Azurerm_application_gateway ciphers: here
Don’t align with that of Azure’s supported ciphers: here
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 is required for Azure to gather logging from the App GW, however this cipher suite isn’t shown in the TF supported cipher list above.
Is this a documentation issue? Are all Azure supported suites also supported in the Azurerm_application_gateway module?