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Rally Decoder Job

The Rally decoder job is a variant of the decoder job defined in the com.mozilla.telemetry.decoder.rally package (source). The decoder supports the Rally data donation and sharing platform. More information can be found on the mana page.

See bug 1628539 for initial implementation of the pioneer-v2 decoder and bug 1697342 for implementation of the Glean.js encrypted pings.


The Rally decoder includes three new options: --pioneerEnabled, --pioneerMetadataLocation, and --pioneerKmsEnabled. And example of running the job is as follows, which is captured in the bin/run-pioneer-benchmark script.

mvn compile exec:java -Dexec.mainClass=com.mozilla.telemetry.Decoder -Dexec.args="\
    --runner=Dataflow \
    --profilingAgentConfiguration='{\"APICurated\": true}'
    --project=$project \
    --autoscalingAlgorithm=NONE \
    --workerMachineType=n1-standard-1 \
    --gcpTempLocation=$bucket/tmp \
    --numWorkers=2 \
    --region=us-central1 \
    --pioneerEnabled=true \
    --pioneerMetadataLocation=$bucket/$prefix/metadata/metadata.json \
    --pioneerKmsEnabled=false \
    --pioneerDecompressPayload=false \
    --geoIspDatabase=$bucket/$prefix/metadata/GeoIP2-ISP.mmdb  \
    --geoCityDatabase=$bucket/$prefix/metadata/GeoLite2-City.mmdb \
    --geoCityFilter=$bucket/$prefix/metadata/cities15000.txt \
    --schemasLocation=$bucket/$prefix/metadata/schemas.tar.gz \
    --inputType=file \
    --input=$bucket/$prefix/input/ciphertext/'part-*' \
    --outputType=file \
    --output=$bucket/$prefix/output/ciphertext/ \
    --errorOutputType=file \
    --errorOutput=$bucket/$prefix/error/ciphertext/ \

The --pioneerEnabled flag enables the transform in the decoder pipeline, which comes before schema validation and payload processing. It uses the document specified by the --pioneerMetadataLocation to locate information for the KeyStore. The metadata location takes on the following form validated by this schema:

    "private_key_id": "rally-study-foo",
    "private_key_uri": "src/test/resources/jwe/rally-study-foo.private.json",
    "kms_resource_id": "projects/DUMMY_PROJECT_ID/locations/global/keyRings/test-ingestion-beam-integration/cryptoKeys/study-foo"

The decoder reads the JSON Web Key into memory from the location in the private_key_uri. It can be encrypted using Cloud Key Management Service by specifying kms_resource_id and enabling the --pioneerKmsEnabled flag.

The decoder decrypts pings that follow conventions for Rally or Pioneer pings. All encryption and decryption takes place using JSON Web Encryption (JWE). An envelope is a piece of metadata that surrounds the encrypted data. The Rally envelope is an object with a payload field containing a JWE compact object. After decrypting the payload, the ping takes the form of a Glean ping. The document namespace (as per the HTTP Edge Server Specification) is used to fetch the key from memory.

The Pioneer ping's envelope uses the legacy mechanism of sending data through the Telemetry pipeline as a ping. In addition, the envelope explicitly specifies the routing information for the ping. Finally, the decoder constructs a PubSub message that includes the routing information and decrypted message.

Notable design decisions

Data SRE allocates each Rally study a JWK pair. The client must encode messages with the key to reach the analysis environment. The client may not always have the key, so there are exceptions for the enrollment and deletion pings. The decoder will ignore the payload and extract the pioneer id for these document types.