Add setEnvVar to interactive compute. Closes #1817

src/common/compute/interactive/message.js

@@ -9,7 +9,7 @@
     }
 }(this, function() {
     const Constants = makeEnum('STDOUT', 'STDERR', 'RUN', 'ADD_ARTIFACT',
-        'ADD_FILE', 'ADD_USER_DATA', 'COMPLETE', 'ERROR');
+        'ADD_FILE', 'ADD_USER_DATA', 'COMPLETE', 'ERROR', 'SET_ENV');
 
     function makeEnum() {
         const names = Array.prototype.slice.call(arguments);

src/common/compute/interactive/session.js

@@ -141,6 +141,13 @@ define([
             await this.runTask(task);
         }
 
+        async setEnvVar(name, value) {
+            this.ensureIdle('set env var');
+            const msg = new Message(Message.SET_ENV, [name, value]);
+            const task = new Task(this.ws, msg);
+            await this.runTask(task);
+        }
+
         close() {
             this.ws.close();
         }

src/routers/InteractiveCompute/job-files/start.js

@@ -52,12 +52,19 @@ class InteractiveClient {
                 this.runTask(saveArtifact);
             });
         } else if (msg.type === Message.ADD_FILE) {
-            this.runTask(() => this.writeFile(msg));
+            this.runTask(() => {
+                const [filepath, content] = msg.data;
+                this.writeFile(filepath, content);
+            });
+        } else if (msg.type === Message.SET_ENV) {
+            this.runTask(() => {
+                const [name, value] = msg.data;
+                process.env[name] = value;
+            });
         }
     }
 
-    async writeFile(msg) {
-        const [filepath, content] = msg.data;
+    async writeFile(filepath, content) {
         const dirs = path.dirname(filepath).split(path.sep);
         await mkdirp(...dirs);
         await fs.writeFile(filepath, content);