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A backend for Hiera that provides per-value asymmetric encryption of sensitive data

branch: master
README.md

Hiera eyaml

Build Status

hiera-eyaml is a backend for Hiera that provides per-value encryption of sensitive data within yaml files to be used by Puppet.

:new:v2.0 - commandline tool syntax has changed, see below for details

Advantages over hiera-gpg

A few people found that hiera-gpg just wasn't cutting it for all use cases, one of the best expressed frustrations was written back in June 2013. So Tom created an initial version and this was refined into an elegant solution over the following months.

Unlike hiera-gpg, hiera-eyaml:

  • only encrypts the values (which allows files to be swiftly reviewed without decryption)
  • encrypts the value of each key individually (this means that git diff is meaningful)
  • includes a command line tool for encrypting, decrypting, editing and rotating keys (makes it almost as easy as using clear text files)
  • uses basic asymmetric encryption (PKCS#7) by default (doesn't require any native libraries that need to be compiled & allows users without the private key to encrypt values that the puppet master can decrypt)
  • has a pluggable encryption framework (e.g. GPG encryption (hiera-eyaml-gpg) can be used if you have the need for multiple keys and easier key rotation)

The Hiera eyaml backend uses yaml formatted files with the .eyaml extension. The encrypted strings are prefixed with the encryption method, wrapped with ENC[] and placed in an eyaml file. You can mix your plain values in as well or separate them into different files. Encrypted values can occur within arrays, hashes, nested arrays and nested hashes.

For instance:

---
plain-property: You can see me

encrypted-property: >
    ENC[PKCS7,Y22exl+OvjDe+drmik2XEeD3VQtl1uZJXFFF2NnrMXDWx0csyqLB/2NOWefv
    NBTZfOlPvMlAesyr4bUY4I5XeVbVk38XKxeriH69EFAD4CahIZlC8lkE/uDh
    jJGQfh052eonkungHIcuGKY/5sEbbZl/qufjAtp/ufor15VBJtsXt17tXP4y
    l5ZP119Fwq8xiREGOL0lVvFYJz2hZc1ppPCNG5lwuLnTekXN/OazNYpf4CMd
    /HjZFXwcXRtTlzewJLc+/gox2IfByQRhsI/AgogRfYQKocZgFb/DOZoXR7wm
    IZGeunzwhqfmEtGiqpvJJQ5wVRdzJVpTnANBA5qxeA==]

To edit this you can use the command eyaml edit important.eyaml which will decrypt the file, fire up an editor with the decrypted values and re-encrypt any edited values when you exit the editor. This tool makes editing your encrypted files as simple as clear text files.

Setup

Installing hiera-eyaml

$ gem install hiera-eyaml

Generate keys

The first step is to create a pair of keys:

$ eyaml createkeys

This creates a public and private key with default names in the default location. (./keys)

Storing the keys securely when using Puppet

Since the point of using this module is to securely store sensitive information, it's important to store these keys securely. If using Hiera with Puppet, Your puppetmaster will need to access these keys to perform decryption when the puppet agent runs on a remote node. So for this reason, a suggested location might be to store them in /etc/puppet/secure/keys or /var/lib/puppet/keys depending on your setup.

The permissions for this folder should allow the puppet user (normally 'puppet') execute access to the keys directory, read only access to the keys themselves and restrict everyone else:

$ chown -R puppet:puppet /etc/puppet/secure/keys
$ chmod -R 0500 /etc/puppet/secure/keys
$ chmod 0400 /etc/puppet/secure/keys/*.pem
$ ls -lha /etc/puppet/secure/keys
-r-------- 1 puppet puppet 1.7K Sep 24 16:24 private_key.pkcs7.pem
-r-------- 1 puppet puppet 1.1K Sep 24 16:24 public_key.pkcs7.pem

Encryption

To encrypt something, you only need the public_key, so distribute that to people creating hiera properties

$ eyaml encrypt -f filename            # Encrypt a file
$ eyaml encrypt -s 'hello there'       # Encrypt a string
$ eyaml encrypt -p                     # Encrypt a password (prompt for it)

Use the -l parameter to pass in a label for the encrypted value,

$ eyaml encrypt -l 'some_easy_to_use_label' -s 'yourSecretString'

Decryption

To decrypt something, you need the public_key and the private_key.

To test decryption you can also use the eyaml tool if you have both keys

$ eyaml decrypt -f filename               # Decrypt a file
$ eyaml decrypt -s 'ENC[PKCS7,.....]'     # Decrypt a string

Editing eyaml files

Once you have created a few eyaml files, with a mixture of encrypted and non-encrypted properties, you can edit the encrypted values in place, using the special edit mode of the eyaml utility. Edit mode opens a decrypted copy of the eyaml file in your $EDITOR and will encrypt and modified values when you exit the editor.

$ eyaml edit filename.eyaml         # Edit an eyaml file in place

When editing eyaml files, you will see that the unencrypted plaintext is marked to allow the eyaml tool to identify each encrypted block, along with the encryption method. This is used to make sure that the block is encrypted again only if the clear text value has changed, and is encrypted using the original encryption mechanism (see plugable encryption later).

A decrypted file might look like this:

---
plain-property: You can see me

cipher-property : >
    DEC(1)::PKCS7[You can't see me]!

environments:
    development:
        host: localhost
        password: password
    production:
        host: prod.org.com
        password: >
            DEC(2)::PKCS7[securepassword]!

things:
    - thing 1
    -   - nested thing 1.0
        - >
            DEC(3)::PKCS7[secure nested thing 1.1]!
    -   - nested thing 2.0
        - nested thing 2.1

Whilst editing you can delete existing values and add new one using the same format (as below). Note that it is important to omit the number in brackets for new values. If any duplicate IDs are found then the re-encryption process will be abandoned by the eyaml tool.

some_new_key: DEC::PKCS7[a new value to encrypt]!

Hiera

To use eyaml with hiera and puppet, first configure hiera.yaml to use the eyaml backend

---
:backends:
    - eyaml
    - yaml

:hierarchy:
    - %{environment}
    - common

:yaml:
    :datadir: '/etc/puppet/hieradata'
:eyaml:
    :datadir: '/etc/puppet/hieradata'

    # If using the pkcs7 encryptor (default)
    :pkcs7_private_key: /path/to/private_key.pkcs7.pem
    :pkcs7_public_key:  /path/to/public_key.pkcs7.pem

Then, edit your hiera yaml files, and insert your encrypted values. The default eyaml file extension is .eyaml, however this can be configured in the :eyaml block to set :extension,

:eyaml:
    :extension: 'yaml'

Important Note: The eyaml backend will not parse internally json formatted yaml files, whereas the regular yaml backend will. You'll need to ensure any existing yaml files using json format are converted to syntactically correct yaml format.

---
plain-property: You can see me

cipher-property : >
    ENC[PKCS7,Y22exl+OvjDe+drmik2XEeD3VQtl1uZJXFFF2NnrMXDWx0csyqLB/2NOWefv
    NBTZfOlPvMlAesyr4bUY4I5XeVbVk38XKxeriH69EFAD4CahIZlC8lkE/uDh
    jJGQfh052eonkungHIcuGKY/5sEbbZl/qufjAtp/ufor15VBJtsXt17tXP4y
    l5ZP119Fwq8xiREGOL0lVvFYJz2hZc1ppPCNG5lwuLnTekXN/OazNYpf4CMd
    /HjZFXwcXRtTlzewJLc+/gox2IfByQRhsI/AgogRfYQKocZgFb/DOZoXR7wm
    IZGeunzwhqfmEtGiqpvJJQ5wVRdzJVpTnANBA5qxeA==]

environments:
    development:
        host: localhost
        password: password
    production:
        host: prod.org.com
        password: >
            ENC[PKCS7,Y22exl+OvjDe+drmik2XEeD3VQtl1uZJXFFF2NnrMXDWx0csyqLB/2NOWefv
            NBTZfOlPvMlAesyr4bUY4I5XeVbVk38XKxeriH69EFAD4CahIZlC8lkE/uDh
            jJGQfh052eonkungHIcuGKY/5sEbbZl/qufjAtp/ufor15VBJtsXt17tXP4y
            l5ZP119Fwq8xiREGOL0lVvFYJz2hZc1ppPCNG5lwuLnTekXN/OazNYpf4CMd
            /HjZFXwcXRtTlzewJLc+/gox2IfByQRhsI/AgogRfYQKocZgFb/DOZoXR7wm
            IZGeunzwhqfmEtGiqpvJJQ5wVRdzJVpTnANBA5qxeA==]

things:
    - thing 1
    -   - nested thing 1.0
        - >
            ENC[PKCS7,Y22exl+OvjDe+drmik2XEeD3VQtl1uZJXFFF2NnrMXDWx0csyqLB/2NOWefv
            NBTZfOlPvMlAesyr4bUY4I5XeVbVk38XKxeriH69EFAD4CahIZlC8lkE/uDh
            jJGQfh052eonkungHIcuGKY/5sEbbZl/qufjAtp/ufor15VBJtsXt17tXP4y
            l5ZP119Fwq8xiREGOL0lVvFYJz2hZc1ppPCNG5lwuLnTekXN/OazNYpf4CMd
            /HjZFXwcXRtTlzewJLc+/gox2IfByQRhsI/AgogRfYQKocZgFb/DOZoXR7wm
            IZGeunzwhqfmEtGiqpvJJQ5wVRdzJVpTnANBA5qxeA==]
    -   - nested thing 2.0
        - nested thing 2.1

Configuration file for eyaml

Default parameters for the eyaml command line tool can be provided by creating a configuration YAML file.

The location of the file defaults to ~/.eyaml/config.yaml but can be overriden by setting EYAML_CONFIG environment variable.

The file takes any long form argument that you can provide on the command line. For example, to override the pkcs7 keys:

---
pkcs7_private_key: '~/keys/eyaml/private_key.pkcs7.pem'
pkcs7_public_key: '~/keys/eyaml/public_key.pkcs7.pem'

Or to override to use GPG by default:

---
encrypt_method: 'gpg'
gpg_gnupghome: '~/alternative_gnupghome'
gpg_recipients: 'sihil@example.com,gtmtech@example.com,tpoulton@example.com'

Pluggable Encryption

hiera-eyaml backend is pluggable, so that further encryption types can be added as separate gems to the general mechanism which hiera-eyaml uses. Hiera-eyaml ships with one default mechanism of 'pkcs7', the encryption type widely used to sign smime email messages.

Other encryption types (if the gems for them have been loaded) can be specified using the following formats:

ENC[PKCS7,SOME_ENCRYPTED_VALUE]         # a PKCS7 encrypted value
ENC[GPG,SOME_ENCRYPTED_VALUE]           # a GPG encrypted value (hiera-eyaml-gpg)
... etc ...

When editing eyaml files, you will see that the unencrypted plaintext is marked in such a way as to identify the encryption method. This is so that the eyaml tool knows to encrypt it back using the correct method afterwards:

some_key: DEC(1)::PKCS7[very secret password]!

Encryption plugins

This is a list of available plugins:

  • hiera-eyaml-gpg - Provide GPG encryption
  • hiera-eyaml-plaintext - This is a no-op encryption plugin that simply base64 encodes the values. It exists as an example plugin to create your own and to do integration tests on hiera-eyaml. THIS SHOULD NOT BE USED IN PRODUCTION

Notes

If you do not specify an encryption method within ENC[] tags, it will be assumed to be PKCS7

Also remember that after encrypting your sensitive properties, if anyone has access to your git source, they will see what the property was in previous commits before you encrypted. It's recommended that you roll any passwords when switching from unencrypted to encrypted properties. eg, Developers having write access to a DEV branch will be able to read/view the contents of the PRD branch, as per the design of GIT.

Github has a great guide on removing sensitive data from repos here: https://help.github.com/articles/remove-sensitive-data

Troubleshooting

Installing from behind a corporate/application proxy

$ export HTTP_PROXY=http://yourcorporateproxy:3128/
$ export HTTPS_PROXY=http://yourcorporateproxy:3128/

then run your install

$ gem install hiera-eyaml

Issues

If you have found a bug then please raise an issue here on github.

Some of us hang out on #hiera-eyaml on freenode, please drop by if you want to say hi or have a question.

Tests

In order to run the tests, simply run cucumber in the top level directory of the project.

You'll need to have a few requirements installed:

  • expect (via yum/apt-get or system package)
  • aruba (gem)
  • cucumber (gem)
  • puppet (gem)

Authors

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