Letto

Status

[ABANDONED - REPLACED BY webtask.io] A serverless platform for developers with a great UX

Objective

With Letto, I want to make it easier to build a custom workflow to trigger automated processes based on the events triggered by web services.

It's like IFTTT or Zapier, but developer-oriented, where you would be able to do anything by writing code, but with the ease-of-use of a dedicated SAAS tool (so no code deployment, no developing interactions components, no handling authentication...), you just focus on the workflow you want to create!

Howto

Write a workflow

The data (data.js, secrets.js and workflow scripts) is loaded from the host directory mapped to /tmp/data (see the docker-compose.yml file, under the web service).

In the <dataDir>/workflows directory, you can provide the JS scripts for your workflows.

You may use the exec/js/workflow_example.js file to see how to build a workflow script that is runnable.

Some NPM modules are provided in the NodeJS execution environment, you're free to use them by requiring them. Currently, the following modules are available:

• request
• ovh

Set credentials

cp credentials.js.example credentials.js

Then edit credentials.js to inject credentials you need from JS. This file is not committed.

Integrate with Trello

To integrate with Trello, you will need to:

1. Be able to perform API calls from your workflow, so you will need API credentials.
2. Setup a webhook in Trello to call your Letto endpoint, which is done in Trello through the API only.

We follow the Trello documentation which you will find here, but also provide a summary of instructions to get you on track faster. Please note it may not be up-to-date at your time of reading, and feel free to open a pull-request to fix it!

Getting Trello credentials

You can go on this page to get your API key and a personal token.

NB: At this point, Letto is only intended to enable you to build workflows for yourself. As such, we do not need to get tokens for other users, so using this personal token should be sufficient for now. When we continue improving Letto to make it usable by teams, we'll have to rethink this for sure!

Once you have your credentials, update the credentials.js file using the key and token.

Interact with the API

To learn how to use the Trello API and using the API in their sandbox, go to their Reference documentation.

You can use this to setup your webhooks on Letto's endpoint.

NB: Letto's endpoint is: http[s]://YOUR-DOMAIN:YOUR-PORT/api/triggers/webhook[/YOUR-GROUP]

Running

Prerequisites

docker-compose

Install with:

    sudo curl -L https://github.com/docker/compose/releases/download/1.16.1/docker-compose-`uname -s`-`uname -m` -o /usr/local/bin/docker-compose
    sudo chmod +x /usr/local/bin/docker-compose

letto_data

The letto_data directory, containing the secrets.js, data.js and workflow JS scripts must be present in the home directory.

See letto_data for more information.

Rebuild and run

docker-compose build && docker-compose up web

To run the container manually:

docker run -v /var/run/docker.sock:/var/run/docker.sock -it --rm lettobackend_web:latest

Debug the JS execution

docker run -it --rm -v "$PWD/../data":/tmp/data -v "$PWD/../traces":/tmp/traces -w /usr/src/app lettobackend_execjs:latest node 

Access private repository in CI/CD

This may help to build the Docker image:

# This part enables `go get` to fetch a private repository on gitlab,
# assuming the deploy_key present in the directory is authorized
# for this repo.
RUN mkdir ~/.ssh
RUN mv deploy_key ~/.ssh/id_rsa
RUN mv deploy_key.pub ~/.ssh/id_rsa.pub
RUN echo "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config

Deploy

See letto_infrastructure.