Tag Archives: nodejs

“invalid ELF header” running a NodeJS script on Raspberry Pi


You see something like the following when trying to run your NodeJS script:

Error: [...]/node_modules/epoll/build/Release/epoll.node: invalid ELF header

Possible cause #1:

You’re using a Raspberry Pi (in my case 2 B) with Raspbian with the built-in Node v0.10.29 which is missing a UTF8 patch. See my other post HERE for the solution if you have the following error (you’ll just need to upgrade to v0.12.x or newer):

../node_modules/nan/nan.h:328:47: error: 'REPLACE_INVALID_UTF8' is not a member of 'v8::String'
static const unsigned kReplaceInvalidUtf8 = v8::String::REPLACE_INVALID_UTF8;

Possible cause #2:

You copied your node_modules directory over from your computer to the Raspberry Pi. npm needs to compile some node modules specially for the Raspberry Pi, so simply copying over the modules won’t always work.

Solution for cause #2:

Install your node modules on the Pi itself via npm, not just copy the node_modules directory over. This is because things need to be compiled slightly differently when running on the Pi. In my case epoll is a submodule of the repo “onoff”, so in my case I’d do the following on the Raspberry Pi where I want it installed:

npm install onoff

Note: If you don’t have npm installed on your Raspberry Pi yet, do the following:

sudo apt-get install nodejs npm

‘REPLACE_INVALID_UTF8’ is not a member of ‘v8::String’ installing NodeJS packages on Raspbian (Debian) on Raspberry Pi 2 B


The current distribution of node (v0.10.29) packaged with the Debian distro that comes with the Raspberry Pi 2 B is missing a patch related to UTF8. Because of this you may encounter packages which are unable to compile. You’ll see the following before various errors and eventual failure of installing a package via npm. In my case this failed when trying to install the “onoff” package which relied on “epoll”.

The Error:

../node_modules/nan/nan.h:328:47: error: 'REPLACE_INVALID_UTF8' is not a member of 'v8::String'
static const unsigned kReplaceInvalidUtf8 = v8::String::REPLACE_INVALID_UTF8;


Install a newer version of Node, such as v0.12.x:

curl -sL https://deb.nodesource.com/setup_0.12 | sudo -E bash -
sudo apt-get install -y nodejs

Verify this worked with:

node --version

That’s it! You should now be ready to resume installing your packages. Enjoy.

Websockets not working on Elastic Beanstalk with NodeJS when using nginx as a proxy

Amazon Web Service’s default nginx configuration does not have websocket support enabled by default. I am running SailsJS with Socket.io on NodeJS with the default nginx proxy and discovered that websockets were failing to connect. Creating a directory named .ebextensions in the root of my application and a file named 01_files.config within it with the configuration below solved the problem as it instructs nginx to pass websockets through. Just drop this in, deploy your app, and you should be good to go with your websockets functioning.

.ebextensions/01_files.config contents:

    "/etc/nginx/conf.d/websocketupgrade.conf" :
        mode: "000755"
        owner: root
        group: root
        content: |
             proxy_set_header        Upgrade         $http_upgrade;
             proxy_set_header        Connection      "upgrade";

I searched high and low for a solution to this problem and after finding several similar but functioning solutions I combined them to get the above.

Deploying first SailsJS node.js app to DigitalOcean using Dokku on Mac

Here’s a (very) quick and dirty overview of the steps. Follow everything below in order and you should have your node.js app (optionally running SailsJS) deployed on a dokku server on DigitalOcean within a few minutes.

Useful Links:
* Dokku – https://github.com/progrium/dokku
* MariaDB plugin – https://github.com/Kloadut/dokku-md-plugin

Set your SSH key into DigitalOcean if you haven’t already
* cat ~/.ssh/id_rsa.pub | pbcopy
* Paste this key into digitalocean control panel.

Create Droplet

* Select 1GB
* San Fran
* Dokku
* Select your existing SSH key.
* Virtio + backups (maybe virt network if need to connect)

Set up Dokku

* Visit in your browser: http://YOUR-SERVER-IP/
* Submit, optionally setting the app URL to use subdomains. Most settings should default to correct at this point.

Initialize the app access dokku

* cat ~/.ssh/id_rsa.pub | ssh [email protected] "sudo sshcommand acl-add dokku YOUR-APP-NAME"
** Note that if instead of YOUR-APP-NAME you put a full domain it will use that as the URL instead of setting up a subdomain. Eg api.dustinbolton.com instead of dustinbolton-api

Configuring local app

Initialize the local repo if you have not already
* git init && git add -A && git commit -m "Initial commit"

Assign production (or staging) destination:
* git remote add production [email protected]:YOUR-APP-NAME

Create file to tell server what to run on deployment:
* touch Procfile && open Procfile
* Add the following into this new file & save:
* web: sails lift
** For non-sails framework, instead of “sails lift” this would be “node app.js”.

Deploy & launch the app

* git push -u production master

If you need to manually re-run the app or see the output of the run attempt (such as to troubleshoot):
* ssh [email protected]
cd /home/dokku/YOUR-APP-NAME
dokku run YOUR-APP-NAME sails lift
(or instead of “sails lift”, “node app.js”)

Adapted from the guide at:

MariaDB (mysql drop-in alternative) plugin:

cd /var/lib/dokku/plugins
git clone https://github.com/Kloadut/dokku-md-plugin mariadb
#git clone https://github.com/musicglue/dokku-user-env-compile.git user-env-compile
dokku plugins-install

Create Database Instance

dokku mariadb:create YOUR-APP-NAME
* This creates the mariadb instance and links it to your app automatically since the name matches. The database name is “db” by default.

You can use the credentials displayed or access them via environmental variables such by: process.env.DB_USER

Setting Custom Environment Variables

Database environment variables should automatically exist but I have seen them drop off. I have not found the cause yet and have decided to manually set the one(s) I need for the time being.
dokku config:set YOUR-APP-NAME DATABASE_URL=whateverhere

If you ever need to restart your app. Only change “YOUR-APP-NAME”:

docker restart `cat /home/dokku/YOUR-APP-NAME/CONTAINER`