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Clivern
Clivern

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Getting Started with Hashicorp Nomad

#docker #devops #microservices #kubernetes

Basic Setup (Not Recommended):

  • Download nomad binary & make it executable: 
$ wget https://releases.hashicorp.com/nomad/1.0.5/nomad_1.0.5_linux_amd64.zip
$ unzip nomad_1.0.5_linux_amd64.zip
$ mv nomad /usr/local/bin/
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  • Create configs directory & data directory: 
$ sudo mkdir --parents /opt/nomad
$ sudo mkdir --parents /opt/data/redis
$ sudo mkdir --parents /etc/nomad.d
$ sudo chmod 700 /etc/nomad.d
$ sudo chmod 700 /opt/data

$ sudo touch /etc/nomad.d/nomad.hcl
$ sudo touch /etc/nomad.d/server.hcl
$ sudo touch /etc/nomad.d/client.hcl
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  • Add this configuration to the /etc/nomad.d/nomad.hcl configuration file 
datacenter = "dc1"
data_dir = "/opt/nomad"
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  • Add this configuration to the /etc/nomad.d/client.hcl configuration file 
client {
  enabled = true

  host_volume "redis_data" {
    path      = "/opt/data/redis"
    read_only = false
  }
}

plugin "docker" {
  config {
    volumes {
      enabled      = true
      selinuxlabel = "z"
    }
  }
}
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  • Add this configuration to the /etc/nomad.d/server.hcl configuration file 
acl {
  enabled = true
}
server {
  enabled = true
  bootstrap_expect = 1
}
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  • Create a nomad service file 
$ sudo touch /etc/systemd/system/nomad.service
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  • Add this configuration to the nomad service file /etc/systemd/system/nomad.service 
[Unit]
Description=Nomad
Documentation=https://nomadproject.io/docs/

[Service]
ExecStart=/usr/local/bin/nomad agent -config /etc/nomad.d
Restart=on-failure
RestartSec=2

[Install]
WantedBy=multi-user.target
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  • Start nomad 
sudo systemctl enable nomad
sudo systemctl start nomad
sudo systemctl status nomad
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  • Genertal ACL secrets 
$ nomad acl bootstrap
Accessor ID  = a8b724ef-b5eb-21c0-1a68-b0d3616e1e62
Secret ID    = 07fe0ee6-59bc-8ea0-aeeb-9b4e9edcb555
Name         = Bootstrap Token
Type         = management
Global       = true
Policies     = n/a
Create Time  = 2021-05-10 21:05:21.498072284 +0000 UTC
Create Index = 10
Modify Index = 10

$ export NOMAD_TOKEN=07fe0ee6-59bc-8ea0-aeeb-9b4e9edcb555
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  • Create your first job to deploy a stateless container from the server ui http://127.0.0.1:4646/ui 
job "api" {
  datacenters = ["dc1"]

  group "example" {
    task "server" {
      driver = "docker"

      config {
        image = "hashicorp/http-echo:0.2.1"

        args = [
          "-listen",
          ":5678",
          "-text",
          "hello world",
        ]
      }

      resources {
        network {
          mbits = 10

          port "http" {
            static = "5678"
          }
        }
      }
    }
  }
}
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  • And another one for stateful container 
job "cache" {
  datacenters = ["dc1"]

  group "redis" {

    volume "redis_data" {
      type      = "host"
      read_only = false
      source    = "redis_data"
    }

    task "server" {
      driver = "docker"

      volume_mount {
        volume      = "redis_data"
        destination = "/data"
        read_only   = false
      }

      config {
        image = "redis:4-alpine"

        labels = {
          "sh.hippo.service" = "redis"
          "sh.hippo.service_type" = "cache"
        }

        port_map {
          http = 6379
        }

        command = "redis-server"

        args = [
          "--requirepass",
          "mystery",
        ]
      }

      env = {
        HEALTHY_FOR    = -1,
      }

      resources {
        cpu    = 100
        memory = 256

        network {
          mbits = 10

          port "http" {
            static = "6379"
          }
        }
      }
    }
  }
}
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Multi Nodes Setup (Recommended):

To fully understand how nomad cluster should look like, please check this guide!

Assuming we have two servers, one for the nomad server (Leader) and another for the client. Both servers are in DC1. The leader server has public IP $SERVER_PUBLIC_IP and private IP $SERVER_PRIVATE_IP.

First we run the leader or the nomad server by following the next steps:

  • Download nomad binary & make it executable: 
$ wget https://releases.hashicorp.com/nomad/1.0.5/nomad_1.0.5_linux_amd64.zip
$ unzip nomad_1.0.5_linux_amd64.zip
$ mv nomad /usr/local/bin/
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  • Create configs directory & data directory: 
$ sudo mkdir --parents /opt/nomad
$ sudo mkdir --parents /opt/data/redis
$ sudo mkdir --parents /etc/nomad.d
$ sudo chmod 700 /etc/nomad.d
$ sudo chmod 700 /opt/data

$ sudo touch /etc/nomad.d/nomad.hcl
$ sudo touch /etc/nomad.d/server.hcl
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  • Add this configuration to the /etc/nomad.d/nomad.hcl configuration file 
datacenter = "dc1"
data_dir = "/opt/nomad"
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  • Add this configuration to the /etc/nomad.d/server.hcl configuration file 
acl {
  enabled = true
}

server {
  enabled = true
  bootstrap_expect = 1
}

bind_addr = "$SERVER_PUBLIC_IP"

addresses {
  http = "$SERVER_PUBLIC_IP"
  rpc  = "$SERVER_PRIVATE_IP"
  serf = "$SERVER_PRIVATE_IP"
}

advertise {
  http = "$SERVER_PUBLIC_IP:4646"
  rpc  = "$SERVER_PRIVATE_IP:4647"
  serf = "$SERVER_PRIVATE_IP:4648"
}
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  • Create a nomad service file 
$ sudo touch /etc/systemd/system/nomad.service
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  • Add this configuration to the nomad service file /etc/systemd/system/nomad.service 
[Unit]
Description=Nomad
Documentation=https://nomadproject.io/docs/

[Service]
ExecStart=/usr/local/bin/nomad agent -config /etc/nomad.d
Restart=on-failure
RestartSec=2

[Install]
WantedBy=multi-user.target
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  • Start nomad 
sudo systemctl enable nomad
sudo systemctl start nomad
sudo systemctl status nomad
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  • Genertal ACL secrets 
$ nomad acl bootstrap -address=http://$SERVER_PUBLIC_IP:4646
Accessor ID  = a8b724ef-b5eb-21c0-1a68-b0d3616e1e62
Secret ID    = 07fe0ee6-59bc-8ea0-aeeb-9b4e9edcb555
Name         = Bootstrap Token
Type         = management
Global       = true
Policies     = n/a
Create Time  = 2021-05-10 21:05:21.498072284 +0000 UTC
Create Index = 10
Modify Index = 10

$ export NOMAD_TOKEN=07fe0ee6-59bc-8ea0-aeeb-9b4e9edcb555
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Then we run the client by following the next steps:

  • Download nomad binary & make it executable: 
$ wget https://releases.hashicorp.com/nomad/1.0.5/nomad_1.0.5_linux_amd64.zip
$ unzip nomad_1.0.5_linux_amd64.zip
$ mv nomad /usr/local/bin/
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  • Create configs directory & data directory: 
$ sudo mkdir --parents /opt/nomad
$ sudo mkdir --parents /opt/data/redis
$ sudo mkdir --parents /etc/nomad.d
$ sudo chmod 700 /etc/nomad.d
$ sudo chmod 700 /opt/data

$ sudo touch /etc/nomad.d/nomad.hcl
$ sudo touch /etc/nomad.d/client.hcl
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  • Add this configuration to the /etc/nomad.d/nomad.hcl configuration file 
datacenter = "dc1"
data_dir = "/opt/nomad"
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  • Add this configuration to the /etc/nomad.d/client.hcl configuration file 
client {
  enabled = true

  servers = ["$SERVER_PRIVATE_IP:4647"]

  host_volume "redis_data" {
    path      = "/opt/data/redis"
    read_only = false
  }
}

plugin "docker" {
  config {
    volumes {
      enabled      = true
      selinuxlabel = "z"
    }
  }
}
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  • Create a nomad service file 
$ sudo touch /etc/systemd/system/nomad.service
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  • Add this configuration to the nomad service file /etc/systemd/system/nomad.service 
[Unit]
Description=Nomad
Documentation=https://nomadproject.io/docs/

[Service]
ExecStart=/usr/local/bin/nomad agent -config /etc/nomad.d
Restart=on-failure
RestartSec=2

[Install]
WantedBy=multi-user.target
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  • Start nomad 
sudo systemctl enable nomad
sudo systemctl start nomad
sudo systemctl status nomad
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CNI Plugins in Nomad

Nomad uses CNI plugins when bridge networking is used. To install CNI plugins:

$ curl -L -o cni-plugins.tgz https://github.com/containernetworking/plugins/releases/download/v0.8.0/cni-plugins-linux-amd64-v0.8.0.tgz
$ mkdir -p /opt/cni/bin
$ tar -C /opt/cni/bin -xzf cni-plugins.tgz
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job "clivern" {
  datacenters = ["dc1"]

  group "services" {

    network {

      port "toad0_srv" {
        static = 8080
      }

      port "toad1_srv" {
        static = 8081
      }
    }

    task "toad0" {
      driver = "docker"

      config {
        image = "clivern/toad:release-0.2.4"

        labels = {
          "com.clivern.service" = "toad"
          "com.clivern.service_type" = "web"
        }

        ports = ["toad0_srv"]

        command = "./toad"

        args = [
          "--port",
          "${NOMAD_PORT_toad0_srv}",
        ]
      }

      env = {
        IS_STATEFUL    = "false",
        TOAD0_ADDR     = "${NOMAD_HOST_ADDR_toad0_srv}",
        TOAD1_ADDR     = "${NOMAD_HOST_ADDR_toad1_srv}",
      }

      resources {
        network {
          mbits = 10
        }
      }
    }

    task "toad1" {
      driver = "docker"

      config {
        image = "clivern/toad:release-0.2.3"

        labels = {
          "com.clivern.service" = "toad"
          "com.clivern.service_type" = "web"
        }

        ports = ["toad1_srv"]

        command = "./toad"

        args = [
          "--port",
          "${NOMAD_PORT_toad1_srv}",
        ]
      }

      env = {
        IS_STATEFUL    = "false",
        TOAD0_ADDR     = "${NOMAD_HOST_ADDR_toad0_srv}",
        TOAD1_ADDR     = "${NOMAD_HOST_ADDR_toad1_srv}",
      }

      resources {
        network {
          mbits = 10
        }
      }
    }
  }
}
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References:

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