Unable to bind docker.sock to Docker Service

Question

I am trying to setup a docker service (via terraform) which will run jenkins as containers. I want to bind the host VM's docker docket to the docker service. I tried two options.

1. Docker Service as command
2. Spawn docker service using terraform

While the service gets instantiated successfully, the container doesn't recognize the docker socket. I can see the /var/run/docker.sock file inside the container but docker command wont work.

The code block for your reference.

DOCKER SERVICE COMMAND

docker service  create --name aws --mount=type=bind,src=/var/run/docker.sock,dst=/var/run/docker.sock jenkins/jenkins:lts

TERRAFORM MAIN TF FILE

resource "docker_service" "jenkins_service" {
  name = var.project_name
  task_spec {
    container_spec {
      image = docker_image.jenkins_image.name
      mounts {
        source = var.jenkins_volume
        target = "/var/jenkins_home"
        type   = "bind"
      }
      mounts {
        source = "/var/run/docker.sock"
        target = "/var/run/docker.sock"
        type   = "bind"
      }
    }
    networks = ["${docker_network.jenkins_network.name}"]
  }

  endpoint_spec {
    ports {
      target_port    = "8080"
      published_port = var.web_interface_port
      publish_mode   = "ingress"
      name           = "WEB_INTERFACE"
    }
    ports {
      target_port    = "50000"
      published_port = var.api_interface_port
      publish_mode   = "ingress"
      name           = "API_INTERFACE"
    }
  }
}

Error Message

bash-4.2$ docker exec -u 0 -it 9bc2a468174a bash
root@9bc2a468174a:/# docker
bash: docker: command not found
root@9bc2a468174a:/# ls -ltr /var/run/docker.sock
srwxrwxrwx. 1 root 167 0 Sep 24 11:02 /var/run/docker.sock

Docker Version

-bash-4.2$ docker version
Client:
Version: 18.09.8
API version: 1.39
Go version: go1.10.8
Git commit: 0dd43dd87f
Built: Wed Jul 17 17:40:31 2019
OS/Arch: linux/amd64
Experimental: false

Server: Docker Engine - Community
Engine:
Version: 18.09.8 API version: 1.39 (minimum version 1.12)
Go version: go1.10.8
Git commit: 0dd43dd
Built: Wed Jul 17 17:10:42 2019
OS/Arch: linux/amd64
Experimental: false

Any inputs will be much appreciated.

Regards Senthil Nathan M

Answer 1

bash: docker: command not found.

You don't have docker client installed in your container. Mounting /var/run/docker.sock from host inside the container just makes the container's docker client talk to host's docker daemon. You still need to install at least the docker client in your container.