feat: redis config may be set using env; updated readme

.github/workflows/docker-image.yml

@@ -2,9 +2,9 @@ name: Docker Image CI
 
 on:
   push:
-    branches: [ "main" ]
+    branches: ["main"]
   pull_request:
-    branches: [ "main" ]
+    branches: ["main"]
 
 jobs:
   build:

README.md

@@ -32,7 +32,7 @@ Furthermore, a cron job is executed every n seconds which collects the current s
 
 Thus, the following metrics are collected:
 
-| Metric                    | type      | description                                             |
+| Metric                    | Type      | Description                                             |
 | ------------------------- | --------- | ------------------------------------------------------- |
 | bullmq_processed_duration | histogram | Processing time for completed jobs                      |
 | bullmq_completed_duration | histogram | Completion time for jobs                                |
@@ -46,23 +46,56 @@ Each metric also has the attribute `queue` which indicated which queue the metri
 
 ## How to use
 
+### Variables
+
+These environment variables may be set to overwrite the values in the config file.
+Note that not all values are supported.
+
+| Name           | Description                         |
+| -------------- | ----------------------------------- |
+| REDIS_HOST     | Redis host, e. g. "localhost:6379/" |
+| REDIS_USERNAME | Redis username                      |
+| REDIS_PASSWORD | Redis password                      |
+| REDIS_SSL      | Wether to use ssl                   |
+
+### Local
+
 1. Install the dependencies
 
-```
+```bash
 npm install
 ```
 
 2. Default environment is `local`. This can be set using the `NODE_ENV` variable.
 
-```
+```bash
 export NODE_ENV=production
 ```
 
 3. Make sure that the required config file is present: `./configs/config-${NODE_ENV}.json` (see [local](./configs/config-local.json)).
 4. Start the server
 
-```
+```bash
 npm run dev
 ```
 
 5. Access the resources `http://localhost:8080/bullmq/ui/login` or `http://localhost:8080/prometheus/metrics`
+
+### Docker
+
+The Dockerimage is published using the [local](./configs/config-local.json) configuration. In most cases that will not be sufficient and should be overwritten.
+This can be done using environment variables (see [here](#variables)) or by mounting a separate file.
+
+```bash
+# This needs a config file under ./configs/config-dev.json
+docker run \
+    -it \
+    --mount type=bind,source=$(pwd)/configs,target=/app/configs \
+    --env=NODE_ENV=dev \
+    --env=REDIS_HOST=some-host:6379/ \
+    rgummich/bullmq-exporter
+```
+
+### Kubernetes
+
+In Kubernetes this may be done using [Secrets](https://kubernetes.io/docs/concepts/configuration/secret/).

src/config.ts

@@ -12,8 +12,18 @@ export interface Config {
   users?: Array<any>;
 }
 
+function setFromEnv(key: string, def: any) {
+  const val = process.env[key.toUpperCase()];
+  return val === undefined ? def : val;
+}
+
 const prefix = process.env.NODE_ENV?.toLowerCase() || "local";
 const jsonRaw = readFileSync(`./configs/config-${prefix}.json`);
-const config = JSON.parse(jsonRaw.toString());
+const config = JSON.parse(jsonRaw.toString()) as Config;
+
+config.redis.host = setFromEnv("REDIS_HOST", config.redis.host);
+config.redis.username = setFromEnv("REDIS_USERNAME", config.redis.username);
+config.redis.password = setFromEnv("REDIS_PASSWORD", config.redis.password);
+config.redis.ssl = setFromEnv("REDIS_SSL", config.redis.ssl);
 
-export default config as Config;
+export default config;