api: add API to get applied migrations list

Add new API to get migrations list.

Closes #65

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added:
 - An API for moving existing migration names from the cluster configuration to
   a space.
+- API for getting applied migrations list for the cluster.
 
 ## [0.7.0]
 ### Added:

README.md

@@ -190,6 +190,11 @@ IMPORTANT: code snippets below should be embedded to `init.lua`, so they would t
         end
     ```
 
+* To get a list of applied migrations make a POST request to
+  `http://<your_tarantool_ip>:<http_port>/migrations/applied` or a call
+  `require('migrator').get_applied()`on any cluster instance. This method will return a list of
+  applied migrations grouped by a leader node.
+
 ## Upgrade from 0.* versions.
 
 Applied migrations names storage method has been changed in `1.*` version: applied migrations list

migrator/init.lua

@@ -184,6 +184,34 @@ local function get_applied_local()
     return result
 end
 
+--- Get list of applied migration names in cluster.
+-- Throws an exception in case of any problems
+-- @function get_applied
+-- @return table of applied migrations in cluster grouped by leader aliases.
+local function get_applied()
+    local leaders = rpc.get_candidates('migrator',{leader_only = true })
+    log.info('Preparing getting applied migrations from %s', json.encode(leaders))
+    local result, errmap = pool.map_call('_G.__cluster_rpc_call_local',
+        {'migrator', 'get_applied_local'}, {
+            uri_list = leaders,
+            timeout = get_storage_timeout()
+        })
+    if errmap ~= nil then
+        for uri, err in pairs(errmap) do
+            log.error('Cannot get migrations state from %s: %s',
+                uri, json.encode(err))
+        end
+        error("Failed to get migrations state: " .. json.encode(errmap))
+    end
+
+    local migrations_by_alias = {}
+    for uri, migrations in pairs(result) do
+        migrations_by_alias[get_server_alias(uri)] = migrations
+    end
+
+    return migrations_by_alias
+end
+
 -- Append migration names to the _migrations space.
 local function append_migrations_to_local_space(migrations)
     local copied_migrations = {}
@@ -299,6 +327,12 @@ local function init(opts)
         resp.status = 200
         return resp
     end)
+
+    httpd:route({ path = '/migrations/applied', method = 'POST' }, function(req)
+        local resp = req:render({ json = { applied = get_applied() }})
+        resp.status = 200
+        return resp
+    end)
 end
 
 local function upgrade()
@@ -363,6 +397,8 @@ return {
     get_schema = get_schema,
 
     move_migrations_state = move_migrations_state,
+    get_applied = get_applied,
+    get_applied_local = get_applied_local,
 
     _VERSION = require('migrator.version'),
 }

test/integration/get_applied_test.lua

@@ -0,0 +1,94 @@
+local t = require('luatest')
+local g = t.group('get_migrations_state')
+
+local fio = require('fio')
+
+local cartridge_helpers = require('cartridge.test-helpers')
+local shared = require('test.helper.integration').shared
+local utils = require("test.helper.utils")
+local datadir = fio.pathjoin(shared.datadir, 'get_migrations_state')
+
+g.cluster = cartridge_helpers.Cluster:new({
+    server_command = shared.server_command,
+    datadir = datadir,
+    use_vshard = true,
+    base_advertise_port = 10500,
+    replicasets = {
+        {
+            alias = 'router',
+            uuid = cartridge_helpers.uuid('a'),
+            roles = { 'vshard-router', 'migrator' },
+            servers = { {
+                alias = 'router',
+                instance_uuid = cartridge_helpers.uuid('a', 1)
+            } },
+        },
+        {
+            alias = 'storage-1',
+            uuid = cartridge_helpers.uuid('b'),
+            roles = { 'vshard-storage', 'migrator' },
+            servers = {
+                {
+                    alias = 'storage-1-master',
+                    instance_uuid = cartridge_helpers.uuid('b', 1),
+                    env = {TARANTOOL_HTTP_ENABLED = 'false'},
+                },
+                {
+                    alias = 'storage-1-replica',
+                    instance_uuid = cartridge_helpers.uuid('b', 2),
+                    env = {TARANTOOL_HTTP_ENABLED = 'false'},
+                },
+            },
+        },
+        {
+            alias = 'storage-2',
+            uuid = cartridge_helpers.uuid('c'),
+            roles = { 'vshard-storage', 'migrator' },
+            servers = {
+                {
+                    alias = 'storage-2-master',
+                    instance_uuid = cartridge_helpers.uuid('c', 1),
+                    env = {TARANTOOL_HTTP_ENABLED = 'false'},
+                },
+                {
+                    alias = 'storage-2-replica',
+                    instance_uuid = cartridge_helpers.uuid('c', 2),
+                    env = {TARANTOOL_HTTP_ENABLED = 'false'},
+                },
+            },
+        },
+    },
+})
+
+g.before_all(function() g.cluster:start() end)
+g.after_all(function() g.cluster:stop() end)
+g.after_each(function() utils.cleanup(g) end)
+
+g.test_get_migrations_state = function(cg)
+    local main = cg.cluster.main_server
+
+    local status, resp = main:eval("return pcall(require('migrator').up)")
+    t.assert(status, tostring(resp))
+    t.assert_equals(resp, {
+        ['router'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+        ['storage-1-master'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+        ['storage-2-master'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+    })
+
+    status, resp = main:eval("return pcall(require('migrator').get_applied)")
+    t.assert(status, tostring(resp))
+    t.assert_equals(resp, {
+        ['router'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+        ['storage-1-master'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+        ['storage-2-master'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+    })
+
+    -- Check the same result is returned by http.
+    local result = main:http_request('post', '/migrations/applied', { json = {} })
+    local expected_applied = {
+        ['router'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+        ['storage-1-master'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+        ['storage-2-master'] = { '01_first.lua', '02_second.lua', '03_sharded.lua' },
+    }
+    t.assert_equals(result.json, { applied = expected_applied })
+end