document DEBUG, WSK_NODE_DEBUG vars
diff --git a/README.md b/README.md
index 7d4373a..0d40687 100644
--- a/README.md
+++ b/README.md
@@ -110,6 +110,7 @@
+ [Node.js: Plain usage](#nodejs-plain-usage)
+ [Node.js: Chrome DevTools](#nodejs-chrome-devtools)
+ [Node.js: node-inspect command line](#nodejs-node-inspect-command-line)
++ [Enable debug logging](#enable-debug-logging)
+ [Unsupported action kinds](#unsupported-action-kinds)
+ [Source mounting](#source-mounting)
+ [Live reloading](#live-reloading)
@@ -158,7 +159,7 @@
2. Make sure to not commit this file into source control, by e.g. adding `.env` to a `.gitignore` file.
-2. Add an `envFile` setting to the `.vscode/launch.json`, which you can share with co-workers and commit to source control:
+3. Add an `envFile` setting to the `.vscode/launch.json`, which you can share with co-workers and commit to source control:
```json
"configurations": [
@@ -176,8 +177,6 @@
]
```
-
-
<a name="nodejs-multiple-actions"></a>
### Node.js: Multiple actions
@@ -286,6 +285,40 @@
node-inspect 127.0.0.1:9229
```
+<a name="enable-debug-logging"></a>
+### Enable debug logging
+
+To enable debug logs in your action, you can set environment variables:
+
+1. (nodejs) `DEBUG` environment variable from the popular [debug](https://www.npmjs.com/package/debug) library is passed through to the action. Options:
+ - Run wskdebug using
+
+ ```
+ DEBUG=xyz wskdebug myaction
+ ```
+ - Alternatively put it in the `.env` file (see [above](#nodejs-visual-studio-code))
+
+ ```
+ DEBUG=xyz
+ ```
+2. (nodejs) To control the`NODE_DEBUG` [used](https://nodejs.org/api/util.html#util_util_debuglog_section) by built-in node modules, just set the `WSK_NODE_DEBUG` variable. (It is a separate one in order to not affect `wskdebug` itself which is written in nodejs.) Options:
+ - Run wskdebug using
+
+ ```
+ WSK_NODE_DEBUG=NET wskdebug myaction
+ ```
+ - Alternatively put it in the `.env` file (see above)
+
+ ```
+ WSK_NODE_DEBUG=NET
+ ```
+3. Any other custom environment variables that enable debugging or logging features in your action can be set by controlling the docker run arguments using `--docker-args` (note the leading space before `-e`, which is required):
+
+ ```
+ wskdebug --docker-args " -e DEBUG_VAR=something" myaction
+ ```
+
+
<a name="unsupported-action-kinds"></a>
### Unsupported action kinds
