[cli] allow changing policy load path

doc/parameters.md

@@ -182,3 +182,12 @@ This is a new **experimental** feature for increasing performance. Client
 won't see the backend latency and everything will be processed asynchronously.
 This value determines how many asynchronous reports can be running simultaneously
 before the client is throttled by adding latency.
+
+### `APICAST_POLICY_LOAD_PATH`
+
+**Default**: APICAST_DIR/policies
+**Value:**: string\[:<string>\]
+**Example**: ~/apicast/policies:$PWD/policies
+
+Double colon (`:`) separated list of paths where APIcast should look for policies.
+It can be used to first load policies from a development directory or to load examples.

doc/policies.md

@@ -106,6 +106,12 @@ Lets say the policy needs some 3rd party dependency. Those can be put anywhere i
 
 The policy has access to only code it provides and shared code in `APICAST_DIR/src/`.
 
+You can start APIcast with different policy load path parameter (`--policy-load-path` or `APICAST_POLICY_LOAD_PATH`) to load
+policies from different than the default path. Example:
+```shell
+bin/apicast start --policy-load-path examples/policies:spec/fixtures/policies
+```
+
 ### Policy code
 
 To write your own policy you need to write a Lua module that instantiates a

gateway/src/apicast/cli/command/start.lua

@@ -4,6 +4,7 @@ local min = math.min
 local max = math.max
 local insert = table.insert
 local concat = table.concat
+local format = string.format
 
 local exec = require('resty.execvp')
 local resty_env = require('resty.env')
@@ -109,6 +110,7 @@ local function build_env(options, config)
         APICAST_CONFIGURATION_LOADER = options.boot and 'boot' or 'lazy',
         APICAST_CONFIGURATION_CACHE = options.cache,
         THREESCALE_DEPLOYMENT_ENV = config.name,
+        APICAST_POLICY_LOAD_PATH = options.policy_load_path,
     }
 end
 
@@ -193,6 +195,10 @@ local function configure(cmd)
         "Cache configuration for N seconds. Using 0 will reload on every request (not for production).",
         resty_env.value('APICAST_CONFIGURATION_CACHE'))
 
+    cmd:option("--policy-load-path",
+        "Load path where to find policies. Entries separated by `:`.",
+        resty_env.value('APICAST_POLICY_LOAD_PATH') or format('%s/policies', apicast_root())
+    )
     cmd:mutex(
         cmd:flag('-v --verbose',
             "Increase logging verbosity (can be repeated).")

gateway/src/apicast/policy_loader.lua

@@ -8,8 +8,8 @@
 local format = string.format
 local error = error
 local type = type
+local ipairs = ipairs
 local loadfile = loadfile
-local getenv = os.getenv
 local insert = table.insert
 local setmetatable = setmetatable
 local concat = table.concat
@@ -25,6 +25,9 @@ local root_require = require
 
 local preload = package.preload
 
+local resty_env = require('resty.env')
+local re = require('ngx.re')
+
 --- create a require function not using the global namespace
 -- loading code from policy namespace should have no effect on the global namespace
 -- but poliocy can load shared libraries that would be cached globally
@@ -211,16 +214,24 @@ local mt = {
   __call = function(loader, ...) return loader.env.require(...) end
 }
 
-function _M.new(name, version, dir)
-  local apicast_dir = dir or getenv('APICAST_DIR') or '.'
+do
+  local apicast_dir = resty_env.value('APICAST_DIR') or '.'
+  local policy_load_path = resty_env.value('APICAST_POLICY_LOAD_PATH') or
+      format('%s/policies', apicast_dir)
 
-  local path = {
-    -- first path contains
-    format('%s/policies/%s/%s/?.lua', apicast_dir, name, version),
-  }
+  _M.policy_load_paths = re.split(policy_load_path, ':', 'oj')
+  _M.builtin_policy_load_path = format('%s/src/apicast/policy', apicast_dir)
+end
+
+function _M.new(name, version, paths)
+  local load_paths = {}
+
+  for _, path in ipairs(paths or _M.policy_load_paths) do
+    insert(load_paths, format('%s/%s/%s/?.lua', path, name, version))
+  end
 
   if version == 'builtin' then
-    insert(path, format('%s/src/apicast/policy/%s/?.lua', apicast_dir, name))
+    insert(load_paths, format('%s/%s/?.lua', _M.builtin_policy_load_path, name))
   end
 
   -- need to create global variable package that mimics the native one
@@ -229,7 +240,7 @@ function _M.new(name, version, dir)
     preload = preload,
     searchers = {}, -- http://www.lua.org/manual/5.2/manual.html#pdf-package.searchers
     searchpath = searchpath,
-    path = concat(path, ';'),
+    path = concat(load_paths, ';'),
     cpath = '', -- no C libraries allowed in policies
   }
 

spec/policy_loader_spec.lua

@@ -22,8 +22,8 @@ describe('APIcast Policy Loader', function()
     end)
 
     it('loads two instances of the same policy', function()
-      local test = _M:call('test', '1.0.0-0', 'spec/fixtures')
-      local test2 = _M:call('test', '1.0.0-0', 'spec/fixtures')
+      local test = _M:call('test', '1.0.0-0', { 'spec/fixtures/policies' })
+      local test2 = _M:call('test', '1.0.0-0', { 'spec/fixtures/policies' })
 
       test.one = 1
       assert.falsy(test2.one)
@@ -34,8 +34,8 @@ describe('APIcast Policy Loader', function()
     end)
 
     it('loads two versions of the same policy', function()
-      local test = _M:call('test', '1.0.0-0', 'spec/fixtures')
-      local test2 = _M:call('test', '2.0.0-0', 'spec/fixtures')
+      local test = _M:call('test', '1.0.0-0', { 'spec/fixtures/policies' })
+      local test2 = _M:call('test', '2.0.0-0', { 'spec/fixtures/policies' })
 
       assert.are.same({ '1.0 dependency' }, test.dependency)
       assert.are.same({ '2.0 dependency' }, test2.dependency)