We pre-install these system images on the base build agent to provide our project teams the ability to run emulators on a range of API levels, from API 19 to API 28. X86 is the fastest architecture for emulators, though x86_64 would probably be better to test against because most phones are 64 bit now.
(4.4)
sdkmanager --install "system-images;android-19;google_apis;x86"
(5.0)
sdkmanager --install "system-images;android-21;google_apis;x86"
(5.1)
sdkmanager --install "system-images;android-22;google_apis;x86"
(6.0)
sdkmanager --install "system-images;android-23;google_apis;x86"
(7.0)
sdkmanager --install "system-images;android-24;google_apis;x86"
(7.1)
sdkmanager --install "system-images;android-24;google_apis;x86"
(8.0)
sdkmanager --install "system-images;android-26;google_apis;x86"
(8.1)
sdkmanager --install "system-images;android-27;google_apis;x86"
(9.0)
sdkmanager --install "system-images;android-28;google_apis;x86"