将目录附加到 Amazon Lambda 环境变量 $NODE_PATH

Question

Default Env Variable as per the docs :

NODE_PATH:/opt/nodejs/node8/node_modules/:/opt/nodejs/node_modules:$LAMBDA_RUNTIME_DIR/node_modules

I want to append my custom directory to it (NOT to override all)

NODE_PATH:$NODE_PATH:/opt/nodejs/mycustom-directory

I tried the above from lambda console it overrides all. $NODE_PATH is added as a string. It is not parsing $NODE_PATH

Output I got when printing env:

NODE_PATH=$NODE_PATH:/opt/nodejs/mycustom-directory

Similar Question but no Solution still: AWS lambda add PATH variable?

Answer 1

I came up with the same problem. I wrote a code to check if the lambda function applies the shell variable expansions, and to figure out they don't.

I set environment variable FOO as $NODE_PATH ,

Then, run the check code (in lambda function):

const { FOO } = process.env;
exports.lambdaHandler = async (event, context, callback) => {
  console.log(FOO);
};

The output is:

2019-02-22T08:29:05.714Z    cde21239-628f-4a79-b046-6a14f177f59e    $NODE_PATH

I just rewrite the whole NODE_PATH to be (my custom library path):/opt/nodejs/lib:/opt/nodejs/node8/node_modules/:/opt/nodejs/node_modules:/var/runtime/node_modules

the default value of NODE_PATH is explained there:

https://docs.aws.amazon.com/lambda/latest/dg/current-supported-versions.html

Answer 2

I needed this too, as I am using AWS Lambda Layers, which are placed on the default NODE_PATH , and wanted to also be able to use local roots to avoid long relative paths (such as import bar from foo/bar instead of import bar from ../../../../foo/bar , but I didn't find any way to append to NODE_PATH without losing the default ones - as soon as it's set, the paths to node_modules - including the aws-sdk module, are lost.

The only solutions I can think of are:

1. Explicitly set NODE_PATH to the default value plus your custom one (which adds an ugly dependency to lambda internal environment configuration which you shouldn't have to care about)

2. Put your custom library in a layer. Many times this is a good solution if you can extract sub-modules as separate layers (but it doesn't help for situations like elimination of long relative paths within the application itself like I described above).

3. Append programatically, by having the very first lines of your application do

process.env.NODE_PATH = process.env.NODE_PATH + ":my-custom-path";
require("module").Module._initPaths(); // This re-initalizes the module loader to use the new NODE_PATH.

require('some-custom-module-in-my-custom-path'); // should work
require('aws-sdk') // should also work

This may not be the prettiest hack, but it should do the trick (disclaimer: haven't actually tried this in a AWS Lambda environment but it works locally using Node 12 at least).