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Custom Node Driver UI

Rancher allows UI to be created for custom Node Drivers by registering components for the following two component types:

  • cloud-credential
    • defines a custom component for collecting data for a cloud credential for a given node driver
    • If no cloud credentials are required, the extension can just set the component to false
  • machine-config
    • defined a custom component for the machine pool configuration for a cloud credential for a given node driver

In both cases, the ID when registering should match the Node Driver name.

Cloud Credential​

Cloud Credentials store the username & password, or other similar information, needed to talk to a particular provider. There is typically a 1-to-1 mapping of cloud credentials to drivers. If one provider (e.g. Amazon) has both a Machine driver for RKE (using EC2) and a Cluster driver for Kontainer Engine (using EKS) then you can and should use a single shared type of credential (e.g. aws) for both.

The cloud credential component lives in the top-level cloud-credential directory in the repo. The file should be named the same as the driver, in all lowercase (e.g. cloud-credential/digitalocean.vue).

If there is a reason to rename it or map multiple drivers to the same credential, configure that in shell/store/plugins.js. There is also other info in there about how guesses are taken on what each field is for and how it should be displayed. These can be customized for your driver by importing and calling configureCredential() and mapDriver().

Create a component which displays each field that is relevant to authentication and lets the user configure them. Only the actual auth fields themselves, the rest of configuring the name, description, save buttons, etc is handled outside of the credential component.

Your component should emit a validationChanged event every time a value changes. It should also (but doesn't have to implement a test() method. This may be asynchronous, and should make an API call or similar to see if the provided credentials work. Return true if they're ok and false otherwise. When provided, this is called before saving and the user won't be able to save until their input causes you return true.

Machine Config​

Similar to the Cloud Credential component, the Machine Config component should display just controls for the fields on the driver that are relevant to the configuration of the machine to be created. The machine pool name, saving, etc is handled outside of your component. You probably want to use fetch() to load some info from the provider's API (e.g. list of regions or instance types).

It should live in the top-level machine-config directory, again named the same as the driver and lowercase (e.g. machine-config/digitalocean.vue).

The selected cloud credential ID is available as a credentialId prop. You will always know that ID, and can use it to make API calls (see [#api-calls] below), but must not rely on being able to actually retrieve the cloud credential model corresponding to it. Users with lesser permissions may be able to edit a cluster, but not have permission to see the credential being used to manage it.

API Calls​

Rancher includes a proxy that can be used to make requests to third-party domains (like a cloud provider's API) without requiring that the other end supports CORS or other browser shenanigans. Send requests to /meta/proxy/example.com/whatever/path/you/want and the request will be made from the Rancher server and proxied back to you.

TLS and port 443 are assumed. Add a port after the hostname to change the port (example.com:1234). For plain HTTP, first stop and consider the chain of life decisions which have led you to this point. Then if you still think you need that, use /meta/proxy/http:/example.com:1234 (note one slash after http:, not two). The hostname must be included in the whitelist defined in global settings, or in the configuration for an active node driver. If if isn't your request will be denied. (This prevents a malicious (non-admin) user from abusing the Rancher server as an arbitrary HTTP proxy or reach internal IPs/names that the server can reach directly but the user can't from the outside.)

The rest of the path and query string are sent to the target host as you'd expect.

Normal headers are copied from your request and sent to the target. There are some exceptions for sensitive fields like the user's rancher cookies or saved basic auth creds which will not be copied. If you send an X-Api-Cookie-Header, its value will be sent as the normal Cookie to the target. If you send X-API-Auth-Header, that will be sent out as the normal Authorization.

But normally you want to make a request using a Cloud Credential as the authorization, without knowing what the secret values in that credential are. You ask for this by sending an X-Api-CattleAuth-Header header. The value of the header specifies what credential Id to use, and a signer which describes how that credential should be injected into the request. Common options include awsv4 (Amazon's complicated HMAC signatures), bearer, basic, and digest. For example if you send X-Api-CattleAuth-Header: Basic credId=someCredentialId usernameField=user passwordField=pass, Rancher will retrieve the credential with id someCredentialId, read the values of the user and pass fields from it and add the header Authorization: Basic <base64(user + ":" + pass)> to the proxied request for you.

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