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jdelic's Saltshaker

This is a collection of saltstack formulae designed to bring up an small hosting environment for multiple applications and services. The hosting environment is reusable, the services are primarily there to fulfill my needs and allow experimentation with different DevOps setups.

Cloning this repository is a good basis for your own Salt setup as it implements a number of best practices I discovered and includes a fully fledged SmartStack implementation for internal, external and cross-datacenter services.

It also builds on the principles I have documented in my GoPythonGo build and deployment process.

It has full support for Vagrant, allowing easy testing of new functionality and different setups on your local machine before deploying them. Personally, I'm deploying this configuration on my laptop using Vagrant, on Digital Ocean and my own server on Hetzner which I configure with a XEN Hypervisor running VMs for all my development needs.

Everything in here is based around Debian 9.0 Stretch (i.e. requires systemd and uses Debian package naming).

Using these salt formulae you can bring up:

  • a primarily Python/Django based application environment

  • a Hashicorp Nomad based Docker/application cluster that integrates with the Consul-Smartstack implementation and provides easy application deployment.

  • including a consul/consul-template/haproxy based smartstack implementation for service discovery (you can find an extracted stand- alone version of that in my consul-smartstack repository.

  • a PostgreSQL database configuration for a "fast" database and a separate tablespace on an encrypted partition

  • a Concourse.CI build server environment for your projects

  • an HAProxy based reverse proxying load balancer for applications based around the same smartstack implementation

It also contains configuration for

  • a fully fledged PIM+Mail server with encrypted storage (based on Radicale, Dovecot and OpenSMTPD)

  • single-sign-on for Radicale, Dovecot and OpenSMTPD, other web applications and even PAM using a single database for authentication and providing OAuth2, CAS and SAML (through Dovecot). This is provided through authserver, a separate Django application written by me.

The salt configuration is pretty modular, so you can easily just use this repository to bring up a GoPythonGo build and deployment environment without any of the other stuff.

Configuration deployment

Deploying this salt configuration requires you to:

  1. create a bootstrap server (for example a Amazon EC2 instance, a Dom0 VM on your own Xen server or a Digital Ooean droplet)

  2. Assign that server the saltmaster and consulserver roles

    mkdir -p /etc/roles.d
touch /etc/roles.d/saltmaster
touch /etc/roles.d/consulserver

  3. check out the saltshaker repository

    cd /opt
git clone https://github.com/jdelic/saltshaker
ln -sv /opt/saltshaker/srv/salt /srv/salt
ln -sv /opt/saltshaker/srv/pillar /srv/pillar
ln -sv /opt/saltshaker/srv/reactor /srv/reactor
ln -sv /opt/saltshaker/srv/salt-modules /srv/salt-modules
mkdir -p /etc/salt/master.d /etc/salt/minion.d
ln -sv /opt/saltshaker/etc/salt-master/master.d/saltshaker.conf /etc/salt/master.d/saltshaker.conf
ln -sv /opt/saltshaker/etc/salt-minion/minion.d/saltshaker.conf /etc/salt/minion.d/saltshaker.conf

  4. Install Salt

    wget -O /tmp/install_salt.sh https://bootstrap.saltstack.com
chmod 700 /tmp/install_salt.sh
/tmp/install_salt.sh -M -P

  5. Edit the Pillar data in /srv/pillar. You must create a network configuration for your environment (see Networking below) and assign it to your systems in top.sls. It's especially important to select a count of consul server instances (3 are recommended for a production environment). You also must provide a secrets pillar that contains SSL certificates and such things.

  6. Run salt-call state.highstate -l debug on your master to bring it up.

  7. Bring up additional nodes (at least the count of consul server instances)

  8. Assign them roles, install the salt minion using install_salt.sh -P and call state.highstate. It's obviously much better to automate this step. I did so for the XEN Hypervisor for example using the scripts in role.d together with xen-create-image.

The secrets pillar

You should clone the saltshaker repository and then as a first step, replace the git submodule in srv/pillar/shared/secrets with your own private Git repository.

For my salt states to work, you must provide your ownshared.secrets pillar in srv/pillar/shared/secrets that must contain the following pillars, unless you rework the salt states to use different ones. I use a wildcard certificate for my domains and the configuration pillars for individual servers allow you to specify pillar references to change what certificates are used, but in the default configuration most services refer to the maincert, which is the wildcard certificate:

In shared.secrets.ssl:

  • ssl:maincert:cert - The public X.509 SSL certificate for your domain. You can replace these with cert pillars for your individual domain.
  • ssl:maincert:key: - The private key for your SSL certificate without a passphrase. You can replace this with key pillars for your individual domain.
  • ssl:maincert:certchain - The X.509 certificates tying your CA to a browser-accredited CA, if necessary.
  • ssl:maincert:combined - A concatenation of :cert and :certchain.
  • ssl:maincert:combined-key - A concatenation of :cert, :certchain and :key.

In shared.secrets.vault:

  • ssl:vault:cert - the public X.509 SSL certificate used by the vault role/server. Should contain SANs for vault.local resolving to 127.0.0.1 (see notes on the .local and .internal domains under "Networking" below).
  • ssl:vault:key - its private key
  • ssl:vault:certchain - its CA chain
  • ssl:vault:combined - A concatenation of :cert and :certchain
  • ssl:vault:combined-key - A concatenation of :cert and :certchain and :key.
  • vault:s3:aws-accesskey - The access key for an IAM role that can be used for the Vault S3 backend (if you want to use that). Must have read/write access to a S3 bucket.
  • vault:s3:aws-secretkey - the secret key corresponding to the access key above.

In shared.secrets.concourse:

  • ssh:concourse:public - A SSH2 public RSA key for the concourse.ci TSA SSH host.
  • ssh:concourse:key - The private key for the public host key.

In shared.secrets.postgresql:

  • ssl:postgresql:cert,key,certchain,combined,combined-key in the same structure as the SSL certs mentioned above, containing a SSL cert used to encrypt database traffic through postgresql.local.

I manage these pillars in a private Git repository that I clone to srv/pillar/shared/secrets as a Git submodule. To keep the PEM encoded certificates and keys in the pillar file, I use the following trick:

# pillar file
{% set mycert = "
-----BEGIN CERTIFICATE-----
MIIFBDCCAuwCAQEwDQYJKoZIhvcNAQELBQAwgdgxCzAJBgNVBAYTAkRFMQ8wDQYD
...
-----END CERTIFICATE-----"|indent(12) %}

# because we're using the indent(12) template filter we can then do:
ssl:
    maincert:
        cert: | {{mycert}}

shared.secrets: The managed GPG keyring

The salt config also contains states which manage a shared GPG keyring. All keys added to the dict pillar gpg:keys are iterated by the crypto.gpg state and put into a GPG keyring accessible only by root and the user groupgpg-access. There is a parallel pillar called gpg:fingerprints that is used to check whether a key has already been added. The file system location of the shared keyring is set by the gpg:shared-keyring-location pillar, which by default is /etc/gpg-managed-keyring.

Server configuration

Pillar overrides

Disks

/secure

The roledir grain

Available roles

Salt modules

The dynamicsecrets Pillar

This is a Pillar module that can be configured on the master to provide dynamically generated passwords and RSA keys across an environment managed by a Salt master. The secrets are stored in a single unencrypted sqlite database file that can (and should) be easily backed up (default path: /etc/salt/dynamicsecrets.sqlite). This should be used for non-critical secrets that must be shared between minions and/or where a more secure solution like Hashicorp's Vault is not yet applicable.

To be clear: The purpose of dynamicsecrets is to help bootstrap a cluster of servers where a number of initial secrets must be set and "remembered" across multiple nodes that are configured with Salt. This solution is better than putting hardcoded secrets in your configuration management, but you should really only rely on it to bootstrap your way to an installation of Hashicorp Vault or another solution that solves the secret introduction problem comprehensively!

Secrets from the pillar are assigned to the "roles" grain or minion ids and are therefor only rendered to assigned minions from the master.

# Example configuration
    # Extension modules
    extension_modules: /srv/salt-modules

    ext_pillar:
    - dynamicsecrets:
        config:
            approle-auth-token:
                type: uuid
            concourse-encryption:
                length: 32
            concourse-hostkey:
                length: 2048
                type: rsa
            consul-acl-token:
                type: uuid
                unique-per-host: True
            consul-encryptionkey:
                encode: base64
                length: 16
        grainmapping:
            roles:
                authserver:
                    - approle-auth-token
        hostmapping:
            '*':
                - consul-acl-token

For type: password the Pillar will simply contain the random password string. For type: uuid the Pilar will return a UUID4 built from a secure random source (as long as the OS provides one). For type: rsa the Pillar will return a dict that has the following properties:

  • public_pem the public key in PEM encoding
  • public the public key in ssh-rsa format
  • key the private key in PEM encoding

The dynamicsecrets pillar has been extracted into it's own project at jdelic/dynamicsecrets/.

Deploying applications

Service deployment "through" salt and "on" servers configured by salt

First off, don't get confused by the service configuration and discovery states that seem to be "interwoven" in this repository. The whole setup is meant to

  • allow applications to be deployed from .debs or Docker containers, being discovered through consul and then automatically be registered with a server that has the "loadbalancer" role

  • but also allow salt to install and configure services (like opensmtpd, dovecot, concourse.ci or a PHP application that can not be easily packaged in a .deb) and register that with consul to then make it available through a server that has the "loadbalancer" role

I generally, if in any way possible, would always prefer deploying an application not through salt states, but other means (for example: installing a .deb package on all servers that have the role "apps" through the salt CLI client) or better yet, push Docker containers to Nomad / Kubernetes / Docker Swarm. But if you have to (for example when configuring a service, which is typically part of a Unix system like a mail server) you totally can use salt states for that. This way you don't have to repackage services which are already set up for your system. No need to repackage dovecot in a Docker container, for example, if the Debian Maintainers do such an awesome job of already providing ready-to-run packages anyway! (Also, repeat after me: "Salt, Puppet, Chef and Ansible are not deployment tools!")

As I see it: use the best tool for the job. There is no dogma requiring you to run all services inside a container for example. And a container is not a VM, so services consisting of multiple daemons don't "containerize" easily anyway. And some services really expect to use all available resources on a server (databases, for example) and shouldn't be containerized for that reason. And so on and so forth..... so use whatever feels natural. This salt setup is flexible enough to accommodate all of these options.

Deploying packaged services from .debs (GoPythonGo applications, for example)

Deploying containerized services

Using servers with the nomadserver and apps roles, you have two options:

  1. Use Docker Swarm, which is built into Docker
  2. Use Hashicorp Nomad

They have different pros and cons, but Nomad supports scheduling jobs what are not containerized (as in plain binaries and Java applications). Nomad also directly integrates with Consul clusters outside of the Nomad cluster. So it makes service discovery between applications living inside and outside of the cluster painless. Using the smartstack implementation built into this repository, you can just add smartstack:* tags to the service {} stanza in your Nomad job configuration and service discovery as well as linking services to the loadbalancer will be taken care of.

For plain Docker or Docker Swarm, you will have to run a docker registrator instance on each cluster node, which does the same job as including consul service definitions in Nomad jobs. It registers services run from a docker container with consul, discovering metadata from environment variables in the container. Docker Swarm however, at least until Nomad 0.6 arrives, will have the benefit of supporting VXLAN Overlay networks that can easily be configured to use IPSEC encryption. This gives you a whole new primitive for separating logical networks between your conainerized applications and is something to think about.

Regardless of how the services get registered in Consul, it will in turn propagate the service information through consul-template to haproxy making the services accessible through localhost/docker-bridge based smartstack routers, or even setting up routing to them from nodes with the loadbalancer role, giving you fully automated service deployment for internal and external services.

SmartStack

See consul-smartstack.

Integrating external services (not implemented yet)

Question: But I run my service X on Heroku/Amazon Elastic Beanstalk with autoscaling/Amazon Container Service/Microsoft Azure/Google Compute Engine/ whatever... how do I plug this into this smartstack implementation?

Answer: You create a Salt state that registers these services as smartstack:internal services, assign them a port in your port map and make sure haproxy instances can route to it.This will cause consul-template instances on your machines to pick them up and make them available on localhost:[port]. The ideal machines to assign these states to in my opinion are all machines that have the consulserver role. Registering services with consul that way can either be done by dropping service definitions into /etc/consul/services.d or perhaps use use salt consul states.

A better idea security-wise is to create an "egress router" role that runs a specialized version of haproxy-external that sends traffic from its internal IP to your external services. Then announce the internal IP+Port as an internal smartstack service. The external services can then still be registered with the local Consul cluster, but you also have a defined exit point for traffic to the external network.

Vault

This salt configuration also runs an instance of Hashicorp Vault for better management of secure credentials. It's good practice to integrate your applications with that infrastructure.

Vault will be made available on 127.0.0.1 as an internal smartstack service through haproxy via consul-template on port 8200 once it's been initialized (depending on the backend) and unsealed.

Services, however, must access Vault through a local alias installed in /etc/hosts/ configured in the allenvs.wellknown:vault:smartstack-hostname pillar (default: vault.local), because Vault requires SSL and that in turn requires a valid SAN, so you have to configure Vault with a SSL certificate for a valid hostname. I use my own CA and give Vault a certificate for the SAN vault.local and then pin the CA certificate to my own CA's cert in the allenvs.wellknown:vault:pinned-ca-cert pillar for added security (no other CA can issue such a certificate for any uncompromised host).

Backends

You can configure Vault through the [hosting environment].vault pillar to use either the consul, mysql, S3 or PostgreSQL backends.

Vault database backend

Generally, if you run on multiple VMs sharing a physical server, choose the postgresql backend and choose backup intervals and Vault credential leases with a possible outage in mind. Such a persistent backend will not be highly available, but unless you distribute your VMs across multiple physical machines, your setup will not be HA anyway. So it's better to fail in a way that let's your restore service easily.

Running this setup from this Salt recipe requires at least one server in the local environment to have the database role as it will host the Vault PostgresSQL database. The Salt recipe will automatically set up a vault database on the database role if the vault pillar has the backend set postgresql, because the top.sls file shipped from this repo assigns the vault.database state to the database role.

To sum up: To enable this backend, set the Pillar [server environment].vault.backend to postgresql and assign exactly one server the database role (this salt configuration doesn't support database replication) and at least one server the vault role.

More information at the Vault website.

Vault backend: consul

If you run your VMs in a Cloud or on multiple physical servers, running Vault with the Consul cluster backend will offer high availability. In this case it also makes sense to run at least two instances of Vault. Make sure to distribute them across at least two servers though, otherwise a hardware failure might take down the whole Consul cluster and thereby also erase all of the data.

More information at the Vault website.

Networking

sysctl config

SysCTL is set up to accept

  • net.ipv4.ip_forward IPv4 forwarding so we can route packets to docker and other isolated separate networks
  • net.ipv4.ip_nonlocal_bind to allow local services to bind to IPs and ports even if those don't exist yet. This reduces usage of the 0.0.0.0 wildcard allowing to write more secure configurations.
  • net.ipv4.conf.all.route_localnet allows packets to and from localhost to pass through iptables, making it possible to route them. This is required so we can make consul services available on localhost even though consul runs on its own consul0 dummy interface.

iptables states

iptables is configured by the basics and iptables states to use the connstate/conntrack module to allow incoming and outgoing packets in the RELATED state. So to enable new TCP services in the firewall on each individual machine managed through this saltshaker, only the connection creation needs to be managed in the machine's states.

The naming standard for states that enable ports that get contacted is: (servicename)-tcp-in(port)-recv. For example:

openssh-in22-recv:
    iptables.append:
        - table: filter
        - chain: INPUT
        - jump: ACCEPT
        - source: '0/0'
        - proto: tcp
        - dport: 22
        - match: state
        - connstate: NEW
        - save: True
        - require:
            - sls: iptables

The naming standard for states that enable ports that initiate connections is: (servicename)-tcp-out(port)-send. For example:

dns-tcp-out53-send:
      iptables.append:
          - table: filter
          - chain: OUTPUT
          - jump: ACCEPT
          - destination: '0/0'
          - dport: 53
          - match: state
          - connstate: NEW
          - proto: tcp
          - save: True

Connections to and from localhost are always allowed.

Address overrides and standard interfaces

This saltshaker expects specific interfaces to be used for either internal or external (internet-facing) networking. The interface names are assigned in the local|hetzner.network pillar states in the ifassign states. Commonly the network assignments are this:

  • eth0 is either a local NAT interface (vagrant) or the lowest numbered full network interface.
  • The lowest numbered full network interface is commonly the "internal interface". It's connected to a non-routed local network between the nodes.
  • The next numbered full network interface is commonly the "external interface". It's connected to the internet.
  • The consul0 interface is a dummy interface with a link-local IP of 169.254.1.1. It's used to provide consul HTTP API and DNS API access to local services. A link-local address is used so it can be routed from the docker bridge.
  • docker0 is the default bridge network set up by Docker that containers usually attach to.

Some configurations (like the mailserver states) can expect multiple external network interfaces or at least multiple IP addresses to work correctly.

Therefor many states check a configuration pillar for themselves to figure out whether they should bind to a specific IP and if not, use the first IP assigned to the internal or external network interface. This is usually accomplished by the following Jinja2 recipe:

{{
# first, check whether we have a configuration pillar for the service,
# otherwise return an empty dictionary
pillar.get('authserver', {}).get(
    # check whether the configuration pillar has a configuration option
    # 'bind-ip'. If not, return the first IP of the local internal interface
    'bind-ip',
    # query the machine's interfaces (ip_interfaces) and use the value returned
    # by the interface assiged to be internal in the ifassign pillar
    grains['ip_interfaces'][pillar['ifassign']['internal']][
        # use the first IP or the IP designated in the network pillar
        pillar['ifassign'].get('internal-ip-index', 0)|int()
    ]
)
}}

Please note that commonly external services meant to be reached by the internet listen to internal interfaces on their application servers and are routed to the internet through the smartstack routing built into this configuration..

Reserved top-level domains

This configuration relies on three internal reserved domain suffixes, which must be replaced if they're ever brought up as a TLD on the global DNS. Those are:

  • .local which must resolve to an address in 127.0.0.1/24
  • .internal which must only be used within the non-publically-routed network (i.e. on an "internal" network interface)
  • .consul.service which is the suffix used by Consul for DNS based "service discovery" (repeat after me: DNS is not a service discovery protocol! Use Smartstack instead.)

Configuration

PostgreSQL

Accumulators

PostgreSQL

The PostgreSQL configuration uses two accumulators that record database user pairs (separated by a single space) for the pg_hba.conf file. These accumulators are called:

  • postgresql-hba-md5users-accumulator and
  • postgresql-hba-certusers-accumulator

Each line appended to them creates a line in pg_hba.conf that is hardcoded to start with hostssl, use the PostgreSQL server's internal network and has the authentication method md5 or cert. These accumulators are meant for service configuration to automatically add login rights to the database after creating database roles for the service.

The filename attribute for such file.accumulated states must be set to {{pillar['postgresql']['hbafile']}} which is the configuration pillar identifying the pg_hba.conf file for the installed version of PostgreSQL in the default cluster. The accumulator must also have a require_in directive tying it to the postgresql-hba-config state delivering the pg_hba.conf file to the node.

Example:

mydb-remote-user:
    file.accumulated:
        - name: postgresql-hba-md5users-accumulator
        - filename: {{pillar['postgresql']['hbafile']}}
        - text: {{pillar['vault']['postgres']['dbname']}} {{pillar['vault']['postgres']['dbuser']}}
        - require_in:
            - file: postgresql-hba-config

Apache2

The Apache2 configuration uses an acuumulator apache2-listen-ports to gather all listen directives for its /etc/apache2/ports.conf file. The filename attribute for states setting up new Listen directives, should be set to apache2-ports-config. The values accumulated can be either just port numbers or ip:port pairs.

Example:

apache2-webdav-port:
    file.accumulated:
        - name: apache2-listen-ports
        - filename: /etc/apache2/ports.conf
        - text: {{my_ip}}:{{my_port}}
        - require_in:
            - file: apache2-ports-config

PowerDNS Recursor

This Salt config sets up a PowerDNS recursor on every node that serves as an interface to the Consul DNS API. It's usually only available to local clients on 127.0.0.1:53 and 169.254.1.1:53 from where it forwards to Consul on 169.254.1.1:8600. However, sometimes it's useful to expose the DNS API to other services, for example on a Docker bridge or for other OCI containers.

Accumulators

The PowerDNS configuration uses two accumulators to allow the adding of IPs that PowerDNS Recursor listens on and allow CIDR ranges that can query the recursing DNS server on those IPs:

  • powerdns-recursor-additional-listen-ips and
  • powerdns-recursor-additional-cidrs

As above, the filename attribute for each file.accumulated state that uses one such accumulator must be set to /etc/powerdns/recursor.conf and it must have a require_in directive tying it to the pdns-recursor-config state.

Example:

mynetwork-dns:
    file.accumulated:
          - name: powerdns-recursor-additional-listen-ips
          - filename: /etc/powerdns/recursor.conf
          - text: 10.0.254.1
          - require_in:
              - file: pdns-recursor-config

Contributing

The following style is extraced from what has informally followed during development of this repository and is therefor needed to remain consistent.

General code style

  • Indents are 4 spaces
  • Top-level yaml elements have two newlines between them (just like Python PEP8)
  • Each file has a newline at the end of its last line
  • If you find yourself repeating the same states over and over (like creating an entry in /etc/appconfig/ for each deployed application, write a custom Salt state (see srv/_states/ for examples)
  • aside from MarkDown documentation, lines are up to 120 characters long unless linebreaks are impossible for technical reasons (long URLs, configuration files that don't support line breaks).
  • When breaking lines, search for "natural" points for well-readable line breaks. In natural language these usually are after punctuation. In code, they are usually found after parentheses in function calls or other code constructs, while indenting the next line, or at the end of statements.

yaml code style

  • String values are in single quotes 'xyz'
  • .sls yaml files should end with a vim modeline # vim: syntax=yaml.

Documentation style

Use MarkDown formatted files.

  • formatted to 80 columns.
  • List markers are indented 2 spaces leading to a text indent of 4 (bullets) or 5 (numbers) on the first level.
  • Text starts right below a headline unless it's a first level headline or the paragraph starts off with a list.

State structure

  • Jinja template files get the file extension .jinja.[original extension]
  • Configuration files should be stored near the states configuring the service
  • Only use explicit state ordering when in line with [ORDER.md}(ORDER.md).
  • Put states configuring services in the top-level srv/salt/ folder then create a single state namespace with configuration for specific organizations (like the mn state).

Pillar structure

  • Each state should get its configuration from a pillar.
  • Reuse configuration values through Jinja's {% from 'file' import variable %} since Salt does not support referencing pillars from pillars yet.
  • Use {{salt['file.join'}(...)}}, {{salt['file.basename'}(...)}}, {{salt['file.dirname'}(...)}} to construct paths from imported variables.
  • Pillars may import variables from things in srv/pillars/shared/, srv/pillar/allenvs/ or from their local environment. No cross-environment imports.
  • Each deployment environment ("vagrant", "hetzner", "digialocean", "ec2" are all examples) get their own namespace in srv/pillars/.
  • Each environment has a special state called */wellknown.sls that is assigned to all nodes in that environment for shared configuration values that can reasonably be expected to stay the same across all nodes, are not security critical and are needed or expected to be needed to run more than one service or application.
  • Pillars that are not security critical and are needed for multiple services or applications and can reasonably be expected to stay the same across all environments go into allenvs.wellknown.
  • srv/pillar/shared/ is the namespace for configuration that is shared across environments (or can reasonably expected to be the same, so that it makes sense to only override specific values in the pillars for a specific environment), but is not assigned to all nodes because its contents may be security critical or simply only needed on a single role.

SSL configuration in Pillars

SSL configuration should use the well-known keys sslcert, sslkey and if supported, clients should have access to a pinned-ca-cert pillar so the CA can be verified. sslcert and sslkey should support the magic value default which should make the states render configuration files referring to the pillars ssl:default-cert(-combined) and ssl:default-cert-key.