Add support for Managed Identity auth for physical/Azure

go.mod

@@ -10,8 +10,9 @@ require (
 	cloud.google.com/go v0.56.0
 	cloud.google.com/go/spanner v1.5.1
 	cloud.google.com/go/storage v1.6.0
-	github.com/Azure/azure-storage-blob-go v0.10.0
-	github.com/Azure/go-autorest/autorest v0.11.0
+	github.com/Azure/azure-storage-blob-go v0.11.0
+	github.com/Azure/go-autorest/autorest v0.11.10
+	github.com/Azure/go-autorest/autorest/adal v0.9.5
 	github.com/NYTimes/gziphandler v1.1.1
 	github.com/SAP/go-hdb v0.14.1
 	github.com/Sectorbob/mlab-ns2 v0.0.0-20171030222938-d3aa0c295a8a
@@ -146,7 +147,7 @@ require (
 	go.etcd.io/etcd v0.5.0-alpha.5.0.20200425165423-262c93980547
 	go.mongodb.org/mongo-driver v1.4.2
 	go.uber.org/atomic v1.6.0
-	golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
+	golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0
 	golang.org/x/net v0.0.0-20200625001655-4c5254603344
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
 	golang.org/x/tools v0.0.0-20200521155704-91d71f6c2f04

go.sum

@@ -37,13 +37,13 @@ code.cloudfoundry.org/gofileutils v0.0.0-20170111115228-4d0c80011a0f h1:UrKzEwTg
 code.cloudfoundry.org/gofileutils v0.0.0-20170111115228-4d0c80011a0f/go.mod h1:sk5LnIjB/nIEU7yP5sDQExVm62wu0pBh3yrElngUisI=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
 git.apache.org/thrift.git v0.12.0/go.mod h1:fPE2ZNJGynbRyZ4dJvy6G277gSllfV2HJqblrnkyeyg=
-github.com/Azure/azure-pipeline-go v0.2.2 h1:6oiIS9yaG6XCCzhgAgKFfIWyo4LLCiDhZot6ltoThhY=
-github.com/Azure/azure-pipeline-go v0.2.2/go.mod h1:4rQ/NZncSvGqNkkOsNpOU1tgoNuIlp9AfUH5G1tvCHc=
+github.com/Azure/azure-pipeline-go v0.2.3 h1:7U9HBg1JFK3jHl5qmo4CTZKFTVgMwdFHMVtCdfBE21U=
+github.com/Azure/azure-pipeline-go v0.2.3/go.mod h1:x841ezTBIMG6O3lAcl8ATHnsOPVl2bqk7S3ta6S6u4k=
 github.com/Azure/azure-sdk-for-go v36.2.0+incompatible/go.mod h1:9XXNKU+eRnpl9moKnB4QOLf1HestfXbmab5FXxiDBjc=
 github.com/Azure/azure-sdk-for-go v44.0.0+incompatible h1:e82Yv2HNpS0kuyeCrV29OPKvEiqfs2/uJHic3/3iKdg=
 github.com/Azure/azure-sdk-for-go v44.0.0+incompatible/go.mod h1:9XXNKU+eRnpl9moKnB4QOLf1HestfXbmab5FXxiDBjc=
-github.com/Azure/azure-storage-blob-go v0.10.0 h1:evCwGreYo3XLeBV4vSxLbLiYb6e0SzsJiXQVRGsRXxs=
-github.com/Azure/azure-storage-blob-go v0.10.0/go.mod h1:ep1edmW+kNQx4UfWM9heESNmQdijykocJ0YOxmMX8SE=
+github.com/Azure/azure-storage-blob-go v0.11.0 h1:WCTHKKNkHlzm7lzUNXRSD11784LwJqdrxnwWJxsJQHg=
+github.com/Azure/azure-storage-blob-go v0.11.0/go.mod h1:A0u4VjtpgZJ7Y7um/+ix2DHBuEKFC6sEIlj0xc13a4Q=
 github.com/Azure/go-ansiterm v0.0.0-20170929234023-d6e3b3328b78 h1:w+iIsaOQNcT7OZ575w+acHgRric5iCyQh+xv+KJ4HB8=
 github.com/Azure/go-ansiterm v0.0.0-20170929234023-d6e3b3328b78/go.mod h1:LmzpDX56iTiv29bbRTIsUNlaFfuhWRQBWjQdVyAevI8=
 github.com/Azure/go-autorest v14.2.0+incompatible h1:V5VMDjClD3GiElqLWO7mz2MxNAK/vTfRHdAubSIPRgs=
@@ -54,15 +54,19 @@ github.com/Azure/go-autorest/autorest v0.9.3/go.mod h1:GsRuLYvwzLjjjRoWEIyMUaYq8
 github.com/Azure/go-autorest/autorest v0.10.1/go.mod h1:/FALq9T/kS7b5J5qsQ+RSTUdAmGFqi0vUdVNNx8q630=
 github.com/Azure/go-autorest/autorest v0.11.0 h1:tnO41Uo+/0sxTMFY/U7aKg2abek3JOnnXcuSuba74jI=
 github.com/Azure/go-autorest/autorest v0.11.0/go.mod h1:JFgpikqFJ/MleTTxwepExTKnFUKKszPS8UavbQYUMuw=
+github.com/Azure/go-autorest/autorest v0.11.10 h1:j5sGbX7uj1ieYYkQ3Mpvewd4DCsEQ+ZeJpqnSM9pjnM=
+github.com/Azure/go-autorest/autorest v0.11.10/go.mod h1:eipySxLmqSyC5s5k1CLupqet0PSENBEDP93LQ9a8QYw=
 github.com/Azure/go-autorest/autorest/adal v0.5.0/go.mod h1:8Z9fGy2MpX0PvDjB1pEgQTmVqjGhiHBW7RJJEciWzS0=
 github.com/Azure/go-autorest/autorest/adal v0.6.0/go.mod h1:Z6vX6WXXuyieHAXwMj0S6HY6e6wcHn37qQMBQlvY3lc=
 github.com/Azure/go-autorest/autorest/adal v0.7.0/go.mod h1:Z6vX6WXXuyieHAXwMj0S6HY6e6wcHn37qQMBQlvY3lc=
 github.com/Azure/go-autorest/autorest/adal v0.8.0/go.mod h1:Z6vX6WXXuyieHAXwMj0S6HY6e6wcHn37qQMBQlvY3lc=
 github.com/Azure/go-autorest/autorest/adal v0.8.1/go.mod h1:ZjhuQClTqx435SRJ2iMlOxPYt3d2C/T/7TiQCVZSn3Q=
 github.com/Azure/go-autorest/autorest/adal v0.8.2/go.mod h1:ZjhuQClTqx435SRJ2iMlOxPYt3d2C/T/7TiQCVZSn3Q=
-github.com/Azure/go-autorest/autorest/adal v0.8.3/go.mod h1:ZjhuQClTqx435SRJ2iMlOxPYt3d2C/T/7TiQCVZSn3Q=
 github.com/Azure/go-autorest/autorest/adal v0.9.0 h1:SigMbuFNuKgc1xcGhaeapbh+8fgsu+GxgDRFyg7f5lM=
 github.com/Azure/go-autorest/autorest/adal v0.9.0/go.mod h1:/c022QCutn2P7uY+/oQWWNcK9YU+MH96NgK+jErpbcg=
+github.com/Azure/go-autorest/autorest/adal v0.9.2/go.mod h1:/3SMAM86bP6wC9Ev35peQDUeqFZBMH07vvUOmg4z/fE=
+github.com/Azure/go-autorest/autorest/adal v0.9.5 h1:Y3bBUV4rTuxenJJs41HU3qmqsb+auo+a3Lz+PlJPpL0=
+github.com/Azure/go-autorest/autorest/adal v0.9.5/go.mod h1:B7KF7jKIeC9Mct5spmyCB/A8CG/sEz1vwIRGv/bbw7A=
 github.com/Azure/go-autorest/autorest/azure/auth v0.4.0/go.mod h1:Oo5cRhLvZteXzI2itUm5ziqsoIxRkzrt3t61FeZaS18=
 github.com/Azure/go-autorest/autorest/azure/auth v0.4.2/go.mod h1:90gmfKdlmKgfjUpnCEpOJzsUEjrWDSLwHIG73tSXddM=
 github.com/Azure/go-autorest/autorest/azure/auth v0.5.0 h1:nSMjYIe24eBYasAIxt859TxyXef/IqoH+8/g4+LmcVs=
@@ -80,6 +84,8 @@ github.com/Azure/go-autorest/autorest/mocks v0.2.0/go.mod h1:OTyCOPRA2IgIlWxVYxB
 github.com/Azure/go-autorest/autorest/mocks v0.3.0/go.mod h1:a8FDP3DYzQ4RYfVAxAN3SVSiiO77gL2j2ronKKP0syM=
 github.com/Azure/go-autorest/autorest/mocks v0.4.0 h1:z20OWOSG5aCye0HEkDp6TPmP17ZcfeMxPi6HnSALa8c=
 github.com/Azure/go-autorest/autorest/mocks v0.4.0/go.mod h1:LTp+uSrOhSkaKrUy935gNZuuIPPVsHlr9DSOxSayd+k=
+github.com/Azure/go-autorest/autorest/mocks v0.4.1 h1:K0laFcLE6VLTOwNgSxaGbUcLPuGXlNkbVvq4cW4nIHk=
+github.com/Azure/go-autorest/autorest/mocks v0.4.1/go.mod h1:LTp+uSrOhSkaKrUy935gNZuuIPPVsHlr9DSOxSayd+k=
 github.com/Azure/go-autorest/autorest/to v0.3.0/go.mod h1:MgwOyqaIuKdG4TL/2ywSsIWKAfJfgHDo8ObuUk3t5sA=
 github.com/Azure/go-autorest/autorest/to v0.4.0 h1:oXVqrxakqqV1UZdSazDOPOLvOIz+XA683u8EctwboHk=
 github.com/Azure/go-autorest/autorest/to v0.4.0/go.mod h1:fE8iZBn7LQR7zH/9XU2NcPR4o9jEImooCeWJcYV/zLE=
@@ -313,6 +319,8 @@ github.com/fatih/color v1.9.0 h1:8xPHl4/q1VyqGIPif1F+1V3Y3lSmrq01EabUW3CoW5s=
 github.com/fatih/color v1.9.0/go.mod h1:eQcE1qtQxscV5RaZvpXrrb8Drkc3/DdQ+uUYCNjL+zU=
 github.com/fatih/structs v1.1.0 h1:Q7juDM0QtcnhCpeyLGQKyg4TOIghuNXrkL32pHAUMxo=
 github.com/fatih/structs v1.1.0/go.mod h1:9NiDSp5zOcgEDl+j00MP/WkGVPOlPRLejGD8Ga6PJ7M=
+github.com/form3tech-oss/jwt-go v3.2.2+incompatible h1:TcekIExNqud5crz4xD2pavyTgWiPvpYe4Xau31I0PRk=
+github.com/form3tech-oss/jwt-go v3.2.2+incompatible/go.mod h1:pbq4aXjuKjdthFRnoDwaVPLA+WlJuPGy+QneDUgJi2k=
 github.com/franela/goblin v0.0.0-20200105215937-c9ffbefa60db/go.mod h1:7dvUGVsVBjqR7JHJk0brhHOZYGmfBYOrK0ZhYMEtBr4=
 github.com/franela/goreq v0.0.0-20171204163338-bcd34c9993f8/go.mod h1:ZhphrRTfi2rbfLwlschooIH4+wKKDR4Pdxhh+TRoA20=
 github.com/frankban/quicktest v1.4.0/go.mod h1:36zfPVQyHxymz4cH7wlDmVwDrJuljRB60qkgn7rorfQ=
@@ -774,8 +782,8 @@ github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaO
 github.com/mattn/go-colorable v0.1.4/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-colorable v0.1.6 h1:6Su7aK7lXmJ/U79bYtBjLNaha4Fs1Rg9plHpcH+vvnE=
 github.com/mattn/go-colorable v0.1.6/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
-github.com/mattn/go-ieproxy v0.0.0-20190702010315-6dee0af9227d h1:oNAwILwmgWKFpuU+dXvI6dl9jG2mAWAZLX3r9s0PPiw=
-github.com/mattn/go-ieproxy v0.0.0-20190702010315-6dee0af9227d/go.mod h1:31jz6HNzdxOmlERGGEc4v/dMssOfmp2p5bT/okiKFFc=
+github.com/mattn/go-ieproxy v0.0.1 h1:qiyop7gCflfhwCzGyeT0gro3sF9AIg9HU98JORTkqfI=
+github.com/mattn/go-ieproxy v0.0.1/go.mod h1:pYabZ6IHcRpFh7vIaLfK7rdcWgFEb3SFJ6/gNWuh88E=
 github.com/mattn/go-isatty v0.0.3/go.mod h1:M+lRXTBqGeGNdLjl/ufCoiOlB5xdOkqRJdNxMWT7Zi4=
 github.com/mattn/go-isatty v0.0.4/go.mod h1:M+lRXTBqGeGNdLjl/ufCoiOlB5xdOkqRJdNxMWT7Zi4=
 github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
@@ -855,6 +863,8 @@ github.com/ncw/swift v1.0.47 h1:4DQRPj35Y41WogBxyhOXlrI37nzGlyEcsforeudyYPQ=
 github.com/ncw/swift v1.0.47/go.mod h1:23YIA4yWVnGwv2dQlN4bB7egfYX6YLn0Yo/S6zZO/ZM=
 github.com/nicolai86/scaleway-sdk v1.10.2-0.20180628010248-798f60e20bb2 h1:BQ1HW7hr4IVovMwWg0E0PYcyW8CzqDcVmaew9cujU4s=
 github.com/nicolai86/scaleway-sdk v1.10.2-0.20180628010248-798f60e20bb2/go.mod h1:TLb2Sg7HQcgGdloNxkrmtgDNR9uVYF3lfdFIN4Ro6Sk=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/nwaples/rardecode v1.1.0 h1:vSxaY8vQhOcVr4mm5e8XllHWTiM4JF507A0Katqw7MQ=
 github.com/nwaples/rardecode v1.1.0/go.mod h1:5DzqNKiOdpKKBH87u8VlvAnPZMXcGRhxWkRpHbbfGS0=
 github.com/oklog/oklog v0.3.2/go.mod h1:FCV+B7mhrz4o+ueLpx+KqkyXRGMWOYEvfiXtdGtbWGs=
@@ -1166,6 +1176,8 @@ golang.org/x/crypto v0.0.0-20200221231518-2aa609cf4a9d/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20200604202706-70a84ac30bf9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9 h1:psW17arqaxU48Z5kZ0CQnkZWQJsqcURM6tKiBApRjXI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0 h1:hb9wdF1z5waM+dSIICn1l0DkLVDT3hqhhQsDNUmHPRE=
+golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190510132918-efd6b22b2522/go.mod h1:ZjyILWgesfNpC6sMxTJOJm9Kp84zZh5NQWvqDGG3Qr8=
@@ -1224,6 +1236,7 @@ golang.org/x/net v0.0.0-20190628185345-da137c7871d7/go.mod h1:z5CRVTTTmAJ677TzLL
 golang.org/x/net v0.0.0-20190724013045-ca1201d0de80/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20190813141303-74dc4d7220e7/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20191004110552-13f9640d40b9/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20191112182307-2180aed22343/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20200114155413-6afb5195e5aa/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20200202094626-16171245cfb2/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
@@ -1291,6 +1304,7 @@ golang.org/x/sys v0.0.0-20191001151750-bb3f8db39f24/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191022100944-742c48ecaeb7/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191112214154-59a1497f0cea/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191220142924-d4481acd189f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191228213918-04cbcbbfeed8/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -1312,6 +1326,8 @@ golang.org/x/sys v0.0.0-20200602225109-6fdc65e7d980/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200615200032-f1bc736245b1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200625212154-ddb9806d33ae h1:Ih9Yo4hSPImZOpfGuA4bR/ORKTAbhZo2AbWNRCnevdo=
 golang.org/x/sys v0.0.0-20200625212154-ddb9806d33ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200828194041-157a740278f4 h1:kCCpuwSAoYJPkNc6x0xT9yTtV4oKtARo4RGBQWOfg9E=
+golang.org/x/sys v0.0.0-20200828194041-157a740278f4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.0.0-20160726164857-2910a502d2bf/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -1484,6 +1500,8 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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+gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8XK9/i0At2xKjWk4p6zsU=
+gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/cheggaaa/pb.v1 v1.0.25/go.mod h1:V/YB90LKu/1FcN3WVnfiiE5oMCibMjukxqG/qStrOgw=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/fsnotify.v1 v1.4.7 h1:xOHLXZwVvI9hhs+cLKq5+I5onOuwQLhQwiu63xxlHs4=

physical/azure/azure.go

@@ -13,8 +13,9 @@ import (
 	"time"
 
 	"github.com/Azure/azure-storage-blob-go/azblob"
+	"github.com/Azure/go-autorest/autorest/adal"
 	"github.com/Azure/go-autorest/autorest/azure"
-	metrics "github.com/armon/go-metrics"
+	"github.com/armon/go-metrics"
 	"github.com/hashicorp/errwrap"
 	log "github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/vault/sdk/helper/strutil"
@@ -41,9 +42,11 @@ var _ physical.Backend = (*AzureBackend)(nil)
 
 // NewAzureBackend constructs an Azure backend using a pre-existing
 // bucket. Credentials can be provided to the backend, sourced
-// from the environment, AWS credential files or by IAM role.
+// from the environment, via HCL or by using managed identities.
 func NewAzureBackend(conf map[string]string, logger log.Logger) (physical.Backend, error) {
 	name := os.Getenv("AZURE_BLOB_CONTAINER")
+	useMSI := false
+
 	if name == "" {
 		name = conf["container"]
 		if name == "" {
@@ -63,7 +66,8 @@ func NewAzureBackend(conf map[string]string, logger log.Logger) (physical.Backen
 	if accountKey == "" {
 		accountKey = conf["accountKey"]
 		if accountKey == "" {
-			return nil, fmt.Errorf("'accountKey' must be set")
+			logger.Info("accountKey not set, using managed identity auth")
+			useMSI = true
 		}
 	}
 
@@ -99,9 +103,39 @@ func NewAzureBackend(conf map[string]string, logger log.Logger) (physical.Backen
 		}
 	}
 
-	credential, err := azblob.NewSharedKeyCredential(accountName, accountKey)
-	if err != nil {
-		return nil, errwrap.Wrapf("failed to create Azure client: {{err}}", err)
+	var credential azblob.Credential
+	if useMSI {
+		authToken, err := getAuthTokenFromIMDS(environment.ResourceIdentifiers.Storage)
+		if err != nil {
+			errorMsg := fmt.Sprintf("failed to obtain auth token from IMDS %q: {{err}}",
+				environmentName)
+			return nil, errwrap.Wrapf(errorMsg, err)
+		}
+
+		credential = azblob.NewTokenCredential(authToken.OAuthToken(), func(c azblob.TokenCredential) time.Duration {
+			err = authToken.Refresh()
+			if err != nil {
+				logger.Error("couldn't refresh token credential", "error", err)
+				return 0
+			}
+
+			expIn, err := authToken.Token().ExpiresIn.Int64()
+			if err != nil {
+				logger.Error("couldn't retrieve jwt claim for 'expiresIn' from refreshed token", "error", err)
+				return 0
+			}
+
+			logger.Debug("token refreshed, new token expires in", "access_token_expiry", expIn)
+			c.SetToken(authToken.OAuthToken())
+
+			// tokens are valid for 23h59m (86399s) by default, refresh after ~21h
+			return time.Duration(int(float64(expIn)*0.9)) * time.Second
+		})
+	} else {
+		credential, err = azblob.NewSharedKeyCredential(accountName, accountKey)
+		if err != nil {
+			return nil, errwrap.Wrapf("failed to create Azure client: {{err}}", err)
+		}
 	}
 
 	URL, err := url.Parse(
@@ -179,7 +213,7 @@ func (a *AzureBackend) Get(ctx context.Context, key string) (*physical.Entry, er
 	defer a.permitPool.Release()
 
 	blobURL := a.container.NewBlockBlobURL(key)
-	res, err := blobURL.Download(ctx, 0, 0, azblob.BlobAccessConditions{}, false)
+	res, err := blobURL.Download(ctx, 0, azblob.CountToEnd, azblob.BlobAccessConditions{}, false)
 	if err != nil {
 		var e azblob.StorageError
 		if errors.As(err, &e) {
@@ -194,8 +228,8 @@ func (a *AzureBackend) Get(ctx context.Context, key string) (*physical.Entry, er
 	}
 
 	reader := res.Body(azblob.RetryReaderOptions{})
-
 	defer reader.Close()
+
 	data, err := ioutil.ReadAll(reader)
 
 	ent := &physical.Entry{
@@ -238,7 +272,7 @@ func (a *AzureBackend) List(ctx context.Context, prefix string) ([]string, error
 	a.permitPool.Acquire()
 	defer a.permitPool.Release()
 
-	keys := []string{}
+	var keys []string
 	for marker := (azblob.Marker{}); marker.NotDone(); {
 		listBlob, err := a.container.ListBlobsFlatSegment(ctx, marker, azblob.ListBlobsSegmentOptions{
 			Prefix:     prefix,
@@ -265,3 +299,28 @@ func (a *AzureBackend) List(ctx context.Context, prefix string) ([]string, error
 	sort.Strings(keys)
 	return keys, nil
 }
+
+// getAuthTokenFromIMDS uses the Azure Instance Metadata Service to retrieve a short-lived credential using OAuth
+// more info on this https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/overview
+func getAuthTokenFromIMDS(resource string) (*adal.ServicePrincipalToken, error) {
+	msiEndpoint, err := adal.GetMSIVMEndpoint()
+	if err != nil {
+		return nil, err
+	}
+
+	spt, err := adal.NewServicePrincipalTokenFromMSI(msiEndpoint, resource)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := spt.Refresh(); err != nil {
+		return nil, err
+	}
+
+	token := spt.Token()
+	if token.IsZero() {
+		return nil, err
+	}
+
+	return spt, nil
+}