Integrating Stash with Apache HTTP Server

Configuring Apache HTTP Server

You may find it helpful to refer to the Apache HTTP Server Documentation, which describes how you can control Apache HTTP Server by changing the contents of the httpd.conf file. The section on Apache Module mod_proxy is particularly relevant. Note that any changes you make to the httpd.conf file will be effective upon starting or re-starting Apache HTTP Server.

Step 1: Configure the Tomcat Connector

Find the normal (non-SSL) Connector directive in Tomcat's server.xml file, and add the scheme ,  proxyName , and proxyPort attributes as shown below. Instead of mycompany.com, set the proxyName attribute to the domain name that Apache HTTP Server will be configured to serve. This informs Stash of the domain name and port of the requests that reach it via Apache HTTP Server, and is important to the correct operation of the Stash functions that construct URL's.

<Connector port="7990" 
    protocol="HTTP/1.1"
    connectionTimeout="20000"
    useBodyEncodingForURI="true"
    redirectPort="8443"
    compression="on"
    compressableMimeType="text/html,text/xml,text/plain,text/css,application/json,application/javascript,application/x-javascript"
    scheme="http"
    proxyName="mycompany.com" 
    proxyPort="80" />

Note: Apache HTTP Server's ProxyPreserveHost directive is another way to have the hostname of the incoming request recognised by Stash instead of the hostname at which Stash is actually running. However, the ProxyPreserveHost directive does not cause the scheme to be properly set. Since we have to mess with Tomcat's Connector directive anyway, we recommend that you stick with the above-described approach, and don't bother to set the ProxyPreserveHost in Apache HTTP Server.

For more information about configuring the Tomcat Connector, refer to the Apache Tomcat 7.0 HTTP Connector Reference.

Step 2: Change Stash's base URL

After re-starting Stash, open a browser window and log into Stash using an administrator account. Go to the Stash administration area and click Server settings (under 'Settings'), and change Base URL to match the proxy URL (the URL that Apache HTTP Server will be serving).

Step 3 (optional): Set a context path for Stash

By default, Stash is configured to run with an empty context path; in other words, from the 'root' of the server's name space. In that default configuration, Stash is accessed at:

http://localhost:7990/

It's perfectly fine to run Stash with the empty context path as above. Alternatively, you can set a context path by changing the Context directive in Tomcat's server.xml file:

<Context path="/stash" docBase="${catalina.home}/atlassian-stash" reloadable="false" useHttpOnly="true">
    ....
</Context>

If you do set a context path, it is important that the same path be used in Step 5, when setting up the ProxyPass and ProxyPassReverse directives. You should also append the context path to Stash's base URL (see Step 2).

Step 4: Enable mod_proxy and mod_proxy_http in Apache HTTP Server

In the mod_proxy documentation, you will read that mod_proxy can be used as a forward proxy, or as a reverse proxy (gateway); you want the latter. Where the mod_proxy documentation mentions 'origin server', it refers to your Stash server. Unless you have a good reason for doing otherwise, load mod_proxy and mod_proxy_http dynamically, using the LoadModule directive; that means un-commenting the following lines in the httpd.conf file:

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so

Experienced administrators may be aware of the Apache Connector module, mod_jk. Atlassian does not recommend use of the mod_jk module with Stash, since it has proven itself to be less reliable than mod_proxy.

Step 5: Configure mod_proxy to map requests to Stash

To configure mod_proxy for use with Stash, you need to use the ProxyPass and ProxyPassReverse directives in Apache HTTP Server's httpd.conf file as follows:

ProxyPass        / http://localhost:7990/ connectiontimeout=5 timeout=300
ProxyPassReverse / http://localhost:7990/

Suppose Apache HTTP Server is configured to serve the mycompany.com domain; then the above directives tell Apache HTTP Server to forward web requests of the form http://mycompany.com/* to the Tomcat connector (Stash) running on port 7990 on the same machine.

The connectiontimeout attribute specifies the number of seconds Apache HTTP Server waits for the creation of a connection to Stash.

The timeout attribute specifies the number of seconds Apache HTTP Server waits for data to be sent to Stash.

If you set up a context path for Stash in Step 3, you'll need to use that context path in your ProxyPass and ProxyPassReverse directives. Suppose your context path is set to "/stash", the directives would be as follows:

ProxyPass        /stash http://localhost:7990/stash connectiontimeout=5 timeout=300
ProxyPassReverse /stash http://localhost:7990/stash

If Stash is to run on a different domain and/or different port, you should use that domain and/or port number in the ProxyPass and ProxyPassReverse directives; for example, suppose that Stash will run on port 9900 on private.mycompany.com under the context path /stash, then you would use the following directives:

ProxyPass        /stash http://private.mycompany.com:9900/stash connectiontimeout=5 timeout=300
ProxyPassReverse /stash http://private.mycompany.com:9900/stash

Step 6: Configure mod_proxy to disable forward proxying

If you are using Apache HTTP Server as a reverse proxy only, and not as a forward proxy server, you should turn forward proxying off by including a ProxyRequests directive in the httpd.conf file, as follows:

ProxyRequests Off

Step 7: Allow proxying to Stash from everywhere

Strictly speaking, this step is unnecessary because access to proxied resources is unrestricted by default. Nevertheless, we explicitly allow access to Stash from any host so that this policy will be applied regardless of any subsequent changes to access controls at the global level. Use the Proxy directive in the httpd.conf file as follows:

<Proxy *>
    Order Deny,Allow
    Allow from all
</Proxy>

The Proxy directive provides a context for the directives that are contained within its delimiting tags. In this case, we specify a wild-card url (the asterisk), which applies the two contained directives to all proxied requests.

The Order directive controls the order in which any Allow and Deny directives are applied. In the above configuration, we specify "Deny,Allow", which tells Apache HTTP Server to apply any Deny directives first, and if any match, the request is denied unless it also matches an Allow directive. In fact, "Deny,Allow" is the default; we include it merely for the sake of clarity. Note that we specify one Allow directive, which is described below, and don't specify any Deny directives.

The Allow directive, in this context, controls which hosts can access Stash via Apache HTTP Server. Here, we specify that all hosts are allowed access to Stash.

Step 8 (optional): Configure Apache HTTP Server for SSL

If you want to set up SSL access to Stash, take steps 8(a) to 8(d) below. When you are finished, users will be able to make secure connections to Apache HTTP Server; connections between Apache HTTP Server and Stash will remain unsecured (not using SSL). If you don't want to set up SSL access, you can skip this section entirely.

Note: It would be possible to set up an SSL connection between Apache HTTP Server and Tomcat (Stash), but that configuration is very unusual, and not recommended in most circumstances.

Step 8(a): Configure the Tomcat Connector for SSL

Find the normal (non-SSL) Connector directive in Tomcat's server.xml file, and change the redirectPort , scheme and proxyPort attributes as follows:

<Connector port="7990" 
     protocol="HTTP/1.1"
     connectionTimeout="20000"
     useBodyEncodingForURI="true"
     redirectPort="443"
     compression="on"
     compressableMimeType="text/html,text/xml,text/plain,text/css,application/json,application/javascript,application/x-javascript"
     secure="true"
     scheme="https"
     proxyName="mycompany.com" 
     proxyPort="443" />

The redirectPort directive causes Tomcat-initiated redirections to secured resources to use the specified port. Right now, the Stash configuration of Tomcat does not involve Tomcat-initiated redirections, so the change to redirectPort is redundant. Nevertheless, we suggest that you change it as directed above for the sake of completeness.

Step 8(b): Set up a virtual host in Apache HTTP Server

Un-comment the following LoadModule directive in Apache HTTP Server's httpd.conf file:

LoadModule ssl_module modules/mod_ssl.so

Add the following directives to the httpd.conf file:

Listen 443
<VirtualHost *:443>
    SSLEngine On
    SSLCertificateFile    "/usr/local/apache2/conf/server.crt"
    SSLCertificateKeyFile "/usr/local/apache2/conf/server.key"
    ProxyPass        / http://localhost:7990/ connectiontimeout=5 timeout=300
    ProxyPassReverse / http://localhost:7990/
</VirtualHost>

The Listen directive instructs Apache HTTP Server to listen for incoming requests on port 443. Actually, we could omit that directive in this case, since Apache HTTP Server listens for https requests on port 443 by default. Nevertheless, it's good to make one's intentions explicit.

The VirtualHost directive encloses a number of child directives that apply only and always to requests that arrive at port 443. Since our VirtualHost block does not include a ServerName directive, it inherits the server name from the main server configuration.

The SSLEngine directive toggles the use of the SSL/TLS Protocol Engine. In this case, we're using it to turn SSL on for all requests that arrive at port 443.

The SSLCertificateFile directive tells Apache HTTP Server where to find the PEM-encoded certificate file for the server.

The SSLCertificateKeyFile directive tells Apache HTTP Server where to find the PEM-encoded private key file corresponding to the certificate file identified by the SSLCertificateFile directive. Depending on how the certificate file was generated, it may contain a RSA or DSA private key file, making the SSLCertificateKeyFile directive redundant; however, Apache strongly discourages that practice. The recommended approach is to separate the certificate and the private key. If the private key is encrypted, Apache HTTP Server will require a pass phrase to be entered when it starts up.

The ProxyPass and ProxyPassReverse directives should be set up in manner described in Step 5.

For more information about the support for SSL in Apache HTTP Server, refer to the Apache SSL/TLS Encryption manual. In addition, you will find lots of relevant information in the <apache directory>/conf/extra/httpd-ssl.conf file, which is included in the standard Apache distribution.

Step 8(c): Create SSL certificate and key files

In Step 8(b), you specified server.crt and server.key as the certificate file and private key file respectively. Those two files must be created before we can proceed. This step assumes that OpenSSL is installed on your server.

Generate a server key file:

openssl genrsa -des3 -out server.key 1024

You will be asked to provide a password. Make sure that the password is strong because it will form the one real entry point into the SSL encryption set-up. Make a note of the password because you'll need it when starting Apache HTTP Server later.

Generate a certificate request file (server.csr):

openssl req -new -key server.key -out server.csr

Generate a self-signed certificate (server.crt): 

openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

The above command generates a self-signed certificate that is valid for one year. You can use the certificate signing request to purchase a certificate from a certificate authority. For testing purposes though, the self-signed certificate will suffice. Copy the certificate file and private key file to the locations you specified in Step 8(b).

cp server.key /usr/local/apache2/conf/
cp server.crt /usr/local/apache2/conf/

Step 8(d): Update the base URL for 'https'

Open a browser window and log into Stash using an administrator account. Go to the Stash administration area and click Server settings (under 'Settings'). Change Base URL to use 'https'.

Using a self-signed certificate

There are two implications of using the self-signed certificate:

• When you access Stash in a web browser, you can expect a warning to appear, alerting you that an un-trusted certificate is in use. Before proceeding you will have to indicate to the browser that you trust the certificate.
• When you perform a git clone operation, SSL verification will fail.

error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed while accessing  https://justme@mycompany/git/TP/test.git

GIT_SSL_NO_VERIFY=true git clone  https://justme@mycompany/git/TP/test.git

A note about application links

When an application link is established between Stash and another Atlassian product (e.g. JIRA), and Stash is operating 'behind' Apache HTTP Server, the link from the other product to Stash must be via the proxy URL; that is, the 'reciprocal URL' from, say JIRA, to Stash must comport with the proxy name and port that you set at Step 1.

Troubleshooting

• On Fedora Core 4, people have reported 'permission denied' errors when trying to get mod_proxy (and mod_jk) working. Disabling SELinux (/etc/selinux/config) apparently fixes this.
• Some users have reported problems with user sessions being hijacked when the mod_cache module is enabled. If you have such problems, disable the mod_cache module. Note that this module is enabled by default in some Apache HTTP Server version 2 distributions.
• In general, if you are having problems:

• 1. Ensure that Stash works as expected when running directly from Tomcat on http://localhost:7990/stash.
  2. Watch the log files (usually in /var/log/httpd/ or /var/log/apache2/). Check that you have a LogLevel directive in your httpd.conf, and turn up logging ('LogLevel debug') to get more info.
  3. Check out the Stash Knowledge Base.