#2121·watchtower

Enabling the HTTP API enables a debug endpoint (/debug/vars)

Author: alexharringtonCreated Nov 10, 2025Updated Nov 12, 2025
LabelsType: BugPriority: MediumStatus: Available

Describe the bug

If you enable the HTTP API, then the container appears to respond to an unauthenticated HTTP request to /debug/vars which prints out memory information and potentially the command line used to launch watchtower.

Steps to reproduce

Enable the HTTP API - eg http://localhost:8080 curl -v http://localhost:8080/debug/vars

Expected behavior

404 HTTP response

Screenshots

{
"cmdline": ["/watchtower"],
"memstats": {"Alloc":1336488,"TotalAlloc":185391088,"Sys":20138768,"Lookups":0,"Mallocs":1357463,"Frees":1349511,"HeapAlloc":1336488,"HeapSys":11632640,"HeapIdle":8167424,"HeapInuse":3465216,"HeapReleased":7716864,"HeapObjects":7952,"StackInuse":950272,"StackSys":950272,"MSpanInuse":133488,"MSpanSys":178992,"MCacheInuse":9600,"MCacheSys":15600,"BuckHashSys":4719,"GCSys":5494944,"OtherSys":1861601,"NextGC":4194304,"LastGC":1762771005628600552,"PauseTotalNs":774431195,"PauseNs":[29684,23181,22673,22159,28254,44961,22744,22369,32883,26725,43765,36530,24166,22450,21690,21805,22682,26676,22501,23863,33697,31027,22933,22535,22909,26967,22205,44971,68313,109684,69724,66320,65021,158050,32857,69193,67073,66295,23067,37181,65540,34405,66957,86596,35134,66461,22830,41497,69420,46904,119541,68261,73696,68186,49592,23430,71182,26419,69207,104457,65856,24061,72755,67856,64996,70907,22160,22461,69308,73596,69115,27247,25855,90532,103037,27069,62397,25652,67953,67327,22622,56030,64555,22249,65340,66389,104084,64775,22355,71647,66056,65775,73141,68675,76556,66406,66167,23688,63589,65772,65928,64985,64617,66599,69755,66530,66675,22720,22089,68333,34654,37076,122831,23755,24221,22326,23207,23402,22943,22950,28084,22440,23104,22924,34899,23031,23189,52488,22623,24216,65995,66078,66348,22270,64961,65516,25097,58695,62558,60521,23336,61112,62980,65360,68197,62456,78083,67228,34937,32142,64776,64548,40847,26571,113638,28248,25258,77101,63294,100855,66109,34995,92398,85671,66482,66684,65275,64889,65576,66592,64726,66194,73735,66067,68118,66250,67695,66052,68189,22604,65480,88218,24131,68366,64591,66214,79184,77031,136011,67804,64741,69092,64420,32452,76465,70193,69115,39673,40768,31985,66190,24326,53135,33962,66197,65879,66851,67061,65438,61833,21789,68211,87928,66060,64095,66016,60873,66827,23140,22756,66076,68281,65391,65338,67491,68988,72707,65553,65161,61882,74159,68470,66105,39704,37810,24003,36159,23877,22985,25382,23778,36150,32171,29775,26031,47349,45695,24422,29902,33481,22770,22385,21991,22792,38740,21982],"PauseEnd":[1762757212231928791,1762757332252187282,1762757452272494663,1762757572292808676,1762757692313103475,1762757812333411616,1762757932353695985,1762758052373915161,1762758172394131049,1762758292425593397,1762758412445895197,1762758532466139603,1762758652486521754,1762758772506753239,1762758892527097881,1762759012547450733,1762759132567744261,1762759252587979896,1762759372608266597,1762759492628572598,1762759612648839410,1762759732669172677,1762759852689404991,1762759972709670924,1762760092729959778,1762760212750198945,1762760332770430949,1762760452790701750,1762760572812088385,1762760692832623230,1762760812853353709,1762760932873796678,1762761052894081013,1762761172914966551,1762761292934454988,1762761412955909666,1762761532976197684,1762761652996899140,1762761773016481974,1762761893037159257,1762762013058228938,1762762133078058125,1762762253098976558,1762762373119745915,1762762493139107331,1762762613160413800,1762762733180003403,1762762853200543784,1762762973221738843,1762763093241721247,1762763213262804542,1762763381664518099,1762763501666722716,1762763621668885665,1762763741682327319,1762763861683432110,1762763981685368498,1762764101686560638,1762764221688304458,1762764341690495066,1762764461696205936,1762764581710836163,1762764701732321432,1762764821752672268,1762764991007133553,1762765111009286475,1762765231010400045,1762765351011171017,1762765471012683159,1762765591014623296,1762765711016834262,1762765831018051830,1762765951019039849,1762766071020891061,1762766191023101746,1762766311024366971,1762766431026156744,1762766551027442677,1762766671029212123,1762766791031428077,1762766911036047125,1762767031052289755,1762767151072943738,1762767271092515324,1762767391113924579,1762767511134630911,1762767631154926273,1762767751175336785,1762767871195047250,1762767997552464464,1762768117554613076,1762768237556613096,1762768357558615859,1762768477560704602,1762768597563030647,1762768717565033879,1762768837567091096,1762768957568241922,1762769077570018091,1762769197573784383,1762769317581711189,1762769437602110094,1762769557622680027,1762769678527816964,1762769808957778412,1762769928960140067,1762770048973997203,1762770168986951934,1762770288991075272,1762770409007553595,1762770572243527072,1762770692244344004,1762770860334624243,1762771005628600552,1762740169354281398,1762740289355164875,1762740409357783940,1762740529365816404,1762740649386032176,1762740769406337447,1762740889426690368,1762741009446972895,1762741129467341017,1762741249487632971,1762741369507963201,1762741489528317044,1762741609548682274,1762741729569033802,1762741849589335065,1762741969609877275,1762742089631108835,1762742209651712318,1762742329672239563,1762742449691791237,1762742569713296039,1762742689733912284,1762742809753560745,1762742929774581320,1762743049795144738,1762743169815550563,1762743289835307663,1762743409856470975,1762743529876966975,1762743649897666087,1762743769918070506,1762743889938455835,1762744009959116203,1762744129979767247,1762744249999128430,1762744370019598177,1762744490040780390,1762744610061508418,1762744730081133615,1762744850101553120,1762744970122912624,1762745090142583744,1762745210163081894,1762745330184369851,1762745450204738283,1762745570225599743,1762745690245659917,1762745810265219512,1762745930286444901,1762746050306873597,1762746170327130327,1762746290347862544,1762746410368312541,1762746530388883709,1762746650409542692,1762746770429926962,1762746890450529245,1762747010471104237,1762747130491490218,1762747250512311782,1762747370532585507,1762747490553172536,1762747610573704692,1762747730594277351,1762747850614657928,1762747970645551540,1762748090667019726,1762748210687312550,1762748330707094229,1762748450728598500,1762748570749018883,1762748690769380325,1762748810789620202,1762748930810253606,1762749050831095050,1762749170851292754,1762749290871731093,1762749410892276578,1762749530912881987,1762749650932689463,1762749770954029721,1762749890974450968,1762750010994973286,1762750131014812728,1762750251035264214,1762750371055634763,1762750491076859084,1762750611096404493,1762750731117427359,1762750851137347239,1762750971158454243,1762751091179249469,1762751211199585621,1762751331220258712,1762751451240853669,1762751571261287858,1762751691281230350,1762751811302739882,1762751931323214218,1762752051343760902,1762752171364235621,1762752291384755547,1762752411405441400,1762752531425896302,1762752651445635091,1762752771466110100,1762752891487368428,1762753011508114824,1762753131528561780,1762753251549192153,1762753371569576215,1762753491590127709,1762753611610717150,1762753731631126472,1762753851651783536,1762753971672235951,1762754091692827615,1762754211713438386,1762754331734155868,1762754451753741486,1762754571774147019,1762754691805597445,1762754811825955673,1762754931846219630,1762755051866541348,1762755171886799346,1762755291907144505,1762755411927509533,1762755531947844383,1762755651968202796,1762755771988434706,1762755892008829540,1762756012029171898,1762756132049397631,1762756252069758958,1762756372090044353,1762756492110664943,1762756612130492691,1762756732150806095,1762756852171094961,1762756972191341865,1762757092211620377],"NumGC":14962,"NumForcedGC":0,"GCCPUFraction":0.0000016155301181285644,"EnableGC":true,"DebugGC":false,"BySize":[{"Size":0,"Mallocs":0,"Frees":0},{"Size":8,"Mallocs":21121,"Frees":20896},{"Size":16,"Mallocs":336526,"Frees":332974},{"Size":24,"Mallocs":210781,"Frees":209941},{"Size":32,"Mallocs":102742,"Frees":102176},{"Size":48,"Mallocs":131439,"Frees":130763},{"Size":64,"Mallocs":94873,"Frees":94599},{"Size":80,"Mallocs":42295,"Frees":42150},{"Size":96,"Mallocs":80130,"Frees":79810},{"Size":112,"Mallocs":25042,"Frees":24848},{"Size":128,"Mallocs":17235,"Frees":17195},{"Size":144,"Mallocs":41440,"Frees":41387},{"Size":160,"Mallocs":10574,"Frees":10402},{"Size":176,"Mallocs":7031,"Frees":6985},{"Size":192,"Mallocs":5975,"Frees":5966},{"Size":208,"Mallocs":9383,"Frees":9295},{"Size":224,"Mallocs":5000,"Frees":4991},{"Size":240,"Mallocs":263,"Frees":261},{"Size":256,"Mallocs":13004,"Frees":12986},{"Size":288,"Mallocs":10461,"Frees":10421},{"Size":320,"Mallocs":10903,"Frees":10889},{"Size":352,"Mallocs":12749,"Frees":12727},{"Size":384,"Mallocs":1488,"Frees":1485},{"Size":416,"Mallocs":398,"Frees":156},{"Size":448,"Mallocs":702,"Frees":693},{"Size":480,"Mallocs":2743,"Frees":2741},{"Size":512,"Mallocs":5456,"Frees":5449},{"Size":576,"Mallocs":5379,"Frees":5349},{"Size":640,"Mallocs":323,"Frees":286},{"Size":704,"Mallocs":4839,"Frees":4826},{"Size":768,"Mallocs":578,"Frees":567},{"Size":896,"Mallocs":3304,"Frees":3278},{"Size":1024,"Mallocs":2620,"Frees":2568},{"Size":1152,"Mallocs":3329,"Frees":3304},{"Size":1280,"Mallocs":538,"Frees":525},{"Size":1408,"Mallocs":4369,"Frees":4345},{"Size":1536,"Mallocs":3643,"Frees":3614},{"Size":1792,"Mallocs":395,"Frees":373},{"Size":2048,"Mallocs":2111,"Frees":2092},{"Size":2304,"Mallocs":72,"Frees":64},{"Size":2688,"Mallocs":225,"Frees":215},{"Size":3072,"Mallocs":1808,"Frees":1807},{"Size":3200,"Mallocs":393,"Frees":392},{"Size":3456,"Mallocs":59,"Frees":59},{"Size":4096,"Mallocs":5367,"Frees":5356},{"Size":4864,"Mallocs":222,"Frees":213},{"Size":5376,"Mallocs":441,"Frees":429},{"Size":6144,"Mallocs":41,"Frees":38},{"Size":6528,"Mallocs":31,"Frees":29},{"Size":6784,"Mallocs":0,"Frees":0},{"Size":6912,"Mallocs":172,"Frees":172},{"Size":8192,"Mallocs":2554,"Frees":2548},{"Size":9472,"Mallocs":109,"Frees":98},{"Size":9728,"Mallocs":3,"Frees":3},{"Size":10240,"Mallocs":24,"Frees":23},{"Size":10880,"Mallocs":3,"Frees":1},{"Size":12288,"Mallocs":24,"Frees":23},{"Size":13568,"Mallocs":7,"Frees":7},{"Size":14336,"Mallocs":28,"Frees":28},{"Size":16384,"Mallocs":483,"Frees":483},{"Size":18432,"Mallocs":2,"Frees":0}]}
}

Environment

  • Platform Ubuntu 22.04
  • Architecture amd64
  • Docker Version Docker version 28.2.2, build 28.2.2-0ubuntu1~22.04.1

Your logs

N/A

Additional context

No response