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Secrets Handling

Using Your Credhub

Credhub can be used to store secure properties that you don't want committed into a config file. Within your pipeline, the config file can then reference that Credhub value for runtime evaluation.

An example workflow would be storing an SSH key.

  1. Authenticate with your credhub instance.
  2. Generate an ssh key: credhub generate --name="/private-foundation/opsman_ssh_key" --type=ssh
  3. Create an Ops Manager configuration file that references the name of the property.
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opsman-configuration:
  azure:
    ssh_public_key: ((opsman_ssh_key.public_key))
  1. Configure your pipeline to use the credhub-interpolate task. It takes an input files, which should contain your configuration file from (3).

The declaration within a pipeline might look like:

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jobs:
- name: example-job
  plan:
  - get: platform-automation-tasks
  - get: platform-automation-image
  - get: config
  - task: credhub-interpolate
    image: platform-automation-image
    file: platform-automation-tasks/tasks/credhub-interpolate.yml
    input_mapping:
      files: config
    params:
      # depending on credhub configuration
      # ether CA cert or secret are required
      CREDHUB_CA_CERT: ((credhub_ca_cert))
      CREDHUB_SECRET: ((credhub_secret))

      # all required
      CREDHUB_CLIENT: ((credhub_client))
      CREDHUB_SERVER: ((credhub_server))
      PREFIX: /private-foundation
      SKIP_MISSING: true  

Notice the PREFIX has been set to /private-foundation, the path prefix defined for your cred in (2). This allows the config file to have values scoped, for example, per foundation. params should be filled in by the credhub created with your Concourse instance.

Info

You can set the param SKIP_MISSING:false to enforce strict checking of your vars files during intrpolation. This is true by default to support credential management from multiple sources. For more information, see the Multiple Sources section.

This task will reach out to the deployed credhub and fill in your entry references and return an output named interpolated-files that can then be read as an input to any following tasks.

Our configuration will now look like

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opsman-configuration:
 azure:
   ssh_public_key: ssh-rsa AAAAB3Nz...

Info

If using this you need to ensure the concourse worker can talk to credhub so depending on how you deployed credhub and/or worker this may or may not be possible. This inverts control that now workers need to access credhub vs default is atc injects secrets and passes them to the worker.

Storing values for Multi-foundation

Credhub

In the example above, bosh int did not replace the ((placeholder_credential)): ((cloud_controller_encrypt_key.secret)). For security, values such as secrets and keys should not be saved off in static files (such as an ops file). In order to rectify this, you can use a secret management tool, such as Credhub, to sub in the necessary values to the deployment manifest.

Let's assume basic knowledge and understanding of the credhub-interpolate task described in the Secrets Handling section of the documentation.

For multiple foundations, credhub-interpolate will work the same, but PREFIX param will differ per foundation. This will allow you to keep your base.yml the same for each foundation with the same ((placeholder_credential)) reference. Each foundation will require a separate credhub-interpolate task call with a unique prefix to fill out the missing pieces of the template.

Vars Files

Vars files can be used for your Secrets Handling.

Take the example below:

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# base.yml
# An incomplete yaml response from om staged-config
product-name: cf

product-properties:
  .cloud_controller.apps_domain:
    value: ((cloud_controller_apps_domain))
  .cloud_controller.encrypt_key:
    value:
      secret: ((cloud_controller_encrypt_key.secret))
  .properties.security_acknowledgement:
    value: X
  .properties.cloud_controller_default_stack:
    value: default

network-properties:
  network:
    name: DEPLOYMENT
  other_availability_zones:
  - name: AZ01
  singleton_availability_zone:
    name: AZ01

resource-config:
  diego_cell:
    instances: 5
    instance_type:
      id: automatic
  uaa:
    instances: 1
    instance_type:
      id: automatic

In our first foundation, we have the following vars.yml, optional for the configure-product task.

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# vars.yml
cloud_controller_encrypt_key.secret: super-secret-encryption-key
cloud_controller_apps_domain: cfapps.domain.com

The vars.yml could then be passed to configure-product with base.yml as the config file. The task will then sub the ((cloud_controller_encrypt_key.secret)) and ((cloud_controller_apps_domain)) specified in vars.yml and configure the product as normal.

An example of how this might look in a pipeline(resources not listed):

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jobs:
- name: configure-product
  plan:
  - aggregate:
    - get: platform-automation-image
      params:
        unpack: true
    - get: platform-automation-tasks
      params:
        unpack: true
    - get: configuration
    - get: variable
  - task: configure-product
    image: platform-automation-image
    file: platform-automation-tasks/tasks/configure-product.yml
    input_mapping:
      config: configuration
      env: configuration
      vars: variable
    params:
      CONFIG_FILE: base.yml
      VARS_FILES: vars.yml
      ENV_FILE: env.yml

Multiple Sources

Both vars files and credhub may be used to interpolate variables into base.yml. Using the same example from above:

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# base.yml
# An incomplete yaml response from om staged-config
product-name: cf

product-properties:
  .cloud_controller.apps_domain:
    value: ((cloud_controller_apps_domain))
  .cloud_controller.encrypt_key:
    value:
      secret: ((cloud_controller_encrypt_key.secret))
  .properties.security_acknowledgement:
    value: X
  .properties.cloud_controller_default_stack:
    value: default

network-properties:
  network:
    name: DEPLOYMENT
  other_availability_zones:
  - name: AZ01
  singleton_availability_zone:
    name: AZ01

resource-config:
  diego_cell:
    instances: 5
    instance_type:
      id: automatic
  uaa:
    instances: 1
    instance_type:
      id: automatic

We have one parametrized variable that is secret and might not want to have stored in a plain text vars file, ((cloud_controller_encrypt_key.secret)), but ((cloud_controller_apps_domain)) is fine in a vars file. In order to support a base.yml with credentials from multiple sources (i.e. credhub and vars files), you will need to SKIP_MISSING: true in the credhub-interpolate task. This is enabled by default by the credhub-interpolate task.

The workflow would be the same as Credhub, but when passing the interpolated base.yml as a config into the next task, you would add in a Vars File to fill in the missing variables.

An example of how this might look in a pipeline (resources not listed), assuming:

  • The ((base.yml)) above
  • ((cloud_controller_encrypt_key.secret)) is stored in credhub
  • ((cloud_controller_apps_domain)) is stored in director-vars.yml
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jobs:
- name: example-credhub-interpolate
  plan:
  - get: platform-automation-tasks
  - get: platform-automation-image
  - get: config
  - task: credhub-interpolate
    image: platform-automation-image
    file: platform-automation-tasks/tasks/credhub-interpolate.yml
    input_mapping:
      files: config
    params:
      # depending on credhub configuration
      # ether Credhub CA cert or Credhub secret are required
      CREDHUB_CA_CERT: ((credhub_ca_cert))
      CREDHUB_SECRET: ((credhub_secret))

      # all required
      CREDHUB_CLIENT: ((credhub_client))
      CREDHUB_SERVER: ((credhub_server))
      PREFIX: /private-foundation
      SKIP_MISSING: true
- name: example-configure-director
  plan:
  - get:   
  - task: configure-director
    image: platform-automation-image
    file: platform-automation-tasks/tasks/configure-director.yml
    params:
      VARS_FILES: vars/director-vars.yml
      ENV_FILE: env/env.yml
      DIRECTOR_CONFIG_FILE: config/director.yml

Multiple Key Lookups in a Single Task

When using Credhub in a single foundation or multi-foundation manner, we want to avoid duplicating identical credentials (duplication makes credential rotation harder).

In order to have Credhub read in credentials from multiple paths (not relative to your PREFIX), you must provide the absolute path to any credentials not in your relative path.

For example, using an alternative base.yml:

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# An incomplete yaml response from om staged-config
product-name: cf

product-properties:
  .cloud_controller.apps_domain:
    value: ((cloud_controller_apps_domain))
  .cloud_controller.encrypt_key:
    value:
      secret: ((/alternate_prefix/cloud_controller_encrypt_key.secret))
  .properties.security_acknowledgement:
    value: X
  .properties.cloud_controller_default_stack:
    value: default

Let's say in our job, we define the prefix as "foundation1". The parameterized values in the example above will be interpolated as follows:

((cloud_controller_apps_domain)) uses a relative path for Credhub. When running credhub-interpolate, the task will prepend the PREFIX. This value is stored in Credhub as /foundation1/cloud_controller_apps_domain.

((/alternate_prefix/cloud_controller_encrypt_key.secret)) (note the leading slash) uses an absolute path for Credhub. When running credhub-interpolate, the task will not prepend the prefix. This value is stored in Credhub at it's absolute path /alternate_prefix/cloud_controller_encrypt_key.secret.

Any value with a leading / slash will never use the PREFIX to look up values in Credhub. Therefore, you can have multiple key lookups in a single interpolate task.