About provisioning Jenkins with a service account

Whether you can or must provision Jenkins with a service account varies by security mode.

permissive: optional
strict: required

To increase the security of your cluster and conform to the principle of least privilege, we recommend provisioning Jenkins with a service account in permissive mode. Otherwise, Marathon and Metronome will act as if Jenkins was provisioned with a service account which has the superuser permission.

To set up a service account for Jenkins, complete the following steps.

Create a key pair.
Create a service account.
Create a service account secret.
Provision the service account with the necessary permissions.
Create a config.json file.

Requirement: In strict mode, the name of the service account must match the name that the service uses as its principal. By default, Jenkins uses jenkins-principal as the name of its principal. That’s the value that we use in the following procedures. Should you modify the default, you must change jenkins-principal throughout to match.

Note: We will use jenkins-secret as the name of the secret, jenkins-private-key.pem as the name of the file containing the private key, and jenkins-public-key.pem as the name of the file containing the public key. We recommend using these names, as it will make it easier to copy and paste the commands. If you change the names, make sure to modify the commands before issuing them.

Important: We store the secret in the jenkins path. This protects it from other services, so we do not recommend changing this.

Create a key pair

First, you’ll need to generate a 2048-bit RSA public-private key pair. While you can use any tool to accomplish this, the Enterprise DC/OS CLI is the most convenient because it returns the keys in the exact format required.

Prerequisite: You must have the DC/OS CLI installed and the Enterprise DC/OS CLI installed.

Create a public-private key pair and save each value into a separate file within the current directory.
```
dcos security org service-accounts keypair jenkins-private-key.pem jenkins-public-key.pem
```
Type ls to view the two new files created by the command. You may also want to open the files themselves and verify their contents.

Create a service account

About creating a service account

Next, you must create a service account. This section uses the Enterprise DC/OS CLI to accomplish this.

Prerequisite: You must have the DC/OS CLI installed, the Enterprise DC/OS CLI installed, and be logged in as a superuser via dcos auth login.

Use the following command to create a new service account called jenkins-principal with the public key you just generated.
```
dcos security org service-accounts create -p jenkins-public-key.pem -d "Jenkins service account" jenkins-principal
```
Verify your new service account using the following command.
```
dcos security org service-accounts show jenkins-principal
```

About creating a service account secret

Next, you need to create a secret associated with the service account that contains the private key.

Prerequisite: You must have the DC/OS CLI installed, the Enterprise DC/OS CLI installed, and be logged in as a superuser via dcos auth login.

Depending on your security mode, use one of the following commands to create a new secret called jenkins-secret in the jenkins path. Locating the secret inside the jenkins path will ensure that only the Jenkins service can access it. The secret will contain the private key, the name of the service account, and other data.

strict:
```
dcos security secrets create-sa-secret --strict jenkins-private-key.pem jenkins-principal jenkins/jenkins-secret
```
permissive:
```
dcos security secrets create-sa-secret jenkins-private-key.pem jenkins-principal jenkins/jenkins-secret
```
Ensure the secret was created successfully:
```
dcos security secrets list /
```
If you have jq 1.5 or later installed, you can also use the following command to retrieve the secret and ensure that it contains the correct service account ID and private key.
```
dcos security secrets get /jenkins/jenkins-secret --json | jq -r .value | jq
```
Important: While reviewing the secret, ensure that the login_endpoint URL uses HTTPS if you are in strict mode and HTTP if you are in permissive mode. If the URL begins with https and you are in permissive mode, try upgrading the Enterprise DC/OS CLI, deleting the secret, and recreating it.
Now that you have stored the private key in the Secret Store, we recommend deleting the private key file from your file system. This will prevent bad actors from using the private key to authenticate to DC/OS.
```
rm -rf jenkins-private-key.pem
```

Provision the service account with permissions

About the permissions

The permissions needed vary according to your security mode. In permissive mode, the Jenkins service account does not need any permissions. If you plan to upgrade at some point to strict mode, we recommending assigning them the permissions needed in strict mode to make the upgrade easier. The permissions will not have any effect until the cluster is in strict mode. If you plan to remain in permissive mode indefinitely, skip to Create a config.json file.

If you are in strict mode or want to be ready to upgrade to strict mode, continue to the next section.

Role and Quota

The DC/OS Jenkins service starting with DC/OS 2.0 supports multi-tenancy. Users should familiarize themselves with Quota and Resource Managment Primitives in DC/OS.

Note: We will use /dev/jenkins as the name of the service.

DC/OS 2.0 and later clusters dev will be the group in which the Jenkins service will be deployed as well as the role which the service will use. In strict mode, the service will require permissions granted for this dev role.
DC/OS 1.13 and older clusters dev will be the group in which the Jenkins service will be deployed. The role used by the service can be configured with the default of *. In strict mode, the service will require permissions granted for this * role.

Role used by Jenkins Agents

DC/OS 2.0 and later clusters - When quota is enforced on the group, the Jenkins agents will inherit the same role as the Jenkins master.
DC/OS 1.13 and older clusters - The role used by the Jenkins agents can be configured via role.jenkins-agent-role in the configuration options.

Creating and assigning the permissions

The DC/OS Enterprise CLI can be used to rapidly provision the Jenkins service account. You must also log in via dcos auth login as a superuser.

Note: Replace dev & nobody with the appropriate role and user for your deployment.


 dcos security org users grant jenkins-principal dcos:mesos:master:framework:role:dev create
 dcos security org users grant jenkins-principal dcos:mesos:master:reservation:role:dev create
 dcos security org users grant jenkins-principal dcos:mesos:master:volume:role:dev create
 
 dcos security org users grant jenkins-principal dcos:mesos:master:task:user:nobody create
 dcos security org users grant jenkins-principal dcos:mesos:agent:task:user:nobody create

 dcos security org users grant jenkins-principal dcos:mesos:master:reservation:principal:jenkins-principal delete
 dcos security org users grant jenkins-principal dcos:mesos:master:volume:principal:jenkins-principal delete

Create a config.json file

The contents of the config.json file will vary according to your security mode. We provide two examples below, one for each security mode. Locate the sample appropriate to your security mode, copy the JSON, paste it into a new file, and save it as config.json.

strict mode

{
  "security": {
    "secret-name": "jenkins/jenkins-secret",
    "strict-mode": true
  },
  "service": {
    "name": "/dev/jenkins",
    "user": "nobody"
  }
}

permissive mode

{
  "security": {
    "secret-name": "jenkins/jenkins-secret"
  },
  "service": {
    "name": "/dev/jenkins",
    "user": "nobody"
  }
}

If you have modified any of the values shown in the previous sections, change the values in the following JSON as appropriate.

Install Jenkins

To install the service, complete the following steps.

Use the following command.

dcos package install --options=config.json jenkins

Paste the following path into your browser, replacing cluster-url with your actual cluster URL: https://<cluster-url>/service/dev/jenkins/configure.
Scroll to the Mesos cloud area.
Next to the Framework credentials field, click the Add button and select Jenkins.
In the Username field, type jenkins-principal.
In the Password field, type any value.
Once you have completed your entries, click Add.
Click Apply and then click Save.
Select the new jenkins-principal account in the Framework credentials list box.
Click New item in the side menu.
Click the Freestyle project button, type Test service account in the Enter an item name field, and press ENTER.
Scroll down to the Build area.
Click Add build step and select Execute shell.
Type echo "hello world" in the Command field.
Click Save.
The browser should display a Project test service account page.
Click Build now from the side menu.
After some time, the job should turn green in the Build history box. Congratulations! You have succeeded in setting Jenkins up with a service account.

You can also provide the config.json file to someone else to install Jenkins. Please see the Jenkins documentation for more information about how to use the JSON file to install the service.

Provisioning Jenkins

This topic describes when and how to provision Jenkins with a service account.