WiFi is enabled but doesn't try to connect

Question

I'm puzzling over the network configuration in Stretch with dhcpcd. The ethernet connection works fine. WiFi is detected but it doesn't try to connect at all. Surely I'm missing an obvious step...

/etc/wpa_supplicant/wpa_supplicant.conf

country=IT
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
ap_scan=1
update_config=1
network={
    ssid="---"
    psk="---"
    key_mgmt=WPA-PSK
}

/etc/dhcpcd.conf

hostname
clientid
persistent
noarp
option rapid_commit
option domain_name_servers, domain_name, domain_search, host_name
option classless_static_routes
option ntp_servers
option interface_mtu
require dhcp_server_identifier
slaac private

profile static_eth0
static ip_address=192.168.1.200/24
static routers=192.168.1.1
static domain_name_servers=192.168.1.1

interface eth0
fallback static_eth0

interface wlan0
static ip_address=192.168.178.222/24
static routers=192.168.178.1
static domain_name_servers=192.168.178.1

$lsusb

Bus 001 Device 005: ID 0bda:8179 Realtek Semiconductor Corp. RTL8188EUS 802.11n Wireless Network Adapter

$dmesg | tail

[    4.921791] r8188eu: module is from the staging directory, the quality is unknown, you have been warned.
[    5.004467] Chip Version Info: CHIP_8188E_Normal_Chip_TSMC_D_CUT_1T1R_RomVer(0)
[    5.147308] usbcore: registered new interface driver r8188eu
[    5.317772] rtc-ds1307 1-0068: rtc core: registered ds1307 as rtc0
[    5.317829] rtc-ds1307 1-0068: 56 bytes nvram
[    6.222872] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
[    6.223792] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[    6.925950] MAC Address = f4:f2:6d:1c:f8:64
[    6.930023] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[    7.755753] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[    7.757473] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xC5E1
[   26.332142] random: crng init done

$ifconfig

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.178.73  netmask 255.255.255.0  broadcast 192.168.178.255
        inet6 fe80::2a22:1789:bfb0:6a48  prefixlen 64  scopeid 0x20<link>
        ether b8:27:eb:33:e9:1e  txqueuelen 1000  (Ethernet)
        RX packets 848  bytes 58502 (57.1 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 766  bytes 131138 (128.0 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 fe80::24b:5bfc:8a9e:b148  prefixlen 64  scopeid 0x20<link>
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1  (Local Loopback)
        RX packets 25  bytes 7740 (7.5 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 25  bytes 7740 (7.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlan0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether f4:f2:6d:1c:f8:64  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

$iwconfig

eth0      no wireless extensions.

lo        no wireless extensions.

wlan0     unassociated  Nickname:"<WIFI@REALTEK>"
          Mode:Auto  Frequency=2.412 GHz  Access Point: Not-Associated   
          Sensitivity:0/0  
          Retry:off   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

$ ps aux | grep wpa

root       309  0.0  0.4   9552  4028 ?        Ss   18:30   0:00 /sbin/wpa_supplicant -u -s -O /run/wpa_supplicant

Which log should I check?