Juju

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Juju (formerly Ensemble) is an open source service orchestration management tool developed by Canonical Ltd., the company behind Ubuntu. Juju allows software to be quickly deployed, integrated and scaled on a wide choice of cloud services or servers.

Juju can deploy to LXC [1] (for local environments), OpenStack (for HP Cloud), Windows Azure, Joyent or Amazon EC2

Kapil Thangavelu wrote JuDo - A juju provider for Digital Ocean using a client side plugin and manual provisioning.

Links[edit | edit source]

  1. https://jujucharms.com/get-started
  2. https://jujucharms.com/docs/1.20/config-manual
  3. https://jujucharms.com/docs/1.20/config-aws
  4. https://jujucharms.com/docs/1.20/config-digitalocean
  5. https://jujucharms.com/docs/1.20/config-vagrant

TLDR[edit | edit source]

sudo add-apt-repository ppa:juju/stable
sudo apt-get update

sudo apt-get install juju-quickstart
sudo apt-get install juju-core
# to just show existing/default
# juju generate-config --show
juju generate-config
# edit .juju/environments.yaml to add your AWS KEYS
juju bootstrap
juju status
# assuming it shows a single machine numbered '0'
juju deploy apache2 --to 0
juju deploy mediawiki --to 0
# in our test, this deployed cs:trusty/mediawiki-3
juju deploy mysql --to 0
juju add-relation mediawiki:db mysql
juju expose apache2
juju expose mediawiki
juju status
juju ssh 0

You'll end up with an address like this [2]http://52.5.215.128/mediawiki/index.php/Special:Version with

  • Ubuntu 14.04.2 LTS (Trusty Tahr)
  • Apache 2.4.7 (Ubuntu) (with MaxRequestWorkers at 2048 which would require 32 servers while servers is set at 16 = sloppy)
  • MediaWiki 1.19.14+dfsg-1 installed with no extensions, and no git
  • PHP 5.5.9-1ubuntu4.7 (apache2handler)
  • MySQL 5.5.41-0ubuntu0.14.04.1-log


You can see what keys were added to the machine juju authorised-keys list and verify the key fingerprint for the key you want to use ssh-keygen -lf /home/user/.ssh/id_rsa

but you have to know/guess what user was installed by your charm

ssh -i /home/user/.ssh/id_rsa -o IdentitiesOnly=true -vvv ubuntu@ec2-55-5-555-55.compute-1.amazonaws.com

The above 'recipe' installs this MediaWiki charm which has been deployed 813 times as of this writing. BFD. It didn't work for me (I had to add Apache). Although this charm invokes a2enconf, I don't see any code which installs or verifies Apache2 as a dependency in the install hook. So, yeah, garbage. They should read the docs about how to write a charm. The example explicitly installs, configures and starts Apache as part of a simple web service. But the documentation is very sparse. The only "interface" (a primary element of orchestration) that is documented is 'mysql' and even that is barely covered.


The Wordpress charm is written better because it works, and actually offers a simple switch between nginx and Apache. Although it's a bit more 'polished' the WordPress Charm is still a bunch of bash scripts that end up installing things all over the place (standard locations?). It installs php-fpm (FastCGI Process Manager, which is an alternative PHP FastCGI implementation) It does use git, but is it configurable as to who/what/where you can pull from? I figured out that for the Wordpress charm, you can see the 'components' in the 'charm' directory.

In general, I'm very unimpressed with the implementation of the Charm Store. The underlying technology doesn't seem fully baked either, but I profess that I didn't look into it much.


Help[edit | edit source]

juju help

Juju -- devops distilled
https://juju.ubuntu.com/

Juju provides easy, intelligent service orchestration on top of environments
such as Amazon EC2, HP Cloud, OpenStack, MaaS, or your own local machine.

Basic commands:
  juju init             generate boilerplate configuration for juju environments
  juju bootstrap        start up an environment from scratch

  juju deploy           deploy a new service
  juju add-relation     add a relation between two services
  juju expose           expose a service

  juju help bootstrap   more help on e.g. bootstrap command
  juju help commands    list all commands
  juju help glossary    glossary of terms
  juju help topics      list all help topics

Provider information:
  juju help azure-provider       use on Windows Azure
  juju help ec2-provider         use on Amazon EC2
  juju help hpcloud-provider     use on HP Cloud
  juju help local-provider       use on this computer
  juju help openstack-provider   use on OpenStack

Commands[edit | edit source]

juju help commands
add-machine          alias for 'machine add'
add-relation         add a relation between two services
add-unit             add one or more units of an already-deployed service
api-endpoints        print the API server address(es)
api-info             print the field values used to connect to the environment's API servers
authorised-keys      alias for 'authorized-keys'
authorized-keys      manage authorized ssh keys
backups              create, manage, and restore backups of juju's state
block                block an operation that would alter a running environment
bootstrap            start up an environment from scratch
cached-images        manage cached os images
debug-hooks          launch a tmux session to debug a hook
debug-log            display the consolidated log file
deploy               deploy a new service
destroy-environment  terminate all machines and other associated resources for an environment
destroy-machine      alias for 'machine remove'
destroy-relation     alias for 'remove-relation'
destroy-service      alias for 'remove-service'
destroy-unit         alias for 'remove-unit'
ensure-availability  ensure the availability of Juju state servers
env                  alias for 'switch'
environment          manage environments
expose               expose a service
generate-config      alias for 'init'
get                  get service configuration options
get-constraints      view constraints on the environment or a service
get-env              alias for 'environment get'
get-environment      alias for 'environment get'
help                 show help on a command or other topic
help-tool            show help on a juju charm tool
init                 generate boilerplate configuration for juju environments
machine              manage machines
publish              publish charm to the store
remove-machine       alias for 'machine remove'
remove-relation      remove a relation between two services
remove-service       remove a service from the environment
remove-unit          remove service units from the environment
resolved             marks unit errors resolved
retry-provisioning   retries provisioning for failed machines
run                  run the commands on the remote targets specified
scp                  launch a scp command to copy files to/from remote machine(s)
set                  set service config options
set-constraints      set constraints on the environment or a service
set-env              alias for 'environment set'
set-environment      alias for 'environment set'
ssh                  launch an ssh shell on a given unit or machine
stat                 alias for 'status'
status               output status information about an environment
switch               show or change the default juju environment name
sync-tools           copy tools from the official tool store into a local environment
terminate-machine    alias for 'machine remove'
unblock              unblock an operation that would alter a running environment
unexpose             unexpose a service
unset                set service config options back to their default
unset-env            alias for 'environment unset'
unset-environment    alias for 'environment unset'
upgrade-charm        upgrade a service's charm
upgrade-juju         upgrade the tools in a juju environment
user                 manage user accounts and access control
version              print the current version


Setting up a MediaWiki instance with Juju, using the https://jujucharms.com/mediawiki/trusty/3 charm was completely unacceptable. The charm doesn't even setup a web server environment at all so it doesn't work "out of the box". When I specified an Apache2 charm https://jujucharms.com/apache2/trusty/13/ the configuration has a miscompiled PHP and also conflicting configurations (ServerLimit, MaxRequestWorkers) that causes errors in the log.

root@ip-172-31-57-182:~# /usr/sbin/apache2 -S
[Thu Apr 09 13:42:06.748287 2015] [core:warn] [pid 2247] AH00111: Config variable ${APACHE_LOCK_DIR} is not defined
[Thu Apr 09 13:42:06.748800 2015] [core:warn] [pid 2247] AH00111: Config variable ${APACHE_PID_FILE} is not defined
[Thu Apr 09 13:42:06.749138 2015] [core:warn] [pid 2247] AH00111: Config variable ${APACHE_RUN_USER} is not defined
[Thu Apr 09 13:42:06.749457 2015] [core:warn] [pid 2247] AH00111: Config variable ${APACHE_RUN_GROUP} is not defined
[Thu Apr 09 13:42:06.749808 2015] [core:warn] [pid 2247] AH00111: Config variable ${APACHE_LOG_DIR} is not defined
[Thu Apr 09 13:42:06.786167 2015] [:crit] [pid 2247:tid 139742374446976] Apache is running a threaded MPM, but your PHP Module is not compiled to be threadsafe.  You need to recompile PHP.
AH00013: Pre-configuration failed
root@ip-172-31-57-182:~# /usr/sbin/apache2 -M
[Thu Apr 09 13:42:19.687521 2015] [core:warn] [pid 2248] AH00111: Config variable ${APACHE_LOCK_DIR} is not defined
[Thu Apr 09 13:42:19.688010 2015] [core:warn] [pid 2248] AH00111: Config variable ${APACHE_PID_FILE} is not defined
[Thu Apr 09 13:42:19.688345 2015] [core:warn] [pid 2248] AH00111: Config variable ${APACHE_RUN_USER} is not defined
[Thu Apr 09 13:42:19.688604 2015] [core:warn] [pid 2248] AH00111: Config variable ${APACHE_RUN_GROUP} is not defined
[Thu Apr 09 13:42:19.688886 2015] [core:warn] [pid 2248] AH00111: Config variable ${APACHE_LOG_DIR} is not defined
[Thu Apr 09 13:42:19.700934 2015] [:crit] [pid 2248:tid 140047498663808] Apache is running a threaded MPM, but your PHP Module is not compiled to be threadsafe.  You need to recompile PHP.
AH00013: Pre-configuration failed

References[edit source]

  1. See also: Docker
  2. When setting up a service on EC2, make sure to obtain and assign an "elastic IP" so that the instance has a static IP. Otherwise every shutdown will result in a different public IP address being assigned to the instance.