Cloud Functions Bucket File Editor

Browser based text editor for files in gcloud storage buckets.

• Edit files in storage buckets from anywhere even a Chromebook
• No need for gsutil or gcsfuse, specialized text editors
• No need for VMs, Containers, Cloud Run, Cloud Shells/IDE
• No frills, just enough for html textarea based file editor
• Doesn't use IAM/Google accounts, implements own authentication

Deployment

Gconsole UI

Cloud Functions -> Create Function

• Authentication: Allow unauthenticated invocations
• Runtime: Go
• Entry point: CFEdit
• Inline Editor: paste code of cfedit.go
• Change project name and restrict to specific bucket
• Add user accounts for basic auth

Gcloud CLI

Edit cfedit.go

• Change project name and restrict to specific bucket
• Add user accounts see user authentication section

Run:

$ gcloud functions deploy cfedit \
    --entry-point=CFEdit \
    --runtime=go116 \
    --trigger-http \
    --allow-unauthenticated \
    --source=/path/to/cfedit

Delete:

$ gcloud functions delete cfedit

User Authentication

Cfedit uses HTTP Basic Auth with hardcoded user database. I specifically wanted to avoid forcing users to have Google accounts, IAM + OAuth2 complexities and JavaScript based Google Sign-in buttons.

User Database

The user database is stored in a struct inside var() section of cfedit.go.

users = []struct{ login, salt, hash string }{
  {login: "admin", salt: "abc", hash: "hash of salt+pass"},
  {login: "editor", salt: "def", hash: "hash of salt+pass"},
}

Adding a user

To add a user simply add a new line with {login: "foo", salt: "bar", hash: "..."},.

To generate the password hash:

$ echo -n "SaltMyPassword" | shasum -a 256 | cut -f 1 -d" "

The salt is simply a unique random string you pick. The only requirement is that has to be different for each user. For example if login is foo, salt is bar and password is baz:

$ echo -n "barbaz" | shasum -a 256 | cut -f 1 -d" "
c8f8b724728a6d6684106e5e64e94ce811c9965d19dd44dd073cf86cf43bc238

users = []struct{ login, salt, hash string } {
	{login: "foo", salt: "bar", hash: "c8f8b724728a6d6684106e5e64e94ce811c9965d19dd44dd073cf86cf43bc238"},
}

No authentication

To disable authentication entirely remove/comment out all users.

Local Development

Create a Service Account under IAM. Create and download a json key file.

Run locally:

$ GOOGLE_APPLICATION_CREDENTIALS=~/project-1234345.json go run local/main.go

Reference:

https://cloud.google.com/functions/docs/running/function-frameworks#go https://github.com/GoogleCloudPlatform/functions-framework-go

Roadmap

• rate limit on auth attempts
• create new empty file, rename, delete
• upload/download files
• subfolders/prefixes https://cloud.google.com/storage/docs/listing-objects#storage-list-objects-go
• preconditions and race conditions https://cloud.google.com/storage/docs/generations-preconditions#examples_of_race_conditions
• possibly use a better editor such as editarea, codemirror, monaco, codejar https://en.wikipedia.org/wiki/Comparison_of_JavaScript-based_source_code_editors or markdown editor like TinyMCE, CKEditor

Legal

Copyright (c) 2021 Google LLC
This is not an officially supported Google product