Chamber

Chamber is a tool for managing secrets. Currently it does so by storing secrets in SSM Parameter Store, an AWS service for storing secrets.

For detailed info about using chamber, please read The Right Way To Manage Secrets

v3.0 Breaking Changes

• Use of the SSM Parameter Store's path-based API is now required. Support added in v2.0 to avoid it has been removed. The CHAMBER_NO_PATHS environment variable no longer has any effect. You must migrate to the new storage format using the instructions below, using a 2.x version of chamber.
• The --min-throttle-delay option no longer has any effect. Support for specifying a minimum throttle delay has been removed from the underlying AWS SDK with no direct replacement. Instead, set the new --retry-mode option to "adaptive" to use an experimental model that accounts for throttling errors.
• Context arguments are required for Store methods. This is a consequence of migrating to a new AWS SDK. This change has no effect for CLI users, but those using chamber as a library must update their code to pass contexts.
• The deprecated NewS3Store constructor has been removed. Use NewS3StoreWithBucket instead.

v2.0 Breaking Changes

Starting with version 2.0, chamber uses parameter store's path based API by default. Chamber pre-2.0 supported this API using the CHAMBER_USE_PATHS environment variable. The paths based API has performance benefits and is the recommended best practice by AWS.

As a side effect of this change, if you didn't use path based secrets before 2.0, you will need to set CHAMBER_NO_PATHS to enable the old behavior. This option is deprecated, and We recommend only using this setting for supporting existing applications.

To migrate to the new format, you can take advantage of the export and import commands. For example, if you wanted to convert secrets for service foo to the new format using chamber 2.0, you can do:

CHAMBER_NO_PATHS=1 chamber export foo | chamber import foo -

v2.13.0 Breaking Changes

Support for very old versions of Go has been dropped, and chamber will only test against versions of Go covered by the Go Release Policy, e.g. the two most recent major versions. This will ensure that we can reliably update dependencies as needed. Additionally, chamber binaries will be built with the latest stable version of Go at the time of release.

Installing

If you have a functional go environment, you can install with:

go install github.com/segmentio/chamber/v3@latest

Caveat About chamber version and go install

Note that installing with go install will not produce an executable containing any versioning information. This information is passed at compilation time when the Makefile is used for compilation. Without this information, chamber version outputs the following:

$ chamber version
chamber dev

See the wiki for more installation options like Docker images, Linux packages, and precompiled binaries.

Authenticating

Using chamber requires you to be running in an environment with an authenticated AWS user which has the appropriate permission to read/write values to SSM Parameter Store.

This is going to vary based on your organization but chamber needs AWS credentials to run.

One of the easiest ways to do so is by using aws-vault. To adjust these instructions for your needs, examine the env output of Aws-Vault: How It Works and use your organization's secrets tool accordingly with chamber.

An aws-vault Usage Example With Chamber

aws-vault exec prod -- chamber

For this reason, it is recommended that you create an alias in your shell of choice to save yourself some typing, for example (from my .zshrc):

alias chamberprod='aws-vault exec production -- chamber'

Setting Up KMS

Chamber expects to find a KMS key with alias parameter_store_key in the account that you are writing/reading secrets. You can follow the AWS KMS documentation to create your key, and follow this guide to set up your alias.

If you are a Terraform user, you can create your key with the following:

resource "aws_kms_key" "parameter_store" {
  description             = "Parameter store kms master key"
  deletion_window_in_days = 10
  enable_key_rotation     = true
}

resource "aws_kms_alias" "parameter_store_alias" {
  name          = "alias/parameter_store_key"
  target_key_id = "${aws_kms_key.parameter_store.id}"
}

If you'd like to use an alternate KMS key to encrypt your secrets, you can set the environment variable CHAMBER_KMS_KEY_ALIAS. As an example, the following will use your account's default SSM alias: CHAMBER_KMS_KEY_ALIAS=aws/ssm

Usage

Writing Secrets

$ chamber write <service> <key> <value|->

This operation will write a secret into the secret store. If a secret with that key already exists, it will increment the version and store a new value.

If - is provided as the value argument, the value will be read from standard input.

Secret keys are normalized automatically. The - will be _ and the letters will be converted to upper case (for example a secret with key secret_key and secret-key will become SECRET_KEY).

Reserved Service Names

Starting with version 3.0, the service name "_chamber" is reserved for chamber's internal use. You will be warned when using the service for any chamber operation.

Tagging on Write

$ chamber write <service> <key> <value> --tags key1=value1,key2=value2

This operation will write a secret into the secret store with the specified tags. Tagging on write is only available for new secrets.

Tagging Secrets

$ chamber tag write <service> <key> tag1=value1 tag2=value2
Key Value
tag1  value1
tag2  value2
$ chamber tag read <service> <key>
Key Value
tag1  value1
tag2  value2
$ chamber tag delete <service> <key> tag1
$ chamber tag read <service> <key>
Key Value
tag2  value2

Writing tags normally leaves other tags intact. If you want to replace all tags with the new ones, use --delete-other-tags flag. Note: The option may change before the next major release.

$ chamber tag write --delete-other-tags <service> <key> tag1=value1
Key Value
tag1  value1

Listing Secrets

$ chamber list service
Key         Version                  LastModified      User
apikey      2                        06-09 17:30:56    daniel-fuentes
other       1                        06-09 17:30:34    daniel-fuentes

Listing secrets should show the key names for a given service, along with other useful metadata including when the secret was last modified, who modified it, and what the current version is.

$ chamber list -e service
Key         Version                  LastModified      User             Value
apikey      2                        06-09 17:30:56    daniel-fuentes   apikeyvalue
other       1                        06-09 17:30:34    daniel-fuentes   othervalue

Listing secrets with expand parameter should show the key names and values for a given service, along with other useful metadata including when the secret was last modified, who modified it, and what the current version is.

Historic view

$ chamber history service key
Event       Version     Date            User
Created     1           06-09 17:30:19  daniel-fuentes
Updated     2           06-09 17:30:56  daniel-fuentes

The history command gives a historical view of a given secret. This view is useful for auditing changes, and can point you toward the user who made the change so it's easier to find out why changes were made.

Exec

$ chamber exec <service...> -- <your executable>

exec populates the environment with the secrets from the specified services and executes the given command. Secret keys are converted to upper case (for example a secret with key secret_key will become SECRET_KEY).

Secrets from services are loaded in the order specified in the command. For example, if you do chamber exec app apptwo -- ... and both apps have a secret named api_key, the api_key from apptwo will be the one set in your environment.

Reading

$ chamber read service key
Key             Value                           Version         LastModified    User
key             secret                          1               06-09 17:30:56  daniel-fuentes

read provides the ability to print out the value of a single secret, as well as the secret's additional metadata. It does not provide the ability to print out multiple secrets in order to discourage accessing extra secret material that is unneeded. Parameter store automatically versions secrets and passing the --version/-v flag to read can print older versions of the secret. Default version (-1) is the latest secret.

Exporting

$ chamber export [--format <format>] [--output-file <file>]  <service...>
{"key":"secret"}

export provides ability to export secrets in various file formats. The following file formats are supported:

• json (default)
• yaml
• java-properties
• csv
• tsv
• dotenv
• tfvars

File is written to standard output by default but you may specify an output file.

Caveat About Environment Variables

chamber can emit environment variables in both dotenv format and exported shell environment variables. As chamber allows creating key names that are themselves not valid shell variable names, secrets emitted in this format will have their keys modified t