Merge branch 'authservice-docs-update' into 'master'

Authservice docs update

See merge request platform-one/big-bang/bigbang!413

chart/values.yaml

@@ -341,7 +341,7 @@ addons:
       path: "./chart"
       tag: "0.1.6-bb.4"
 
-    # -- Values to passthrough to the authservice chart: https://repo1.dso.mil/platform-one/big-bang/apps/sandbox/authservice.git
+    # -- Values to passthrough to the authservice chart: https://repo1.dso.mil/platform-one/big-bang/apps/core/authservice.git
     values: {}
 
     # -- Additional authservice chain configurations.

charter/packages/authservice/Architecture.md

+# Authservice
+
+An implementation of [Envoy](https://envoyproxy.io) [External Authorization](https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/ext_authz_filter),
+focused on delivering authN/Z solutions for [Istio](https://istio.io) and [Kubernetes](https://kubernetes.io).
+
+## Overview
+
+`authservice` helps delegate the [OIDC Authorization Code Grant Flow](https://openid.net/specs/openid-connect-core-1_0.html#CodeFlowAuth)
+to the Istio mesh. `authservice` is compatible with any standard OIDC Provider as well as other Istio End-user Auth features,
+including [Authentication Policy](https://istio.io/docs/tasks/security/authn-policy/) and [RBAC](https://istio.io/docs/tasks/security/rbac-groups/).
+Together, they allow developers to protect their APIs and web apps without any application code required.
+
+```mermaid
+graph LR
+  pod("URL") --> authservice
+  envoyfilter --> |redirect| pod2("IdP")
+  pod2 --> |token| apppods
+
+  subgraph "Authservice"
+    subgraph "Any Namespace"
+      apppods("Application Pod(s)")
+    end
+
+    subgraph "istio-system Namespace"
+      envoyfilter{{"Envoy Filter"}}
+    end
+    
+    subgraph "Authservice Namespace"
+      authservice{{"Authservice Service"}} --> envoyfilter
+    end
+        
+  end
+
+  subgraph "Session Storage (Redis)"
+    authservice --> database3[("Authservice DB")]
+  end
+
+  subgraph "Logging"
+    authservice --> fluent(Fluentbit) --> logging-ek-es-http
+    logging-ek-es-http{{Elastic Service<br />logging-ek-es-http}} --> elastic[(Elastic Storage)]
+  end
+```
+
+## Big Bang Touchpoints
+
+### Licensing
+
+[Authservice](https://github.com/istio-ecosystem/authservice) utilizes an Apache-2.0 License. The Iron Bank repo for the hardened authservice image can be found [here](https://repo1.dso.mil/dsop/istio-ecosystem/authservice) and the Big Bang repo for the authservice Helm Chart can be found [here](https://repo1.dso.mil/platform-one/big-bang/apps/core/authservice).
+
+### Single Sign On
+
+Authservice provides OIDC Single Sign On capabilities for apps that don't have native support. 
+
+Pods just need to have istio-injection, a single label which by default is `protect=keycloak` applied to the pods, and a corresponding chain to load into authservice.
+
+This label can be adjusted via following values in the Big Bang chart:
+
+```yaml
+addons:
+  authservice:
+    values:
+      selector:
+        key: protect
+        value: keycloak
+```
+
+The corresponding chain loaded in to authservice via the values in the Big Bang chart:
+For more information see the [README.md](https://repo1.dso.mil/platform-one/big-bang/apps/core/authservice/-/blob/main/README.md) in the Authservice package.
+
+```yaml
+addons:
+  authservice:
+    chains:
+      example:
+        callback_uri: ...
+        match: ...
+        client_id: ...
+        client_secret: ...
+```
+
+### Storage
+
+Authservice can be configured to use a redis server for distributed state storage. This Redis instance is used for OIDC token storage/retrieval.
+
+```yaml
+addons:
+  authservice:
+    redis:
+      host: "redis.mydomain.com"
+      port: "6379"
+      password: "password"
+```
+
+### High Availability
+
+When setting `replicaCount` above `1`, Authservice will utilize an HA redis deployment, but it can also be configured to use an external redis such as Elasticache.
+
+Authservice also utilizes a horizontal pod autoscaler, which can be configured with min & max replicas and target CPU & memory utilization:
+
+```yaml
+addons:
+  authservice:
+    values:
+      replicaCount: 2
+      autoscaling:
+        enabled: false
+        minReplicas: 1
+        maxReplicas: 3
+        targetCPUUtilizationPercentage: 80
+        targetMemoryUtilizationPercentage: 80
+```
+
+### UI
+
+There is no UI feature for authservice.
+
+### Logging
+
+Within Big Bang, logs are captured by fluentbit and shipped to elastic by default.
+
+### Healthchecks
+
+The authservice Dockerfile includes a [healthcheck](https://repo1.dso.mil/dsop/istio-ecosystem/authservice/-/blob/master/Dockerfile#L23-24) and the authservice Helm Chart includes [liveness & readiness probes](https://repo1.dso.mil/platform-one/big-bang/apps/core/authservice/-/blob/main/chart/templates/deployment.yaml#L42-47) in its deployment:
+```yaml
+livenessProbe:
+  tcpSocket:
+    port: 10003
+readinessProbe:
+  tcpSocket:
+    port: 10003
+```
+
+### Dependant Packages
+
+When setting `replicaCount` above `1`, a redis configuration is required.
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