Hoang Ong hoangong

clean up unused images that is older than 30 days:

0 0 * * 0 /usr/bin/docker image prune -a --force --filter "until=$(date -d "30 days ago" +%Y-%m-%d)T00:00:00"

Regular Expressions

Basic Syntax

/.../: Start and end regex delimiters
|: Alternation
(): Grouping

Kafka 0.11.0.0 (Confluent 3.3.0) added support to manipulate offsets for a consumer group via cli kafka-consumer-groups command.

List the topics to which the group is subscribed

kafka-consumer-groups --bootstrap-server <kafkahost:port> --group <group_id> --describe

Note the values under "CURRENT-OFFSET" and "LOG-END-OFFSET". "CURRENT-OFFSET" is the offset where this consumer group is currently at in each of the partitions.

Reset the consumer offset for a topic (preview)

	import java.math.BigInteger
	import java.security.spec.RSAPublicKeySpec
	import java.security.{KeyFactory, PublicKey}
	import java.util.Base64

	import akka.actor.ActorSystem
	import akka.event.LoggingAdapter
	import akka.http.scaladsl.Http
	import akka.http.scaladsl.model.HttpRequest
	import akka.http.scaladsl.model.headers.{Authorization, OAuth2BearerToken}


	rm -rf output && mkdir output

	bin/./scalapbc \
	--proto_path=/path/your/proto \
	--proto_path=/path/to/googleapis-master/ \ # download from https://github.com/googleapis/googleapis
	--proto_path=/path/to/protobuf-master/src/ \ # download from https://github.com/protocolbuffers/protobuf
	--scala_out=output rpc.proto

	# do this once for server private key:
	openssl ecparam -genkey -name prime256v1 -out tls.key

	# both server and all clients have to use the same cert file tls.cert
	openssl req -new -sha256 \
	-key tls.key \
	-subj "/CN=localhost/O=lnd" \
	-reqexts SAN \
	-config <(cat /etc/ssl/openssl.cnf \
	<(printf "\n[SAN]\nsubjectAltName=DNS:localhost,DNS:aaaa,DNS:bbbb,IP:192.168.1.xxx")) \

	list CAs
	keytool -list -keystore $(/usr/libexec/java_home)/jre/lib/security/cacerts

	Add new CA
	sudo keytool -keystore $(/usr/libexec/java_home)/jre/lib/security/cacerts -importcert -alias new_cert -file cer_file.cer/pem

	default pass: changeit

	sudo -u postgres psql postgres
	CREATE USER testuser WITH PASSWORD '123123';
	CREATE DATABASE testdb;
	GRANT ALL PRIVILEGES ON DATABASE testdb to testuser;