"No package 'libconfig' found" error on build

[mkritz]

When running the "docker build" cmd as defined in the Setup section, the following error appears at step 31/31:

checking for pkg-config... /usr/bin/pkg-config
checking pkg-config is at least version 0.9.0... yes
checking for JANUS... no
configure: error: Package requirements (
glib-2.0 >= 2.34
libconfig
nice
jansson >= 2.5
libssl >= 1.0.1
libcrypto
) were not met:

No package 'libconfig' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables JANUS_CFLAGS
and JANUS_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
The command '/bin/sh -c cd /janus-gateway && sh autogen.sh && git checkout origin/master && git reset --hard 3ff54ec && PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure --enable-post-processing --enable-boringssl --disable-data-channels --disable-rabbitmq --disable-mqtt --disable-plugin-echotest --disable-unix-sockets --enable-dtls-settimeout --disable-plugin-recordplay --disable-plugin-sip --disable-plugin-videocall --disable-plugin-voicemail --disable-plugin-textroom --disable-plugin-audiobridge --disable-plugin-nosip --disable-all-handlers && make && make install && make configs' returned a non-zero code: 1

Thank you!