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Generic cloud-init generator for Container Optimized OS

This helper module manages a cloud-config configuration that can start a container on Container Optimized OS (COS). Either a complete cloud-config template can be provided via the cloud_config variable with optional template variables via the config_variables, or a generic cloud-config can be generated based on typical parameters needed to start a container.

The module renders the generated cloud config in the cloud_config output, which can be directly used in instances or instance templates via the user-data metadata attribute.

Examples

Default configuration

This example will create a cloud-config that starts Envoy Proxy and expose it on port 80. For a complete example, look at the sibling envoy-traffic-director module that uses this module to start Envoy Proxy and connect it to Traffic Director.

module "cos-envoy" {
  source          = "./fabric/modules/cloud-config-container/cos-generic-metadata"
  container_image = "envoyproxy/envoy:v1.14.1"
  container_name  = "envoy"
  container_args  = "-c /etc/envoy/envoy.yaml --log-level info --allow-unknown-static-fields"
  container_volumes = [
    { host = "/etc/envoy/envoy.yaml", container = "/etc/envoy/envoy.yaml" }
  ]
  docker_args = "--network host --pid host"
  # file paths are mocked to run this example in tests
  files = {
    "/var/run/envoy/customize.sh" = {
      content     = file("/dev/null") # file("customize.sh")
      owner       = "root"
      permissions = "0744"
    }
    "/etc/envoy/envoy.yaml" = {
      content     = file("/dev/null") # file("envoy.yaml")
      owner       = "root"
      permissions = "0644"
    }
  }
  run_commands = [
    "iptables -t nat -N ENVOY_IN_REDIRECT",
    "iptables -t nat -A ENVOY_IN_REDIRECT -p tcp -j REDIRECT --to-port 15001",
    "iptables -t nat -A PREROUTING -p tcp -m tcp --dport 80 -j ENVOY_IN_REDIRECT",
    "iptables -t filter -A INPUT -p tcp -m tcp --dport 15001 -m state --state NEW,ESTABLISHED -j ACCEPT",
    "/var/run/envoy/customize.sh",
    "systemctl daemon-reload",
    "systemctl start envoy",
  ]
  users = [{
    username = "envoy",
    uid      = 1337
  }]
}

# tftest modules=0 resources=0

Variables

name description type required default
container_image Container image. string
authenticate_gcr Setup docker to pull images from private GCR. Requires at least one user since the token is stored in the home of the first user defined. bool false
boot_commands List of cloud-init bootcmds. list(string) []
cloud_config Cloud config template path. If provided, takes precedence over all other arguments. string null
config_variables Additional variables used to render the template passed via cloud_config. map(any) {}
container_args Arguments for container. string ""
container_name Name of the container to be run. string "container"
container_volumes List of volumes. list(object({…})) []
docker_args Extra arguments to be passed for docker. string null
file_defaults Default owner and permissions for files. object({…}) {…}
files Map of extra files to create on the instance, path as key. Owner and permissions will use defaults if null. map(object({…})) {}
run_as_first_user Run as the first user if users are specified. bool true
run_commands List of cloud-init runcmds. list(string) []
users List of usernames to be created. If provided, first user will be used to run the container. list(object({…})) […]

Outputs

name description sensitive
cloud_config Rendered cloud-config file to be passed as user-data instance metadata.