From e36ee5eb9552788f637014de2430744524808a27 Mon Sep 17 00:00:00 2001 From: jannfis Date: Fri, 16 Dec 2022 14:41:38 -0500 Subject: [PATCH] docs: Document applications in any namespace (#10678) * docs: Document applications in any namespace Signed-off-by: jannfis * Fix some code blocks Signed-off-by: jannfis * Fix link Signed-off-by: jannfis * docs: Document applications in any namespace Signed-off-by: jannfis * Fix some code blocks Signed-off-by: jannfis * Fix link Signed-off-by: jannfis * Apply reviewer comments Signed-off-by: jannfis Signed-off-by: jannfis Signed-off-by: schakrad --- docs/operator-manual/app-any-namespace.md | 220 ++++++++++++++++++++++ mkdocs.yml | 1 + 2 files changed, 221 insertions(+) create mode 100644 docs/operator-manual/app-any-namespace.md diff --git a/docs/operator-manual/app-any-namespace.md b/docs/operator-manual/app-any-namespace.md new file mode 100644 index 0000000000000..1471aa0d221cb --- /dev/null +++ b/docs/operator-manual/app-any-namespace.md @@ -0,0 +1,220 @@ +# Applications in any namespace + +**Current feature state**: Beta + +!!! warning + Please read this documentation carefully before you enable this feature. Misconfiguration could lead to potential security issues. + +## Introduction + +As of version 2.5, Argo CD supports managing `Application` resources in namespaces other than the control plane's namespace (which is usually `argocd`), but this feature has to be explicitly enabled and configured appropriately. + +Argo CD administrators can define a certain set of namespaces where `Application` resources may be created, updated and reconciled in. However, applications in these additional namespaces will only be allowed to use certain `AppProjects`, as configured by the Argo CD administrators. This allows ordinary Argo CD users (e.g. application teams) to use patterns like declarative management of `Application` resources, implementing app-of-apps and others without the risk of a privilege escalation through usage of other `AppProjects` that would exceed the permissions granted to the application teams. + +Some manual steps will need to be performed by the Argo CD administrator in order to enable this feature. + +!!! note + This feature is considered beta as of now. Some of the implementation details may change over the course of time until it is promoted to a stable status. We will be happy if early adopters use this feature and provide us with bug reports and feedback. + +## Prerequisites + +### Cluster-scoped Argo CD installation + +This feature can only be enabled and used when your Argo CD is installed as a cluster-wide instance, so it has permissions to list and manipulate resources on a cluster scope. It will *not* work with an Argo CD installed in namespace-scoped mode. + +### Switch resource tracking method + +Also, while technically not necessary, it is strongly suggested that you switch the application tracking method from the default `label` setting to either `annotation` or `annotation+label`. The reasonsing for this is, that application names will be a composite of the namespace's name and the name of the `Application`, and this can easily exceed the 63 characters length limit imposed on label values. Annotations have a notably greater length limit. + +To enable annotation based resource tracking, refer to the documentation about [resource tracking methods](../../user-guide/resource_tracking/) + +## Implementation details + +### Overview + +In order for an application to be managed and reconciled outside the Argo CD's control plane namespace, two prerequisites must match: + +1. The `Application`'s namespace must be explicitly enabled using the `--application-namespaces` parameter for the `argocd-application-controller` and `argocd-server` workloads. This parameter controls the list of namespaces that Argo CD will be allowed to source `Application` resources from globally. Any namespace not configured here cannot be used from any `AppProject`. +1. The `AppProject` referenced by the `.spec.project` field of the `Application` must have the namespace listed in its `.spec.sourceNamespaces` field. This setting will determine whether an `Application` may use a certain `AppProject`. If an `Application` specifies an `AppProject` that is not allowed, Argo CD refuses to process this `Application`. As stated above, any namespace configured in the `.spec.sourceNamespaces` field must also be enabled globally. + +`Applications` in different namespaces can be created and managed just like any other `Application` in the `argocd` namespace previously, either declaratively or through the Argo CD API (e.g. using the CLI, the web UI, the REST API, etc). + +### Reconfigure Argo CD to allow certain namespaces + +#### Change workload startup parameters + +In order to enable this feature, the Argo CD administrator must reconfigure the `argocd-server` and `argocd-application-controller` workloads to add the `--application-namespaces` parameter to the container's startup command. + +The `--application-namespaces` parameter takes a comma-separated list of namespaces where `Applications` are to be allowed in. Each entry of the list supports shell-style wildcards such as `*`, so for example the entry `app-team-*` would match `app-team-one` and `app-team-two`. To enable all namespaces on the cluster where Argo CD is running on, you can just specify `*`, i.e. `--application-namespaces=*`. + +The startup parameters for both, the `argocd-server` and the `argocd-application-controller` can also be conveniently set up and kept in sync by specifying the `application.namespaces` settings in the `argocd-cmd-params-cm` ConfigMap _instead_ of changing the manifests for the respective workloads. For example: + +```yaml +data: + application.namespaces: app-team-one, app-team-two +``` + +would allow the `app-team-one` and `app-team-two` namespaces for managing `Application` resources. After a change to the `argocd-cmd-params-cm` namespace, the appropriate workloads need to be restarted: + +```bash +kubectl rollout restart -n argocd deployment argocd-server +kubectl rollout restart -n argocd statefulset argocd-application-controller +``` + +#### Adapt Kubernetes RBAC + +We decided to not extend the Kubernetes RBAC for the `argocd-server` workload by default for the time being. If you want `Applications` in other namespaces to be managed by the Argo CD API (i.e. the CLI and UI), you need to extend the Kubernetes permissions for the `argocd-server` ServiceAccount. + +We supply a `ClusterRole` and `ClusterRoleBinding` suitable for this purpose in the `examples/k8s-rbac/argocd-server-applications` directory. For a default Argo CD installation (i.e. installed to the `argocd` namespace), you can just apply them as-is: + +```shell +kubectl apply -f examples/k8s-rbac/argocd-server-applications/ +``` + +!!! note + At some later point in time, we may make this cluster role part of the default installation manifests. + +### Allowing additional namespaces in an AppProject + +Any user with Kubernetes access to the Argo CD control plane's namespace (`argocd`), especially those with permissions to create or update `Applications` in a declarative way, is to be considered an Argo CD admin. + +This prevented unprivileged Argo CD users from declaratively creating or managing `Applications` in the past. Those users were constrained to using the API instead, subject to Argo CD RBAC which ensures only `Applications` in allowed `AppProjects` were created. + +For an `Application` to be created outside the `argocd` namespace, the `AppProject` referred to in the `Application`'s `.spec.project` field must include the `Application`'s namespace in its `.spec.sourceNamespaces` field. + +For example, consider the two following (incomplete) `AppProject` specs: + +```yaml +kind: AppProject +apiVersion: argoproj.io/v1alpha1 +metadata: + name: project-one + namespace: argocd +spec: + sourceNamespaces: + - namespace-one +``` + +and + +```yaml +kind: AppProject +apiVersion: argoproj.io/v1alpha1 +metadata: + name: project-two + namespace: argocd +spec: + sourceNamespaces: + - namespace-two +``` + +In order for an Application to set `.spec.project` to `project-one`, it would have to be created in either namespace `namespace-one` or `argocd`. Likewise, in order for an Application to set `.spec.project` to `project-two`, it would have to be created in either namespace `namespace-two` or `argocd`. + +If an Application in `namespace-two` would set their `.spec.project` to `project-one` or an Application in `namespace-one` would set their `.spec.project` to `project-two`, Argo CD would consider this as a permission violation and refuse to reconcile the Application. + +Also, the Argo CD API will enforce these constraints, regardless of the Argo CD RBAC permissions. + +The `.spec.sourceNamespaces` field of the `AppProject` is a list that can contain an arbitrary amount of namespaces, and each entry supports shell-style wildcard, so that you can allow namespaces with patterns like `team-one-*`. + +!!! warning + Do not add user controlled namespaces in the `.spec.sourceNamespaces` field of any privileged AppProject like the `default` project. Always make sure that the AppProject follows the principle of granting least required privileges. Never grant access to the `argocd` namespace within the AppProject. + +!!! note + For backwards compatibility, Applications in the Argo CD control plane's namespace (`argocd`) are allowed to set their `.spec.project` field to reference any AppProject, regardless of the restrictions placed by the AppProject's `.spec.sourceNamespaces` field. + +### Application names + +For the CLI and UI, applications are now referred to and displayed as in the format `/`. + +For backwards compatibility, if the namespace of the Application is the control plane's namespace (i.e. `argocd`), the `` can be omitted from the application name when referring to it. For example, the application names `argocd/someapp` and `someapp` are semantically the same and refer to the same application in the CLI and the UI. + +### Application RBAC + +The RBAC syntax for Application objects has been changed from `/` to `//` to accomodate the need to restrict access based on the source namespace of the Application to be managed. + +For backwards compatibility, Applications in the `argocd` namespace can still be refered to as `/` in the RBAC policy rules. + +Wildcards do not make any distinction between project and application namespaces yet. For example, the following RBAC rule would match any application belonging to project `foo`, regardless of the namespace it is created in: + +``` +p, somerole, applications, get, foo/*, allow +``` + +If you want to restrict access to be granted only to `Applications` in project `foo` within namespace `bar`, the rule would need to be adapted as follows: + +``` +p, somerole, applications, get, foo/bar/*, allow +``` + +## Managing applications in other namespaces + +### Declaratively + +For declarative management of Applications, just create the Application from a YAML or JSON manifest in the desired namespace. Make sure that the `.spec.project` field refers to an AppProject that allows this namespace. For example, the following (incomplete) Application manifest creates an Application in the namespace `some-namespace`: + +```yaml +kind: Application +apiVersion: argoproj.io/v1alpha1 +metadata: + name: some-app + namespace: some-namespace +spec: + project: some-project + # ... +``` + +The project `some-project` will then need to specify `some-namespace` in the list of allowed source namespaces, e.g. + +```yaml +kind: AppProject +apiVersion: argoproj.io/v1alpha1 +metadata: + name: some-project + namespace: argocd +spec: + sourceNamespaces: + - some-namespace +``` + +### Using the CLI + +You can use all existing Argo CD CLI commands for managing applications in other namespaces, exactly as you would use the CLI to manage applications in the control plane's namespace. + +For example, to retrieve the `Application` named `foo` in the namespace `bar`, you can use the following CLI command: + +```shell +argocd app get foo/bar +``` + +Likewise, to manage this application, keep referring to it as `foo/bar`: + +```bash +# Create an application +argocd app create foo/bar ... +# Sync the application +argocd app sync foo/bar +# Delete the application +argocd app delete foo/bar +# Retrieve application's manifest +argocd app manifests foo/bar +``` + +As stated previously, for applications in the Argo CD's control plane namespace, you can omit the namespace from the application name. + +### Using the UI + +Similar to the CLI, you can refer to the application in the UI as `foo/bar`. + +For example, to create an application named `bar` in the namespace `foo` in the web UI, set the application name in the creation dialogue's _Application Name_ field to `foo/bar`. If the namespace is omitted, the control plane's namespace will be used. + +### Using the REST API + +If you are using the REST API, the namespace for `Application` cannot be specified as the application name, and resources need to be specified using the optional `appNamespace` query parameter. For example, to work with the `Application` resource named `foo` in the namespace `bar`, the request would look like follows: + +```bash +GET /api/v1/applications/foo?appNamespace=bar +``` + +For other operations such as `POST` and `PUT`, the `appNamespace` parameter must be part of the request's payload. + +For `Application` resources in the control plane namespace, this parameter can be omitted. diff --git a/mkdocs.yml b/mkdocs.yml index 843cee50b85ac..208b28f7724b3 100644 --- a/mkdocs.yml +++ b/mkdocs.yml @@ -22,6 +22,7 @@ nav: - operator-manual/architecture.md - operator-manual/installation.md - operator-manual/declarative-setup.md + - operator-manual/app-any-namespace.md - operator-manual/ingress.md - User Management: - operator-manual/user-management/index.md