apache2 #20

Add to new model

Description

The Apache Software Foundation's goal is to build a secure, efficient
and extensible HTTP server as standards-compliant open source
software. The result has long been the number one web server on the
Internet. It features support for HTTPS, virtual hosting, CGI, SSI,
IPv6, easy scripting and database integration, request/response
filtering, many flexible authentication schemes, and more.

Tags:

app-servers

Juju charm for Apache

The Apache Software Foundation's goal is to build a secure,
efficient and extensible HTTP server as standards-compliant open
source software. The result has long been the number one web server
on the Internet. It features support for HTTPS, virtual hosting,
CGI, SSI, IPv6, easy scripting and database integration,
request/response filtering, many flexible authentication schemes,
and more.

Development

The following steps are needed for testing and development of the
charm, but not for deployment:

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:chrisjohnston/flake8
sudo apt-get update
sudo apt-get install python-flake8 python-nose python-coverage \
                     python-testtools python-pyasn1 python-pyasn1-modules

To fetch additional source dependencies and run the tests:

make build

... will run the unit tests, run flake8 over the source to warn
about formatting issues and output a code coverage summary of the
'hooks.py' module.

How to deploy the charm

Assuming you have a copy of the charm into a charms/$distrocodename/apache2
directory relative to your current directory.

... then to perform a deployment execute the following steps:

juju deploy --repository=charms local:apache2
juju set apache2 "vhost_http_template=$(base64 < http_vhost.tmpl)"


# and / or
juju set apache2 "vhost_https_template=$(base64 < https_vhost.tmpl)"

If you want a simple reverseproxy relation to your services (only
really useful if you have a single unit on the other side of the
relation):

juju add-relation apache2:reverseproxy haproxy:website
# and / or
juju add-relation apache2:reverseproxy squid-reverseproxy:cached-website

Alternatively, you can use the balancer relation so that requests
are load balanced across multiple units of your services. For more information see the section on Using the balancer relation:

juju add-relation apache2:balancer haproxy:website
# and / or
juju add-relation apache2:balancer squid-reverseproxy:cached-website

VirtualHost templates

The charm expects a jinja2 template to be passed in. The variables
in the template should relate to the services that apache will be
proxying -- obviously no variables need to be specified if no
proxying is needed.

Virtual host templates can also be specified via relation. See the
vhost-config relation section below for more information.

The vhost_template_vars config allows for further customisation of the vhost
templates. For example, you can have a single template for a particular
service, but use vhost_template_vars to customise it slightly for
devel/staging/production environments.

Using the reverseproxy relation

The charm will create the service variable, with the unit_name,
when the reverseproxy relationship is joined and present this to
the template at which point the vhost will be generated from the
template again. All config settings are also available to the
template.

For example to access squid then the {{ squid }} variable should
be used. This will be populated with the hostname:port of the squid
service. The individual hostname and port can also be accessed via
squid_hostname and squid_port.

Note: The service name should be used, not the charm name. If
deploying a charm with a different service name, use that
instead.

The joining charm may set an all_services variable which
contains a list of services it provides in yaml format (list of
associative arrays):

# ... in haproxy charm, website-relation-joined
relation-set all_services="
  - {service_name: gunicorn, service_port: 80}
  - {service_name: solr, service_port: 8080}
  - {service_name: my-webapp, service_port: 9090}
"

then variables for each service would be available to the jinja2
template in <juju_service_name>_<sub_service_name>. In our example
above haproxy contains stanzas named gunicorn, solr and my-webapp.
These are accessed as {{ haproxy_gunicorn }}, {{ haproxy_solr }} and
{{ haproxy_mywebapp }} respectively. If any unsupported characters
are in your juju service name or the service names exposed through
"all_services", they will be stripped.

For example a vhost that will pass all traffic on to an haproxy instance:

<VirtualHost *:80>
    ServerName radiotiptop.org.uk

    CustomLog /var/log/apache2/radiotiptop-access.log combined
    ErrorLog /var/log/apache2/radiotiptop-error.log

    DocumentRoot /srv/radiotiptop/www/root

    ProxyRequests off
    <Proxy *>
        Order Allow,Deny
        Allow from All
        ErrorDocument 403 /offline.html
        ErrorDocument 500 /offline.html
        ErrorDocument 502 /offline.html
        ErrorDocument 503 /offline.html
    </Proxy>

    ProxyPreserveHost off
    ProxyPassReverse / http://{{ haproxy_gunicorn }}/

    RewriteEngine on

    RewriteRule ^/$ /index.html [L]
    RewriteRule ^/(.*)$ http://{{ haproxy_gunicorn }}/$1 [P,L]
</VirtualHost>

Using the balancer relation

Using the balancer relation will set up named balancers using
Apache's mod_balancer. Each balancer will be named after the
sitenames or all_services setting exported from the other side
of the relation. Requests sent through those balancers will have a
X-Balancer-Name header set, which can be used by the related
service to appropriatedly route requests internally.

The joining charm may set an all_services variable which
contains a list of services it provides in yaml format (list of
associative arrays):

# ... in haproxy charm, website-relation-joined
relation-set all_services="
  - {service_name: gunicorn, service_port: 80}
  - {service_name: solr, service_port: 8080}
  - {service_name: my-webapp, service_port: 9090}
"

Each separate service name will cause a new balancer definition to be created on the Apache side, like:


ProxySet lbmethod=byrequests
RequestHeader set X-Balancer-Name "gunicorn"

For example a vhost that will pass specific requests to the gunicorn service that's defined in haproxy:

<VirtualHost *:80>
    ServerName radiotiptop.org.uk

    CustomLog /var/log/apache2/radiotiptop-access.log combined
    ErrorLog /var/log/apache2/radiotiptop-error.log

    DocumentRoot /srv/radiotiptop/www/root

    ProxyRequests off
    <Proxy *>
        Order Allow,Deny
        Allow from All
        ErrorDocument 403 /offline.html
        ErrorDocument 500 /offline.html
        ErrorDocument 502 /offline.html
        ErrorDocument 503 /offline.html
    </Proxy>

    ProxyPreserveHost on

    RewriteEngine on

    RewriteRule ^/$ /index.html [L]
    RewriteRule ^/(.*)$ balancer://gunicorn/$1 [P,L]
</VirtualHost>

Using the vhost-config relation

The nice thing about this relation, is as long as a charm support it, deploying
apache as a front-end for a web service should be as simple as establishing the
relation. If you need more details for how to implement this, read on.

The template files themselves can be specified via this relation. This makes
deployment of your infrastructure simpler, since users no longer need to
specify a vhosts config option when using apache2 (though they still can). A
candidate charm should provide a relation on the apache-vhost-config
interface. This charm should simply set the following data when relating:

relation-set vhosts="- {port: '443', template: dGVtcGxhdGU=}\n- {port: '80', template: dGVtcGxhdGU=}\n"

Notice the vhosts definition is in yaml, the format is simple. vhosts
should contain a yaml encoded data structure of a list of key value hashes, or
dictionaries. In each dictionary, port should be set to the port this vhost
should listen on, template should be set to the base64 encoded template file.
You can include as many of these dictionaries as you would like. If you have
colliding port numbers across your juju infrastructure, the results will be a
bit unpredictable.

For example, if using python for your relating charm, the code to generate a
yaml_string for a vhost on port 80 would be similar to this:

import yaml
import base64
template = get_template()
vhosts = [{"port": "80", "template": base64.b64encode(template)}]
yaml_string = yaml.dump(vhosts)

Note, that if you are opening a non-standard port (80 and 443 are opened and
understood by the default install of apache2 in Ubuntu) you will need to
instruct Apache to Listen on that port in your vhost file. Something like the
following will work in your vhost template:

Listen 8080
<VirtualHost *:8080>
...
</VirtualHost>

Relation settings that apache2 provides

When your charm relates it will be provided with the following:

  • servername - The Apache2 servername. This is typically needed by web
    applications so they know how to write URLs.

  • ssl_cert - If you asked for a selfsigned certificate, that cert will
    be available in this setting as a base64 encoded string.

Using the apache-website relation

The apache-website relation provides a very flexible way of configuring an
Apache2 website, using subordinate charms. It can support reverse proxies,
static websites, and probably many other forms.

To support this relation, a charm must set

  • domain - The fully-qualified domain name of the site.

  • enabled - Must be set to 'true' when the web site is ready to be used.

  • site_config - A vhost configuration block.

  • site_modules - A list of modules required by the site. If any of these
    appear in disable_modules, the site will not be enabled. Otherwise, any
    required modules will be loaded.

  • ports - A space-separated list of ports that the site uses.

Using the logs relation

The logs relation is for use with a logging subordinate charm. The beaver
subordinate can be deployed and related to apache and logstash. Beaver will
tail apache logs and send the logs to logstash.

Certs, keys and chains

ssl_keylocation, ssl_certlocation and ssl_chainlocation are
file names in the charm /data directory. If found, they will be
copied as follows:

  • /etc/ssl/private/
  • /etc/ssl/certs/
  • /etc/ssl/certs/

ssl_key and ssl_cert can also be specified which are are assumed
to be base64 encoded. If specified, they will be written to
appropriate directories given the values in ssl_keylocation and
ssl_certlocation as listed above.

ssl_cert may also be set to SELFSIGNED, which will generate a
certificate. This, of course, is mostly useful for testing and
staging purposes. The generated certifcate/key will be placed
according to ssl_certlocation and ssl_keylocation as listed
above.

ssl_protocol, ssl_honor_cipher_order, and ssl_cipher_suite can
be used to override SSL/TLS version and the cipher suites supported.
These default to what Canonical IS recommends and is using. Before
making any changes, please see the Mozilla Security/Server Side TLS.

{enable,disable}_modules

Space separated list of modules to be enabled or disabled. If a module to
be enabled cannot be found then the charm will attempt to install it.

OpenId

The openid_provider option takes a comma seperated list of OpenID
providers and places them in /etc/apache2/security/allowed-ops.txt. That
file can then be refernced by the allowed-op-list-url option when using
apache_openid

TODO:

  • Document the use of balancer, nrpe, logging and website-cache

  • Method to deliver site content. This maybe by converting the
    charm to a subordinate and making it the master charms problem

  • Implement secure method for delivering key. Juju will likely
    need to provide this.

  • Tuning. No tuning options are present. Convert apache2.conf to a
    template and expose config options

  • The all_services variable can be passed as part of the http interface and is
    optional. However its kind of secret and it would be more obvious if a
    seperate interface was used like http-allservices.

Configuration

ssl_honor_cipher_order
(string) Enable server cipher suite preference.
On
logrotate_rotate
(string) daily, weekly, monthly, or yearly?
daily
logrotate_count
(int) The number of days we want to retain logs for
365
mpm_startservers
(int) Add desc
2
trace_enabled
(string) Security setting. Set to one of On Off extended
On
ssl_protocol
(string) SSL Protocols to enable.
ALL -SSLv2 -SSLv3
servername
(string) ServerName for vhost, defaults to the units public-address
mpm_threadsperchild
(int) Add desc
64
use_rsyslog
(boolean) Change logging behaviour to log both access and error logs via rsyslog
mpm_type
(string) worker or prefork
worker
lb_balancer_timeout
(int) How long the backends in mod_proxy_balancer will timeout, in seconds
60
mpm_serverlimit
(int) Add desc
128
openid_provider
(string) Comma seperated list of OpenID providers for authentication.
mpm_maxrequestsperchild
(int) Add desc
vhost_https_template
(string) Apache vhost template (base64 encoded).
apt-source
(string) From where to install packages. This is the PPA source line. Note that due to a bug in software-properties add-apt-repository cannot add the ondrej/apache2 ppa, so the default value here is a full sources line.
disable_modules
(string) List of modules to disable
status autoindex
nagios_check_http_params
(string) The parameters to pass to the nrpe plugin check_http.
nagios_servicegroups
(string) A comma-separated list of nagios servicegroups. If left empty, the nagios_context will be used as the servicegroup
server_tokens
(string) Security setting. Set to one of Full OS Minimal Minor Major Prod
OS
mpm_maxsparethreads
(int) Add desc
75
logrotate_dateext
(boolean) Use daily extension like YYYMMDD instead of simply adding a number
True
vhost_http_template
(string) Apache vhost template (base64 encoded).
vhost_template_vars
(string) Additional custom variables for the vhost templating, in python dict format
package_status
(string) The status of service-affecting packages will be set to this value in the dpkg database. Useful valid values are "install" and "hold".
install
enable_modules
(string) List of modules to enable
ssl_chain
(string) base64 encoded chain certificates file. If ssl_cert is specified as SELFSIGNED, this will be ignored.
apt-key-id
(string) A PGP key id. This is used with PPA and the source option to import a PGP public key for verifying repository signatures. This value must match the PPA for apt-source.
ssl_certlocation
(string) Name and location of ssl certificate in charm/data directory. If not found, will ignore. Basename of this file will be used as the basename of the cert rooted at /etc/ssl/certs. Can be used in conjunction with the ssl_cert parameter to specify the cert as a configuration setting.
mpm_minsparethreads
(int) Add desc
25
ssl_cert
(string) base64 encoded server certificate. If the keyword 'SELFSIGNED' is used, the certificate and key will be autogenerated as self-signed.
ssl_keylocation
(string) Name and location of ssl keyfile in charm/data directory. If not found, will ignore. Basename of this file will be used as the basename of the key rooted at /etc/ssl/private. Can be used in conjuntion with the ssl_key parameter to specify the key as a configuration setting.
nagios_context
(string) Used by the nrpe-external-master subordinate charm. A string that will be prepended to instance name to set the host name in nagios. So for instance the hostname would be something like: juju-postgresql-0 If you're running multiple environments with the same services in them this allows you to differentiate between them.
juju
ssl_key
(string) base64 encoded server certificate key. If ssl_cert is specified as SELFSIGNED, this will be ignored.
config_change_command
(string) The command to run whenever config has changed. Accepted values are "reload" or "restart" - any other value will mean neither is executed after a config change (which may be desired, if you're running a production server and would rather handle these out of band). Note: some variables like the mpm settings require a restart to go into effect.
reload
mpm_maxclients
(int) Add desc
2048
server_signature
(string) Security setting. Set to one of On Off EMail
On
extra_packages
(string) List of extra packages to be installed (e.g. commercial GeoIP package)
ssl_chainlocation
(string) Name and location of the ssl chain file. Basename of this file will be used as the basename of the chain file rooted at /etc/ssl/certs.
ssl_cipher_suite
(string) List of server cipher suites.
EECDH+AESGCM+AES128:EDH+AESGCM+AES128:EECDH+AES128:EDH+AES128:ECDH+AESGCM+AES128:aRSA+AESGCM+AES128:ECDH+AES128:DH+AES128:aRSA+AES128:EECDH+AESGCM:EDH+AESGCM:EECDH:EDH:ECDH+AESGCM:aRSA+AESGCM:ECDH:DH:aRSA:HIGH:!MEDIUM:!aNULL:!NULL:!LOW:!3DES:!DSS:!EXP:!PSK:!SRP
mpm_threadlimit
(int) Add desc
64