Simple example app showing how to connect to a db
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vault.go Add support for reading credentials from vault Apr 27, 2018

Simple webapp connecting to a MySQL database

A simple webapp to test connecting to MySQL databases.


In short the application does the following:

  • Read parameters (also from environment variables)
  • Ping the given db (with simple wait and retry logic)
  • Report once a connection can be made (or exit in case it can't)
  • Expose a /health endpoint

The following parameters are supported:

Usage of ./dbwebapp:
  -dbHost string
    	Db host to connect to. (default "localhost")
  -dbName string
    	Db to use.
  -dbPass string
        Db password to connect with. Requires dbUser. Takes precedence over vault methods
  -dbPort string
    	Db port to connect to. (default "3306")
  -dbUser string
        Db user to connect with. Requires dbPass. Takes precedence over vault methods
  -vaultAddr string
        Vault address to use. (default "http://localhost:8200")
  -vaultRoleId string
        Role ID to access vault with. Requires vaultSecretId.
  -vaultSecretId string
        Secret ID to access vault with. Requires vaultRoleId.
  -vaultToken string
        Token to access vault with. Takes precedence over vaultRoleId and vaultSecredId.

Parameters can also be passed using environment variables (parameter name or uppercase version), i.e. to start with actual credb credentials:

DBUSER=user DBPASS=pass DBNAME=db DBHOST=host DBPORT=port ./dbwebapp


dbUser=user dbPass=pass dbName=db dbHost=host dbPort=port ./dbwebapp

Usage with vault

We support two ways of vault integration:

Vault tokens

To run with an explicit vault token (to obtain db credentials from vault):

VAULTTOKEN=76b0d0fa-e7ac-f29e-d3e2-d1b4fc98300c ./dbwebapp

In this case the secret is expected to be under secrets/dbwebapp username=user password=pass

The required secret engine in vault is kv:

vault secrets enable -path=secrets kv
vault kv put secrets/dbwebapp username=dbwebapp password=dbwebapp

The according policy would be:

path "secrets/dbwebapp" {
  capabilities = ["read"]

Created by:

vault policy write dbwebapp /policies/dbwebapp-policy.hcl

Tokens can be created by:

vault token create -policy=dbwebapp

The result of this command can be passed to the application via the VAULTTOKEN parameter.

AppRole auth method

Similarly for the approle method we need first need to specify a policy:

path "auth/approle/login" {
  capabilities = ["create", "read"]

path "database/creds/vault-mysql-role" {
  capabilities = ["read"]

And to enable the auth backend, secrets engine and create a role:

vault write auth/approle/role/dbwebapp policies="dbwebapp" role_id="dbrole"
vault write auth/approle/role/dbwebapp/custom-secret-id secret_id=testsecret1
vault secrets enable database
vault write database/config/mysql-database \
    plugin_name=mysql-database-plugin \
    connection_url="{{username}}:{{password}}@tcp(mysql-server:3306)/" \
    allowed_roles="vault-mysql-role" \
    username="vault" \
vault write database/roles/vault-mysql-role \
    db_name=mysql-database \
    creation_statements="CREATE USER '{{name}}'@'%' IDENTIFIED BY '{{password}}';GRANT SELECT ON dbwebappdb.* TO '{{name}}'@'%';" \
    default_ttl="1h" \

Finally, MySQL needs to allow vault access to generate credentials on demand:


CREATE USER 'vault'@'%' IDENTIFIED BY 'vault';
GRANT CREATE USER ON *.* to 'vault'@'%';

Usage with approle credentials (to create db credentials on thefly via the db secrets engine) :

VAULTADDR=http://localhost:8200 VAULTROLEID=roleId VAULTSECRETID=secretId ./dbwebapp

The role id and secred id are used to authenitcate at auth/approle/login and the token returned from this call will be used to acquire temporary db credentials from database/creds/vault-mysql-role.

Leases on renewable tokens are renewed regularly.


On linux systems it is sufficient to run make to build the go binary and a minimal docker container.