Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/460290

Since https://github.com/golang/crypto/commit/eb61739cd99fb244c7cd188d3c5bae54824e781d
it is now possible to restrict the host_key_algorithms.
This commit allows sshd to restrict them in the server config.

This adds support for specifying host certificates via the
`host_cert_files` option and advertises the signed key to the
client. This acts similarly to OpenSSH's `HostCertificate` parameter:
gitlab-sshd attempts to match a host key to its certificate, and then
substitutes the matching host key with a certificate signed by a
trusted certificate authority's key.

This is the first requirement to supporting SSH certificates. This
will enable the client to trust the server if both trust a common
certificate authority. The `TrustedUserCAKeys` option will need to be
supported later for the server to trust all user keys signed by this
certificate authority.

Relates to https://gitlab.com/gitlab-org/gitlab-shell/-/issues/495

The config option is basically a copy of LoginGraceTime OpenSSH
option.

If an SSH connection is hanging unauthenticated, after some period
of time, the connection gets canceled. The value is configurable,
the server waits for 60 seconds by default.

It seems that a lot of users rely on this, let's return it and
deprecated later to make the migration less disruptive

We don't support diffie-hellman-group14-sha1 via OpenSSH currently
Let's avoid introducing it in gitlab-sshd because it's using
weak hashing algorithm

Issue: https://gitlab.com/gitlab-org/gitlab-shell/-/issues/576

ProxyHeaderTimeout must be small to avoid DoS risk

Let's make the value configurable and 500ms by default

MACs, Ciphers and KEX algorithms now can be configured
If the values are empty, reasonable defaults are used

Git clients sometimes open a connection and leave it idling,
like when compressing objects.
Settings like timeout client in HAProxy might cause these
idle connections to be terminated.

Let's send the keepalive message in order to prevent a client
from closing

It would give us more flexibility when we decide to enable
PROXY protocol

This reverts commit 3a2c8f2c47774a35d840ec8baf54341beede5d43.

Contributes to https://gitlab.com/gitlab-org/gitlab-shell/-/issues/541

Changelog: removed

The option isn't required to accept self-signed certs

On the other hand, if the option set to true it makes
machine-in-the-middle attack possible

Let's clarify it in the code that the option is deprecated

Edited log_format description comment, if for 'text' if a user need 'text' logging

Add a basic monitoring endpoint to the sshd command.
* Listen on localhost port 9122 by default.
* Integrate build/version info.
* Update example config.

https://gitlab.com/gitlab-org/gitlab-shell/-/issues/121



Signed-off-by: Ben Kochie <superq@gmail.com>

The config.yml.example didn't include a field I was expecting to be
there, which lead me to believe the field didn't exist. This change adds
the `secret` YAML field, and describes how it interacts with the
secrets_file.

From
https://gitlab.com/gitlab-org/omnibus-gitlab/-/merge_requests/4498#note_397401883,
if you specify a relative path such as:

```
external_url 'http://gitlab.example.com/gitlab'
```

gitlab-shell doesn't have a way to pass the `/gitlab` to the host. For example, let's say we have:

```
gitlab_url: "http+unix://%2Fvar%2Fopt%2Fgitlab%2Fgitlab-workhorse%2Fsocket"
```

If we have `/gitlab` as the relative path, how do we specify what is the
UNIX socket path and what is the relative path? If we specify:

```
gitlab_url: "http+unix:///var/opt/gitlab/gitlab-workhorse.socket/gitlab
```

This is ambiguous. Is the socket in
`/var/opt/gitlab/gitlab-workhorse.socket/gitlab` or in
`/var/opt/gitlab/gitlab-workhorse.socket`?

To fix this, this merge request adds an optional
`gitlab_relative_url_root` config parameter:

```
gitlab_url: "http+unix://%2Fvar%2Fopt%2Fgitlab%2Fgitlab-workhorse%2Fsocket"
gitlab_relative_url_root: /gitlab
```

This is only used with UNIX domain sockets to disambiguate the socket
and base URL path. If `gitlab_url` uses `http://` or `https://`, then
`gitlab_relative_url_root` is ignored.

Relates to https://gitlab.com/gitlab-org/gitlab-shell/-/issues/476

The unicorn replacement 'puma' uses a unix socket in the example config [1] instead of a tcp port.
Using the non-existing tcp port results in "Internal API unreachable" on
git operations.

[1] https://gitlab.com/gitlab-org/gitlab/-/blob/master/config/puma.rb.example#L34

It now lives within gitaly

In order to uncomment it in the Makefile of GDK

Adds distributed tracing instrumentation to GitLab-Shell using LabKit

Given the gitaly-* now proxy the data from the client to the Gitaly
server, the environment variables aren't used. Therefor we don't have to
set them either. Only exception to the rule, is the GITALY_TOKEN.

These changes also remove the `GIT_TRACE` options, introduced by
192e2bd3.

Part of: https://gitlab.com/gitlab-org/gitaly/issues/1300