max_fds gauge
process_max_fds 1.048576e+06
# HELP process_open_fds Number of open file descriptors.
# TYPE process_open_fds gauge
process_open_fds 12
# HELP process_resident_memory_bytes Resident memory size in bytes.
# TYPE process_resident_memory_bytes gauge
process_resident_memory_bytes 1.703936e+07
# HELP process_start_time_seconds Start time of the process since unix epoch in seconds.
# TYPE process_start_time_seconds gauge
process_start_time_seconds 1.64123574422e+09
# HELP process_virtual_memory_bytes Virtual memory size in bytes.
# TYPE process_virtual_memory_bytes gauge
process_virtual_memory_bytes 7.35379456e+08
# HELP process_virtual_memory_max_bytes Maximum amount of virtual memory available in bytes.
# TYPE process_virtual_memory_max_bytes gauge
process_virtual_memory_max_bytes 1.8446744073709552e+19
# HELP promhttp_metric_handler_requests_in_flight Current number of scrapes being served.
# TYPE promhttp_metric_handler_requests_in_flight gauge
promhttp_metric_handler_requests_in_flight 1
# HELP promhttp_metric_handler_requests_total Total number of scrapes by HTTP status code.
# TYPE promhttp_metric_handler_requests_total counter
promhttp_metric_handler_requests_total{code="200"} 3
promhttp_metric_handler_requests_total{code="500"} 0
promhttp_metric_handler_requests_total{code="503"} 0
Update
A more reliable way to do this is to use a wrapper script in order to perform an application-specific health check as described in https://docs.docker.com/compose/startup-order/. With the following directory structure,
.
├── docker-compose.yml
└── kafka-exporter
├── Dockerfile
└── run.sh
the following Dockerfile,
FROM bitnami/kafka-exporter:latest
COPY run.sh /opt/bitnami/kafka-exporter/bin
ENTRYPOINT ["run.sh"]
and the following run.sh,
#!/bin/sh
while ! bin/kafka_exporter; do
echo "Waiting for the Kafka cluster to come up..."
sleep 1
done
and the following docker-compose.yml,
version: '2'
networks:
app-tier:
driver: bridge
services:
zookeeper:
image: 'bitnami/zookeeper:latest'
environment:
- 'ALLOW_ANONYMOUS_LOGIN=yes'
networks:
- app-tier
kafka:
image: 'bitnami/kafka:latest'
environment:
- KAFKA_CFG_ZOOKEEPER_CONNECT=zookeeper:2181
- ALLOW_PLAINTEXT_LISTENER=yes
networks:
- app-tier
kafka-exporter:
build: kafka-exporter
ports:
- "9308:9308"
networks:
- app-tier
entrypoint: ["run.sh"]
myapp:
image: 'bitnami/kafka:latest'
environment:
- KAFKA_CFG_ZOOKEEPER_CONNECT=zookeeper:2181
- ALLOW_PLAINTEXT_LISTENER=yes
networks:
- app-tier
Upon running docker-compose build && docker-compose up, I can see from the logs that after ~2 seconds (on the third attempt) the Kafka Exporter starts successfully:
> docker logs bitnami-docker-kafka-kafka-exporter-1 -f
I0104 16:05:39.765921 8 kafka_exporter.go:769] Starting kafka_exporter (version=1.4.2, branch=non-git, revision=non-git)
F0104 16:05:40.525065 8 kafka_exporter.go:865] Error Init Kafka Client: kafka: client has run out of available brokers to talk to (Is your cluster reachable?)
Waiting for the Kafka cluster to come up...
I0104 16:05:41.538482 16 kafka_exporter.go:769] Starting kafka_exporter (version=1.4.2, branch=non-git, revision=non-git)
F0104 16:05:42.295872 16 kafka_exporter.go:865] Error Init Kafka Client: kafka: client has run out of available brokers to talk to (Is your cluster reachable?)
Waiting for the Kafka cluster to come up...
I0104 16:05:43.307293 24 kafka_exporter.go:769] Starting kafka_exporter (version=1.4.2, branch=non-git, revision=non-git)
I0104 16:05:43.686798 24 kafka_exporter.go:929] Listening on HTTP :9308

Answer 2

Its bit difficult to run all the required dependencies for kafka-exporter.
Myself did few simple steps as following below.
Step 1
docker pull danielqsj/kafka-exporter:latest
Step 2
./bin/zookeeper-server-start.sh config/zookeeper.properties
Step 3
./bin/kafka-server-start.sh config/server.properties
Step 4
docker run -ti --rm -p 9308:9308 danielqsj/kafka-exporter --kafka.server=host.docker.internal:9092 --log.enable-sarama
If you note the above command i used "host.docker.internal" which will helps kafka-exporter to listen on my machines localhost.