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https://github.com/marcel-dempers/docker-development-youtube-series.git
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consumer wip
This commit is contained in:
marcel-dempers
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commit
81476f540d
@ -194,7 +194,7 @@ cat /tmp/kafka-logs/Orders-2/*.log
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So far we've taken a look at staring up Kafka and Zookeeper instances with
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docker commands. </br>
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We've explored the kafka configuration and how to produce and consume message. </br>
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We've explored the kafka configuration and how to produce and consume messages. </br>
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Let's put it all together in a docker compose file. </br>
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With compose we'd like to be able to build our containers, pointing to a
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@ -1,17 +1,17 @@
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module producer
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module consumer
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go 1.16
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require (
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github.com/DataDog/zstd v1.4.8 // indirect
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github.com/Shopify/toxiproxy v2.1.4+incompatible // indirect
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github.com/davecgh/go-spew v1.1.1 // indirect
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github.com/eapache/go-resiliency v1.2.0 // indirect
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github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21 // indirect
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github.com/eapache/queue v1.1.0 // indirect
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github.com/frankban/quicktest v1.13.0 // indirect
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github.com/golang/snappy v0.0.3 // indirect
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github.com/julienschmidt/httprouter v1.3.0 // indirect
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github.com/pierrec/lz4 v2.6.0+incompatible // indirect
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github.com/pierrec/lz4 v2.6.1+incompatible // indirect
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github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 // indirect
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github.com/sirupsen/logrus v1.8.1 // indirect
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gopkg.in/Shopify/sarama.v1 v1.20.1 // indirect
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gopkg.in/Shopify/sarama.v1 v1.20.1
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)
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@ -1,5 +1,7 @@
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github.com/DataDog/zstd v1.4.8 h1:Rpmta4xZ/MgZnriKNd24iZMhGpP5dvUcs/uqfBapKZY=
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github.com/DataDog/zstd v1.4.8/go.mod h1:g4AWEaM3yOg3HYfnJ3YIawPnVdXJh9QME85blwSAmyw=
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github.com/Shopify/toxiproxy v2.1.4+incompatible h1:TKdv8HiTLgE5wdJuEML90aBgNWsokNbMijUGhmcoBJc=
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github.com/Shopify/toxiproxy v2.1.4+incompatible/go.mod h1:OXgGpZ6Cli1/URJOF1DMxUHB2q5Ap20/P/eIdh4G0pI=
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github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
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github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
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github.com/eapache/go-resiliency v1.2.0 h1:v7g92e/KSN71Rq7vSThKaWIq68fL4YHvWyiUKorFR1Q=
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@ -8,19 +10,22 @@ github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21 h1:YEetp8
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github.com/eapache/go-xerial-snappy v0.0.0-20180814174437-776d5712da21/go.mod h1:+020luEh2TKB4/GOp8oxxtq0Daoen/Cii55CzbTV6DU=
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github.com/eapache/queue v1.1.0 h1:YOEu7KNc61ntiQlcEeUIoDTJ2o8mQznoNvUhiigpIqc=
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github.com/eapache/queue v1.1.0/go.mod h1:6eCeP0CKFpHLu8blIFXhExK/dRa7WDZfr6jVFPTqq+I=
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github.com/frankban/quicktest v1.13.0 h1:yNZif1OkDfNoDfb9zZa9aXIpejNR4F23Wely0c+Qdqk=
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github.com/frankban/quicktest v1.13.0/go.mod h1:qLE0fzW0VuyUAJgPU19zByoIr0HtCHN/r/VLSOOIySU=
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github.com/golang/snappy v0.0.3 h1:fHPg5GQYlCeLIPB9BZqMVR5nR9A+IM5zcgeTdjMYmLA=
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github.com/golang/snappy v0.0.3/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
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github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=
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github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
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github.com/pierrec/lz4 v2.6.0+incompatible h1:Ix9yFKn1nSPBLFl/yZknTp8TU5G4Ps0JDmguYK6iH1A=
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github.com/pierrec/lz4 v2.6.0+incompatible/go.mod h1:pdkljMzZIN41W+lC3N2tnIh5sFi+IEE17M5jbnwPHcY=
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github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
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github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
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github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
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github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
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github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
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github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
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github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
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github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
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github.com/pierrec/lz4 v2.6.1+incompatible h1:9UY3+iC23yxF0UfGaYrGplQ+79Rg+h/q9FV9ix19jjM=
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github.com/pierrec/lz4 v2.6.1+incompatible/go.mod h1:pdkljMzZIN41W+lC3N2tnIh5sFi+IEE17M5jbnwPHcY=
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github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 h1:N/ElC8H3+5XpJzTSTfLsJV/mx9Q9g7kxmchpfZyxgzM=
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github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475/go.mod h1:bCqnVzQkZxMG4s8nGwiZ5l3QUCyqpo9Y+/ZMZ9VjZe4=
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github.com/sirupsen/logrus v1.8.1 h1:dJKuHgqk1NNQlqoA6BTlM1Wf9DOH3NBjQyu0h9+AZZE=
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github.com/sirupsen/logrus v1.8.1/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
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github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
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golang.org/x/sys v0.0.0-20191026070338-33540a1f6037 h1:YyJpGZS1sBuBCzLAR1VEpK193GlqGZbnPFnPV/5Rsb4=
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golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
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golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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gopkg.in/Shopify/sarama.v1 v1.20.1 h1:Gi09A3fJXm0Jgt8kuKZ8YK+r60GfYn7MQuEmI3oq6hE=
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gopkg.in/Shopify/sarama.v1 v1.20.1/go.mod h1:AxnvoaevB2nBjNK17cG61A3LleFcWFwVBHBt+cot4Oc=
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@ -16,7 +16,9 @@ var kafkaTopic = os.Getenv("KAFKA_TOPIC")
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var kafkaVersion = os.Getenv("KAFKA_VERSION")
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var kafkaGroup = os.Getenv("KAFKA_GROUP")
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func main() {
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version, err := sarama.ParseKafkaVersion(kafkaVersion)
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config := sarama.NewConfig()
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config.Version = version
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@ -54,7 +56,6 @@ func main() {
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consumer.ready = make(chan bool)
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}
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}()
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<-consumer.ready // Await till the consumer has been set up
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fmt.Println("Sarama consumer up and running!...")
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@ -68,6 +69,7 @@ func main() {
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}
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cancel()
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wg.Wait()
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if err = client.Close(); err != nil {
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fmt.Printf("Error closing client: %v", err)
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panic(err)
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@ -75,11 +77,11 @@ func main() {
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}
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// Consumer represents a Sarama consumer group consumer
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type Consumer struct {
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ready chan bool
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}
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// Setup is run at the beginning of a new session, before ConsumeClaim
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func (consumer *Consumer) Setup(sarama.ConsumerGroupSession) error {
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// Mark the consumer as ready
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@ -112,4 +114,3 @@ func (consumer *Consumer) ConsumeClaim(session sarama.ConsumerGroupSession, clai
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return nil
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}
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@ -2,8 +2,9 @@
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* [Start a Kafka environment](#Start-a-Kafka-environment)
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* [Building a consumer in Go](#Building-a-consumer-in-Go)
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* [Create a Kafka Topic](#Create-a-Kafka-Topic)
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* [Starting our Kafka Consumer](#Starting-our-Kafka-Consumer)
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* [Consume Messages in Random Order](#Consume-Messages-in-Random-Order)
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* [Consume Messages in Order](#Consume-Messages-in-Order)
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## Start a Kafka environment
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@ -12,24 +13,36 @@ Let's start our Kafka components:
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```
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cd messaging/kafka
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#only start the kafka containers, not everything!
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docker compose up -d zookeeper-1 kafka-1 kafka-2 kafka-3
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#ensure its running!
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docker ps
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```
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### Create a Topic: Orders
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To create a topic, we can `exec` into any container on our kafka network and create it. </br>
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We'll need a Topic for our orders:
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```
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docker compose up -d kafka-producer
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docker exec -it kafka-producer bash
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docker exec -it zookeeper-1 bash
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# create
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/kafka/bin/kafka-topics.sh \
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--create \
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--zookeeper zookeeper-1:2181 \
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--replication-factor 1 \
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--partitions 3 \
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--topic Orders
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# describe
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/kafka/bin/kafka-topics.sh \
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--describe \
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--zookeeper zookeeper-1:2181 \
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--topic Orders
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exit
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```
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Now that we have our Kafka infrastructure, let's create our consumer.
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@ -209,6 +222,50 @@ kafka-consumer-go:
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```
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To build our consumer, we'll need a `dockerfile`:
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```
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FROM golang:1.16-alpine as dev-env
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RUN apk add --no-cache git gcc musl-dev
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WORKDIR /app
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```
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Let's build our container so we can compile our `go` code:
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```
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cd .\messaging\kafka\applications\consumer\
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docker build . -t consumer
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docker run -it -v ${PWD}:/app consumer sh
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ls -l
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go mod init consumer
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go mod tidy
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go build
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```
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Now that we have our `go.mod` and `go.sum` files, and code is comiling, we can proceed to create a container that runs our app. Let's extend the `dockerfile`
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```
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FROM dev-env as build-env
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COPY go.mod /go.sum /app/
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RUN go mod download
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COPY . /app/
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RUN CGO_ENABLED=0 go build -o /consumer
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FROM alpine:3.10 as runtime
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COPY --from=build-env /consumer /usr/local/bin/consumer
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RUN chmod +x /usr/local/bin/consumer
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ENTRYPOINT ["consumer"]
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```
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Now we can proceed to build it:
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```
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@ -216,36 +273,90 @@ cd .\messaging\kafka\
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docker compose build kafka-consumer-go
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```
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Now before we start it, we want to create a Kafka Topic.
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## Create a Kafka Topic
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Let's split the terminal and we'll create the topic from the producer. <br/>
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You can create the topic from any container.
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```
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docker compose up -d kafka-producer
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docker exec -it kafka-producer bash
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```
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Create the Topic for Orders:
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```
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/kafka/bin/kafka-topics.sh \
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--create \
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--zookeeper zookeeper-1:2181 \
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--replication-factor 1 \
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--partitions 3 \
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--topic Orders
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```
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## Starting our Kafka Consumer
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Now with the Topic ready, our consumer can start and subscribe to the orders topic:
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Now with our Kafka environment and topic ready, our consumer can start and subscribe to the orders topic:
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```
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cd messaging/kafka
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docker compose up kafka-consumer-go
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```
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## Consume Messages in Random Order
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Let's produce messages in a loop
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```
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cd .\messaging\kafka\
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docker compose up -d kafka-producer
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docker exec -it kafka-producer bash
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```
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Produce messages in a loop:
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```
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upperlim=10
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for ((i=0; i<=upperlim; i++)); do
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echo "{ 'id' : 'order-$i', 'data' : 'random-data'}" | \
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/kafka/bin/kafka-console-producer.sh \
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--broker-list kafka-1:9092,kafka-2:9092,kafka-3:9092 \
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--topic Orders > /dev/null
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done
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```
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<p>
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Notice messages go into partition in round robin.
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Partition provides distribution of messages so all our messages
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don't take up all the space on a single broker and distributed
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more evenly
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</p>
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<p>
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Notice when we stop and restart out consumer, it does not
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re-consume message from the beginning.
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</p>
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<p>
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This is because the brokers remember the offset where the consumer
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has read up to in our case as we use consumer groups.
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</p>
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Reading messages will occur in random order because they exist in different partitions:
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```
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cd .\messaging\kafka\
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docker compose up -d kafka-consumer
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docker exec -it kafka-consumer bash
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/kafka/bin/kafka-console-consumer.sh \
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--bootstrap-server kafka-1:9092,kafka-2:9092,kafka-3:9092 \
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--topic Orders --from-beginning
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```
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Notice we receive messages out of order and also able to read
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messages from the beginning too.
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## Consume Messages in Order
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To consume messages in given order, we need to use message keys.
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When using keys, Kafka will place all messages with a given key in the same
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partition.
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This is useful for event based transactional systems where order is important.
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Let's say we have `order-11` and we want to update it 10 times.
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Order here is important so we'l structure our message with a key.
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```
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upperlim=10
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for ((i=0; i<=upperlim; i++)); do
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echo "order-11: { 'id' : 'order-11', 'data' : '$i'}" | \
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/kafka/bin/kafka-console-producer.sh \
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--broker-list kafka-1:9092,kafka-2:9092,kafka-3:9092 \
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--topic Orders > /dev/null \
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--property "parse.key=true" --property "key.separator=:"
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done
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```
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