Merge pull request kiwigrid#3 from b13n1u/http_req

Add an option to send a http GET or POST after config map change.

README.md

@@ -4,7 +4,7 @@
 
 # What?
 
-This is a docker container intended to run inside a kubernetes cluster to collect config maps with a specified label and store the included files in an local folder. The main target is to be run as a sidecar container to supply an application with information from the cluster. The contained python script is working with the Kubernetes API 1.10
+This is a docker container intended to run inside a kubernetes cluster to collect config maps with a specified label and store the included files in an local folder. It can also send a html request to a specified URL after a configmap change. The main target is to be run as a sidecar container to supply an application with information from the cluster. The contained python script is working with the Kubernetes API 1.10
 
 # Why?
 
@@ -13,6 +13,7 @@ Currently (April 2018) there is no simple way to hand files in configmaps to a s
 # How?
 
 Run the container created by this repo together you application in an single pod with a shared volume. Specify which label should be monitored and where the files should be stored.
+By adding additional env variables the container can send a html request to specified URL.
 
 # Features
 
@@ -35,3 +36,20 @@ Example for a simple deployment can be found in `example.yaml`. Depending on the
   - description: Folder where the files should be placed
   - required: true
   - type: string
+
+- `REQ_URL`
+  - description: URL to which send a request after a configmap got reloaded
+  - required: false
+  - type: URI
+
+- `REQ_METHOD`
+  - description: Request method GET(default) or POST
+  - required: false
+  - type: string
+
+- `REQ_PAYLOAD`
+  - description: If you use POST you can also provide json payload
+  - required: false
+  - type: json
+
+

sidecar/sidecar.py

@@ -1,6 +1,9 @@
 from kubernetes import client, config, watch
 import os
 import sys
+import requests
+from requests.packages.urllib3.util.retry import Retry
+from requests.adapters import HTTPAdapter
 
 
 def writeTextToFile(folder, filename, data):
@@ -9,6 +12,25 @@ def writeTextToFile(folder, filename, data):
         f.close()
 
 
+def request(url, method, payload):
+    r = requests.Session()
+    retries = Retry(total = 5,
+            connect = 5,
+            backoff_factor = 0.2,
+            status_forcelist = [ 500, 502, 503, 504 ])
+    r.mount('http://', HTTPAdapter(max_retries=retries))
+    r.mount('https://', HTTPAdapter(max_retries=retries))
+    if url is None:
+        print("No url provided. Doing nothing.")
+        # If method is not provided use GET as default
+    elif method == "GET" or method is None:
+        res = r.get("%s" % url, timeout=10)
+        print ("%s request sent to %s. Response: %d %s" % (method, url, res.status_code, res.reason))
+    elif method == "POST":
+        res = r.post("%s" % url, json=payload, timeout=10)
+        print ("%s request sent to %s. Response: %d %s" % (method, url, res.status_code, res.reason))
+
+
 def removeFile(folder, filename):
     completeFile = folder +"/"+filename
     if os.path.isfile(completeFile):
@@ -17,7 +39,7 @@ def removeFile(folder, filename):
         print("Error: %s file not found" % completeFile)
 
 
-def watchForChanges(label, targetFolder):
+def watchForChanges(label, targetFolder, url, method, payload):
     v1 = client.CoreV1Api()
     w = watch.Watch()
     for event in w.stream(v1.list_config_map_for_all_namespaces):
@@ -36,8 +58,12 @@ def watchForChanges(label, targetFolder):
                 print("File in configmap %s %s" % (filename, eventType))
                 if (eventType == "ADDED") or (eventType == "MODIFIED"):
                     writeTextToFile(targetFolder, filename, dataMap[filename])
+                    if url is not None:
+                        request(url, method, payload)
                 else:
                     removeFile(targetFolder, filename)
+                    if url is not None:
+                        request(url, method, payload)
 
 
 def main():
@@ -50,9 +76,14 @@ def main():
     if targetFolder is None:
         print("Should have added FOLDER as environment variable! Exit")
         return -1
+
+    method = os.getenv('REQ_METHOD')
+    url = os.getenv('REQ_URL')
+    payload = os.getenv('REQ_PAYLOAD')
+
     config.load_incluster_config()
     print("Config for cluster api loaded...")
-    watchForChanges(label, targetFolder)
+    watchForChanges(label, targetFolder, url, method, payload)
 
 
 if __name__ == '__main__':