Who wrote/compose the La Vie en rose?

All the record notes credit Edith Piaf as writing the lyrics of the song herself; the melody was by the Spanish-born composer Louis Guglielmi ("Louiguy") who wrote a lot of sentimental ballads popular at the time. When he was writing for Piaf he was already an established musician, and it's unlikely that he would have had to sleep on the pavement to get an audience with her.