Merge pull request #4029 from ekarlso/add-azure-workload-identity-support

add azure workload identity support

changelog/unreleased/issue-3698

@@ -0,0 +1,8 @@
+Enhancement: Add support for Managed / Worload Identity to azure backend
+
+Restic now additionally supports authenticating to Azure using Workload
+Identity or Managed Identity credentials which are automatically injected in
+several environments such as a managed Kubernetes cluster.
+
+https://github.com/restic/restic/issues/3698
+https://github.com/restic/restic/pull/4029

doc/030_preparing_a_new_repo.rst

@@ -523,20 +523,24 @@ Microsoft Azure Blob Storage
 ****************************
 
 You can also store backups on Microsoft Azure Blob Storage. Export the Azure
-Blob Storage account name and key as follows:
+Blob Storage account name:
 
 .. code-block:: console
 
     $ export AZURE_ACCOUNT_NAME=<ACCOUNT_NAME>
+
+For authentication export one of the following variables:
+
+.. code-block:: console
+
+    # For storage account key
     $ export AZURE_ACCOUNT_KEY=<SECRET_KEY>
-
+    # For SAS
-or
-
-.. code-block:: console
-
-    $ export AZURE_ACCOUNT_NAME=<ACCOUNT_NAME>
     $ export AZURE_ACCOUNT_SAS=<SAS_TOKEN>
 
+Alternatively, if run on Azure, restic will automatically uses service accounts configured
+via the standard environment variables or Workload / Managed Identities.
+
 Restic will by default use Azure's global domain ``core.windows.net`` as endpoint suffix.
 You can specify other suffixes as follows:
 

go.mod

@@ -3,6 +3,7 @@ module github.com/restic/restic
 require (
 	cloud.google.com/go/storage v1.30.1
 	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.6.1
+	github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.3.0
 	github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.0.0
 	github.com/anacrolix/fuse v0.2.0
 	github.com/cenkalti/backoff/v4 v4.2.0
@@ -40,10 +41,11 @@ require (
 	cloud.google.com/go/compute/metadata v0.2.3 // indirect
 	cloud.google.com/go/iam v0.13.0 // indirect
 	github.com/Azure/azure-sdk-for-go/sdk/internal v1.3.0 // indirect
+	github.com/AzureAD/microsoft-authentication-library-for-go v1.0.0 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
-	github.com/dnaeon/go-vcr v1.2.0 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/felixge/fgprof v0.9.3 // indirect
+	github.com/golang-jwt/jwt/v4 v4.5.0 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/google/pprof v0.0.0-20230111200839-76d1ae5aea2b // indirect
@@ -55,9 +57,11 @@ require (
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/klauspost/cpuid/v2 v2.2.4 // indirect
 	github.com/kr/fs v0.1.0 // indirect
+	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/minio/md5-simd v1.1.2 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 // indirect
 	github.com/rs/xid v1.5.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/sirupsen/logrus v1.9.2 // indirect

go.sum

@@ -12,12 +12,14 @@ cloud.google.com/go/storage v1.30.1 h1:uOdMxAs8HExqBlnLtnQyP0YkvbiDpdGShGKtx6U/o
 cloud.google.com/go/storage v1.30.1/go.mod h1:NfxhC0UJE1aXSx7CIIbCf7y9HKT7BiccwkR7+P7gN8E=
 github.com/Azure/azure-sdk-for-go/sdk/azcore v1.6.1 h1:SEy2xmstIphdPwNBUi7uhvjyjhVKISfwjfOJmuy7kg4=
 github.com/Azure/azure-sdk-for-go/sdk/azcore v1.6.1/go.mod h1:bjGvMhVMb+EEm3VRNQawDMUyMMjo+S5ewNjflkep/0Q=
-github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.1.0 h1:QkAcEIAKbNL4KoFr4SathZPhDhF4mVwpBMFlYjyAqy8=
+github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.3.0 h1:vcYCAze6p19qBW7MhZybIsqD8sMV8js0NyQM8JDnVtg=
+github.com/Azure/azure-sdk-for-go/sdk/azidentity v1.3.0/go.mod h1:OQeznEEkTZ9OrhHJoDD8ZDq51FHgXjqtP9z6bEwBq9U=
 github.com/Azure/azure-sdk-for-go/sdk/internal v1.3.0 h1:sXr+ck84g/ZlZUOZiNELInmMgOsuGwdjjVkEIde0OtY=
 github.com/Azure/azure-sdk-for-go/sdk/internal v1.3.0/go.mod h1:okt5dMMTOFjX/aovMlrjvvXoPMBVSPzk9185BT0+eZM=
 github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.0.0 h1:u/LLAOFgsMv7HmNL4Qufg58y+qElGOt5qv0z1mURkRY=
 github.com/Azure/azure-sdk-for-go/sdk/storage/azblob v1.0.0/go.mod h1:2e8rMJtl2+2j+HXbTBwnyGpm5Nou7KhvSfxOq8JpTag=
-github.com/AzureAD/microsoft-authentication-library-for-go v0.5.1 h1:BWe8a+f/t+7KY7zH2mqygeUD0t8hNFXe08p1Pb3/jKE=
+github.com/AzureAD/microsoft-authentication-library-for-go v1.0.0 h1:OBhqkivkhkMqLPymWEppkm7vgPQY2XsHoEkaMQ0AdZY=
+github.com/AzureAD/microsoft-authentication-library-for-go v1.0.0/go.mod h1:kgDmCTgBzIEPFElEF+FK0SdjAor06dRq2Go927dnQ6o=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/Julusian/godocdown v0.0.0-20170816220326-6d19f8ff2df8/go.mod h1:INZr5t32rG59/5xeltqoCJoNY7e5x/3xoY9WSWVWg74=
 github.com/anacrolix/fuse v0.2.0 h1:pc+To78kI2d/WUjIyrsdqeJQAesuwpGxlI3h1nAv3Do=
@@ -45,7 +47,6 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dnaeon/go-vcr v1.2.0 h1:zHCHvJYTMh1N7xnV7zf1m1GPBF9Ad0Jk/whtQ1663qI=
-github.com/dnaeon/go-vcr v1.2.0/go.mod h1:R4UdLID7HZT3taECzJs4YgbbH6PIGXB6W/sc5OLb6RQ=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
 github.com/dvyukov/go-fuzz v0.0.0-20200318091601-be3528f3a813/go.mod h1:11Gm+ccJnvAhCNLlf5+cS9KjtbaD5I5zaZpFMsTHWTw=
@@ -63,7 +64,8 @@ github.com/felixge/fgprof v0.9.3/go.mod h1:RdbpDgzqYVh/T9fPELJyV7EYJuHB55UTEULNu
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
 github.com/go-ole/go-ole v1.2.6 h1:/Fpf6oFPoeFik9ty7siob0G6Ke8QvQEuVcuChpwXzpY=
 github.com/go-ole/go-ole v1.2.6/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiUsvbm0=
-github.com/golang-jwt/jwt v3.2.1+incompatible h1:73Z+4BJcrTC+KczS6WvTPvRGOp1WmfEP4Q1lOd9Z/+c=
+github.com/golang-jwt/jwt/v4 v4.5.0 h1:7cYmW1XlMY7h7ii7UhUyChSgS5wUJEnm9uZVTGqOWzg=
+github.com/golang-jwt/jwt/v4 v4.5.0/go.mod h1:m21LjoU+eqJr34lmDMbreY2eSTRJ1cv77w39/MY0Ch0=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da h1:oI5xCqsCo564l8iNU+DwB5epxmsaqB+rhGL0m5jtYqE=
@@ -128,6 +130,7 @@ github.com/kr/fs v0.1.0/go.mod h1:FFnZGqtBN9Gxj7eW1uZ42v5BccTP0vu6NEaFoC2HwRg=
 github.com/kurin/blazer v0.5.4-0.20230113224640-3887e1ec64b5 h1:OUlGa6AAolmjyPtILbMJ8vHayz5wd4wBUloheGcMhfA=
 github.com/kurin/blazer v0.5.4-0.20230113224640-3887e1ec64b5/go.mod h1:4FCXMUWo9DllR2Do4TtBd377ezyAJ51vB5uTBjt0pGU=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
+github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/minio/md5-simd v1.1.2 h1:Gdi1DZK69+ZVMoNHRXJyNcxrMA4dSxoYHZSQbirFg34=
 github.com/minio/md5-simd v1.1.2/go.mod h1:MzdKDxYpY2BT9XQFocsiZf/NKVtR7nkE4RoEpN+20RM=
 github.com/minio/minio-go/v7 v7.0.56 h1:pkZplIEHu8vinjkmhsexcXpWth2tjVLphrTZx6fBVZY=
@@ -139,10 +142,10 @@ github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9Gz0M=
 github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
-github.com/modocache/gover v0.0.0-20171022184752-b58185e213c5/go.mod h1:caMODM3PzxT8aQXRPkAt8xlV/e7d7w8GM5g0fa5F0D8=
 github.com/ncw/swift/v2 v2.0.1 h1:q1IN8hNViXEv8Zvg3Xdis4a3c4IlIGezkYz09zQL5J0=
 github.com/ncw/swift/v2 v2.0.1/go.mod h1:z0A9RVdYPjNjXVo2pDOPxZ4eu3oarO1P91fTItcb+Kg=
-github.com/pkg/browser v0.0.0-20210115035449-ce105d075bb4 h1:Qj1ukM4GlMWXNdMBuXcXfz/Kw9s1qm0CLY32QxuSImI=
+github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 h1:KoWmjvw+nsYOo29YJK9vDA65RGE3NrOnUtO7a+RF9HU=
+github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8/go.mod h1:HKlIX3XHQyzLZPlr7++PzdhaXEj94dEiJgZDTsxEqUI=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/profile v1.7.0 h1:hnbDkaNWPCLMO9wGLdBFTIZvzDrDfBM2072E1S9gJkA=
@@ -238,6 +241,7 @@ golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210616045830-e2b7044e8c71/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211007075335-d3039528d8ac/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220408201424-a24fb2fb8a0f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
@@ -318,7 +322,6 @@ gopkg.in/ini.v1 v1.67.0 h1:Dgnx+6+nfE+IfzjUEISNeydPJh9AXNNsWbGP9KzCsOA=
 gopkg.in/ini.v1 v1.67.0/go.mod h1:pNLf8WUiyNEtQjuu5G5vTm06TEv9tsIgeAvK8hOrP4k=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.3/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

internal/backend/azure/azure.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/streaming"
+	"github.com/Azure/azure-sdk-for-go/sdk/azidentity"
 	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
 	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blob"
 	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/bloberror"
@@ -101,7 +102,16 @@ func open(cfg Config, rt http.RoundTripper) (*Backend, error) {
 			return nil, errors.Wrap(err, "NewAccountSASClientFromEndpointToken")
 		}
 	} else {
-		return nil, errors.New("no azure authentication information found")
+		debug.Log(" - using DefaultAzureCredential")
+		cred, err := azidentity.NewDefaultAzureCredential(nil)
+		if err != nil {
+			return nil, errors.Wrap(err, "NewDefaultAzureCredential")
+		}
+
+		client, err = azContainer.NewClient(url, cred, opts)
+		if err != nil {
+			return nil, errors.Wrap(err, "NewClient")
+		}
 	}
 
 	be := &Backend{