Set a few configuration options an env variables.

For docker containers it would be useful if any configuration variables
defining how to connect to the angular ui and how it connects to the
DSpace 7 REST endpoint could be overriden by environment variables. We
should not extend configuration by environment variables too much.

src/config.ts

@@ -4,6 +4,7 @@ import { InjectionToken } from '@angular/core';
 import { Config } from './config/config.interface';
 import { ServerConfig } from './config/server-config.interface';
 import { GlobalConfig } from './config/global-config.interface';
+import { hasValue } from './app/shared/empty.util';
 
 const GLOBAL_CONFIG: InjectionToken<GlobalConfig> = new InjectionToken<GlobalConfig>('config');
 
@@ -55,6 +56,41 @@ if (envConfigFile) {
   }
 }
 
+// allow to override a few important options by environment variables
+function createServerConfig(host?: string,  port?: string, nameSpace?: string, ssl?: string): ServerConfig {
+  const result = { host, nameSpace } as any;
+
+  if (hasValue(port)) {
+    result.port = Number(port);
+  }
+
+  if (hasValue(ssl)) {
+    result.ssl = ssl.trim().match(/^(true|1|yes)$/i) ? true : false;
+  }
+
+  return result;
+}
+
+const processEnv = {
+  ui: createServerConfig(
+    process.env.DSPACE_HOST,
+    process.env.DSPACE_PORT,
+    process.env.DSPACE_NAMESPACE,
+    process.env.DSPACE_SSL) as ServerConfig,
+  rest: createServerConfig(
+    process.env.DSPACE_REST_HOST,
+    process.env.DSPACE_REST_PORT,
+    process.env.DSPACE_REST_NAMESPACE,
+    process.env.DSPACE_REST_SSL) as ServerConfig
+} as GlobalConfig;
+
+// merge the environment variables with our configuration.
+try {
+  merge(processEnv)
+} catch (e) {
+  console.warn('Unable to merge environment variable into the configuration')
+}
+
 buildBaseUrls();
 
 // set config for whether running in production