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Edit signing images (docker#8882)
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* Edit signing images

* Incorporate feedback

* Final edits

- Change example Security member name
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@bermudezmt
bermudezmt authored and Dawn W Docker committed Jun 11, 2019
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145 changes: 70 additions & 75 deletions ee/dtr/user/manage-images/sign-images/index.md
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Expand Up @@ -7,53 +7,51 @@ redirect_from:
- /ee/dtr/user/manage-images/sign-images/manage-trusted-repositories/
---

2 Key components of the Docker Trusted Registry are the Notary Server and Notary
Signer. These 2 containers give us the required components to use Docker Content
Trust right out of the box. [Docker Content
Trust](/engine/security/trust/content_trust/) allows us to sign image tags,
therefore whoever pulls the image can validate that they are getting the image
you create, or a forged one.

As part of Docker Trusted Registry both the Notary server and the Registry
server are accessed through a front end Proxy, with both components sharing the
UCP's RBAC Engine. Therefore no additional configuration of the Docker Client
is required to use trust.

Docker Content Trust is integrated into the Docker CLI, allowing you to
configure repositories, add signers and sign images all through the `$ docker
trust` command.
Two key components of the Docker Trusted Registry are the Notary Server and the Notary
Signer. These two containers provide the required components for using Docker Content
Trust (DCT) out of the box. [Docker Content
Trust](/engine/security/trust/content_trust/) allows you to sign image tags,
therefore giving consumers a way to verify the integrity of your image.

As part of DTR, both the Notary and the Registry
servers are accessed through a front-end proxy, with both components sharing the
UCP's RBAC (Role-based Access Control) Engine. Therefore, you do not need additional Docker client
configuration in order to use DCT.

DCT is integrated with the Docker CLI, and allows you to:
- Configure repositories
- Add signers, and
- Sign images using the `docker trust` command

![image without signature](../../../images/sign-an-image-1.svg)

## Sign images that UCP can trust

UCP has a feature which will prevent [untrusted
images](/ee/ucp/admin/configure/run-only-the-images-you-trust/) from being
deployed on the cluster. To use this feature, we first need to upload and sign
images into DTR. To tie the signed images back to UCP, we will actually sign the
images with private keys of UCP users. Inside of a UCP Client bundle the
`key.pem` can be used a User's private key, with the `cert.pem` being a public
key within a x509 certificate.
deployed on the cluster. To use the feature, you need to sign and push images to your DTR.
To tie the signed images back to UCP, you need to sign the
images with the private keys of the UCP users. From a UCP client bundle, use
`key.pem` as your private key, and `cert.pem` as your public key
on an `x509` certificate.

To sign images in a way that UCP trusts them, you need to:
To sign images in a way that UCP can trust, you need to:

1. Download a Client Bundle for a User you want to use to sign the images.
2. Load the private key of the User into your workstations trust store.
1. Download a client bundle for the user account you want to use for signing the images.
2. Add the user's private key to your machine's trust store.
3. Initialize trust metadata for the repository.
4. Delegate signing for that repository to the UCP User.
5. Sign the Image.
4. Delegate signing for that repository to the UCP user.
5. Sign the image.

In this example we're going to pull a nginx image from the Docker Hub, re-tag it
as `dtr.example.com/dev/nginx:1`, push the image to DTR and sign it in a way
that is trusted by UCP. If you manage multiple repositories, you'll have to do
the same procedure for each repository.
The following example shows the `nginx` image getting pulled from Docker Hub, tagged
as `dtr.example.com/dev/nginx:1`, pushed to DTR, and signed in a way
that is trusted by UCP.

### Import a UCP User's Private Key
### Import a UCP user's private key

Once you have download and extracted a UCP User's client bundle into your local
directory, you need to load the Private key into the local Docker trust store
`(~/.docker/trust)`. The name used here is purely metadata to help keep track of
which keys you have imported.
After downloading and extracting a UCP client bundle into your local
directory, you need to load the private key into the local Docker trust store
`(~/.docker/trust)`. To illustrate the process, we will use `jeff` as an example user.

```bash
$ docker trust key load --name jeff key.pem
Expand All @@ -63,16 +61,16 @@ Repeat passphrase for new jeff key with ID a453196:
Successfully imported key from key.pem
```

### Initialize the trust metadata and add the Public Key
### Initialize the trust metadata and add the user's public certificate

Next, we need to initiate trust metadata for a DTR repository. If you have not
done so already, navigate to the **DTR web UI**, and create a repository for
your image. In this example we've created the `prod/nginx` repository.
Next,initiate trust metadata for a DTR repository. If you have not
already done so, navigate to the **DTR web UI**, and create a repository for
your image. This example uses the `nginx` repository in the `prod` namespace.

As part of initiating the repository, we will add the public key of the UCP User
as a signer. You will be asked for a number of passphrases to protect the keys.
Make a note of these passphrases, and see [Managing Delegations in a Notary Server](/engine/security/trust/trust_delegation/#managing-delegations-in-a-notary-server)
to learn more about managing keys.
As part of initiating the repository, the public key of the UCP user needs to be added
to the Notary server as a signer for the repository. You will be asked for a number of
passphrases to protect the keys.Make a note of these passphrases, and
see [Managing Delegations in a Notary Server](/engine/security/trust/trust_delegation/#managing-delegations-in-a-notary-server) to learn more about managing keys.


```bash
Expand All @@ -86,7 +84,7 @@ Successfully initialized "dtr.example.com/prod/nginx"
Successfully added signer: jeff to dtr.example.com/prod/nginx
```

We can inspect the trust metadata of the repository to make sure the User has
Inspect the trust metadata of the repository to make sure the user has
been added correctly.

```bash
Expand All @@ -105,11 +103,10 @@ Administrative keys for dtr.example.com/prod/nginx
Root Key: b74854cb27cc25220ede4b08028967d1c6e297a759a6939dfef1ea72fbdd7b9a
```

### Sign the Image
### Sign the image

Finally, we will sign an image tag. These steps download the Image from the
Docker Hub, retag the Image to the DTR repository, push the image up to DTR, as
well as signing the tag with the UCP User's keys.
Finally, user `jeff` can sign an image tag. The following steps include downloading the image from Hub, tagging the image for Jeff's DTR repository, pushing the image to Jeff's DTR, as
well as signing the tag with Jeff's keys.

```bash
$ docker pull nginx:latest
Expand All @@ -128,7 +125,7 @@ Enter passphrase for jeff key with ID 927f303:
Successfully signed dtr.example.com/prod/nginx:1
```

We can inspect the trust metadata again to make sure the image tag has been
Inspect the trust metadata again to make sure the image tag has been
signed successfully.

```bash
Expand All @@ -150,63 +147,62 @@ Administrative keys for dtr.example.com/prod/nginx:1
Root Key: b74854cb27cc25220ede4b08028967d1c6e297a759a6939dfef1ea72fbdd7b9a
```

Or we can have a look at the signed image from within the **DTR UI**.
Alternatively, you can review the signed image from the DTR web UI.

![DTR](../../../images/sign-an-image-3.png){: .with-border}

### Adding Additional Delegations
### Add delegations

If you wanted to sign this image with multiple UCP Users, maybe if you had a use
case where an image needed to be signed by a member of the `Security` team and a
member of the `Developers` team. Then you can add multiple signers to a
repository.
You have the option to sign an image using multiple UCP users' keys. For example, an image
needs to be signed by a member of the `Security` team and a
member of the `Developers` team. Let's assume `jeff` is a member of the Developers team.
In this case, we only need to add a member of the Security team.

To do so, first load a private key from a UCP User of the Security Team's in to
the local Docker Trust Store.
To do so, first add the private key of the Security team member to
the local Docker trust store.

```bash
$ docker trust key load --name security key.pem
$ docker trust key load --name ian key.pem
Loading key from "key.pem"...
Enter passphrase for new security key with ID 5ac7d9a:
Repeat passphrase for new security key with ID 5ac7d9a:
Enter passphrase for new ian key with ID 5ac7d9a:
Repeat passphrase for new ian key with ID 5ac7d9a:
Successfully imported key from key.pem
```

Upload the Public Key to the Notary Server and Sign the Image. You will be asked
for both the Developers passphrase, as well as the Security Users passphrase to
Upload the user's public key to the Notary Server and sign the image. You will be asked
for `jeff`, the developer's passphrase, as well as the `ian` user's passphrase to
sign the tag.

```bash
$ docker trust signer add --key cert.pem security dtr.example.com/prod/nginx
Adding signer "security" to dtr.example.com/prod/nginx...
$ docker trust signer add --key cert.pem ian dtr.example.com/prod/nginx
Adding signer "ian" to dtr.example.com/prod/nginx...
Enter passphrase for repository key with ID e0d15a2:
Successfully added signer: security to dtr.example.com/prod/nginx
Successfully added signer: ian to dtr.example.com/prod/nginx

$ docker trust sign dtr.example.com/prod/nginx:1
Signing and pushing trust metadata for dtr.example.com/prod/nginx:1
Existing signatures for tag 1 digest 5b49c8e2c890fbb0a35f6050ed3c5109c5bb47b9e774264f4f3aa85bb69e2033 from:
jeff
Enter passphrase for jeff key with ID 927f303:
Enter passphrase for security key with ID 5ac7d9a:
Enter passphrase for ian key with ID 5ac7d9a:
Successfully signed dtr.example.com/prod/nginx:1
```

Finally, we can check the tag again to make sure it is now signed by 2
signatures.
Finally, check the tag again to make sure it includes two signers.

```bash
$ docker trust inspect --pretty dtr.example.com/prod/nginx:1

Signatures for dtr.example.com/prod/nginx:1

SIGNED TAG DIGEST SIGNERS
1 5b49c8e2c890fbb0a35f6050ed3c5109c5bb47b9e774264f4f3aa85bb69e2033 jeff, security
1 5b49c8e2c890fbb0a35f6050ed3c5109c5bb47b9e774264f4f3aa85bb69e2033 jeff, ian

List of signers and their keys for dtr.example.com/prod/nginx:1

SIGNER KEYS
jeff 927f30366699
security 5ac7d9af7222
ian 5ac7d9af7222

Administrative keys for dtr.example.com/prod/nginx:1

Expand All @@ -218,13 +214,12 @@ For more advanced use cases like this, see [Delegations for content trust](/engi

## Delete trust data

If an Administrator wants to delete a DTR repository that contains Trust
metadata, they will be prompted to delete the trust metadata first before the
repository can be removed.
If an administrator wants to delete a DTR repository that contains trust
metadata, they will be prompted to delete the trust metadata first before removing the repository.

To delete trust metadata we need to use the Notary CLI. For information on how
to download and configure the Notary CLI head
[here](/engine/security/trust/trust_delegation/#configuring-the-notary-client)
To delete trust metadata, you need to use the Notary CLI. For information on how
to download and configure the Notary CLI see
[Configuring the Notary client](/engine/security/trust/trust_delegation/#configuring-the-notary-client)


```bash
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