Improved short polling. Cached cluster data for 30mins with "forceRef…

…resh" option. Externalised server-side defaults into environment-based configuration files.

UI:
- Implemented short polling logic - query the server up to 120 times with 5s intervals
- Added "Reload Server Cache" button to UI to force server to refresh cluster data.
- Upgraded bootstrap from v3.3.5 to v3.3.7 for glyphicons including "glyphicons-halflings-regular" fonts.
- Improved error handling.

Server:
- Externalised server-side defaults into environment-based configuration files.
- Added ClusterState & ClusterStateCache to cache cluster data.
- Added FetchStatus to represent current status of fetching cluster data.
- Improved error handling.
- Added test suite - run tests with "npm run test"

ClientServerInteraction-SequenceDiagram.puml

@@ -0,0 +1,59 @@
+@startuml
+skinparam sequenceArrowThickness 2
+skinparam roundcorner 20
+skinparam maxmessagesize 60
+skinparam sequenceParticipant underline
+
+actor User
+participant "Browser" as A
+participant "Request" as B
+participant "Background Processing" as C
+participant "ClusterStateCache" as D
+
+activate D
+
+User -> A: Select Cluster
+activate A
+
+A -> B: "/api/instance_summaries_with_tasks"
+activate B
+
+B -> C: Get State
+activate C
+C -> D: Create
+activate D
+C -> D: INITIAL
+C --> B: INITIAL
+
+B --> A: INITIAL
+deactivate B
+
+C -> D: FETCHING
+
+A -> B: "/api/instance_summaries_with_tasks"
+activate B
+B -> C: Get State
+C --> B: FETCHING
+B --> A: FETCHING
+deactivate B
+
+C -> D: FETCHED
+
+A -> B: "/api/instance_summaries_with_tasks"
+activate B
+B -> C: Get State
+C --> B: FETCHED
+B --> A: FETCHED
+deactivate B
+
+D -> D : Expire
+deactivate D
+
+A --> User: Render Graph
+deactivate A
+
+
+deactivate C
+deactivate D
+
+@enduml

FetchStatus-StateDiagram.puml

@@ -0,0 +1,38 @@
+@startuml
+
+'[*]      --> null
+[*]     --> INITIAL
+INITIAL  --> FETCHING
+FETCHING --> FETCHED
+'INITIAL  --> null  : Expired
+'FETCHING --> null  : Expired
+'FETCHED  --> null  : Expired
+'ERROR    --> null  : Expired
+INITIAL  --> ERROR : Failed
+FETCHING --> ERROR : Failed
+FETCHED  --> ERROR : Failed
+
+'FETCHED  --> [*]   : Success
+'ERROR    --> [*]   : Error
+
+@enduml
+
+@startuml
+
+[*]      --> null
+null     --> INITIAL
+INITIAL  --> FETCHING
+FETCHING --> FETCHED
+INITIAL  --> null  : Expired
+FETCHING --> null  : Expired
+FETCHED  --> null  : Expired
+ERROR    --> null  : Expired
+INITIAL  --> ERROR
+FETCHING --> ERROR
+FETCHED  --> ERROR
+
+'FETCHED  --> [*]   : Success
+'ERROR    --> [*]   : Error
+
+@enduml
+

bin/www

@@ -7,12 +7,13 @@
 var app = require('../app');
 var debug = require('debug')('c3vis:server');
 var http = require('http');
+var config = require('../config/config');
 
 /**
  * Get port from environment and store in Express.
  */
 
-var port = normalizePort(process.env.PORT || '3000');
+var port = normalizePort(config.port);
 app.set('port', port);
 
 /**

config/config.js

@@ -0,0 +1,11 @@
+const _ = require('lodash');
+
+// Assume running in 'dev' environment if NODE_ENV environment variable not defined
+const targetEnvironment = (process.env.NODE_ENV || 'dev');
+
+// Load default configuration from defaults.js
+// and extend with environment-specific configuration
+module.exports = _.merge(
+    require('./defaults.js'),
+    require(`./env/${targetEnvironment}.js`) || {}
+);

config/defaults.js

@@ -0,0 +1,14 @@
+module.exports = {
+  port: process.env.PORT || 3000,
+  clusterStateCacheTtl: 30 * 60 * 1000,  // Invalidate clusters in cache after 30 minutes
+  aws: {
+    configFile: './aws_config.json',
+    apiDelay: 100, // milliseconds to pause between AWS API calls to prevent API rate limiting
+    listInstancesPageSize: 100,          // max 100
+    describeInstancesPageSize: 100,      // max 100
+    listTasksPageSize: 100,              // max 100
+    describeTasksPageSize: 100,          // max 100
+    maxSimultaneousDescribeTasksCalls: 2,
+    maxSimultaneousDescribeTaskDefinitionCalls: 1,
+  }
+};

config/env/dev.js

@@ -0,0 +1,3 @@
+module.exports = {
+  // add dev environment config overrides here and enable at startup with NODE_ENV=dev environment variable
+};

config/env/prod.js

@@ -0,0 +1,3 @@
+module.exports = {
+  // add production environment config overrides here and enable at startup with NODE_ENV=prod environment variable
+};

config/env/test.js

@@ -0,0 +1,3 @@
+module.exports = {
+  // add test environment config overrides here and enable at startup with NODE_ENV=test environment variable
+};