diff --git a/garden-service/src/plugins/kubernetes/actions.ts b/garden-service/src/plugins/kubernetes/actions.ts
index e0b0e1e925..2db11a5cd9 100644
--- a/garden-service/src/plugins/kubernetes/actions.ts
+++ b/garden-service/src/plugins/kubernetes/actions.ts
@@ -121,7 +121,13 @@ export async function execInService(params: ExecInServiceParams<ContainerModule>
   }
 
   // exec in the pod via kubectl
-  const kubecmd = ["exec", "-i", pod.metadata.name, "--", ...command]
+  const opts: string[] = []
+
+  if (interactive) {
+    opts.push("-it")
+  }
+
+  const kubecmd = ["exec", ...opts, pod.metadata.name, "--", ...command]
   const res = await kubectl(api.context, namespace).call(kubecmd, {
     ignoreError: true,
     timeout: 999999,
@@ -185,10 +191,13 @@ export async function runModule(
     "--restart=Never",
     "--command",
     "--rm",
-    "-i",
     "--quiet",
   ]
 
+  if (interactive) {
+    opts.push("-it")
+  }
+
   const kubecmd = [
     "run", `run-${module.name}-${Math.round(new Date().getTime())}`,
     ...opts,
diff --git a/garden-service/src/plugins/kubernetes/kubectl.ts b/garden-service/src/plugins/kubernetes/kubectl.ts
index a2d39771de..682e1c8bf5 100644
--- a/garden-service/src/plugins/kubernetes/kubectl.ts
+++ b/garden-service/src/plugins/kubernetes/kubectl.ts
@@ -32,9 +32,9 @@ export class Kubectl {
   }
 
   async call(args: string[], opts: SpawnOpts = {}) {
-    const { data, ignoreError = false, timeout = KUBECTL_DEFAULT_TIMEOUT } = opts
-    const preparedArgs = this.prepareArgs(args, opts)
-    return spawn("kubectl", preparedArgs, { ignoreError, data, timeout })
+    const { data, ignoreError = false, timeout = KUBECTL_DEFAULT_TIMEOUT, tty } = opts
+    const preparedArgs = this.prepareArgs(args)
+    return spawn("kubectl", preparedArgs, { ignoreError, data, timeout, tty })
   }
 
   async json(args: string[], opts: SpawnOpts = {}): Promise<any> {
@@ -48,10 +48,10 @@ export class Kubectl {
   }
 
   spawn(args: string[]): ChildProcess {
-    return _spawn("kubectl", this.prepareArgs(args, {}))
+    return _spawn("kubectl", this.prepareArgs(args))
   }
 
-  private prepareArgs(args: string[], { tty }: SpawnOpts) {
+  private prepareArgs(args: string[]) {
     const opts: string[] = []
 
     if (this.namespace) {
@@ -66,10 +66,6 @@ export class Kubectl {
       opts.push(`--kubeconfig=${this.configPath}`)
     }
 
-    if (tty) {
-      opts.push("--tty")
-    }
-
     return opts.concat(args)
   }
 }
diff --git a/garden-service/src/types/plugin/outputs.ts b/garden-service/src/types/plugin/outputs.ts
index a30af0d7ff..968ec026b4 100644
--- a/garden-service/src/types/plugin/outputs.ts
+++ b/garden-service/src/types/plugin/outputs.ts
@@ -87,11 +87,14 @@ export const execInServiceResultSchema = Joi.object()
       .required()
       .description("The exit code of the command executed in the service container."),
     output: Joi.string()
+      .allow("")
       .required()
       .description("The output of the executed command."),
     stdout: Joi.string()
+      .allow("")
       .description("The stdout output of the executed command (if available)."),
     stderr: Joi.string()
+      .allow("")
       .description("The stderr output of the executed command (if available)."),
   })