docs: Add keycloak PKCE and argo-cd cli method documentation (#20698)

* Add keycloak PKCE and argo-cd cli method

Signed-off-by: Grégoire Bellon-Gervais <gregoire.bellon-gervais@docaposte.fr>

* add company

Signed-off-by: Grégoire Bellon-Gervais <gregoire.bellon-gervais@docaposte.fr>

* Oups

Signed-off-by: Grégoire Bellon-Gervais <gregoire.bellon-gervais@docaposte.fr>

* Docaposte in a separated pr

Signed-off-by: Grégoire Bellon-Gervais <gregoire.bellon-gervais@docaposte.fr>

* Fix typo and improve doc

Signed-off-by: Grégoire Bellon-Gervais <gregoire.bellon-gervais@docaposte.fr>

* A good idea :)

Signed-off-by: Grégoire Bellon-Gervais <gregoire.bellon-gervais@docaposte.fr>

---------

Signed-off-by: Grégoire Bellon-Gervais <gregoire.bellon-gervais@docaposte.fr>

docs/operator-manual/user-management/keycloak.md

@@ -1,14 +1,23 @@
 # Keycloak
+Keycloak and ArgoCD integration can be configured in two ways with Client authentication and with PKCE.
 
-# Integrating Keycloak and ArgoCD
+If you need to authenticate with __argo-cd command line__, you must choose PKCE way.
+
+* [Keycloak and ArgoCD with Client authentication](#keycloak-and-argocd-with-client-authentication)
+* [Keycloak and ArgoCD with PKCE](#keycloak-and-argocd-with-pkce)
+
+## Keycloak and ArgoCD with Client authentication
+
+These instructions will take you through the entire process of getting your ArgoCD application authenticating with Keycloak.
 
-These instructions will take you through the entire process of getting your ArgoCD application authenticating with Keycloak. 
 You will create a client within Keycloak and configure ArgoCD to use Keycloak for authentication, using groups set in Keycloak
 to determine privileges in Argo.
 
-## Creating a new client in Keycloak
+### Creating a new client in Keycloak
 
-First we need to setup a new client. Start by logging into your keycloak server, select the realm you want to use (`master` by default)
+First we need to setup a new client.
+
+Start by logging into your keycloak server, select the realm you want to use (`master` by default)
 and then go to __Clients__ and click the __Create client__ button at the top.
 
 ![Keycloak add client](../../assets/keycloak-add-client.png "Keycloak add client")
@@ -19,60 +28,26 @@ Enable the __Client authentication__.
 
 Configure the client by setting the __Root URL__, __Web origins__, __Admin URL__ to the hostname (https://{hostname}).
 
-Also you can set __Home URL__ to your _/applications_ path and __Valid Post logout redirect URIs__ to "+".
+Also you can set __Home URL__ to _/applications_ path and __Valid Post logout redirect URIs__ to "https://{hostname}/applications".
 
 The Valid Redirect URIs should be set to https://{hostname}/auth/callback (you can also set the less secure https://{hostname}/* for testing/development purposes,
 but it's not recommended in production).
 
 ![Keycloak configure client](../../assets/keycloak-configure-client.png "Keycloak configure client")
 
-Make sure to click __Save__. There should be a tab called __Credentials__. You can copy the Secret that we'll use in our ArgoCD 
-configuration.
+Make sure to click __Save__.
+
+There should be a tab called __Credentials__. You can copy the Client Secret that we'll use in our ArgoCD configuration.
 
 ![Keycloak client secret](../../assets/keycloak-client-secret.png "Keycloak client secret")
 
-## Configuring the groups claim
-
-In order for ArgoCD to provide the groups the user is in we need to configure a groups claim that can be included in the authentication token.
-To do this we'll start by creating a new __Client Scope__ called _groups_.
-
-![Keycloak add scope](../../assets/keycloak-add-scope.png "Keycloak add scope")
-
-Once you've created the client scope you can now add a Token Mapper which will add the groups claim to the token when the client requests
-the groups scope. In the Tab "Mappers", click on "Configure a new mapper" and choose __Group Membership__.
-Make sure to set the __Name__ as well as the __Token Claim Name__ to _groups_. Also disable the "Full group path".
-
-![Keycloak groups mapper](../../assets/keycloak-groups-mapper.png "Keycloak groups mapper")
-
-We can now configure the client to provide the _groups_ scope. Go back to the client we've created earlier and go to the Tab "Client Scopes".
-Click on "Add client scope", choose the _groups_ scope and add it either to the __Default__ or to the __Optional__ Client Scope. If you put it in the Optional
-category you will need to make sure that ArgoCD requests the scope in its OIDC configuration. Since we will always want group information, I recommend
-using the Default category.
-
-![Keycloak client scope](../../assets/keycloak-client-scope.png "Keycloak client scope")
-
-Create a group called _ArgoCDAdmins_ and have your current user join the group.
-
-![Keycloak user group](../../assets/keycloak-user-group.png "Keycloak user group")
-
-## Configuring ArgoCD OIDC
+### Configuring ArgoCD OIDC
 
 Let's start by storing the client secret you generated earlier in the argocd secret _argocd-secret_.
 
-1. First you'll need to encode the client secret in base64: `$ echo -n '83083958-8ec6-47b0-a411-a8c55381fbd2' | base64`
-2. Then you can edit the secret and add the base64 value to a new key called _oidc.keycloak.clientSecret_ using `$ kubectl edit secret argocd-secret`.
-   
-Your Secret should look something like this:
-
-```yaml
-apiVersion: v1
-kind: Secret
-metadata:
-  name: argocd-secret
-data:
-  ...
-  oidc.keycloak.clientSecret: ODMwODM5NTgtOGVjNi00N2IwLWE0MTEtYThjNTUzODFmYmQy   
-  ...
+You can patch it with value copied previously:
+```bash
+kubectl -n argo-cd patch secret argocd-secret --patch='{"stringData": { "oidc.keycloak.clientSecret": "<REPLACE_WITH_CLIENT_SECRET>" }}'
 ```
 
 Now we can configure the config map and add the oidc configuration to enable our keycloak authentication.
@@ -103,7 +78,110 @@ Make sure that:
 - __clientSecret__ points to the right key you created in the _argocd-secret_ Secret
 - __requestedScopes__ contains the _groups_ claim if you didn't add it to the Default scopes
 
-## Configuring ArgoCD Policy
+## Keycloak and ArgoCD with PKCE
+
+These instructions will take you through the entire process of getting your ArgoCD application authenticating with Keycloak.
+
+You will create a client within Keycloak and configure ArgoCD to use Keycloak for authentication, using groups set in Keycloak
+to determine privileges in Argo.
+
+You will also be able to authenticate using argo-cd command line.
+
+### Creating a new client in Keycloak
+
+First we need to setup a new client.
+
+Start by logging into your keycloak server, select the realm you want to use (`master` by default)
+and then go to __Clients__ and click the __Create client__ button at the top.
+
+![Keycloak add client](../../assets/keycloak-add-client.png "Keycloak add client")
+
+Leave default values.
+
+![Keycloak add client Step 2](../../assets/keycloak-add-client-pkce_2.png "Keycloak add client Step 2")
+
+Configure the client by setting the __Root URL__, __Web origins__, __Admin URL__ to the hostname (https://{hostname}).
+
+Also you can set __Home URL__ to _/applications_ path and __Valid Post logout redirect URIs__ to "https://{hostname}/applications".
+
+The Valid Redirect URIs should be set to:
+- http://localhost:8085/auth/callback (needed for argo-cd cli, depends on value from [--sso-port](../../user-guide/commands/argocd_login.md))
+- https://{hostname}/auth/callback
+- https://{hostname}/pkce/verify
+
+![Keycloak configure client](../../assets/keycloak-configure-client-pkce.png "Keycloak configure client")
+
+Make sure to click __Save__.
+
+Now go to a tab called __Advanced__, look for parameter named __Proof Key for Code Exchange Code Challenge Method__ and set it to __S256__
+
+![Keycloak configure client Step 2](../../assets/keycloak-configure-client-pkce_2.png "Keycloak configure client Step 2")
+Make sure to click __Save__.
+
+### Configuring ArgoCD OIDC
+Now we can configure the config map and add the oidc configuration to enable our keycloak authentication.
+You can use `$ kubectl edit configmap argocd-cm`.
+
+Your ConfigMap should look like this:
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: argocd-cm
+data:
+  url: https://argocd.example.com
+  oidc.config: |
+    name: Keycloak
+    issuer: https://keycloak.example.com/realms/master
+    clientID: argocd
+    enablePKCEAuthentication: true
+    requestedScopes: ["openid", "profile", "email", "groups"]
+```
+
+Make sure that:
+
+- __issuer__ ends with the correct realm (in this example _master_)
+- __issuer__ on Keycloak releases older than version 17 the URL must include /auth (in this example /auth/realms/master)
+- __clientID__ is set to the Client ID you configured in Keycloak
+- __enablePKCEAuthentication__ must be set to true to enable correct ArgoCD behaviour with PKCE
+- __requestedScopes__ contains the _groups_ claim if you didn't add it to the Default scopes
+
+## Configuring the groups claim
+
+In order for ArgoCD to provide the groups the user is in we need to configure a groups claim that can be included in the authentication token.
+
+To do this we'll start by creating a new __Client Scope__ called _groups_.
+
+![Keycloak add scope](../../assets/keycloak-add-scope.png "Keycloak add scope")
+
+Once you've created the client scope you can now add a Token Mapper which will add the groups claim to the token when the client requests
+the groups scope.
+
+In the Tab "Mappers", click on "Configure a new mapper" and choose __Group Membership__.
+
+Make sure to set the __Name__ as well as the __Token Claim Name__ to _groups_. Also disable the "Full group path".
+
+![Keycloak groups mapper](../../assets/keycloak-groups-mapper.png "Keycloak groups mapper")
+
+We can now configure the client to provide the _groups_ scope.
+
+Go back to the client we've created earlier and go to the Tab "Client Scopes".
+
+Click on "Add client scope", choose the _groups_ scope and add it either to the __Default__ or to the __Optional__ Client Scope.
+
+If you put it in the Optional
+category you will need to make sure that ArgoCD requests the scope in its OIDC configuration.
+Since we will always want group information, I recommend
+using the Default category.
+
+![Keycloak client scope](../../assets/keycloak-client-scope.png "Keycloak client scope")
+
+Create a group called _ArgoCDAdmins_ and have your current user join the group.
+
+![Keycloak user group](../../assets/keycloak-user-group.png "Keycloak user group")
+
+## Configuring ArgoCD Policy
 
 Now that we have an authentication that provides groups we want to apply a policy to these groups.
 We can modify the _argocd-rbac-cm_ ConfigMap using `$ kubectl edit configmap argocd-rbac-cm`.
@@ -126,8 +204,23 @@ You can now login using our new Keycloak OIDC authentication:
 
 ![Keycloak ArgoCD login](../../assets/keycloak-login.png "Keycloak ArgoCD login")
 
+If you have used PKCE method, you can also authenticate using command line:
+```bash
+argocd login argocd.example.com --sso --grpc-web
+```
+
+argocd cli will start to listen on localhost:8085 and open your web browser to allow you to authenticate with Keycloak.
+
+Once done, you should see
+
+![Authentication successful!](../../assets/keycloak-authentication-successful.png "Authentication successful!")
+
 ## Troubleshoot
 If ArgoCD auth returns 401 or when the login attempt leads to the loop, then restart the argocd-server pod.
 ```
 kubectl rollout restart deployment argocd-server -n argocd
 ```
+
+If you migrate from Client authentification to PKCE, you can have the following error `invalid_request: Missing parameter: code_challenge_method`.
+
+It could be a redirect issue, try in private browsing or clean browser cookies.