In short: not entirely.
There are many steps necessary to produce the views and abstractions shown on the website. The basic decoding is done with
this
decoder. The aggregation of the decoded data is then done by a mix of different technologies (Storm, Spark, Cassandra, Impala) and the actual implementation is extremely specific to OpenSky's applications and infrastructure.
Anyway, it should be more or less easy to reproduce it since in the end it comes down to a sequence of "group by" operations on time and aircraft (identified by its icao ID).