ironic-prometheus-exporter causes Docker mount havoc

After some time of running you get this:

/dev/mapper/rl-var on /var/lib/docker/volumes/ironic/_data/metrics type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota)
overlay on /var/lib/docker/overlay2/45470a4eccc17bce0529f27ca53ad858912b760e1323b1b38b24db42acced940/merged type overlay (rw,relatime,seclabel,lowerdir=/var/lib/docker/overlay2/l/4YYYRSNXVSH3HAVFMRM5PKXVN2:/var/lib/docker/overlay2/l/WQTW7VIVPA7MB2OMPJVIB2Z6DD:/var/lib/docker/overlay2/l/G6XRI6AT7O264ZEIMFRUQIIXCY:/var/lib/docker/overlay2/l/AYY663FWIKUZ2G5RJMLPSDY2XK:/var/lib/docker/overlay2/l/7NVNFTRSQUXYLQ4D4DCCM7UMBM:/var/lib/docker/overlay2/l/SEFLTAD6IDMW6KXBEEBEUF55RU:/var/lib/docker/overlay2/l/UWRXZAWCPBF3BF75JLEU7SM3YG:/var/lib/docker/overlay2/l/N6NTYI6LPCAFKIIM4QP6NQWLXZ:/var/lib/docker/overlay2/l/RBX3TQ6W3TWXKI5PRPQCKPDYFF:/var/lib/docker/overlay2/l/U76VGJVU23Q5RDRZHSTYIVEFOR:/var/lib/docker/overlay2/l/Q7SWZWJKDRRMAO4ZB6E26DSOPC:/var/lib/docker/overlay2/l/SYO42ZP6X6VNA5YVGXL52QO6UZ:/var/lib/docker/overlay2/l/BKVY62HLJJ5IZNRBADH4HNHWSA:/var/lib/docker/overlay2/l/MZ3BVICMMQTJX7XFQOAEGTDM5F:/var/lib/docker/overlay2/l/E52JCBKNQ7W22ME63JWEOC5J5R:/var/lib/docker/overlay2/l/EWQLVAICDUKV6GS5QEL4QSFPWA:/var/lib/docker/overlay2/l/FQBSYQTTOSRKTYEAW4KSQWBCSG:/var/lib/docker/overlay2/l/3GXNZ4BBQGAFK7XXPPYZKQQI7T:/var/lib/docker/overlay2/l/UGYVZCJ262ODJRJDLW5EBTS6WK:/var/lib/docker/overlay2/l/RSMM3VLIKQQE5RV57WZOPPMQDL:/var/lib/docker/overlay2/l/UY2HU5CW34WZRZEDEA3ZI7FHPR:/var/lib/docker/overlay2/l/CNFGWTFBSBKLHWC5W4OJRZOWVE:/var/lib/docker/overlay2/l/O5A4QQ42FVPV4H4HIKEHFZSEVC:/var/lib/docker/overlay2/l/TIGHYPXJV6QVMY3FWS2B56VVH6:/var/lib/docker/overlay2/l/RTWRXS6QIYJINGWASER5K5TIAO:/var/lib/docker/overlay2/l/2BQB5KMQANJJKVOVBSSCGX4TEM:/var/lib/docker/overlay2/l/A6NLZNEKR2FTLMEFX6YLPKQZ34:/var/lib/docker/overlay2/l/XKCN6ZF2K3PSWTYD3EWNUMZYQC:/var/lib/docker/overlay2/l/6Q2LNP4PWH7AU5GXBYGOXEFVXU:/var/lib/docker/overlay2/l/YO3OWQTG3646EV2BWC32DYFNCB:/var/lib/docker/overlay2/l/S5SME4FIVZW52X7YTFXGPHIWLZ:/var/lib/docker/overlay2/l/A7BZ6VKZQVLRYH3I2G4QXEMFK2:/var/lib/docker/overlay2/l/HONYMYEWJBMJ6NUKN3TC7RI4IP,upperdir=/var/lib/docker/overlay2/45470a4eccc17bce0529f27ca53ad858912b760e1323b1b38b24db42acced940/diff,workdir=/var/lib/docker/overlay2/45470a4eccc17bce0529f27ca53ad858912b760e1323b1b38b24db42acced940/work)