harbor: Harbor Registry does not support AssumeRoleWithWebIdentity

Given that the AWS SDK supports assuming a role through a WebIdentity, pods running in EKS should be able to assume a role with a web identity as documented here

Expected behavior and actual behavior:

• Expected: Pods using ServiceAccounts annotated to assume a role with a web identity should have access/denial to resources as specified in the policies attached to the role.

• Actual: Since pods are not assuming the role, one cannot, for instance, use s3 as a storage backend for the registry.

Steps to reproduce the problem: On EKS, annotate the serviceAccount and cycle the pods; you will see the environment variables AWS SDK needs, but the role is not assumed. Instead, the ec2 instance role is used.

Versions: Please specify the versions of following systems.

• harbor version: [2.0.2] (via helm chart)
• kubernetes 1.17

Additional context:

time="2020-08-26T14:06:37.339344937Z" level=info msg="redis: connect cache.registry.ops.internal.penneo.com:6379" go.version=go1.14.5 instance.id=a88be6db-6417-4ae5-8aeb-a8fb6339ba41 redis.connect.duration=2.041877ms service=registry version=v2.7.1.m
time="2020-08-26T14:06:37.367875774Z" level=debug msg="s3aws.GetContent("/docker/registry/v2/repositories/library/doggo-api/_layers/sha256/d6ff36c9ec4822c9ff8953560f7ba41653b348a9c1136755e653575f58fbded7/link")" auth.user.name="harbor_registry_user" go.version=go1.14.5 http.request.host=registry.host http.request.id=fbfa917d-a7f4-41bd-8a82-8438fadc5f25 http.request.method=HEAD http.request.remoteaddr=172.30.11.169 http.request.uri="/v2/library/doggo-api/blobs/sha256:d6ff36c9ec4822c9ff8953560f7ba41653b348a9c1136755e653575f58fbded7" http.request.useragent="docker/19.03.8 go/go1.12.17 git-commit/afacb8b kernel/4.19.76-linuxkit os/linux arch/amd64 UpstreamClient(Docker-Client/19.03.8 \(darwin\))" trace.duration=26.84362ms trace.file="/go/src/github.com/docker/distribution/registry/storage/driver/base/base.go" trace.func="github.com/docker/distribution/registry/storage/driver/base.(*Base).GetContent" trace.id=4d98e52c-a803-4b85-b92e-d51b8fa2fd5d trace.line=95 vars.digest="sha256:d6ff36c9ec4822c9ff8953560f7ba41653b348a9c1136755e653575f58fbded7" vars.name="library/doggo-api"
time="2020-08-26T14:06:37.367975651Z" level=error msg="response completed with error" auth.user.name="harbor_registry_user" err.code=unknown err.detail="s3aws: AccessDenied: Access Denied
	status code: 403, request id: 4DD7564DBB51808B, host id: QBjvn4SoNmDkk8u2y9MDqTV/e8nnTlonTAlj7oKLxnxcYxiVDn8LliG7hiQYcmhfch9xY5EDlnc=" err.message="unknown error" go.version=go1.14.5 http.request.host=registry.host http.request.id=fbfa917d-a7f4-41bd-8a82-8438fadc5f25 http.request.method=HEAD http.request.remoteaddr=172.30.11.169 http.request.uri="/v2/library/doggo-api/blobs/sha256:d6ff36c9ec4822c9ff8953560f7ba41653b348a9c1136755e653575f58fbded7" http.request.useragent="docker/19.03.8 go/go1.12.17 git-commit/afacb8b kernel/4.19.76-linuxkit os/linux arch/amd64 UpstreamClient(Docker-Client/19.03.8 \(darwin\))" http.response.contenttype="application/json; charset=utf-8" http.response.duration=106.022665ms http.response.status=500 http.response.written=123 vars.digest="sha256:d6ff36c9ec4822c9ff8953560f7ba41653b348a9c1136755e653575f58fbded7" vars.name="library/doggo-api"
127.0.0.1 - - [26/Aug/2020:14:06:37 +0000] "HEAD /v2/library/doggo-api/blobs/sha256:d6ff36c9ec4822c9ff8953560f7ba41653b348a9c1136755e653575f58fbded7 HTTP/1.1" 500 123 "" "docker/19.03.8 go/go1.12.17 git-commit/afacb8b kernel/4.19.76-linuxkit os/linux arch/amd64 UpstreamClient(Docker-Client/19.03.8 \\(darwin\\))"
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