# 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](https://cloud.google.com/container-optimized-os/docs) (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](https://www.envoyproxy.io) and expose it on port 80. For a complete example, look at the sibling [`envoy-traffic-director`](../envoy-traffic-director/README.md) module that uses this module to start Envoy Proxy and connect it to [Traffic Director](https://cloud.google.com/traffic-director).
```hcl
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](variables.tf#L47) | Container image. | string
| ✓ | |
| [authenticate_gcr](variables.tf#L17) | 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](variables.tf#L23) | List of cloud-init `bootcmd`s. | list(string)
| | []
|
| [cloud_config](variables.tf#L29) | Cloud config template path. If provided, takes precedence over all other arguments. | string
| | null
|
| [config_variables](variables.tf#L35) | Additional variables used to render the template passed via `cloud_config`. | map(any)
| | {}
|
| [container_args](variables.tf#L41) | Arguments for container. | string
| | ""
|
| [container_name](variables.tf#L52) | Name of the container to be run. | string
| | "container"
|
| [container_volumes](variables.tf#L58) | List of volumes. | list(object({…}))
| | []
|
| [docker_args](variables.tf#L67) | Extra arguments to be passed for docker. | string
| | null
|
| [file_defaults](variables.tf#L73) | Default owner and permissions for files. | object({…})
| | {…}
|
| [files](variables.tf#L85) | 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](variables.tf#L95) | Run as the first user if users are specified. | bool
| | true
|
| [run_commands](variables.tf#L101) | List of cloud-init `runcmd`s. | list(string)
| | []
|
| [users](variables.tf#L107) | 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](outputs.tf#L17) | Rendered cloud-config file to be passed as user-data instance metadata. | |