Thrall embedding

[tonytw1]

What does this change?

Embedding runs without the embedding lambda using ImageLoader and Thrall.

Tweaks to the general optionally of the embedder so that the absence of an embedding implementation gracefully ignores the embedding related code paths.

Generalises the embedding implementation then
migrates the embedding implementation from Bedrock to Gemini Embedding 2 for running in Google Cloud.

Embedding implementations define an embeddingSourceImageFormat to indicate what format it needs it's input images to be in.

ImageOperations defines a new createEmbeddingSource to produce this image format.

Image Loader calls createEmbeddingSource during the image upload process placing the formatted image in a new embedding sources S3 Bucket.

Image loader continues to publish the SQS embedding messages but Thrall is now the receiver.

Thrall gets a new SQS listener to consume the embedding messages, call the embedding API and publish the currentUpdateEmbedding messages onto the low priority queue for indexing.

Stores calculated embeddings in an S3 bucket so that they can be reused when reindexing.

Nudges More Like this to be more of a boolean filter and enables it for all images which have an embedding.

Requires this mapping patch:

curl -X PUT "https://<ES_HOST>:9200/<INDEX_NAME>/_mapping" \
    -H "Content-Type: application/json" \
    -d '{
      "properties": {
        "embedding": {
          "dynamic": "strict",
          "properties": {
            "geminiEmbedding2": {
              "dynamic": "strict",
              "properties": {
                "image": {
                  "type": "dense_vector",
                  "dims": 768,
                  "index": true,
                  "similarity": "cosine",
                  "index_options": {
                    "type": "int8_hnsw",
                    "m": 16,
                    "ef_construction": 100
                  }
                }
              }
            }
          }
        }
      }
    }'

How should a reviewer test this change?

How can success be measured?

Who should look at this?

Tested? Documented?

• locally by committer
• locally by Guardian reviewer
• on the Guardian's TEST environment
• relevant documentation added or amended (if needed)