[stable/prometheus-redis-exporter] Adding abbility to use custom script (#14552)

* Added support for custom LUA scripts

Signed-off-by: Alexander Zimmermann <alexander.zimmermann@mt-ag.com>

* Removed unnecessary comments

Signed-off-by: Alexander Zimmermann <alexander.zimmermann@mt-ag.com>

* Bumping chart version and removed whitespaces

Signed-off-by: Alexander Zimmermann <alexander.zimmermann@mt-ag.com>

* Removed unnecessary comments

Signed-off-by: Alexander Zimmermann <alexander.zimmermann@mt-ag.com>

* Added documentation for script.keyname parameter

Signed-off-by: Alexander Zimmermann <alexander.zimmermann@mt-ag.com>

* Restored imagePullSecret-part

Signed-off-by: Alexander Zimmermann <alexander.zimmermann@mt-ag.com>

stable/prometheus-redis-exporter/Chart.yaml

@@ -2,7 +2,7 @@ apiVersion: v1
 appVersion: 0.28.0
 description: Prometheus exporter for Redis metrics
 name: prometheus-redis-exporter
-version: 2.0.0
+version: 2.0.1
 home: https://github.com/oliver006/redis_exporter
 sources:
   - https://github.com/oliver006/redis_exporter

stable/prometheus-redis-exporter/README.md

@@ -66,6 +66,8 @@ The following table lists the configurable parameters and their default values.
 | `serviceMonitor.telemetryPath` | Path to redis-exporter telemtery-path                  |                            |
 | `serviceMonitor.labels`        | Labels for the servicemonitor passed to Prometheus Operator      |  `{}`            |
 | `serviceMonitor.timeout`       | Timeout after which the scrape is ended                |                            |
+| `script.configmap`     | Let you run a custom lua script from a configmap. The corresponding environment variable `REDIS_EXPORTER_SCRIPT` will be set automatically ||
+| `script.keyname`       | Name of the key inside configmap which contains your script ||
 
 For more information please refer to the [redis_exporter](https://github.com/oliver006/redis_exporter) documentation.
 
@@ -82,3 +84,35 @@ Alternatively, a YAML file that specifies the values for the parameters can be p
 ```bash
 $ helm install --name my-release -f values.yaml stable/prometheus-redis-exporter
 ```
+### Using a custom LUA-Script
+First, you need to deploy the script with a configmap. This is an example script from mentioned in the [redis_exporter-image repository](https://github.com/oliver006/redis_exporter/blob/master/contrib/sample_collect_script.lua)
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: prometheus-redis-exporter-script
+data:
+  script: |-
+    -- Example collect script for -script option
+    -- This returns a Lua table with alternating keys and values.
+    -- Both keys and values must be strings, similar to a HGETALL result.
+    -- More info about Redis Lua scripting: https://redis.io/commands/eval
+
+    local result = {}
+
+    -- Add all keys and values from some hash in db 5
+    redis.call("SELECT", 5)
+    local r = redis.call("HGETALL", "some-hash-with-stats")
+    if r ~= nil then
+        for _,v in ipairs(r) do
+            table.insert(result, v) -- alternating keys and values
+        end
+    end
+
+    -- Set foo to 42
+    table.insert(result, "foo")
+    table.insert(result, "42") -- note the string, use tostring() if needed
+
+    return result
+```
+If you want to use this script for collecting metrics, you could do this by just set `script.configmap` to the name of the configmap (e.g. `prometheus-redis-exporter-script`) and `script.keyname` to the configmap-key holding the script (eg. `script`). The required variables inside the container will be set automatically.

stable/prometheus-redis-exporter/templates/deployment.yaml

@@ -42,8 +42,17 @@ spec:
           env:
             - name: REDIS_ADDR
               value: {{ join "," .Values.redisAddress }}
+{{- if .Values.script }}
+            - name: REDIS_EXPORTER_SCRIPT
+              value: /script/script.lua
+{{- end }}
 {{- if .Values.env }}
 {{ toYaml .Values.env | indent 12 }}
+{{- end }}
+{{- if .Values.script }}
+          volumeMounts:
+              - mountPath: /script
+                name: script-mount
 {{- end }}
           livenessProbe:
             httpGet:
@@ -55,6 +64,15 @@ spec:
               port: exporter-port
           resources:
 {{ toYaml .Values.resources | indent 12 }}
+    {{- if .Values.script }}
+      volumes:
+        - name: script-mount
+          configMap:
+             name: {{ .Values.script.configmap }}
+             items:
+              - key: {{ .Values.script.keyname }}
+                path: script.lua
+    {{- end }}
     {{- if .Values.nodeSelector }}
       nodeSelector:
 {{ toYaml .Values.nodeSelector | indent 8 }}

stable/prometheus-redis-exporter/values.yaml

@@ -18,11 +18,11 @@ image:
 extraArgs: {}
 # Additional Environment variables
 env: {}
-  # - name: REDIS_PASSWORD
-  #   valueFrom:
-  #     secretKeyRef:
-  #       key: redis-password
-  #       name: redis-config-0.0.2
+# - name: REDIS_PASSWORD
+#   valueFrom:
+#     secretKeyRef:
+#       key: redis-password
+#       name: redis-config-0.0.2
 service:
   type: ClusterIP
   port: 9121
@@ -52,3 +52,8 @@ serviceMonitor:
   # labels:
   # Set timeout for scrape
   # timeout: 10s
+
+# Used to mount a LUA-Script via config map and use it for metrics-collection
+# script:
+#   configmap: prometheus-redis-exporter-script
+#   keyname: script