If you wish to avoid storing secrets in plaintext in the Agent’s configuration files, you can use the secrets management package.

The Agent is able to leverage the secrets package to call a user-provided executable to handle retrieval and decryption of secrets, which are then loaded in memory by the Agent. This approach allows users to rely on any secrets management backend (such as HashiCorp Vault or AWS Secrets Manager), and select their preferred authentication method to establish initial trust with it. As a convenience containerized deployments of the Agent are pre-packaged with Helper Scripts to use for this executable.

Starting with version 6.12, the secrets management package is generally available on Linux for metrics, APM, and process monitoring, as well as on Windows for metrics and APM.

Using secrets

Defining secrets in configurations

Use the ENC[] notation to denote a secret as the value of any YAML field in your configuration.

Secrets are supported in any configuration backend, such as file, etcd, consul, and environment variables.

Secrets are also supported in datadog.yaml. The agent first loads the main configuration and reloads it after decrypting the secrets. This means that secrets cannot be used in the secret_* settings.

Secrets are always strings, you cannot use them to set an integer or Boolean value.

Example:

instances:
  - server: db_prod
    # two valid secret handles
    user: "ENC[db_prod_user]"
    password: "ENC[db_prod_password]"

    # The `ENC[]` handle must be the entire YAML value, which means that
    # the following is NOT detected as a secret handle:
    password2: "db-ENC[prod_password]"

Here, there are two secrets: db_prod_user and db_prod_password. These are the secrets’ handles, and each uniquely identifies a secret within your secrets management backend.

Between the brackets, any character is allowed as long as the YAML configuration is valid. This means that quotes must be escaped. For instance:

"ENC[{\"env\": \"prod\", \"check\": \"postgres\", \"id\": \"user_password\"}]"

In the above example, the secret’s handle is the string {"env": "prod", "check": "postgres", "id": "user_password"}.

There is no need to escape inner [ and ]. For instance:

"ENC[user_array[1234]]"

In the above example, the secret’s handle is the string user_array[1234].

Secrets are resolved after Autodiscovery template variables are resolved, this means you can use them in a secret handle. For instance:

instances:
  - server: %%host%%
    user: ENC[db_prod_user_%%host%%]
    password: ENC[db_prod_password_%%host%%]

Providing an executable

To retrieve secrets, you must provide an executable that is able to authenticate to and fetch secrets from your secrets management backend.

The Agent caches secrets internally in memory to reduce the number of calls (useful in a containerized environment for example). The Agent calls the executable every time it accesses a check configuration file that contains at least one secret handle for which the secret is not already loaded in memory. In particular, secrets that have already been loaded in memory do not trigger additional calls to the executable. In practice, this means that the Agent calls the user-provided executable once per file that contains a secret handle at startup, and might make additional calls to the executable later if the Agent or instance is restarted, or if the Agent dynamically loads a new check containing a secret handle (for example, from Autodiscovery).

APM and Process Monitoring run in their own process/service, and because processes don’t share memory, each needs to be able to load/decrypt secrets. Thus, if datadog.yaml contains secrets, each process might call the executable once. For example, storing the api_key as a secret in the datadog.yaml file with APM and Process Monitoring enabled might result in 3 calls to the secret backend.

By design, the user-provided executable needs to implement any error handling mechanism that a user might require. Conversely, the Agent needs to be restarted if a secret has to be refreshed in memory (for example, revoked password).

Relying on a user-provided executable has multiple benefits:

• Guaranteeing that the Agent does not attempt to load in memory parameters for which there isn’t a secret handle.
• Ability for the user to limit the visibility of the Agent to secrets that it needs (for example, by restraining the accessible list of secrets in the key management backend)
• Freedom and flexibility in allowing users to use any secrets management backend without having to rebuild the Agent.
• Enabling each user to solve the initial trust problem from the Agent to their secrets management backend. This occurs in a way that leverages each user’s preferred authentication method and fits into their continuous integration workflow.

Configuration

Set the following variable in datadog.yaml:

secret_backend_command: <EXECUTABLE_PATH>

Agent security requirements

The Agent runs the secret_backend_command executable as a sub-process. The execution patterns differ on Linux and Windows.

Note: The executable shares the same environment variables as the Agent.

Never output sensitive information on stderr. If the binary exits with a different status code than 0, the Agent logs the standard error output of the executable to ease troubleshooting.

The executable API

The executable respects a simple API: it reads JSON from the standard input and outputs JSON containing the decrypted secrets to the standard output.

If the exit code of the executable is anything other than 0, the integration configuration currently being decrypted is considered erroneous and is dropped.

API example input

The executable receives a JSON payload from the standard input, containing the list of secrets to fetch:

{"version": "1.0", "secrets": ["secret1", "secret2"]}

• version: is a string containing the format version (currently 1.0).
• secrets: is a list of strings; each string is a handle from a configuration corresponding to a secret to fetch.

API example output

The executable is expected to output to the standard output a JSON payload containing the fetched secrets:

{
  "secret1": {"value": "secret_value", "error": null},
  "secret2": {"value": null, "error": "could not fetch the secret"}
}

The expected payload is a JSON object, where each key is one of the handles requested in the input payload. The value for each handle is a JSON object with 2 fields:

• value: a string; the actual secret value to be used in the check configurations (can be null in the case of error).
• error: a string; the error message, if needed. If error is anything other than null, the integration configuration that uses this handle is considered erroneous and is dropped.

Example executable

The following is a dummy Go program prefixing every secret with decrypted_:

package main

import (
  "encoding/json"
  "fmt"
  "io/ioutil"
  "os"
)

type secretsPayload struct {
  Secrets []string `json:secrets`
  Version int      `json:version`
}

func main() {
  data, err := ioutil.ReadAll(os.Stdin)

  if err != nil {
    fmt.Fprintf(os.Stderr, "Could not read from stdin: %s", err)
    os.Exit(1)
  }
  secrets := secretsPayload{}
  json.Unmarshal(data, &secrets)

  res := map[string]map[string]string{}
  for _, handle := range secrets.Secrets {
    res[handle] = map[string]string{
      "value": "decrypted_" + handle,
    }
  }

  output, err := json.Marshal(res)
  if err != nil {
    fmt.Fprintf(os.Stderr, "could not serialize res: %s", err)
    os.Exit(1)
  }
  fmt.Printf(string(output))
}

This updates this configuration (in the check file):

instances:
  - server: db_prod
    user: ENC[db_prod_user]
    password: ENC[db_prod_password]

to this (in the Agent’s memory):

instances:
  - server: db_prod
    user: decrypted_db_prod_user
    password: decrypted_db_prod_password

Helper scripts for Autodiscovery

Many Datadog integrations require credentials to retrieve metrics. To avoid hardcoding these credentials in an Autodiscovery template, you can use secrets management to separate them from the template itself.

Starting with version 7.32.0, the helper script is available in the Agent’s container image as /readsecret_multiple_providers.sh, and you can use it to fetch secrets from files in addition to Kubernetes Secrets. The two scripts provided in previous versions (readsecret.sh and readsecret.py) are supported, but can only read from files.

Script for reading from multiple secret providers

Multiple providers usage

The script readsecret_multiple_providers.sh can be used to read from both files as well as Kubernetes Secrets. These Secrets must follow the format ENC[provider@some/path]. For example:

datadog:
  [...]
  secretBackend:
    command: "/readsecret_multiple_providers.sh"

DD_SECRET_BACKEND_COMMAND=/readsecret_multiple_providers.sh

Read from file example

The Agent can read a specified file relative to the path provided. This file can be brought in from Kubernetes Secrets, Docker Swarm Secrets, or any other custom method.

If the Agent container has the file /etc/secret-volume/password whose contents are the plaintext password, you can reference this with a notation like ENC[file@/etc/secret-volume/password].

Kubernetes Secrets

Kubernetes supports exposing Secrets as files inside a pod. Consider an example. A Secret, Secret: test-secret, has the data db_prod_password: example. This Secret is mounted to the Agent container according to the following configuration:

  containers:
    - name: agent
      #(...)
      volumeMounts:
        - name: secret-volume
          mountPath: /etc/secret-volume
  #(...)
  volumes:
    - name: secret-volume
      secret:
        secretName: test-secret

In this example, the Agent container contains the file /etc/secret-volume/db_prod_password with the contents of example. This is referenced in the configuration by using ENC[file@/etc/secret-volume/db_prod_password].

Notes:

• The Secret must exist in the same namespace as the pod it is being mounted in.
• The script is able to access all subfolders, including the sensitive /var/run/secrets/kubernetes.io/serviceaccount/token. As such, Datadog recommends using a dedicated folder instead of /var/run/secrets.

Docker Swarm secrets

Docker swarm secrets are mounted in the /run/secrets folder. For example, the Docker secret db_prod_passsword is located in /run/secrets/db_prod_password in the Agent container. This would be referenced in the configuration with ENC[file@/run/secrets/db_prod_password].

Read from Kubernetes Secret example

The following setup allows the Agent to directly read Kubernetes Secrets within both its own and other namespaces. Note that to do this, the Agent’s ServiceAccount must be granted permissions with the appropriate Roles and RoleBindings.

If Secret: database-secret exists in Namespace: database and contains the data password: example, this is referenced in the configuration with ENC[k8s_secret@database/database-secret/password]. With this setup, the Agent pulls this Secret directly from Kubernetes, which can be helpful when referencing a Secret that exists in a different namespace than the Agent is in.

This requires additional permissions that are manually granted to the Agent’s Service Account. For example, consider the following the RBAC policy:

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: datadog-secret-reader
  namespace: database
rules:
  - apiGroups: [""]
    resources: ["secrets"]
    resourceNames: ["database-secret"]
    verbs: ["get", "watch", "list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: datadog-read-secrets
  namespace: database
subjects:
  - kind: ServiceAccount
    name: datadog-agent
    apiGroup: ""
    namespace: default
roleRef:
  kind: Role
  name: datadog-secret-reader
  apiGroup: ""

This Role gives access to the Secret: database-secret in the Namespace: database. The RoleBinding links up this permission to the ServiceAccount: datadog-agent in the Namespace: default. This needs to be manually added to your cluster with respect to your resources deployed.

In addition to these permissions, you need to enable the script to read from multiple providers "/readsecret_multiple_providers.sh" when using the Kubernetes Secrets provider.

(Legacy) Scripts for reading from files

Datadog Agent v7.32 introduces the readsecret_multiple_providers.sh script. Datadog recommends that you use this script instead of /readsecret.py and /readsecret.sh from Agent v6.12. Note that /readsecret.py and /readsecret.sh are still included and supported in the Agent to read files.

Usage

These scripts require a folder passed as an argument. Secret handles are interpreted as file names, relative to this folder. To avoid leaking sensitive information, these scripts refuse to access any file out of the root folder specified (including symbolic link targets).

These scripts are incompatible with OpenShift restricted SCC operations and require that the Agent runs as the root user.

Docker

Docker Swarm secrets are mounted in the /run/secrets folder. These can be read by passing the following environment variables to your Agent container:

DD_SECRET_BACKEND_COMMAND=/readsecret.py
DD_SECRET_BACKEND_ARGUMENTS=/run/secrets

With this setup, the Datadog Agent reads any secret files located in the /run/secrets directory. For example, the configuration ENC[password] would have the Agent search for the /run/secrets/password file.

Kubernetes

Kubernetes supports exposing Secrets as files inside a pod. For example, if your Secrets are mounted in /etc/secret-volume, use the following environment variables:

DD_SECRET_BACKEND_COMMAND=/readsecret.py
DD_SECRET_BACKEND_ARGUMENTS=/etc/secret-volume

With this setup, the Datadog Agent reads any secret files located in the /etc/secret-volume directory. For example, the configuration ENC[password] would have the Agent search for the /etc/secret-volume/password file.

Troubleshooting

Listing detected secrets

The secret command in the Agent CLI shows any errors related to your setup. For example, if the rights on the executable are incorrect. It also lists all handles found, and where they are located.

On Linux, the command outputs file mode, owner and group for the executable. On Windows, ACL rights are listed.

$> datadog-agent secret
=== Checking executable rights ===
Executable path: /path/to/you/executable
Check Rights: OK, the executable has the correct rights

Rights Detail:
file mode: 100700
Owner username: dd-agent
Group name: dd-agent

=== Secrets stats ===
Number of secrets decrypted: 3
Secrets handle decrypted:
- api_key: from datadog.yaml
- db_prod_user: from postgres.yaml
- db_prod_password: from postgres.yaml

PS C:\> & "$env:ProgramFiles\Datadog\Datadog Agent\bin\agent.exe" secret
=== Checking executable rights ===
Executable path: C:\path\to\you\executable.exe
Check Rights: OK, the executable has the correct rights

Rights Detail:
Acl list:
stdout:

Path   : Microsoft.PowerShell.Core\FileSystem::C:\path\to\you\executable.exe
Owner  : BUILTIN\Administrators
Group  : WIN-ITODMBAT8RG\None
Access : NT AUTHORITY\SYSTEM Allow  FullControl
         BUILTIN\Administrators Allow  FullControl
         WIN-ITODMBAT8RG\ddagentuser Allow  ReadAndExecute, Synchronize
Audit  :
Sddl   : O:BAG:S-1-5-21-2685101404-2783901971-939297808-513D:PAI(A;;FA;;;SY)(A;;FA;;;BA)(A;;0x1200
         a9;;;S-1-5-21-2685101404-2783901971-939297808-1001)

=== Secrets stats ===
Number of secrets decrypted: 3
Secrets handle decrypted:
- api_key: from datadog.yaml
- db_prod_user: from sqlserver.yaml
- db_prod_password: from sqlserver.yaml

Seeing configurations after secrets were injected

To quickly see how the check’s configurations are resolved, you can use the configcheck command:

sudo -u dd-agent -- datadog-agent configcheck

=== a check ===
Source: File Configuration Provider
Instance 1:
host: <decrypted_host>
port: <decrypted_port>
password: <obfuscated_password>
~
===

=== another check ===
Source: File Configuration Provider
Instance 1:
host: <decrypted_host2>
port: <decrypted_port2>
password: <obfuscated_password2>
~
===

Note: The Agent needs to be restarted to pick up changes on configuration files.

Debugging your secret_backend_command

To test or debug outside of the Agent, you can mimic how the Agent runs it:

sudo -u dd-agent bash -c "echo '{\"version\": \"1.0\", \"secrets\": [\"secret1\", \"secret2\"]}' | /path/to/the/secret_backend_command"

.\secrets_tester.ps1 -user ddagentuser -password a_new_password -executable C:\path\to\your\executable.exe -payload '{"version": "1.0", "secrets": ["secret_ID_1", "secret_ID_2"]}'
Creating new Process with C:\path\to\your\executable.exe
Waiting a second for the process to be up and running
Writing the payload to Stdin
Waiting a second so the process can fetch the secrets
stdout:
{"secret_ID_1":{"value":"secret1"},"secret_ID_2":{"value":"secret2"}}
stderr: None
exit code:
0

Agent refusing to start

The first thing the Agent does on startup is to load datadog.yaml and decrypt any secrets in it. This is done before setting up the logging. This means that on platforms like Windows, errors occurring when loading datadog.yaml aren’t written in the logs, but on stderr. This can occur when the executable given to the Agent for secrets returns an error.

If you have secrets in datadog.yaml and the Agent refuses to start:

• Try to start the Agent manually to be able to see stderr.
• Remove the secrets from datadog.yaml and test with secrets in a check configuration file first.

Testing Kubernetes Permissions

When reading Secrets directly from Kubernetes you can double check your permissions with the kubectl auth command. The general form of this is:

kubectl auth can-i get secret/<SECRET_NAME> -n <SECRET_NAMESPACE> --as system:serviceaccount:<AGENT_NAMESPACE>:<AGENT_SERVICE_ACCOUNT>

Consider the previous Kubernetes Secrets example, where the Secret Secret:database-secret exists in the Namespace: database, and the Service Account ServiceAccount:datadog-agent exists in the Namespace: default.

In this case, use the following command:

kubectl auth can-i get secret/database-secret -n database --as system:serviceaccount:default:datadog-agent

This command returns whether the permissions are valid for the Agent to view this Secret.

Further Reading

お役に立つドキュメント、リンクや記事:

AutodiscoveryDOCUMENTATION