Update README.md

Author: ReLive27

oauth2-jwk-with-vault/README.md

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+## Installing Vault with Docker
+
+### 1. Pull the Vault Image
+First, pull the specified version of the Vault image (1.13.3):
+```bash
+docker pull vault:1.13.3
+```
+
+### 2. Run the Vault Container
+Run the Vault container in development mode:
+```bash
+docker run --cap-add=IPC_LOCK -d --name=dev-vault vault:1.13.3
+```
+
+### 3. View Vault Startup Logs
+View the Vault startup logs to obtain the Root Token:
+```bash
+docker logs -f dev-vault
+```
+
+Example log output:
+```
+             Api Address: http://127.0.0.1:8200
+                     Cgo: disabled
+         Cluster Address: https://127.0.0.1:8201
+              Listener 1: tcp (addr: "127.0.0.1:8200", cluster address: "127.0.0.1:8201", max_request_duration: "1m30s", max_request_size: "33554432", tls: "disabled")
+               Log Level: info
+                   Mlock: supported: false, enabled: false
+           Recovery Mode: false
+                 Storage: inmem
+                 Version: Vault v1.13.3
+
+WARNING! dev mode is enabled! In this mode, Vault runs entirely in-memory
+and starts unsealed with a single unseal key. The root token is already
+authenticated to the CLI, so you can immediately begin using Vault.
+
+You may need to set the following environment variable:
+
+    $ export VAULT_ADDR='http://127.0.0.1:8200'
+
+The unseal key and root token are displayed below in case you want to
+seal/unseal the Vault or re-authenticate.
+
+Unseal Key: 1+yv+v5mz+aSCK67X6slL3ECxb4UDL8ujWZU/ONBpn0=
+Root Token: s.XmpNPoi9sRhYtdKHaQhkHP6x
+
+Development mode should NOT be used in production installations!
+```
+
+### 4. Configure the Vault Client
+Start a new terminal session and enter the container:
+```bash
+docker exec -it dev-vault /bin/sh
+```
+
+Set the Vault address:
+```bash
+export VAULT_ADDR='http://127.0.0.1:8200'
+```
+
+Set the Root Token as an environment variable:
+```bash
+export VAULT_TOKEN="s.XmpNPoi9sRhYtdKHaQhkHP6x"
+```
+
+### 5. Verify the Vault Server is Running
+Within the container, run the following command to check the server status:
+```bash
+vault status
+```
+
+If you encounter an error like:
+```
+Error checking seal status: Get "https://127.0.0.1:8200/v1/sys/seal-status": http: server gave HTTP response to HTTPS client
+```
+Ensure that the `VAULT_ADDR` environment variable is configured correctly.
+
+## Configure Vault Token in Services
+Configure the Root Token in the `application.yml` files of both the authorization-service and resource-service as `${vault_token}`. After starting the services, visit [http://127.0.0.1:8070/client/test](http://127.0.0.1:8070/client/test) in your browser.
+
+## References
+- [Vault Installation Guide](https://learn.hashicorp.com/tutorials/vault/getting-started-install?in=vault/getting-started)
+- [Vault Development Server Guide](https://learn.hashicorp.com/tutorials/vault/getting-started-dev-server?in=vault/getting-started)
+- [Vault Docker Image Details](https://registry.hub.docker.com/_/vault)