Hi, I recently started working with Kafka, but I’m having trouble getting the schema registry to start in this project. GitHub - p4535992/kafka-learning
TESTED WITH 7.6.1 and 7.9.5
I get this error in the logs :
docker logs kafka-schema-registry --tail 200
return:
Using log4j config /etc/schema-registry/log4j.properties
===> User
uid=1000(appuser) gid=1000(appuser) groups=1000(appuser)
===> Configuring …
===> Running preflight checks …
===> Check if Kafka is healthy …
[2026-01-08 10:04:43,870] INFO AdminClientConfig values:
auto.include.jmx.reporter = true
bootstrap.servers = [kafka101:29092, kafka102:29092, kafka103:29092]
client.dns.lookup = use_all_dns_ips
client.id =
connections.max.idle.ms = 300000
default.api.timeout.ms = 60000
metadata.max.age.ms = 300000
metric.reporters =
metrics.num.samples = 2
metrics.recording.level = INFO
metrics.sample.window.ms = 30000
receive.buffer.bytes = 65536
reconnect.backoff.max.ms = 1000
reconnect.backoff.ms = 50
request.timeout.ms = 30000
retries = 2147483647
retry.backoff.ms = 100
sasl.client.callback.handler.class = null
sasl.jaas.config = null
sasl.kerberos.kinit.cmd = /usr/bin/kinit
sasl.kerberos.min.time.before.relogin = 60000
sasl.kerberos.service.name = null
sasl.kerberos.ticket.renew.jitter = 0.05
sasl.kerberos.ticket.renew.window.factor = 0.8
sasl.login.callback.handler.class = null
sasl.login.class = null
sasl.login.connect.timeout.ms = null
sasl.login.read.timeout.ms = null
sasl.login.refresh.buffer.seconds = 300
sasl.login.refresh.min.period.seconds = 60
sasl.login.refresh.window.factor = 0.8
sasl.login.refresh.window.jitter = 0.05
sasl.login.retry.backoff.max.ms = 10000
sasl.login.retry.backoff.ms = 100
sasl.mechanism = GSSAPI
sasl.oauthbearer.clock.skew.seconds = 30
sasl.oauthbearer.expected.audience = null
sasl.oauthbearer.expected.issuer = null
sasl.oauthbearer.jwks.endpoint.refresh.ms = 3600000
sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms = 10000
sasl.oauthbearer.jwks.endpoint.retry.backoff.ms = 100
sasl.oauthbearer.jwks.endpoint.url = null
sasl.oauthbearer.scope.claim.name = scope
sasl.oauthbearer.sub.claim.name = sub
sasl.oauthbearer.token.endpoint.url = null
security.protocol = PLAINTEXT
security.providers = null
send.buffer.bytes = 131072
socket.connection.setup.timeout.max.ms = 30000
socket.connection.setup.timeout.ms = 10000
ssl.cipher.suites = null
ssl.enabled.protocols = [TLSv1.2, TLSv1.3]
ssl.endpoint.identification.algorithm = https
ssl.engine.factory.class = null
ssl.key.password = null
ssl.keymanager.algorithm = SunX509
ssl.keystore.certificate.chain = null
ssl.keystore.key = null
ssl.keystore.location = null
ssl.keystore.password = null
ssl.keystore.type = JKS
ssl.protocol = TLSv1.3
ssl.provider = null
ssl.secure.random.implementation = null
ssl.trustmanager.algorithm = PKIX
ssl.truststore.certificates = null
ssl.truststore.location = null
ssl.truststore.password = null
ssl.truststore.type = JKS
(org.apache.kafka.clients.admin.AdminClientConfig)
===> User
uid=1000(appuser) gid=1000(appuser) groups=1000(appuser)
===> Configuring …
===> Running preflight checks …
===> Check if Kafka is healthy …
[2026-01-08 10:10:31,517] INFO AdminClientConfig values:
auto.include.jmx.reporter = true
bootstrap.servers = [kafka101:29092, kafka102:29092, kafka103:29092]
client.dns.lookup = use_all_dns_ips
client.id =
connections.max.idle.ms = 300000
default.api.timeout.ms = 60000
metadata.max.age.ms = 300000
metric.reporters =
metrics.num.samples = 2
metrics.recording.level = INFO
metrics.sample.window.ms = 30000
receive.buffer.bytes = 65536
reconnect.backoff.max.ms = 1000
reconnect.backoff.ms = 50
request.timeout.ms = 30000
retries = 2147483647
retry.backoff.ms = 100
sasl.client.callback.handler.class = null
sasl.jaas.config = null
sasl.kerberos.kinit.cmd = /usr/bin/kinit
sasl.kerberos.min.time.before.relogin = 60000
sasl.kerberos.service.name = null
sasl.kerberos.ticket.renew.jitter = 0.05
sasl.kerberos.ticket.renew.window.factor = 0.8
sasl.login.callback.handler.class = null
sasl.login.class = null
sasl.login.connect.timeout.ms = null
sasl.login.read.timeout.ms = null
sasl.login.refresh.buffer.seconds = 300
sasl.login.refresh.min.period.seconds = 60
sasl.login.refresh.window.factor = 0.8
sasl.login.refresh.window.jitter = 0.05
sasl.login.retry.backoff.max.ms = 10000
sasl.login.retry.backoff.ms = 100
sasl.mechanism = GSSAPI
sasl.oauthbearer.clock.skew.seconds = 30
sasl.oauthbearer.expected.audience = null
sasl.oauthbearer.expected.issuer = null
sasl.oauthbearer.jwks.endpoint.refresh.ms = 3600000
sasl.oauthbearer.jwks.endpoint.retry.backoff.max.ms = 10000
sasl.oauthbearer.jwks.endpoint.retry.backoff.ms = 100
sasl.oauthbearer.jwks.endpoint.url = null
sasl.oauthbearer.scope.claim.name = scope
sasl.oauthbearer.sub.claim.name = sub
sasl.oauthbearer.token.endpoint.url = null
security.protocol = PLAINTEXT
security.providers = null
send.buffer.bytes = 131072
socket.connection.setup.timeout.max.ms = 30000
socket.connection.setup.timeout.ms = 10000
ssl.cipher.suites = null
ssl.enabled.protocols = [TLSv1.2, TLSv1.3]
ssl.endpoint.identification.algorithm = https
ssl.engine.factory.class = null
ssl.key.password = null
ssl.keymanager.algorithm = SunX509
ssl.keystore.certificate.chain = null
ssl.keystore.key = null
ssl.keystore.location = null
ssl.keystore.password = null
ssl.keystore.type = JKS
ssl.protocol = TLSv1.3
ssl.provider = null
ssl.secure.random.implementation = null
ssl.trustmanager.algorithm = PKIX
ssl.truststore.certificates = null
ssl.truststore.location = null
ssl.truststore.password = null
ssl.truststore.type = JKS
(org.apache.kafka.clients.admin.AdminClientConfig)
[2026-01-08 10:11:16,205] INFO Kafka version: 7.6.1-ccs (org.apache.kafka.common.utils.AppInfoParser)
[2026-01-08 10:11:16,263] INFO Kafka commitId: 11e81ad2a49db00b (org.apache.kafka.common.utils.AppInfoParser)
[2026-01-08 10:11:16,289] INFO Kafka startTimeMs: 1767867075440 (org.apache.kafka.common.utils.AppInfoParser)
[2026-01-08 10:12:11,015] ERROR Error while getting broker list. (io.confluent.admin.utils.ClusterStatus)
java.util.concurrent.ExecutionException: org.apache.kafka.common.errors.TimeoutException: Timed out waiting for a node assignment. Call: listNodes
at java.base/java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:395)
at java.base/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2005)
at org.apache.kafka.common.internals.KafkaFutureImpl.get(KafkaFutureImpl.java:165)
at io.confluent.admin.utils.ClusterStatus.isKafkaReady(ClusterStatus.java:147)
at io.confluent.admin.utils.cli.KafkaReadyCommand.main(KafkaReadyCommand.java:149)
Caused by: org.apache.kafka.common.errors.TimeoutException: Timed out waiting for a node assignment. Call: listNodes
[2026-01-08 10:12:10,982] INFO [AdminClient clientId=adminclient-1] Metadata update failed (org.apache.kafka.clients.admin.internals.AdminMetadataManager)
org.apache.kafka.common.errors.TimeoutException: Timed out waiting to send the call. Call: fetchMetadata
[2026-01-08 10:12:12,485] INFO Expected 1 brokers but found only 0. Trying to query Kafka for metadata again … (io.confluent.admin.utils.ClusterStatus)
[2026-01-08 10:12:12,492] ERROR Expected 1 brokers but found only 0. Brokers found . (io.confluent.admin.utils.ClusterStatus)
The command
docker exec kafka-schema-registry bash -lc “nc -vz kafka101 29092; nc -vz kafka102 29092; nc -vz kafka103 29092”
seem ok and return:
Ncat: Version 7.92
Ncat: Connected to 172.18.0.10:29092.
Ncat: 0 bytes sent, 0 bytes received in 2.14 seconds.
Ncat: Version 7.92
Ncat: Connected to 172.18.0.9:29092.
Ncat: 0 bytes sent, 0 bytes received in 1.58 seconds.
Ncat: Version 7.92
Ncat: Connected to 172.18.0.8:29092.
Ncat: 0 bytes sent, 0 bytes received in 1.91 seconds.