docker containers - missing attribute - docker

Question

I needed a custom centos image with docker installed. So I built it using centos image and tagged it custom (shown below).
$ docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
centos custom 84766562f881 4 hours ago 664MB
centos/systemd latest 05d3c1e2d0c1 7 weeks ago 202MB
I am trying to deploy couple of containers using Terraform on my local machine, each with a unique name that comes from another file. The docker images are on local machine. Here's the TF code.
$ cat main.tf
provider "docker" {
}
resource "docker_image" "centos" {
name = "centos:custom"
}
resource "docker_container" "app_swarm" {
image = "${docker_image.centos.custom}"
count = "${length(var.docker_cont)}"
name = "${element(var.docker_cont, count.index)}"
}
When I run terraform apply, I get this error which I am not sure how to fix. Can someone point me in the right direction please?
Error: Error running plan: 1 error(s) occurred:
* docker_container.app_swarm: 3 error(s) occurred:
* docker_container.app_swarm[0]: Resource 'docker_image.centos' does not have attribute 'custom' for variable 'docker_image.centos.custom'
* docker_container.app_swarm[1]: Resource 'docker_image.centos' does not have attribute 'custom' for variable 'docker_image.centos.custom'
* docker_container.app_swarm[2]: Resource 'docker_image.centos' does not have attribute 'custom' for variable 'docker_image.centos.custom'
Yes, the other file exists with names, its a simple list.
EDIT:
Thanks David, tried your suggestion and amended the code to look like-
provider "docker" {
}
resource "docker_image" "centos" {
name = "centos:custom"
}
resource "docker_container" "app_swarm" {
image = "${docker_image.centos.latest}"
count = "${length(var.docker_cont)}"
name = "${element(var.docker_cont, count.index)}"
}
But now I get this error.
Error: Error applying plan:
1 error(s) occurred:
* docker_image.centos: 1 error(s) occurred:
* docker_image.centos: Unable to read Docker image into resource: Unable to pull image centos:custom: error pulling image centos:custom: Error response from daemon: manifest for centos:custom not found
I guess I will have to setup a local Docker repository to get this working but I am not sure?

Answer 1

You can only use the specific fields listed in the docker_image resource documentation in the ${docker_image.centos...} interpolation. In particular, even though you don't use the tag :latest, you need a .latest property reference:
image = "${docker_image.centos.latest}"
(If the image actually is one you've built locally, you may also want to specify the keep_locally option on your docker_image resource so that terraform destroy won't delete it.)