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Using a service account as an OAuth client

Service accounts as OAuth clients

You can use a service account as a constrained form of OAuth client. Service accounts can request only a subset of scopes that allow access to some basic user information and role-based power inside of the service account’s own namespace:

  • user:info

  • user:check-access

  • role:<any_role>:<service_account_namespace>

  • role:<any_role>:<service_account_namespace>:!

When using a service account as an OAuth client:

  • client_id is system:serviceaccount:<service_account_namespace>:<service_account_name>.

  • client_secret can be any of the API tokens for that service account. For example:

    $ oc sa get-token <service_account_name>

  • To get WWW-Authenticate challenges, set an serviceaccounts.openshift.io/oauth-want-challenges annotation on the service account to true.

  • redirect_uri must match an annotation on the service account.

Redirect URIs for service accounts as OAuth clients

Annotation keys must have the prefix serviceaccounts.openshift.io/oauth-redirecturi. or serviceaccounts.openshift.io/oauth-redirectreference. such as:

serviceaccounts.openshift.io/oauth-redirecturi.<name>

In its simplest form, the annotation can be used to directly specify valid redirect URIs. For example:

"serviceaccounts.openshift.io/oauth-redirecturi.first":  "https://example.com"
"serviceaccounts.openshift.io/oauth-redirecturi.second": "https://other.com"

The first and second postfixes in the above example are used to separate the two valid redirect URIs.

In more complex configurations, static redirect URIs may not be enough. For example, perhaps you want all Ingresses for a route to be considered valid. This is where dynamic redirect URIs via the serviceaccounts.openshift.io/oauth-redirectreference. prefix come into play.

For example:

"serviceaccounts.openshift.io/oauth-redirectreference.first": "{\"kind\":\"OAuthRedirectReference\",\"apiVersion\":\"v1\",\"reference\":{\"kind\":\"Route\",\"name\":\"jenkins\"}}"

Since the value for this annotation contains serialized JSON data, it is easier to see in an expanded format:


{
  "kind": "OAuthRedirectReference",
  "apiVersion": "v1",
  "reference": {
    "kind": "Route",
    "name": "jenkins"
  }
}

Now you can see that an OAuthRedirectReference allows us to reference the route named jenkins. Thus, all Ingresses for that route will now be considered valid. The full specification for an OAuthRedirectReference is:


{
  "kind": "OAuthRedirectReference",
  "apiVersion": "v1",
  "reference": {
    "kind": ..., (1)
    "name": ..., (2)
    "group": ... (3)
  }
}
1 kind refers to the type of the object being referenced. Currently, only route is supported.
2 name refers to the name of the object. The object must be in the same namespace as the service account.
3 group refers to the group of the object. Leave this blank, as the group for a route is the empty string.

Both annotation prefixes can be combined to override the data provided by the reference object. For example:

"serviceaccounts.openshift.io/oauth-redirecturi.first":  "custompath"
"serviceaccounts.openshift.io/oauth-redirectreference.first": "{\"kind\":\"OAuthRedirectReference\",\"apiVersion\":\"v1\",\"reference\":{\"kind\":\"Route\",\"name\":\"jenkins\"}}"

The first postfix is used to tie the annotations together. Assuming that the jenkins route had an Ingress of https://example.com, now https://example.com/custompath is considered valid, but https://example.com is not. The format for partially supplying override data is as follows:

Type Syntax

Scheme

"https://"

Hostname

"//website.com"

Port

"//:8000"

Path

"examplepath"

Specifying a hostname override will replace the hostname data from the referenced object, which is not likely to be desired behavior.

Any combination of the above syntax can be combined using the following format:

<scheme:>//<hostname><:port>/<path>

The same object can be referenced more than once for more flexibility:

"serviceaccounts.openshift.io/oauth-redirecturi.first":  "custompath"
"serviceaccounts.openshift.io/oauth-redirectreference.first": "{\"kind\":\"OAuthRedirectReference\",\"apiVersion\":\"v1\",\"reference\":{\"kind\":\"Route\",\"name\":\"jenkins\"}}"
"serviceaccounts.openshift.io/oauth-redirecturi.second":  "//:8000"
"serviceaccounts.openshift.io/oauth-redirectreference.second": "{\"kind\":\"OAuthRedirectReference\",\"apiVersion\":\"v1\",\"reference\":{\"kind\":\"Route\",\"name\":\"jenkins\"}}"

Assuming that the route named jenkins has an Ingress of https://example.com, then both https://example.com:8000 and https://example.com/custompath are considered valid.

Static and dynamic annotations can be used at the same time to achieve the desired behavior:

"serviceaccounts.openshift.io/oauth-redirectreference.first": "{\"kind\":\"OAuthRedirectReference\",\"apiVersion\":\"v1\",\"reference\":{\"kind\":\"Route\",\"name\":\"jenkins\"}}"
"serviceaccounts.openshift.io/oauth-redirecturi.second": "https://other.com"