Habitat Container

Based on sirajr/centos-systemd, this container aids iterative development of Habitat packages, as well as testing of Supervisors and Rings. Available on Docker Hub

Start the Container

Start the container minimally using:

$ podman run -d --name habitat sirajr/habitat
33d9afdf53a9e9dadb167a732c5a6e4846c598b8ca7572e0a807ee7cd57b9e61

You can then connect to the container using podman exec, where the Supervisor will be installed as a SystemD service hab-sup:

$ podman exec --interactive --tty habitat /bin/bash

From here you may modify the configuration, install packages/load services, etc.

Interacting with the Supervisor

View the Supervisor status:

[root@33d9afdf53a9 /]# systemctl status hab-sup
● hab-sup.service - Habitat Supervisor
   Loaded: loaded (/etc/systemd/system/hab-sup.service; disabled; vendor preset: disabled)
   Active: active (running) since Wed 2020-02-12 14:50:55 UTC; 1min 8s ago
     Docs: https://habitat.sh
 Main PID: 19 (hab-launch)
   CGroup: /docker/75f65b0b1da83e331e29365d378f938688616db8e299f70d308b2c538e732ba5/system.slice/hab-sup.service
           ├─19 /hab/pkgs/core/hab-launcher/13154/20200211164210/bin/hab-launch run --listen-ctl 0.0.0.0:9632
           └─34 /hab/pkgs/core/hab-sup/1.5.29/20200211164216/bin/hab-sup run --listen-ctl 0.0.0.0:9632
   
Feb 12 14:50:55 75f65b0b1da8 hab[19]: → Using core/xz/5.2.4/20190115013348
Feb 12 14:50:55 75f65b0b1da8 hab[19]: → Using core/zlib/1.2.11/20190115003728
...

Tail the Supervisor's log using journalctl:

[root@33d9afdf53a9 /]# journalctl --follow --unit hab-sup
-- Logs begin at Wed 2020-02-12 14:50:55 UTC. --
...
Feb 12 14:50:55 75f65b0b1da8 hab[19]: hab-sup(MR): Starting http-gateway on 0.0.0.0:9631

The Supervisor API

To access the Supervisor HTTP API or the Control Gateway, add -P to the podman run command to expose ports 9631/9632 on TCP on random host ports. You may specify specific ports using -p <container-port>:[<optional-host-port>]:

$ podman run -d -p 9631:9631 siraj-habitat

$ curl --silent localhost:9631/butterfly | jq
{
  "member": {
    "members": {},
    ...

Peering

To peer multiple containers, we can make use of the default bridge network. To do this, start up multiple containers, then use the podman inspect command to retrieve the IP address:

$ podman run -d --name supervisor-1 -p 9631:9631 siraj-habitat
bb1094e08831cee0e3377b0774a5d3dc55b2adefd64c1c7e34c1deec7461a53d

$ podman run -d --name supervisor-2 siraj-habitat
96d630782aaa5e84ce54948d568392fa485f91d2653d98ad9675238f94ccb994"

$ podman inspect supervisor-1 | jq -r '.[0].NetworkSettings.Networks.bridge.IPAddress'
172.17.0.2

This IP address must now be added as a --peer argument to the other supervisors using the SystemD unit file at /etc/systemd/system/hab-sup.service:

 [Unit]
 Description=Habitat Supervisor
 Documentation=https://habitat.sh

 [Service]
 Environment=HAB_LICENSE=accept-no-persist
-ExecStart=/bin/hab sup run --listen-ctl 0.0.0.0:9632
+ExecStart=/bin/hab sup run --listen-ctl 0.0.0.0:9632 --peer 172.17.0.2
 ExecStop=/bin/hab sup term
 Restart=on-success
 RestartSec=2

 [Install]
 WantedBy=default.target

Followed by a daemon-reload and a restart.

[root@96d630782aaa /]# systemctl daemon-reload
[root@96d630782aaa /]# systemctl restart hab-sup

We can now query the API from either node, or from the host if we've forwarded ports from either machine.

$ curl -s localhost:9631/butterfly | jq '.membership | keys'
[
  "aee86873f6f24d4a9efc920b2f01876b",
  "e8a6ba0f989e43d39e35e6da8a411440"
]

Developing Habitat Packages

The container can be useful for testing packages that are deployed in specifically configured environments (such as through a cookbook, etc.) and aids in debugging the behaviour of packages in clustered scenarios, as well as being able to test

To make full use of this container's functionality it is suggested to export HAB_BLDR_URL,HAB_AUTH_TOKEN,HAB_ORIGIN and mount the Habitat cache and our project directory to run builds or install packages to test outside the studio:

$ podman run -d -e HAB_BLDR_URL -e HAB_AUTH_TOKEN -e HAB_ORIGIN --volume ${HOME}/.hab/cache:/hab/cache --volume $(pwd):/workspace siraj-habitat
917c59943c59

$ podman exec --interactive --tty 917c59943c59 /bin/bash

[root@917c59943c59 /]# source /workspace/results/last_build.env

[root@917c59943c59 /]# hab pkg install /workspace/results/$pkg_artifact

[root@917c59943c59 /]# hab svc load $pkg_ident

[root@917c59943c59 /]# journalctl -fu hab-sup
Feb 12 16:43:17 0e032bdb5c2c hab[20]: hab-sup(AG): The <pkg_ident> service was successfully loaded
...

Mounting of the cache results in faster build times/downloads as well as removes the need for re-downloading origin keys on every container.