📝 Adds Docker Directory solution and link to docs

docs/troubleshooting.md

@@ -9,6 +9,8 @@
 - [404 On Static Hosting](#404-on-static-hosting)
 - [Yarn Build or Run Error](#yarn-error)
 - [Auth Validation Error: "should be object"](#auth-validation-error-should-be-object)
+- [Keycloak Redirect Error](#keycloak-redirect-error)
+- [Docker Directory Error](#docker-directory)
 - [Config Not Updating](#config-not-updating)
 - [Config Still not Updating](#config-still-not-updating)
 - [Styles and Assets not Updating](#styles-and-assets-not-updating)
@@ -114,6 +116,41 @@ auth:
 
 ---
 
+## Keycloak Redirect Error
+
+Check the [browser's console output](#how-to-open-browser-console), if you've not set any headers, you will likely see a CORS error here, which would be the source of the issue.
+
+You need to allow Dashy to make requests to Keycloak, and Keycloak to redirect to Dashy. The way you do this depends on how you're hosting these applications / which proxy you are using, and examples can be found in the [Management Docs](/docs/management.md#setting-headers).
+
+For example, add the access control header to Keycloak, like:
+
+`Access-Control-Allow-Origin [URL-of Dashy]`
+
+Note that for requests that transport sensitive info like credentials, setting the accept header to a wildcard (`*`) is not allowed - see [MDN Docs](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#requests_with_credentials), so you will need to specify the actual URL.
+
+You should also ensure that Keycloak is correctly configured, with a user, realm and application, and be sure that you have set a valid redirect URL in Keycloak ([screenshot](https://user-images.githubusercontent.com/1862727/148599768-db4ee4f8-72c5-402d-8f00-051d999e6267.png)).
+
+For more details on how to set headers, see the [Example Headers](/docs/management.md#setting-headers) in the management docs, or reference the documentation for your proxy.
+
+See also: #479, #409, #507, #491, #341, #520
+
+---
+
+## Docker Directory
+
+```
+Error response from daemon: OCI runtime create failed: container_linux.go:380:
+starting container process caused: process_linux.go:545: container init caused:
+rootfs_linux.go:76: mounting "/home/ubuntu/my-conf.yml" to rootfs at 
+"/app/public/conf.yml" caused: mount through procfd: not a directory: 
+unknown: Are you trying to mount a directory onto a file (or vice-versa)?
+Check if the specified host path exists and is the expected type.
+```
+
+If you get an error similar to the one above, you are mounting a directory to the config file's location, when a plain file is expected. Create a YAML file, (`touch my-conf.yml`), populate it with a sample config, then pass it as a volume: `-v ./my-local-conf.yml:/app/public/conf.yml` 
+
+---
+
 ## Config Not Updating
 
 Dashy has the option to save settings and config locally, in browser storage. Anything here will take precedence over whatever is in your config file, sometimes with unintended consequences. If you've updated the config file manually, and are not seeing changes reflected in the UI, then try visiting the site in Incognito mode. If that works, then the solution is just to clear local storage. This can be done from the config menu, under "Clear Local Settings".