AliCloud secrets engine

The AliCloud secrets engine dynamically generates AliCloud access tokens based on RAM policies, or AliCloud STS credentials based on RAM roles. This generally makes working with AliCloud easier, since it does not involve clicking in the web UI. The AliCloud access tokens are time-based and are automatically revoked when the Vault lease expires. STS credentials are short-lived, non-renewable, and expire on their own.

Setup

Most secrets engines must be configured in advance before they can perform their functions. These steps are usually completed by an operator or configuration management tool.

Enable the AliCloud secrets engine:
```
$ vault secrets enable alicloud
Success! Enabled the alicloud secrets engine at: alicloud/
```
By default, the secrets engine will mount at the name of the engine. To enable the secrets engine at a different path, use the -path argument.
Create a custom policy in AliCloud that will be used for the access key you will give Vault. See "Example RAM Policy for Vault".
Create a user in AliCloud with a name like "hashicorp-vault", and directly apply the new custom policy to that user in the "User Authorization Policies" section.
Create an access key for that user in AliCloud, which is an action available in AliCloud's UI on the user's page.
Configure that access key as the credentials that Vault will use to communicate with AliCloud to generate credentials:
```
$ vault write alicloud/config \
    access_key=0wNEpMMlzy7szvai \
    secret_key=PupkTg8jdmau1cXxYacgE736PJj4cA
```
Alternatively, the AliCloud secrets engine can pick up credentials set as environment variables, or credentials available through instance metadata. Since it checks current credentials on every API call, changes in credentials will be picked up almost immediately without a Vault restart.
If available, we recommend using instance metadata for these credentials as they are the most secure option. To do so, simply ensure that the instance upon which Vault is running has sufficient privileges, and do not add any config.
Configure a role describing how credentials will be granted.
To generate access tokens using only policies that have already been created in AliCloud:
```
$ vault write alicloud/role/policy-based \
    remote_policies='name:AliyunOSSReadOnlyAccess,type:System' \
    remote_policies='name:AliyunRDSReadOnlyAccess,type:System'
```
To generate access tokens using only policies that will be dynamically created in AliCloud by Vault:
```
$ vault write alicloud/role/policy-based \
    inline_policies=-<<EOF
[
    {
      "Statement": [
        {
          "Action": "rds:Describe*",
          "Effect": "Allow",
          "Resource": "*"
        }
      ],
      "Version": "1"
    },
    {...}
]
EOF
```
Both inline_policies and remote_policies may be used together. However, neither may be used configuring how to generate STS credentials, like so:
```
$ vault write alibaba/role/role-based \
      role_arn='acs:ram::5138828231865461:role/hastrustedactors'
```
Any role_arn specified must have added "trusted actors" when it was being created. These can only be added at role creation time. Trusted actors are entities that can assume the role. Since we will be assuming the role to gain credentials, the access_key and secret_key in the config must qualify as a trusted actor.

Helpful links

Example RAM policy for Vault

While AliCloud credentials can be supplied by environment variables, an explicit setting in the alicloud/config, or through instance metadata, the resulting credentials need sufficient permissions to issue secrets. The necessary permissions vary based on the ways roles are configured.

This is an example RAM policy that would allow you to create credentials using any type of role:

{
  "Statement": [
    {
      "Action": [
        "ram:CreateAccessKey",
        "ram:DeleteAccessKey",
        "ram:CreatePolicy",
        "ram:DeletePolicy",
        "ram:AttachPolicyToUser",
        "ram:DetachPolicyFromUser",
        "ram:CreateUser",
        "ram:DeleteUser",
        "sts:AssumeRole"
      ],
      "Effect": "Allow",
      "Resource": "*"
    }
  ],
  "Version": "1"
}

However, the policy you use should only allow the actions you actually need for how your roles are configured.

If any roles are using inline_policies, you need the following actions:

If any roles are using remote_policies, you need the following actions:

All listed for inline_policies
"ram:CreatePolicy"
"ram:DeletePolicy"

If any roles are using role_arn, you need the following actions:

"sts:AssumeRole"

Usage

After the secrets engine is configured and a user/machine has a Vault token with the proper permission, it can generate credentials.

Generate a new access key by reading from the /creds endpoint with the name of the role:

$ vault read alicloud/creds/policy-based
Key                Value
---                -----
lease_id           alicloud/creds/policy-based/f3e92392-7d9c-09c8-c921-575d62fe80d8
lease_duration     768h
lease_renewable    true
access_key         0wNEpMMlzy7szvai
secret_key         PupkTg8jdmau1cXxYacgE736PJj4cA

The access_key and secret_key returned are also known is an "AccessKeyId"and "AccessKeySecret", respectively, in the Alibaba's docs.

Retrieving creds for a role using a role_arn will carry the additional fields of expiration and security_token, like so:

$ vault read alicloud/creds/role-based
Key                Value
---                -----
lease_id           alicloud/creds/role-based/f3e92392-7d9c-09c8-c921-575d62fe80d9
lease_duration     59m59s
lease_renewable    false
access_key         STS.L4aBSCSJVMuKg5U1vFDw
secret_key         wyLTSmsyPGP1ohvvw8xYgB29dlGI8KMiH2pKCNZ9
security_token     CAESrAIIARKAAShQquMnLIlbvEcIxO6wCoqJufs8sWwieUxu45hS9AvKNEte8KRUWiJWJ6Y+YHAPgNwi7yfRecMFydL2uPOgBI7LDio0RkbYLmJfIxHM2nGBPdml7kYEOXmJp2aDhbvvwVYIyt/8iES/R6N208wQh0Pk2bu+/9dvalp6wOHF4gkFGhhTVFMuTDRhQlNDU0pWTXVLZzVVMXZGRHciBTQzMjc0KgVhbGljZTCpnJjwySk6BlJzYU1ENUJuCgExGmkKBUFsbG93Eh8KDEFjdGlvbkVxdWFscxIGQWN0aW9uGgcKBW9zczoqEj8KDlJlc291cmNlRXF1YWxzEghSZXNvdXJjZRojCiFhY3M6b3NzOio6NDMyNzQ6c2FtcGxlYm94L2FsaWNlLyo=
expiration         2018-08-15T21:58:00Z

API

The AliCloud secrets engine has a full HTTP API. Please see the AliCloud secrets engine API for more details.