Add higress lua canary script (#116)

Signed-off-by: SpecialYang <[email protected]>

lua_configuration/trafficrouting_ingress/higress.lua

@@ -0,0 +1,46 @@
+annotations = {}
+-- obj.annotations is ingress annotations, it is recommended not to remove the part of the lua script, it must be kept
+if ( obj.annotations )
+then
+    annotations = obj.annotations
+end
+-- indicates the ingress is nginx canary api
+annotations["nginx.ingress.kubernetes.io/canary"] = "true"
+-- First, set all canary api to nil
+annotations["nginx.ingress.kubernetes.io/canary-by-cookie"] = nil
+annotations["nginx.ingress.kubernetes.io/canary-by-header"] = nil
+annotations["nginx.ingress.kubernetes.io/canary-by-header-pattern"] = nil
+annotations["nginx.ingress.kubernetes.io/canary-by-header-value"] = nil
+annotations["nginx.ingress.kubernetes.io/canary-weight"] = nil
+-- if rollout.spec.strategy.canary.steps.weight is nil, obj.weight will be -1,
+-- then we need remove the canary-weight annotation
+if ( obj.weight ~= "-1" )
+then
+    annotations["nginx.ingress.kubernetes.io/canary-weight"] = obj.weight
+end
+-- if don't contains headers, immediate return annotations
+if ( not obj.matches )
+then
+    return annotations
+end
+-- headers & cookie apis
+-- traverse matches
+for _,match in ipairs(obj.matches) do
+    local header = match.headers[1]
+    -- cookie
+    if ( header.name == "canary-by-cookie" )
+    then
+        annotations["nginx.ingress.kubernetes.io/canary-by-cookie"] = header.value
+    else
+        annotations["nginx.ingress.kubernetes.io/canary-by-header"] = header.name
+        -- if regular expression
+        if ( header.type == "RegularExpression" )
+        then
+            annotations["nginx.ingress.kubernetes.io/canary-by-header-pattern"] = header.value
+        else
+            annotations["nginx.ingress.kubernetes.io/canary-by-header-value"] = header.value
+        end
+    end
+end
+-- must be return annotations
+return annotations