Add Hashicorp Vault Integration (GitHub) (#105)

Co-authored-by: Mathias Fredriksson <mafredri@gmail.com>

vault-github/README.md

@@ -0,0 +1,84 @@
+---
+display_name: Hashicorp Vault Integration (GitHub)
+description: Authenticates with Vault using GitHub
+icon: ../.icons/vault.svg
+maintainer_github: coder
+verified: true
+tags: [helper, integration, vault, github]
+---
+
+# Hashicorp Vault Integration (GitHub)
+
+This module lets you authenticate with [Hashicorp Vault](https://www.vaultproject.io/) in your Coder workspaces using [external auth](https://coder.com/docs/v2/latest/admin/external-auth) for GitHub.
+
+```hcl
+module "vault" {
+    source     = "https://registry.coder.com/modules/vault-github"
+    agent_id   = coder_agent.example.id
+    vault_addr = "https://vault.example.com"
+}
+
+# A workaround until we have https://github.com/coder/terraform-provider-coder/issues/170
+resource "coder_agent" "example" {
+    ...
+    env = {
+        VAULT_ADDR = "https://vault.example.com"
+    }
+    ...
+}
+
+```
+
+Then you can use the Vault CLI in your workspaces to fetch secrets from Vault:
+
+```shell
+vault kv get -mount=secret my-secret
+```
+
+or using the Vault API:
+
+```shell
+curl -H "X-Vault-Token: ${VAULT_TOKEN}" -X GET "${VAULT_ADDR}/v1/secret/data/my-secret"
+```
+
+![Vault login](../.images/vault-login.png)
+
+## Configuration
+
+To configure the Vault module, you must set up a Vault GitHub auth method. See the [Vault documentation](https://www.vaultproject.io/docs/auth/github) for more information.
+
+## Examples
+
+### Configure Vault integration with a different Coder GitHub external auth ID (i.e., not the default `github`)
+
+```hcl
+module "vault" {
+    source               = "https://registry.coder.com/modules/vault"
+    agent_id             = coder_agent.example.id
+    vault_addr           = "https://vault.example.com"
+    coder_github_auth_id = "my-github-auth-id"
+}
+```
+
+### Configure Vault integration with a different Coder GitHub external auth ID and a different Vault GitHub auth path
+
+```hcl
+module "vault" {
+    source                 = "https://registry.coder.com/modules/vault"
+    agent_id               = coder_agent.example.id
+    vault_addr             = "https://vault.example.com"
+    coder_github_auth_id   = "my-github-auth-id"
+    vault_github_auth_path = "my-github-auth-path"
+}
+```
+
+### Configure Vault integration and install a specific version of the Vault CLI
+
+```hcl
+module "vault" {
+    source            = "https://registry.coder.com/modules/vault"
+    agent_id          = coder_agent.example.id
+    vault_addr        = "https://vault.example.com"
+    vault_cli_version = "1.15.0"
+}
+```