The　normal　operation　of　data　center　network　management　tasks　relies　on　accurate　measurement　of　the　network　status.　In-band　Network　Telemetry　(INT)　leverages　programmable　data　planes　to　provide　fine-grained　and　accurate　network　status.　However,　existing　INT-related　works　have　not　considered　the　telemetry　data　required　for　dynamic　adjustments　of　INT　under　uninterrupted　conditions,　including　additions,　deletions,　and　modifications.　To　address　this　issue,　this　paper　proposes　OpenINT,　a　lightweight　and　flexible　In-band　Network　Telemetry　system.　The　key　innovation　of　OpenINT　lies　in　decoupling　telemetry　operations　in　the　data　plane,　using　three　generic　sub-modules　to　achieve　lightweight　telemetry.　Meanwhile,　the　control　plane　utilizes　heuristic　algorithms　for　dynamic　planning　to　achieve　near-optimal　telemetry　paths.　Additionally,　OpenINT　provides　primitives　for　defining　network　measurement　tasks,　which　abstract　the　underlying　telemetry　architecture＇s　details,　enabling　network　operator　to　conveniently　access　network　status.　A　prototype　of　OpenINT　is　implemented　on　a　programmable　switch　equipped　with　the　Tofino　chip.　Experimental　results　demonstrate　that　OpenINT　achieves　highly　flexible　dynamic　telemetry　and　significantly　reduces　network　overhead.　©　2024　IEEE.