Add license

.tool-versions

@@ -1,4 +1,2 @@
 elixir 1.16.2-otp-26
 erlang 26.0.2
-tilt 0.33.11
-kind 0.22.0

LICENSE

@@ -0,0 +1,12 @@
+ISC License
+
+Copyright 2024 Pascal Schmid
+
+Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby 
+granted, provided that the above copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL 
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, 
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+OF THIS SOFTWARE.

README.md

@@ -1,14 +1,43 @@
-# KafkaexLagExporter
+# KafkaExLagExporter
 
 This project will collect Kafka consumer lag and provide them via Prometheus.
 
+## Metrics
+
+[Prometheus](https://prometheus.io/) is a standard way to represent metrics in a modern cross-platform manner. 
+KafkaExLagExporter exposes several metrics as an HTTP endpoint that can be readily scraped by Prometheus.
+
+**`kafka_consumergroup_group_topic_sum_lag`**
+
+Labels: `cluster_name, group, topic, consumer_id, member_host`
+
+The sum of the difference between the last produced offset and the last consumed offset of all partitions in this
+topic for this group.
+
+**`kafka_consumergroup_group_lag`**
+
+Labels: `cluster_name, group, partition, topic, member_host, consumer_id`
+
+The difference between the last produced offset and the last consumed offset for this partition in this topic
+partition for this group.
+
 ## Start
 
 ```bash
-docker run -ti --net="host" -e KAFKA_BROKERS=localhost:9093,localhost:9094,localhost:9095 lechindianer/kafkaex_lag_exporter:0.1
+docker run -ti --net="host" -e KAFKA_BROKERS=redpanda:29092 -p 4000:4000 lechindianer/kafkaex_lag_exporter:0.2.0
 ```
 
-Now you can check the exposed metrics at [localhost:4000](localhost:4000).
+Now you can check the exposed metrics at [http://localhost:4000](http://localhost:4000).
+
+## Configuration
+
+KafkaExLagExporter uses 5 seconds as default interval to update the lags. If you want to configure it to use another
+value set `KAFKA_EX_INTERVAL_MS`, i.e.
+
+```bash
+docker run -ti --net="host" -e KAFKA_BROKERS=redpanda:29092 -e KAFKA_EX_INTERVAL_MS=10000 -p 4000:4000 \
+  lechindianer/kafkaex_lag_exporter:0.2.0
+```
 
 ## Developing
 
@@ -18,24 +47,38 @@ To start the project locally:
 KAFKA_BROKERS="localhost:9092" iex -S mix 
 ```
 
-There is also a docker-compose file included which will start Kafka, serve Kowl (Web UI for Kafka) and start
+There is also a Docker compose file included which will start Kafka, serve Kowl (Web UI for Kafka) and start
 KafkaexLagExporter:
 
 ```bash 
-docker-compose up --build
+docker compose up --build
 ```
 
-Kowl is served at [localhost:8080](localhost:8080).
+Kowl is served at [http://localhost:8080](http://localhost:8080).
 
 ### Tests
 
 ```bash
 MIX_ENV=test mix test --no-start
+```
 
-# Don't forget to check credo for code violations:
+###  Code style
+
+Don't forget to check [credo](https://hexdocs.pm/credo/overview.html) for code violations:
+
+```bash
 mix credo
 ```
 
+This project also leverages the use of typespecs in order to provide static code checking:
+
+```bash
+mix dialyzer
+```
+
 ## Links
 
 Source is on [Gitlab](https://gitlab.com/lechindianer/kafkaex-lag-exporter).
+
+The initial project [Kafka Lag Exporter](https://github.com/seglo/kafka-lag-exporter) was a huge inspiration for me
+creating my first real Elixir project. Thank you!

Tiltfile

@@ -1,3 +0,0 @@
-allow_k8s_contexts('default')
-
-include('konvert/Tiltfile')

config.yaml

@@ -1,8 +0,0 @@
-kafka:
-  brokers:
-    - kafka1:9092
-    - kafka2:9092
-    - kafka3:9092
-
-# server:
-  # listenPort: 8080

docker-compose.yml

@@ -32,7 +32,7 @@ services:
       - redpanda_network
 
   console:
-    image: docker.redpanda.com/redpandadata/console:v2.2.4
+    image: docker.redpanda.com/redpandadata/console:v2.4.6
     entrypoint: /bin/sh
     command: -c "echo \"$$CONSOLE_CONFIG_FILE\" > /tmp/config.yml; /app/console"
     environment:
@@ -63,7 +63,6 @@ services:
     image: quay.io/cloudhut/owl-shop:latest
     networks:
       - redpanda_network
-    #platform: 'linux/amd64'
     environment:
       - SHOP_KAFKA_BROKERS=redpanda:29092
       - SHOP_KAFKA_TOPICREPLICATIONFACTOR=1
@@ -78,7 +77,6 @@ services:
     container_name: connect
     networks:
       - redpanda_network
-    #platform: 'linux/amd64'
     depends_on:
       - redpanda
     ports:
@@ -109,6 +107,8 @@ services:
       - '4000:4000'
     environment:
       - KAFKA_BROKERS=redpanda:29092
+    networks:
+      - redpanda_network
     depends_on:
       - redpanda
     restart: "unless-stopped"

init_cluster.sh

@@ -1,15 +0,0 @@
-#!/usr/bin/env bash
-
-kind delete cluster
-
-kind create cluster --config kind.yaml
-
-kubectl wait -A --for=condition=ready pod --field-selector=status.phase!=Succeeded --timeout=15m
-
-kubectl get cm -n kube-system kube-proxy -o yaml | sed 's/maxPerCore.*/maxPerCore: 0/' | kubectl apply -n kube-system -f -
-
-kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.7.1/deploy/static/provider/kind/deploy.yaml
-
-LB_IP=$(kubectl get svc -n ingress-nginx ingress-nginx-controller -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
-
-echo "address=/kind.cluster/$LB_IP"

kind.yaml

@@ -1,24 +0,0 @@
-kind: Cluster
-apiVersion: kind.x-k8s.io/v1alpha4
-nodes:
-  - role: control-plane
-    kubeadmConfigPatches:
-      - |
-        kind: InitConfiguration
-        nodeRegistration:
-          kubeletExtraArgs:
-            node-labels: "ingress-ready=true"
-    extraPortMappings:
-      - containerPort: 80
-        hostPort: 80
-        protocol: TCP
-      - containerPort: 443
-        hostPort: 443
-        protocol: TCP
-#    image: kindest/node:v1.26.3@sha256:61b92f38dff6ccc29969e7aa154d34e38b89443af1a2c14e6cfbd2df6419c66f
-  - role: worker
-#    image: kindest/node:v1.26.3@sha256:61b92f38dff6ccc29969e7aa154d34e38b89443af1a2c14e6cfbd2df6419c66f
-  - role: worker
-#    image: kindest/node:v1.26.3@sha256:61b92f38dff6ccc29969e7aa154d34e38b89443af1a2c14e6cfbd2df6419c66f
-  - role: worker
-#    image: kindest/node:v1.26.3@sha256:61b92f38dff6ccc29969e7aa154d34e38b89443af1a2c14e6cfbd2df6419c66f

konvert/Tiltfile

@@ -1,21 +0,0 @@
-k8s_yaml('./redpanda-owl-shop-default-networkpolicy.yaml')
-k8s_yaml('./redpanda-persistentvolumeclaim.yaml')
-k8s_yaml('./redpanda-deployment.yaml')
-k8s_yaml('./redpanda-owl-shop-redpanda-network-networkpolicy.yaml')
-k8s_yaml('./redpanda-service.yaml')
-
-k8s_yaml('./connect-service.yaml')
-k8s_yaml('./connect-deployment.yaml')
-
-k8s_yaml('./owl-shop-deployment.yaml')
-
-k8s_yaml('./console-deployment.yaml')
-k8s_yaml('./console-service.yaml')
-k8s_yaml('./console-ingress.yaml')
-
-docker_build('kafka-lag-exporter', './..')
-
-k8s_yaml('./kafka-lag-exporter-deployment.yaml')
-k8s_yaml('./kafka-lag-exporter-service.yaml')
-
-k8s_resource(workload='kafka-lag-exporter', port_forwards=4000)

konvert/connect-deployment.yaml

@@ -1,48 +0,0 @@
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  creationTimestamp: null
-  labels:
-    io.kompose.service: connect
-  name: connect
-spec:
-  replicas: 1
-  selector:
-    matchLabels:
-      io.kompose.service: connect
-  template:
-    metadata:
-      labels:
-        io.kompose.network/redpanda-owl-shop-redpanda-network: "true"
-        io.kompose.service: connect
-    spec:
-      containers:
-        - env:
-            - name: CONNECT_BOOTSTRAP_SERVERS
-              value: redpanda:29092
-            - name: CONNECT_CONFIGURATION
-              value: |
-                key.converter=org.apache.kafka.connect.converters.ByteArrayConverter
-                value.converter=org.apache.kafka.connect.converters.ByteArrayConverter
-                group.id=connectors-cluster
-                offset.storage.topic=_internal_connectors_offsets
-                config.storage.topic=_internal_connectors_configs
-                status.storage.topic=_internal_connectors_status
-                config.storage.replication.factor=-1
-                offset.storage.replication.factor=-1
-                status.storage.replication.factor=-1
-                offset.flush.interval.ms=1000
-                producer.linger.ms=50
-                producer.batch.size=131072
-            - name: CONNECT_GC_LOG_ENABLED
-              value: "false"
-            - name: CONNECT_HEAP_OPTS
-              value: -Xms512M -Xmx512M
-            - name: CONNECT_LOG_LEVEL
-              value: info
-          image: docker.redpanda.com/redpandadata/connectors:latest
-          name: connect
-          ports:
-            - containerPort: 8083
-      hostname: connect
-      restartPolicy: Always

konvert/connect-service.yaml

@@ -1,13 +0,0 @@
-apiVersion: v1
-kind: Service
-metadata:
-  labels:
-    io.kompose.service: connect
-  name: connect
-spec:
-  ports:
-    - name: "8083"
-      port: 8083
-      targetPort: 8083
-  selector:
-    io.kompose.service: connect

konvert/console-deployment.yaml

@@ -1,48 +0,0 @@
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  creationTimestamp: null
-  labels:
-    io.kompose.service: console
-  name: console
-spec:
-  replicas: 1
-  selector:
-    matchLabels:
-      io.kompose.service: console
-  template:
-    metadata:
-      labels:
-        io.kompose.network/redpanda-owl-shop-redpanda-network: "true"
-        io.kompose.service: console
-    spec:
-      containers:
-        - args:
-            - -c
-            - echo "$(CONSOLE_CONFIG_FILE)" > /tmp/config.yml; /app/console
-          command:
-            - /bin/sh
-          env:
-            - name: CONFIG_FILEPATH
-              value: /tmp/config.yml
-            - name: CONSOLE_CONFIG_FILE
-              value: |
-                kafka:
-                  brokers: ["redpanda:29092"]
-                  schemaRegistry:
-                    enabled: true
-                    urls: ["http://redpanda:8081"]
-                redpanda:
-                  adminApi:
-                    enabled: true
-                    urls: ["http://redpanda:9644"]
-                connect:
-                  enabled: true
-                  clusters:
-                    - name: local-connect-cluster
-                      url: http://connect:8083
-          image: docker.redpanda.com/redpandadata/console:v2.2.4
-          name: console
-          ports:
-            - containerPort: 8080
-      restartPolicy: Always

konvert/console-ingress.yaml

@@ -1,17 +0,0 @@
-apiVersion: networking.k8s.io/v1
-kind: Ingress
-metadata:
-  name: ingress-myserviceb
-spec:
-  rules:
-    - host: console.lechindianer.hack
-      http:
-        paths:
-          - path: /
-            pathType: Prefix
-            backend:
-              service:
-                name: console
-                port:
-                  number: 8080
-  ingressClassName: nginx

konvert/console-service.yaml

@@ -1,13 +0,0 @@
-apiVersion: v1
-kind: Service
-metadata:
-  labels:
-    io.kompose.service: console
-  name: console
-spec:
-  ports:
-    - name: "8080"
-      port: 8080
-      targetPort: 8080
-  selector:
-    io.kompose.service: console

konvert/kafka-lag-exporter-deployment.yaml

@@ -1,26 +0,0 @@
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    io.kompose.service: kafka-lag-exporter
-  name: kafka-lag-exporter
-spec:
-  replicas: 1
-  selector:
-    matchLabels:
-      io.kompose.service: kafka-lag-exporter
-  template:
-    metadata:
-      labels:
-        io.kompose.network/redpanda-owl-shop-default: "true"
-        io.kompose.service: kafka-lag-exporter
-    spec:
-      containers:
-        - env:
-            - name: KAFKA_BROKERS
-              value: redpanda:29092
-          image: kafka-lag-exporter
-          name: kafka-lag-exporter
-          ports:
-            - containerPort: 4000
-      restartPolicy: Always

konvert/kafka-lag-exporter-service.yaml

@@ -1,13 +0,0 @@
-apiVersion: v1
-kind: Service
-metadata:
-  labels:
-    io.kompose.service: kafka-lag-exporter
-  name: kafka-lag-exporter
-spec:
-  ports:
-    - name: "4000"
-      port: 4000
-      targetPort: 4000
-  selector:
-    io.kompose.service: kafka-lag-exporter

konvert/owl-shop-deployment.yaml

@@ -1,31 +0,0 @@
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    io.kompose.service: owl-shop
-  name: owl-shop
-spec:
-  replicas: 1
-  selector:
-    matchLabels:
-      io.kompose.service: owl-shop
-  template:
-    metadata:
-      creationTimestamp: null
-      labels:
-        io.kompose.network/redpanda-owl-shop-redpanda-network: "true"
-        io.kompose.service: owl-shop
-    spec:
-      containers:
-        - env:
-            - name: SHOP_KAFKA_BROKERS
-              value: redpanda:29092
-            - name: SHOP_KAFKA_TOPICREPLICATIONFACTOR
-              value: "1"
-            - name: SHOP_TRAFFIC_INTERVAL_DURATION
-              value: 0.1s
-            - name: SHOP_TRAFFIC_INTERVAL_RATE
-              value: "6"
-          image: quay.io/cloudhut/owl-shop:latest
-          name: owl-shop
-      restartPolicy: Always

konvert/redpanda-deployment.yaml

@@ -1,44 +0,0 @@
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    io.kompose.service: redpanda
-  name: redpanda
-spec:
-  replicas: 1
-  selector:
-    matchLabels:
-      io.kompose.service: redpanda
-  strategy:
-    type: Recreate
-  template:
-    metadata:
-      labels:
-        io.kompose.network/redpanda-owl-shop-redpanda-network: "true"
-        io.kompose.service: redpanda
-    spec:
-      containers:
-        - args:
-            - redpanda start
-            - --smp 1
-            - --overprovisioned
-            - --kafka-addr PLAINTEXT://0.0.0.0:29092,OUTSIDE://0.0.0.0:9092
-            - --advertise-kafka-addr PLAINTEXT://redpanda:29092,OUTSIDE://localhost:9092
-            - --pandaproxy-addr 0.0.0.0:8082
-            - --advertise-pandaproxy-addr localhost:8082
-          image: docker.redpanda.com/redpandadata/redpanda:v23.1.8
-          name: redpanda
-          ports:
-            - containerPort: 8081
-            - containerPort: 8082
-            - containerPort: 9092
-            - containerPort: 9644
-            - containerPort: 29092
-          volumeMounts:
-            - mountPath: /var/lib/redpanda/data
-              name: redpanda
-      restartPolicy: Always
-      volumes:
-        - name: redpanda
-          persistentVolumeClaim:
-            claimName: redpanda

konvert/redpanda-owl-shop-default-networkpolicy.yaml

@@ -1,13 +0,0 @@
-apiVersion: networking.k8s.io/v1
-kind: NetworkPolicy
-metadata:
-  name: redpanda-owl-shop-default
-spec:
-  ingress:
-    - from:
-        - podSelector:
-            matchLabels:
-              io.kompose.network/redpanda-owl-shop-default: "true"
-  podSelector:
-    matchLabels:
-      io.kompose.network/redpanda-owl-shop-default: "true"

konvert/redpanda-owl-shop-redpanda-network-networkpolicy.yaml

@@ -1,13 +0,0 @@
-apiVersion: networking.k8s.io/v1
-kind: NetworkPolicy
-metadata:
-  name: redpanda-owl-shop-redpanda-network
-spec:
-  ingress:
-    - from:
-        - podSelector:
-            matchLabels:
-              io.kompose.network/redpanda-owl-shop-redpanda-network: "true"
-  podSelector:
-    matchLabels:
-      io.kompose.network/redpanda-owl-shop-redpanda-network: "true"

konvert/redpanda-persistentvolumeclaim.yaml

@@ -1,12 +0,0 @@
-apiVersion: v1
-kind: PersistentVolumeClaim
-metadata:
-  labels:
-    io.kompose.service: redpanda
-  name: redpanda
-spec:
-  accessModes:
-    - ReadWriteOnce
-  resources:
-    requests:
-      storage: 100Mi

konvert/redpanda-service.yaml

@@ -1,25 +0,0 @@
-apiVersion: v1
-kind: Service
-metadata:
-  labels:
-    io.kompose.service: redpanda
-  name: redpanda
-spec:
-  ports:
-    - name: "8081"
-      port: 8081
-      targetPort: 8081
-    - name: "8082"
-      port: 8082
-      targetPort: 8082
-    - name: "9092"
-      port: 9092
-      targetPort: 9092
-    - name: "9644"
-      port: 9644
-      targetPort: 9644
-    - name: "29092"
-      port: 29092
-      targetPort: 29092
-  selector:
-    io.kompose.service: redpanda

lib/kafkaex_lag_exporter/behaviours/kafka_utils_behaviour.ex

@@ -3,16 +3,6 @@ defmodule KafkaexLagExporter.KafkaUtils.Behaviour do
 
   @callback connection(atom) :: {list({charlist, non_neg_integer}), Keyword.t()}
 
-  @callback resolve_offsets(binary, :earliest | :latest, atom) ::
-              list({non_neg_integer, integer})
-
-  @callback fetch_committed_offsets(binary, binary, atom) ::
-              list({non_neg_integer, non_neg_integer})
-
-  @callback lag(binary, binary, atom) :: list({non_neg_integer, integer})
-
-  @callback lag_total(binary, binary, atom) :: non_neg_integer
-
   @callback get_consumer_group_names({host :: atom, port :: non_neg_integer}) :: list(binary)
 
   @callback get_consumer_group_info(
@@ -21,23 +11,20 @@ defmodule KafkaexLagExporter.KafkaUtils.Behaviour do
               list(binary)
             ) :: list({consumer_group :: binary, topics :: list(binary)})
 
+  @callback lag(binary, binary, atom) :: list({non_neg_integer, integer})
+
   def connection(client), do: impl().connection(client)
 
-  def resolve_offsets(topic, type, client), do: impl().resolve_offsets(topic, type, client)
-
-  def fetch_committed_offsets(topic, consumer_group, client),
-    do: impl().fetch_committed_offsets(topic, consumer_group, client)
-
-  def lag(topic, consumer_group, client), do: impl().lag(topic, consumer_group, client)
-
-  def lag_total(topic, consumer_group, client),
-    do: impl().lag_total(topic, consumer_group, client)
-
-  def get_consumer_group_names({host, port}), do: impl().get_consumer_group_names({host, port})
+  def get_consumer_group_names(endpoint), do: impl().get_consumer_group_names(endpoint)
 
   def get_consumer_group_info(endpoint, list, consumer_group_names),
     do: impl().get_consumer_group_info(endpoint, list, consumer_group_names)
 
+  def lag(topic, consumer_group, client), do: impl().lag(topic, consumer_group, client)
+
+  def fetch_committed_offsets(topic, consumer_group, client),
+    do: impl().fetch_committed_offsets(topic, consumer_group, client)
+
   defp impl,
     do: Application.get_env(:kafkaex_lag_exporter, :kafka_utils, KafkaexLagExporter.KafkaUtils)
 end

lib/kafkaex_lag_exporter/consumer_offset_fetcher.ex

@@ -4,10 +4,9 @@ defmodule KafkaexLagExporter.ConsumerOffsetFetcher do
   alias KafkaexLagExporter.ConsumerOffset
   alias KafkaexLagExporter.KafkaUtils
 
-  # TODO fix type
   @spec get(KafkaexLagExporter.KafkaWrapper.Behaviour.endpoint()) :: %{
-          lags: list(binary),
-          sum: list(binary)
+          lags: list(ConsumerOffset.t()),
+          sum: list(ConsumerOffset.t())
         }
   def get(endpoint) do
     consumer_group_names = KafkaUtils.get_consumer_group_names(endpoint)

lib/kafkaex_lag_exporter/consumer_offset_runner.ex

@@ -5,8 +5,6 @@ defmodule KafkaexLagExporter.ConsumerOffsetRunner do
 
   require Logger
 
-  @interval 5_000
-
   def start_link(default) when is_list(default) do
     GenServer.start_link(__MODULE__, default, name: __MODULE__)
   end
@@ -18,23 +16,29 @@ defmodule KafkaexLagExporter.ConsumerOffsetRunner do
     clients = Application.get_env(:brod, :clients)
     endpoints = clients[:kafka_client][:endpoints] || [{"redpanda", 29_092}]
 
+    interval =
+      System.get_env("KAFKA_EX_INTERVAL_MS", "5000")
+      |> String.to_integer()
+
     Logger.info("Reveived Kafka endpoints: #{inspect(endpoints)}")
+    Logger.info("Updating lag information every #{interval} milliseconds")
 
-    Process.send_after(self(), :tick, @interval)
+    Process.send_after(self(), :tick, interval)
 
-    {:ok, %{endpoints: endpoints}}
+    {:ok, %{endpoints: endpoints, interval: interval}}
   end
 
   @impl true
   def handle_info(:tick, state) do
     [endpoint | _] = state.endpoints
+    interval = state.interval
 
-    %{sum: lag_sum, lags: lags} = KafkaexLagExporter.ConsumerOffsetFetcher.get(endpoint)
+    %{lags: lags, sum: lag_sum} = KafkaexLagExporter.ConsumerOffsetFetcher.get(endpoint)
 
     KafkaexLagExporter.Metrics.group_lag_per_partition(endpoint, lags)
     KafkaexLagExporter.Metrics.group_sum_lag(endpoint, lag_sum)
 
-    Process.send_after(self(), :tick, @interval)
+    Process.send_after(self(), :tick, interval)
 
     {:noreply, state}
   end

lib/kafkaex_lag_exporter/kafka_utils.ex

@@ -7,8 +7,6 @@ defmodule KafkaexLagExporter.KafkaUtils do
 
   alias KafkaexLagExporter.KafkaWrapper.Behaviour, as: KafkaWrapper
 
-  require Logger
-
   @default_client :client1
 
   def connection, do: connection(@default_client)
@@ -32,54 +30,8 @@ defmodule KafkaexLagExporter.KafkaUtils do
   end
 
   @impl true
-  def resolve_offsets(topic, type, client) do
-    {endpoints, sock_opts} = connection(client)
-
-    {:ok, partitions_count} = KafkaWrapper.get_partitions_count(client, topic)
-
-    for i <- Range.new(0, partitions_count - 1),
-        {:ok, offset} =
-          KafkaWrapper.resolve_offset(endpoints, topic, i, type, sock_opts) do
-      {i, offset}
-    end
-  end
-
-  @impl true
-  def fetch_committed_offsets(_topic, consumer_group, client) do
-    {endpoints, sock_opts} = connection(client)
-
-    {:ok, response} = KafkaWrapper.fetch_committed_offsets(endpoints, sock_opts, consumer_group)
-
-    for r <- response,
-        pr <- r[:partitions],
-        do: {pr[:partition_index], pr[:committed_offset]}
-  end
-
-  @impl true
-  def lag(topic, consumer_group, client) do
-    offsets =
-      resolve_offsets(topic, :latest, client)
-      |> Enum.sort_by(fn {key, _value} -> key end)
-
-    committed_offsets =
-      fetch_committed_offsets(topic, consumer_group, client)
-      |> Enum.sort_by(fn {key, _value} -> key end)
-
-    for {{part, current}, {_part2, committed}} <- Enum.zip(offsets, committed_offsets) do
-      {part, current - committed}
-    end
-  end
-
-  @impl true
-  def lag_total(topic, consumer_group, client) do
-    for {_part, recs} <- lag(topic, consumer_group, client), reduce: 0 do
-      acc -> acc + recs
-    end
-  end
-
-  @impl true
-  def get_consumer_group_names({host, port}) do
-    [{_, groups} | _] = KafkaWrapper.list_all_groups([{host, port}], [])
+  def get_consumer_group_names(endpoint) do
+    [{_, groups} | _] = KafkaWrapper.list_all_groups([endpoint], [])
 
     groups
     |> Enum.filter(fn {_, _, protocol} -> protocol === "consumer" end)
@@ -92,25 +44,69 @@ defmodule KafkaexLagExporter.KafkaUtils do
 
     group_descriptions
     |> Enum.flat_map(fn %{group_id: consumer_group, members: members} ->
-      get_member_info(members)
-      |> Enum.map(fn {topic_names, consumer_id, member_host} ->
-        {consumer_group, topic_names, consumer_id, member_host}
-      end)
+      get_member_info(consumer_group, members)
     end)
   end
 
+  @impl true
+  def lag(topic, consumer_group, client) do
+    offsets =
+      resolve_offsets(topic, client)
+      |> Enum.sort_by(fn {key, _value} -> key end)
+
+    committed_offsets =
+      fetch_committed_offsets(topic, consumer_group, client)
+      |> Enum.sort_by(fn {key, _value} -> key end)
+
+    for {{part, current}, {_, committed}} <- Enum.zip(offsets, committed_offsets) do
+      {part, current - committed}
+    end
+  end
+
+  @spec resolve_offsets(binary, atom) :: list({non_neg_integer, integer})
+  defp resolve_offsets(topic, client) do
+    {endpoints, sock_opts} = connection(client)
+
+    {:ok, partitions_count} = KafkaWrapper.get_partitions_count(client, topic)
+
+    for i <- Range.new(0, partitions_count - 1),
+        {:ok, offset} = KafkaWrapper.resolve_offset(endpoints, topic, i, :latest, sock_opts) do
+      {i, offset}
+    end
+  end
+
+  @spec fetch_committed_offsets(binary, binary, atom) ::
+          list({non_neg_integer, non_neg_integer})
+  defp fetch_committed_offsets(_topic, consumer_group, client) do
+    {endpoints, sock_opts} = connection(client)
+
+    {:ok, response} = KafkaWrapper.fetch_committed_offsets(endpoints, sock_opts, consumer_group)
+
+    for r <- response, pr <- r[:partitions] do
+      {pr[:partition_index], pr[:committed_offset]}
+    end
+  end
+
   @spec get_member_info(
+          binary,
           list(%{client_host: binary, member_assignment: binary, member_id: binary})
         ) ::
-          list({topic_names :: list(binary), consumer_id :: binary, member_host :: binary})
-  defp get_member_info(members) do
-    Enum.map(members, fn %{
+          list(
+            {consumer_group :: binary, topics :: list(binary), consumer_id :: binary,
+             member_host :: binary}
+          )
+  defp get_member_info(consumer_group, members) do
+    members
+    |> Enum.map(fn %{
                      client_host: member_host,
                      member_assignment: member_assignment,
                      member_id: consumer_id
                    } ->
-      topic_names = KafkaexLagExporter.TopicNameParser.parse_topic_names(member_assignment)
-      {topic_names, consumer_id, member_host}
+      topics = KafkaexLagExporter.TopicNameParser.parse_topic_names(member_assignment)
+      {topics, consumer_id, member_host}
+    end)
+    |> Enum.map(fn {topics, consumer_id, member_host} ->
+      {consumer_group, topics, consumer_id, member_host}
     end)
   end
 end

lib/kafkaex_lag_exporter/metrics.ex

@@ -36,9 +36,13 @@ defmodule KafkaexLagExporter.Metrics do
     )
   end
 
+  @spec group_sum_lag(
+          KafkaexLagExporter.KafkaWrapper.Behaviour.endpoint(),
+          list(ConsumerOffset.t())
+        ) :: :ok
   @doc false
-  def group_sum_lag({host, _port}, cunsumer_offsets) do
-    Enum.each(cunsumer_offsets, fn %ConsumerOffset{} = consumer_offset ->
+  def group_sum_lag({host, _port}, consumer_offsets) do
+    Enum.each(consumer_offsets, fn %ConsumerOffset{} = consumer_offset ->
       lag = elem(consumer_offset.lag, 1)
 
       :telemetry.execute(
@@ -55,6 +59,10 @@ defmodule KafkaexLagExporter.Metrics do
     end)
   end
 
+  @spec group_lag_per_partition(
+          KafkaexLagExporter.KafkaWrapper.Behaviour.endpoint(),
+          list(ConsumerOffset.t())
+        ) :: :ok
   @doc false
   def group_lag_per_partition({host, _port}, consumer_offsets) do
     Enum.each(consumer_offsets, fn %ConsumerOffset{} = consumer_offset ->

test/consumer_offset_fetcher_test.exs

@@ -40,9 +40,7 @@ defmodule KafkaexLagExporter.ConsumerOffsetFetcher.Test do
   end
 
   test "should return the calculated lags" do
-    test_endpoint = {"test endpoint", 666}
-
-    %{sum: sum, lags: lags} = KafkaexLagExporter.ConsumerOffsetFetcher.get(test_endpoint)
+    %{sum: sum, lags: lags} = KafkaexLagExporter.ConsumerOffsetFetcher.get({"test endpoint", 666})
 
     assert sum == [
              %ConsumerOffset{

test/kafka_utils_test.exs

@@ -5,9 +5,11 @@ defmodule KafkaexLagExporter.KafkaUtils.Test do
   alias KafkaexLagExporter.KafkaWrapper.Behaviour, as: KafkaWrapper
   alias KafkaexLagExporter.KafkaUtils
 
-  @test_endpoint "test_host:1234"
-  @test_consumer_group "test-consumer-group"
+  @test_endpoint {"test_host", "1234"}
   @test_sock_opts [ssl: []]
+  @test_group_name1 "test-consumer_group1"
+  @test_group_name2 "test-consumer_group"
+  @test_topic_name "test-topic_name"
 
   setup do
     patch(
@@ -19,86 +21,175 @@ defmodule KafkaexLagExporter.KafkaUtils.Test do
     :ok
   end
 
-  describe "resolve_offsets" do
+  describe "get_consumer_group_names" do
     setup do
-      client = :client2
-      topic = "test-topic"
+      consumer_info1 = {:a, @test_group_name1, "consumer"}
+      consumer_info2 = {:b, @test_group_name2, "something-other"}
 
-      patch(
-        KafkaWrapper,
-        :get_partitions_count,
-        fn _, _ -> {:ok, 3} end
+      patch(KafkaWrapper, :list_all_groups, fn _, _ ->
+        [{@test_endpoint, [consumer_info1, consumer_info2]}]
+      end)
+
+      group_names = KafkaUtils.get_consumer_group_names(@test_endpoint)
+
+      [group_names: group_names]
+    end
+
+    test "should list all groups" do
+      assert_called(KafkaWrapper.list_all_groups([@test_endpoint], []))
+    end
+
+    test "should filter for consumer groups and return names", context do
+      assert context[:group_names] === [@test_group_name1]
+    end
+  end
+
+  describe "get_consumer_group_info" do
+    setup do
+      consumer_group_name = "test-group-id1"
+      member_assignment = "test_member_assignment"
+      member_assignment = "test_member_assignment"
+      consumer_id = "test_consumer_id"
+      member_host = "test_member_host"
+
+      patch(KafkaWrapper, :describe_groups, fn _, _, _ ->
+        {
+          :ok,
+          [
+            %{
+              group_id: consumer_group_name,
+              members: [
+                %{
+                  client_host: member_host,
+                  member_assignment: member_assignment,
+                  member_id: consumer_id
+                }
+              ]
+            }
+          ]
+        }
+      end)
+
+      patch(KafkaexLagExporter.TopicNameParser, :parse_topic_names, fn _ -> [@test_topic_name] end)
+
+      group_info =
+        KafkaUtils.get_consumer_group_info(@test_endpoint, [], [
+          @test_group_name1,
+          @test_group_name2
+        ])
+
+      [
+        member_host: member_host,
+        group_info: group_info,
+        consumer_group_name: consumer_group_name,
+        member_assignment: member_assignment,
+        consumer_id: consumer_id
+      ]
+    end
+
+    test "should describe groups" do
+      assert_called(
+        KafkaWrapper.describe_groups(@test_endpoint, [], [@test_group_name1, @test_group_name2])
       )
+    end
 
-      patch(
-        KafkaWrapper,
-        :resolve_offset,
-        fn _, _, _, _, _ -> {:ok, 42} end
+    test "should parse topic names", context do
+      expected_member_assignment = context[:expected_member_assignment]
+
+      assert_called(
+        KafkaexLagExporter.TopicNameParser.parse_topic_names(expected_member_assignment)
       )
+    end
 
-      offsets = KafkaUtils.resolve_offsets(topic, :earliest, client)
+    test "should filter for consumer groups and return names", context do
+      expected_consumer_group_name = context[:consumer_group_name]
+      expected_consumer_id = context[:consumer_id]
+      expected_member_host = context[:member_host]
 
-      [client: client, offsets: offsets, topic: topic]
+      assert context[:group_info] === [
+               {
+                 expected_consumer_group_name,
+                 [@test_topic_name],
+                 expected_consumer_id,
+                 expected_member_host
+               }
+             ]
+    end
+  end
+
+  describe "lag" do
+    setup do
+      consumer_group = "test-consumer-group"
+      client = :client1
+      committed_offset1 = 23
+      committed_offset2 = 42
+      resolved_offset = 50
+
+      partition_info1 = %{partition_index: 0, committed_offset: committed_offset1}
+      partition_info2 = %{partition_index: 1, committed_offset: committed_offset2}
+
+      patch(KafkaWrapper, :get_partitions_count, fn _, _ -> {:ok, 2} end)
+
+      patch(KafkaWrapper, :resolve_offset, fn _, _, _, _, _ -> {:ok, resolved_offset} end)
+
+      patch(KafkaWrapper, :fetch_committed_offsets, fn _, _, _ ->
+        {:ok, [%{name: "test name", partitions: [partition_info1, partition_info2]}]}
+      end)
+
+      lag = KafkaUtils.lag(@test_topic_name, consumer_group, client)
+
+      [
+        lag: lag,
+        consumer_group: consumer_group,
+        client: client,
+        committed_offset1: committed_offset1,
+        committed_offset2: committed_offset2,
+        resolved_offset: resolved_offset
+      ]
+    end
+
+    test "should start connection", context do
+      expected_client = context[:client]
+
+      assert_called(KafkaUtils.connection(expected_client))
     end
 
     test "should get partition count", context do
-      expected_topic = context[:topic]
       expected_client = context[:client]
 
-      assert_called(KafkaWrapper.get_partitions_count(expected_client, expected_topic))
+      assert_called(KafkaWrapper.get_partitions_count(expected_client, @test_topic_name))
     end
 
-    test "should resolve offset per partition", context do
-      expected_topic = context[:topic]
-
+    test "should resolve offsets for each partition" do
       assert_called(
-        KafkaWrapper.resolve_offset(@test_endpoint, expected_topic, 0, :earliest, @test_sock_opts)
+        KafkaWrapper.resolve_offset(@test_endpoint, @test_topic_name, 0, :latest, @test_sock_opts)
       )
 
       assert_called(
-        KafkaWrapper.resolve_offset(@test_endpoint, expected_topic, 1, :earliest, @test_sock_opts)
-      )
-
-      assert_called(
-        KafkaWrapper.resolve_offset(@test_endpoint, expected_topic, 2, :earliest, @test_sock_opts)
+        KafkaWrapper.resolve_offset(@test_endpoint, @test_topic_name, 1, :latest, @test_sock_opts)
       )
     end
 
-    test "should return offsets", context do
-      assert context[:offsets] == [{0, 42}, {1, 42}, {2, 42}]
-    end
-  end
+    test "should fetch committed offsets", context do
+      expected_consumer_group = context[:consumer_group]
 
-  describe "fetch_committed_offsets" do
-    setup do
-      partition_info1 = %{partition_index: 0, committed_offset: 23}
-      partition_info2 = %{partition_index: 1, committed_offset: 42}
-
-      patch(
-        KafkaWrapper,
-        :fetch_committed_offsets,
-        fn _, _, _ ->
-          {:ok, [%{name: "test name", partitions: [partition_info1, partition_info2]}]}
-        end
-      )
-
-      offsets = KafkaUtils.fetch_committed_offsets("test-topic", @test_consumer_group, :test_atom)
-
-      [offsets: offsets]
-    end
-
-    test "should get the committed offsets from KafkaWrapper" do
       assert_called(
         KafkaWrapper.fetch_committed_offsets(
           @test_endpoint,
           @test_sock_opts,
-          @test_consumer_group
+          expected_consumer_group
         )
       )
     end
 
-    test "should return offsets", context do
-      assert context[:offsets] == [{0, 23}, {1, 42}]
+    test "should return calculated lag per partition", context do
+      expected_lag_partition_1 = context[:resolved_offset] - context[:committed_offset1]
+      expected_lag_partition_2 = context[:resolved_offset] - context[:committed_offset2]
+
+      assert context[:lag] === [
+               {0, expected_lag_partition_1},
+               {1, expected_lag_partition_2}
+             ]
     end
   end
 end