AWSPics

An AWS CloudFormation stack to run a serverless password-protected photo gallery

Demo: https://awspics.net
Credentials: "username" / "password"

Goals

Host a self-contained, declarative infrastructure, password-protected, data-driven static photo gallery to share personal pictures with friends and family, without needing to run, maintain (or pay for) servers.

Architecture

There are 7 main components:

CloudFront with restricted bucket access to prevent unauthenticated access to the site or its pictures.
Login lambda function to validate authentication and sign cookies to allow access to restricted buckets.
Source S3 bucket to store original pictures and metadata driving the site.
Resized S3 bucket to store resized versions of the original pictures.
Web S3 bucket to store the static website generated from the data in the source bucket.
Resize lambda function to automatically resize images added to the source S3 bucket and store them in the resized S3 bucket.
Site builder lambda function to automatically rebuild the static website when ~~changes are made to the source S3 bucket~~ a regularly scheduled event fires from Cloudwatch Events.

Pre-requisites

Requires that aws-cli, docker and htpasswd be installed.

You'll also need a domain whose CNAME DNS value you can update.

Instructions

A video walkthrough is available on YouTube.

Configure aws-cli (recommended to use us-east-1, see "Miscellaneous" below):

$ aws configure
AWS Access Key ID [None]: AKIA...
AWS Secret Access Key [None]: illx...
Default region name [None]: us-east-1
Default output format [None]:
$ aws configure set preview.cloudfront true

Create KMS encryption key: aws kms create-key. Keep note of its KeyId in the response. Note that each KMS key costs $1/month.
Create CloudFront Key Pair, take note of the key pair ID and download the private key: https://console.aws.amazon.com/iam/home?region=us-east-1#/security_credential.

Encrypt the CloudFront private key:

aws kms encrypt --key-id $KMS_KEY_ID --plaintext "$(cat pk-*.pem)" \
                --query CiphertextBlob --output text

Create a local htpasswd file with your usernames and passwords. You can generate the hashes from the command line:
```
$ htpasswd -nB username > htpasswd
New password: **********
Re-type new password: **********
```

Encrypt your htpasswd file using KMS again:

aws kms encrypt --key-id $KMS_KEY_ID --plaintext "$(cat htpasswd)" \
                --query CiphertextBlob --output text

Create CloudFront Origin Access Identity, take note of the identity in the response:

aws cloudfront create-cloud-front-origin-access-identity \
               --cloud-front-origin-access-identity-config \
               "CallerReference=$(cat /dev/urandom | base64 | base64 | head -c 14),Comment=AWSPics OAI"

Create Image Magick Lambda Layer for Amazon Linux 2 AMIs.

While logged into AWS, go to this link:
```
<https://serverlessrepo.aws.amazon.com/applications/arn:aws:serverlessrepo:us-east-1:145266761615:applications~image-magick-lambda-layer>
```
Click Deploy (currently the orange button on the upper left).

Then click on your Lambda - Layers and you will see a version ARN that looks like:
```
Name          Version  Version ARN
image-magick  1        arn:aws:lambda:us-east-1:000000000000:layer:image-magick:1
```
Hold on to that ARN for later.

Deployment

Create a configuration file called dist/config.json, based on config.example.json. Make sure you don't commit this file to source control (the dist folder is ignored).

It should contain the following info - minus the comments:

[
  // -------------------
  // PLAIN TEXT SETTINGS
  // -------------------

  // website domain
  "website=website.com",
  // title for the website
  "websiteTitle=My awesome private photo gallery",
  // S3 bucket where the static website generated from the data in the
  // source bucket will be stored
  "webBucket=html-files-here",
  // S3 bucket where original pictures and metadata driving the site will be
  // stored
  "sourceBucket=original-images-here",
  // S3 bucket where resized images will be stored
  "resizedBucket=resized-images-here",
  // Origin Access Identity from step 7
  "originAccessIdentity=EJG...",
  // how long the CloudFront access is granted for, in seconds
  // note that the cookies are session cookies, and will get deleted when the
  // browser is closed anyway
  "sessionDuration=86400",
  // KMS key ID created in step 2
  "kmsKeyId=00000000-0000-0000-0000-000000000000",
  // CloudFront key pair ID from step 3
  // This is not sensitive, and will be one of the cookie values
  "cloudFrontKeypairId=APK...",
  // ------------------
  // Image Magick Lambda Layer ARN
  // - this is needed for ImageMagick to resize images in Node.js 10.x
  // - from step 8 above
  // - context above in README
  // ------------------
  "ImageMagickLayer=arn:aws:lambda:us-east-1:........:layer:image-magick:...",

  // ------------------
  // ENCRYPTED SETTINGS
  // ------------------

  // encrypted CloudFront private key from step 4
  "encryptedCloudFrontPrivateKey=AQICAH...",

  // encrypted contents of the <htpasswd> file from step 6
  "encryptedHtpasswd=AQICAH...",
  
  // ------------------
  // SSL Certificate ARN
  // - provide this if you want to use an existing ACM Certificate.
  // - see below in the README
  // ------------------
  "sslCertificateArn=arn:aws:acm:us-east-1..."

]

You can then deploy the full stack using:

# name of an S3 bucket for storing the Lambda code
# bucket will be created if it doesn't already exist
./deploy <unique_bucket_name_here>

Any subsequent changes that you make to this code can be redeployed with the same command. CloudFormation will create a "changeset" to only update the modified resources.

The first deployment should take about 30 minutes since there's a lot to set up. You'll also receive an email to approve the SSL certificate request, which you should complete quickly, so that the rest of the deployment can proceed.

You will want to update the frequency of the Cloudwatch Events Rule from its default setting at 365 days to something more appropriate to your needs. You can adjust this pre-deployment in the app.yml file or after the fact in the AWS Management console.

Note on ImageMagick Layer for Lambda

When Amazon deprecated Node.js 8.10, they removed ImageMagick from the Amazon Linux 2 AMIs that are required to run Node.js 10.x. Again, ImageMagick is no longer bundled with the Node.js 10.x runtime. This fix may also help with running on Node.js 12.x in the future. This provides a Lambda Layer (essentially a library) for your Lambda function that makes the existing code work with Node.js 10.x.

Note on SSL Cert

AWS Certificate Manager now supports SSL cert verification via DNS validation. It is recommended that you manually request the certificate for your hosted zone and chose DNS validation method for much faster validation. Then use the resulting ARN in your config. You can also leave this config key empty to create the certificate as normal.

Once the initial deployment is done, you'll need to point your domain's DNS settings to add a CNAME to the newly created CloudFront Distribution URL, which you can find by visiting the CloudFront section of the AWS Console. Once the DNS update has propagated, you'll be able to access your private photo gallery at that domain. However, there's no content yet, so you won't see much of anything. You can generate sample albums to see it in action.

Generate Sample Albums

There's a script included that will pull random images from Unsplash to populate your photo gallery with sample content.

./generate_random_albums <number of albums>

How the Authentication Works

The Lambda function responsible for logging in creates signed session cookies when given valid credentials. CloudFront will verify that every request has valid cookies before forwarding them.

Browser                   CloudFront             Lambda              S3
  |                           |                    |                 |
  | ---------- get ---------> |                    |                 |
  |                           |                    |                 |
  |                      [no cookie]               |                 |
  |                           |                    |                 |
  |                           |                    |                 |
  |                           |                    |                 |
  | <------ error page ------ |                    |                 |
  |                                                |                 |
  | -------------------- login ------------------> |                 |
  | <------------------- cookies ----------------- |                 |
  |                                                                  |
  | ---------- get ---------> |                                      |
  |                           |                                      |
  |                      [has cookie]                                |
  |                           |                                      |
  |                           | -----------------------------------> |
  |                           | <------------ html page ------------ |
  | <------ html page ------- |

Miscellaneous

This project only works as-is if everything is set up in the us-east-1 AWS region, because CloudFormation only supports SSL certificates from that region. It's not too difficult to adapt this to work in another region, but you can't rely on the SSL certificate being created in CloudFormation. Create it manually (using either the AWS Console or the CLI) and reference it in the WebDistribution by its ARN explicitly rather than the !Ref SSLCert reference.

GeoRestriction is commented out in the CloudFront configuration in the app.yaml. If you are sharing with friends and family in a specific geographic area, this is a slight improvement to security and cost reduction. The US is provided as an example, but additional countries can be added to a (whitelist/blacklist) based on their two letter ISO 3166-1 alpha-2 country code.

S3 Server Side AES256 encryption is enabled for the source and resized photo buckets and encrypts files using the AWS S3 Master key. Each bucket is configured to force encryption of any file it receives (you will need to check the upload box or specify it in the CLI when uploading photo files to the buckets) and you will get access denied messages if you don't. The Resize function re-encrypts the resized photos with AES256 SSE before uploading them into the resized bucket. Cloudfront with an OAI is able to access files using the S3 Master Key without any issue. One cannot at this time use a KMS key for encrypting bucket data to be accessed via Cloudfront without more complexity.

The EventInvoke config is included for SiteBuilder to prevent it from queueing up invocations and causing multiple cloudfront invalidations at the same time. If you need to run sitebuilder more frequently, adjust the rate of events by editing the CloudWatch Events rule in the Management console or the app.yml file.

Also, you can reduce compute costs and lock down the application several ways: 1) by manually throttling the Resize Function and the SiteBuilder Function in Lambda in the Management console or 2) disabling the CloudWatch Events rule that runs SiteBuilder or 3) manually disabling the trigger for a Lambda function in the Management console.

Default directory for photos is S3://BUCKET_NAME/pics/original/YOUR_ALBUMS_GO_HERE

Troubleshooting

If the project deploys and the login is entered correctly, but you are receiving access denied messages, review your DNS settings. You only need a single DNS A record pointing to the CloudFront Alias for your domain, and time for it to propagate.

If SiteBuilder is hanging or having trouble completing, you may need to adjust the rate limiting delay block in index.js. The current S3 rate limit is 3500 writes a second, and 5500 reads/sec. If you're writing 30 files per album, if you have more than 116 albums, you will hit the rate limit - and SiteBuilder will just hang and you will see the files as a partial listing in the web directory.

Credits

This project is mostly a compilation from multiple existing projects out there.

Credits for update to nodejs 10.x and ImageMagick Layer:

License

AWSPics is MIT licensed.

agstevens/AWSPics