2019-09-10 update

content/blog/enable-global-policies-apicast.md

@@ -0,0 +1,64 @@
+---
+title: "Enable global policies on Apicast 3.6"
+date: 2019-09-10T00:00:00+02:00
+opensource: 
+- 3scale
+---
+
+Recent versions of Apicast have a pluggable policy mechanism to apply different treatments to each exposed API.
+This is very powerful since each service receives its specific configuration.
+However, if the same treatment has to be applied to every service exposed, it becomes an administration overhead.
+
+Hopefully, Apicast has the concept of *Global Policies* that applies to every service exposed by itself.
+An example of a widespread policy, especially during demos, is the CORS policy to allow the API Developer Portal to query the API Gateway directly.
+
+To configure the *Global Policy Chain*, you will have to provide a custom *Environment file*.
+By default, there is one for the [Staging Environment](https://github.com/3scale/APIcast/blob/3.6-stable/gateway/config/staging.lua) and one for the [Production Environment](https://github.com/3scale/APIcast/blob/3.6-stable/gateway/config/production.lua).
+
+Start from those default *Environment Files* and add a `policy_chain` field with your *Policy* inserted wherever you want in the default *Global Policy Chain*.
+The default *Global Policy Chain* can be found in the [`gateway/src/apicast/policy_chain.lua`](https://github.com/3scale/APIcast/blob/b8f7f067dd47936f93bc9bd3e6de224c304d58ea/gateway/src/apicast/policy_chain.lua#L67-L72) file.
+
+**production.lua:**
+```lua
+return {
+    master_process = 'on',
+    lua_code_cache = 'on',
+    configuration_loader = 'boot',
+    configuration_cache = os.getenv('APICAST_CONFIGURATION_CACHE') or 5*60,
+    timer_resolution = '100ms',
+    port = { metrics = 9421 },
+    policy_chain = require('apicast.policy_chain').build({
+        'apicast.policy.load_configuration',
+        'apicast.policy.find_service',
+        'apicast.policy.cors',
+        'apicast.policy.local_chain',
+        'apicast.policy.nginx_metrics'
+    }),
+}
+```
+
+**staging.lua:**
+```lua
+return {
+    master_process = 'on',
+    lua_code_cache = 'on',
+    configuration_loader = 'lazy',
+    configuration_cache = os.getenv('APICAST_CONFIGURATION_CACHE'),
+    port = { metrics = 9421 }, -- see https://github.com/prometheus/prometheus/wiki/Default-port-allocations,
+    policy_chain = require('apicast.policy_chain').build({
+        'apicast.policy.load_configuration',
+        'apicast.policy.find_service',
+        'apicast.policy.cors',
+        'apicast.policy.local_chain',
+        'apicast.policy.nginx_metrics'
+    }),
+}
+```
+
+Then, create a ConfigMap from those two files and mount it in `/opt/app-root/src/config`:
+
+```sh
+oc create configmap apicast-cors --from-file=production.lua --from-file=staging.lua
+oc set volume dc/apicast-production --add --name=apicast-cors -t configmap --configmap-name=apicast-cors -m /opt/app-root/src/config
+oc set volume dc/apicast-staging --add --name=apicast-cors -t configmap --configmap-name=apicast-cors -m /opt/app-root/src/config
+```