GitLab Pages Daemon
This is a simple HTTP server written in Go, made to serve GitLab Pages with
CNAMEs and SNI using HTTP/HTTP2. The minimum supported Go version is v1.11.
This is made to work in small to medium-scale environments. Start-up time scales
with the number of projects being served, so the daemon is currently unsuitable
for very large-scale environments.
How it generates routes
- It reads the
pages-root
directory to list all groups.
- It looks for
config.json
files in pages-root/group/project
directories,
reads them and creates mapping for custom domains and certificates.
- It generates virtual hosts from these data.
- Periodically (every second) it checks the
pages-root/.update
file and reads
its content to verify if there was an update.
To reload the configuration, fill the pages-root/.update
file with random
content. The reload will be done asynchronously, and it will not interrupt the
current requests.
How it serves content
-
When client initiates the TLS connection, the GitLab-Pages daemon looks in
the generated configuration for virtual hosts. If present, it uses the TLS
key and certificate in config.json
, otherwise it falls back to the global
configuration.
-
When client connects to a HTTP port the GitLab-Pages daemon looks in the
generated configuration for a matching virtual host.
-
The URL.Path is split into /<project>/<subpath>
and the daemon tries to
load: pages-root/group/project/public/subpath
.
-
If the file is not found, it will try to load pages-root/group/<host>/public/<URL.Path>
.
-
If requested path is a directory, the index.html
will be served.
-
If .../path.gz
exists, it will be served instead of the main file, with
a Content-Encoding: gzip
header. This allows compressed versions of the
files to be precalculated, saving CPU time and network bandwidth.
HTTPS only domains
Users have the option to enable "HTTPS only pages" on a per-project basis.
This option is also enabled by default for all newly-created projects.
When the option is enabled, a project's config.json
will contain an
https_only
attribute.
When the https_only
attribute is found in the root context, any project pages
served over HTTP via the group domain (i.e. username.gitlab.io
) will be 301
redirected to HTTPS.
When the attribute is found in a custom domain's configuration, any HTTP
requests to this domain will likewise be redirected.
If the attribute's value is false, or the attribute is missing, then
the content will be served to the client over HTTP.
How it should be run?
Ideally the GitLab Pages should run without any load balancer in front of it.
If a load balancer is required, the HTTP can be served in HTTP mode. For HTTPS
traffic, the load balancer should be run in TCP mode. If the load balancer is
run in SSL-offloading mode, custom TLS certificates will not work.
How to run it
Example:
$ make
$ ./gitlab-pages -listen-http ":8090" -pages-root path/to/gitlab/shared/pages -pages-domain example.com
To run on HTTPS ensure you have a root certificate key pair available
$ make
$ ./gitlab-pages -listen-https ":9090" -root-cert=path/to/example.com.crt -root-key=path/to/example.com.key -pages-root path/to/gitlab/shared/pages -pages-domain example.com
Run daemon in secure mode
When compiled with CGO_ENABLED=0
(which is the default), gitlab-pages
is a
static binary and so can be run in chroot with dropped privileges.
To enter this mode, run gitlab-pages
as the root user and pass it the
-daemon-uid
and -daemon-gid
arguments to specify the user you want it to run
as.
The daemon starts listening on ports and reads certificates as root, then
re-executes itself as the specified user. When re-executing it creates a chroot jail
containing a copy of its own binary, /etc/resolv.conf
, and a bind mount of pages-root
.
When -artifacts-server
points to an HTTPS URL we also need a list of certificates for
the trusted Certification Authorities to copy inside the jail.
A file containing such list can be specified using SSL_CERT_FILE
environment variable.
(SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt
on Debian)
This make it possible to listen on privileged ports and makes it harder for the
process to read files outside of pages-root
.
Example:
$ make
$ sudo ./gitlab-pages -listen-http ":80" -pages-root path/to/gitlab/shared/pages -pages-domain example.com -daemon-uid 1000 -daemon-gid 1000
Caveats
The /etc/resolv.conf
file, and any file pointed to by the SSL_CERT_FILE
environment variable, will be copied into the jail. As a result, changes to
these files will not be reflected in Pages until it's restarted.
Bind mounts are unavailable on a range of non-Linux systems. Some of these
systems (e.g., BSD) offer native "jail" functionality. It is recommended to set
up an externally-managed jail and run the Pages daemon within it as an ordinary
user if available.
A less-functional (but just as secure) operation mode is provided via the
-daemon-inplace-chroot
command-line option. If passed, Pages will daemonize
as usual, but chroot directly to the -pages-root
directory instead of building
a complete jail in the system temporary directory. There are some known issues
with this mode, such as:
- Pages service will not be able to resolve the domain name of the auth server and the artifacts server due to missing
/etc/resolv.conf
at the chroot directory. As a workaround, you can manually copy the file to the pages root directory, however, it might cause a conflict with an existing pages data. As a result of DNS not working:
- TLS operation (on some systems) will not work
The default secure mode will also fail for certain Linux-based configurations.
Known cases include:
- The Pages daemon is running inside an unprivileged container
- Bind mount functionality requires the
CAP_SYS_ADMIN
privilege
- This is only available to containers run in privileged mode
- The system temporary directory is mounted
noexec
or nodev
- The jail is created in
$TMPDIR
.
- Character device files are created within the jail
- A copy of the gitlab-pages executable is run from within the bind mount
- AppArmor/SELinux is enabled
- These systems disallow bind-mounting in certain configurations
In these cases, workarounds are similar to those documented for non-Linux
systems - use an external jailing technology, or fall back to the pre-v0.8.0
behaviour using -daemon-inplace-chroot
.
On Linux, Docker and other containerization systems can be used to build a jail
within which the Pages daemon can safely run with secure mode disabled. However,
this configuration is not secure if simply using the default
gitlab/gitlab-ce
and gitlab-gitlab-ee
Docker containers!
Listen on multiple ports
Each of the listen-http
, listen-https
and listen-proxy
arguments can be
provided multiple times. Gitlab Pages will accept connections to them all.
Example:
$ make
$ ./gitlab-pages -listen-http "10.0.0.1:8080" -listen-https "[fd00::1]:8080" -pages-root path/to/gitlab/shared/pages -pages-domain example.com
This is most useful in dual-stack environments (IPv4+IPv6) where both Gitlab
Pages and another HTTP server have to co-exist on the same server.
Listening behind a reverse proxy
When listen-proxy
is used please make sure that your reverse proxy solution is configured to strip the RFC7239 Forwarded headers.
We use gorilla/handlers.ProxyHeaders
middleware. For more information please review the gorilla/handlers#ProxyHeaders documentation.
NOTE: This middleware should only be used when behind a reverse proxy like nginx, HAProxy or Apache. Reverse proxies that don't (or are configured not to) strip these headers from client requests, or where these headers are accepted "as is" from a remote client (e.g. when Go is not behind a proxy), can manifest as a vulnerability if your application uses these headers for validating the 'trustworthiness' of a request.
GitLab access control
GitLab access control is configured with properties auth-client-id
, auth-client-secret
, auth-redirect-uri
, auth-server
and auth-secret
. Client ID, secret and redirect uri are configured in the GitLab and should match. auth-server
points to a GitLab instance used for authentication. auth-redirect-uri
should be http(s)://pages-domain/auth
. Note that if the pages-domain is not handled by GitLab pages, then the auth-redirect-uri
should use some reserved namespace prefix (such as http(s)://projects.pages-domain/auth
). Using HTTPS is strongly encouraged. auth-secret
is used to encrypt the session cookie, and it should be strong enough.
Example:
$ make
$ ./gitlab-pages -listen-http "10.0.0.1:8080" -listen-https "[fd00::1]:8080" -pages-root path/to/gitlab/shared/pages -pages-domain example.com -auth-client-id <id> -auth-client-secret <secret> -auth-redirect-uri https://projects.example.com/auth -auth-secret something-very-secret -auth-server https://gitlab.com
NOTE: Note:
GitLab access control might not work with -daemon-inplace-chroot
option. Please take a look at the caveat section above.
How it works
- GitLab pages looks for
access_control
and id
fields in config.json
files
in pages-root/group/project
directories.
- For projects that have
access_control
set to true
pages will require user to authenticate.
- When user accesses a project that requires authentication, user will be redirected
to GitLab to log in and grant access for GitLab pages.
- When user grant's access to GitLab pages, pages will use the OAuth2
code
to get an access
token which is stored in the user session cookie.
- Pages will now check user's access to a project with a access token stored in the user
session cookie. This is done via a request to GitLab API with the user's access token.
- If token is invalidated, user will be redirected again to GitLab to authorize pages again.
Enable Prometheus Metrics
For monitoring purposes, you can pass the -metrics-address
flag when starting.
This will expose general metrics about the Go runtime and pages application for
Prometheus to scrape.
Example:
$ make
$ ./gitlab-pages -listen-http ":8090" -metrics-address ":9235" -pages-root path/to/gitlab/shared/pages -pages-domain example.com
Structured logging
You can use the -log-format json
option to make GitLab Pages output
JSON-structured logs. This makes it easer to parse and search logs
with tools such as ELK.
Cross-origin requests
GitLab Pages defaults to allowing cross-origin requests for any resource it
serves. This can be disabled globally by passing -disable-cross-origin-requests
when starting the daemon.
Having cross-origin requests enabled allows third-party websites to make use of
files stored on the Pages server, which allows various third-party integrations
to work. However, if it's running on a private network, this may allow websites
on the public Internet to access its contents via your user's browsers -
assuming they know the URL beforehand.
SSL/TLS versions
GitLab Pages defaults to TLS 1.2 as the minimum supported TLS version. This can be
configured by using the -tls-min-version
and -tls-max-version
options. Accepted
values are ssl3
, tls1.0
, tls1.1
, tls1.2
, and tls1.3
(if supported). When tls1.3
is used GitLab Pages will add tls13=1
to GODEBUG
to enable TLS 1.3.
See https://golang.org/src/crypto/tls/tls.go for more.
To specify custom headers that should be send with every request on GitLab pages use the -header
argument.
You can add as many headers as you like.
Example:
./gitlab-pages -header "Content-Security-Policy: default-src 'self' *.example.com" -header "X-Test: Testing" ...
Configuration
The daemon can be configured with any combination of these methods:
- Command-line options
- Environment variables
- Configuration file
- Compile-time defaults
To see the available options and defaults, run:
./gitlab-pages -help
When using more than one method (e.g., configuration file and command-line
options), they follow the order of precedence given above.
To convert a flag name into an environment variable name:
- Drop the leading -
- Convert all - characters into _
- Uppercase the flag
e.g., -pages-domain=example.com
becomes PAGES_DOMAIN=example.com
A configuration file is specified with the -config
flag (or CONFIG
environment variable). Directives are specified in key=value
format, like:
pages-domain=example.com
use-http2=false
License
MIT