update documentation for Docker/Podman

README.md

@@ -4,6 +4,9 @@ This is a reverse engineered API of the official [Helldivers 2](https://store.st
 
 This is **NOT** an official *nor* endorsed API and may stop functioning at any time.
 
+> [!TIP]
+> Hitting rate limits? You can run a local docker image, see [Local development](#running-in-docker--podman)
+
 ### Getting started
 Currently the API does not enforce authentication.
 You can see all active war seasons at `/api/`
@@ -19,6 +22,7 @@ This limit will probably be increased in the future, but given the limited API e
 To avoid hitting rate limits in your clients check the following headers in your response:
 - `X-Ratelimit-Limit` contains the total amount of requests you can make in the given timeframe
 - `X-RateLimit-Remaining` how many requests you can still make in the current window
+- `X-RateLimit-Reset` the unix epoch (in milliseconds) when you can start making more requests
 - `Retry-After` only added to 429 requests, the amount of seconds to wait before making a new request
 
 ### Roadmap
@@ -49,3 +53,34 @@ You can run an interactive shell and the application with
 ```shell
 iex -S mix phx.server
 ```
+
+### Running in Docker / Podman
+Want to run a private instance of the API, or simply want a local container without rate limits
+so you can develop your app without being hit with rate limits constantly?
+
+Fortunately, it's very easy to get a local/private copy of the Helldivers 2 API running!
+All you need is to have either [Docker](https://www.docker.com/) or [Podman](https://podman.io/) installed.
+
+You can build a local image like this (takes a few minutes, but you only need to re-run this when something changes):
+```shell
+# Docker
+docker build -t helldivers2:latest .
+# Or if you're using Podman
+podman build -t helldivers2:latest .
+```
+
+Now to run this container, you'll need a few variables to configure how the API behaves (TLDR below!):
+- `SECRET_KEY_BASE` used by the application for singing private or sensitive information, if you're running a private instance publicly you'll want a secure random string of 64 characters
+- `FLY_APP_NAME` used internally for networking code to find other instances (you can just use `helldivers-2` for this)
+- `FLY_IMAGE_REF` the container reference, this helps cluster to only the same version of the app (you can set this to `0`)
+- `FLY_PRIVATE_IP` - used to uniquely identify this node in the cluster (if you're running a single instance you can use `127.0.0.1`)
+- `RATE_LIMIT_MAX_REQUESTS` - (optional) the max amount of requests the rate limit will allow, set to `0` to disable rate limiting
+- `RATE_LIMIT_INTERVAL` - (optional) how many seconds before the rate limit will reset itself (must be a valid number greater than `0`)
+
+or if you're just setting up a local development instance, you can copy paste the command below:
+```shell
+# Docker
+docker run -e SECRET_KEY_BASE=JlU7vU9xt9uWbf82Z9HrUjAuNGtqwqG8h8AaUc3AOyH0a86wa5Q4DITNLorGmILv -e FLY_APP_NAME=helldivers-2 -e FLY_IMAGE_REF=0 -e FLY_PRIVATE_IP=127.0.0.1 -p 4000:4000 helldivers2:latest
+# Or if you're using Podman
+podman run -e SECRET_KEY_BASE=JlU7vU9xt9uWbf82Z9HrUjAuNGtqwqG8h8AaUc3AOyH0a86wa5Q4DITNLorGmILv -e FLY_APP_NAME=helldivers-2 -e FLY_IMAGE_REF=0 -e FLY_PRIVATE_IP=127.0.0.1 -p 4000:4000 helldivers2:latest
+```