coder/docs/templates/modules.md

Template inheritance

In instances where you want to reuse code across different Coder templates, such as common scripts or resource definitions, we suggest using Terraform Modules.

These modules can be stored externally from Coder, like in a Git repository or a Terraform registry. Below is an example of how to reference a module in your template:

data "coder_workspace" "me" {}

module "coder-base" {
  source = "github.com/my-organization/coder-base"

  # Modules take in variables and can provision infrastructure
  vpc_name            = "devex-3"
  subnet_tags         = { "name": data.coder_workspace.me.name }
  code_server_version = 4.14.1
}

resource "coder_agent" "dev" {
  # Modules can provide outputs, such as helper scripts
  startup_script=<<EOF
  #!/bin/sh
  ${module.coder-base.code_server_install_command}
  EOF
}

Learn more about creating modules and module sources in the Terraform documentation.

Git authentication

If you are importing a module from a private git repository, the Coder server or provisioner needs git credentials. Since this token will only be used for cloning your repositories with modules, it is best to create a token with limited access to repositories and no extra permissions. In GitHub, you can generate a fine-grained token with read only access to repos.

If you are running Coder on a VM, make sure you have git installed and the coder user has access to the following files

# /home/coder/.gitconfig
[credential]
  helper = store

# /home/coder/.git-credentials

# GitHub example:
https://your-github-username:your-github-pat@github.com

If you are running Coder on Docker or Kubernetes, git is pre-installed in the Coder image. However, you still need to mount credentials. This can be done via a Docker volume mount or Kubernetes secrets.

Passing git credentials in Kubernetes

First, create a .gitconfig and .git-credentials file on your local machine. You may want to do this in a temporary directory to avoid conflicting with your own git credentials.

Next, create the secret in Kubernetes. Be sure to do this in the same namespace that Coder is installed in.

export NAMESPACE=coder
kubectl apply -f - <<EOF
apiVersion: v1
kind: Secret
metadata:
  name: git-secrets
  namespace: $NAMESPACE
type: Opaque
data:
  .gitconfig: $(cat .gitconfig | base64 | tr -d '\n')
  .git-credentials: $(cat .git-credentials | base64 | tr -d '\n')
EOF

Then, modify Coder's Helm values to mount the secret.

coder:
  volumes:
    - name: git-secrets
      secret:
        secretName: git-secrets
  volumeMounts:
    - name: git-secrets
      mountPath: "/home/coder/.gitconfig"
      subPath: .gitconfig
      readOnly: true
    - name: git-secrets
      mountPath: "/home/coder/.git-credentials"
      subPath: .git-credentials
      readOnly: true