Question 349966 in Docker Question posted in
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Nomad add the docker task to particular network

I have a redpanda container which I want to use as a sink using vector when I am running this nomad job it is giving this error

Feb 27 08:57:01.931 ERROR rdkafka::client: librdkafka: Global error: Resolve (Local: Host resolution failure): redpanda-0:9092/bootstrap: Failed to resolve 'redpanda-0:9092': Name does not resolve (after 1ms in state CONNECT, 15 identical error(s) suppressed)

this is my nomad job configuration

job "vector-redpanda" {
  datacenters = ["dc1"]
  # system job, runs on all nodes
  type = "system"
  update {
    min_healthy_time = "10s"
    healthy_deadline = "5m"
    progress_deadline = "10m"
    auto_revert = true
  }
  group "vector" {
    count = 1
    restart {
      attempts = 3
      interval = "10m"
      delay = "30s"
      mode = "fail"
    }
    network {
      port "api" {
        to = 8787
      }
      port "redpanda_network" {}
    }
    # docker socket volume
    volume "docker-sock-ro" {
      type = "host"
      source = "docker-sock-ro"
      read_only = true
    }
    ephemeral_disk {
      size    = 500
      sticky  = true
    }
    task "vector" {
      driver = "docker"
      config {
        image = "timberio/vector:0.14.X-alpine"
        ports = ["api", "redpanda_network"]
      }
      # docker socket volume mount
      volume_mount {
        volume = "docker-sock-ro"
        destination = "/var/run/docker.sock"
        read_only = true
      }
      # Vector won't start unless the sinks(backends) configured are healthy
      env {
        VECTOR_CONFIG = "local/vector.toml"
        VECTOR_REQUIRE_HEALTHY = "true"
      }
      # resource limits are a good idea because you don't want your log collection to consume all resources available
      resources {
        cpu    = 500 # 500 MHz
        memory = 256 # 256MB
      }
      # template with Vector's configuration
      template {
        destination = "local/vector.toml"
        change_mode   = "signal"
        change_signal = "SIGHUP"
        # overriding the delimiters to [[ ]] to avoid conflicts with Vector's native templating, which also uses {{ }}
        left_delimiter = "[["
        right_delimiter = "]]"
        data=<<EOH
                data_dir = "alloc/data/vector/"
              [api]
                enabled = true
                address = "0.0.0.0:8787"
                playground = true
              [sources.logs]
                type = "docker_logs"
              [transforms.records_for_redpanda]
                type = "lua"
                inputs = [ "logs" ]
                version = "2"
              [transforms.records_for_redpanda.hooks]
                process = """
                  function (event, emit)
                    event.log.job_id = event.log.label.job_id
                    event.log.task_id = event.log.label.task_id
                    event.log.run_id = event.log.label.run_id
                    event.log.created_at = event.log.timestamp
                    if event.log.run_id ~= "" then
                      emit(event)
                    end
                  end"""
              [sinks.my_kafka_sink]
                type = "kafka"
                inputs = [ "records_for_redpanda" ]
                bootstrap_servers = "redpanda-0:9092"
                topic = "logs_aggregation"
                acknowledgements.enabled = true
                compression = "gzip"
                healthcheck.enabled = false
                encoding.only_fields = ["job_id", "task_id", "run_id", "message", "created_at"]
                        encoding.timestamp_format = "unix"
                        encoding.codec = "json"
                message_timeout_ms = 450000
        EOH
      }
      service {
        check {
          port     = "api"
          type     = "http"
          path     = "/health"
          interval = "30s"
          timeout  = "5s"
        }
      }
      kill_timeout = "30s"
    }
  }
}

I tried the same thing by creating a vector container in the same network as redpanda container network and it worked. I am not sure how I can do it for docker task in nomad.

Tags:

2

Answers


  1. 0

    You have to change

    bootstrap_servers = "redpanda-0:9092"

    With the IP and port allocated for redpanda. You might be interested in templating https://developer.hashicorp.com/nomad/docs/job-specification/template#consul-integration .

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  2. 0

    To fix the issue, add network_mode under the Vector task’s Docker config in your Nomad job file, setting it to the Docker network name where your Redpanda container is running. This ensures Vector and Redpanda are on the same network, allowing Vector to resolve and connect to Redpanda without DNS issues.

    Here’s an example adjustment for your Nomad job specification:

    task "vector" {
  driver = "docker"
  config {
    image = "timberio/vector:0.14.X-alpine"
    ports = ["api", "redpanda_network"]
    network_mode = "your_redpanda_docker_network_name" # <-- Adjust this line with your Docker network name
  }
  ...
}

    Remember to replace "your_redpanda_docker_network_name" with the actual name of the Docker network where your Redpanda container is running.

    This adjustment ensures that the Vector container can resolve and connect to redpanda-0:9092, addressing the DNS resolution failure error you encountered.

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