Merge branch 'docs-debug-harishsr' into 'master'

Port 3 more debug docs to the docs project

Closes #63035

See merge request gitlab-org/gitlab-ce!31368

doc/administration/index.md

@@ -187,13 +187,29 @@ Learn how to install, configure, update, and maintain your GitLab instance.
 - [Debugging tips](troubleshooting/debug.md): Tips to debug problems when things go wrong
 - [Log system](logs.md): Where to look for logs.
 - [Sidekiq Troubleshooting](troubleshooting/sidekiq.md): Debug when Sidekiq appears hung and is not processing jobs.
-- Useful [diagnostics tools](troubleshooting/diagnostics_tools.md) that are sometimes used by the GitLab
-  Support team.
-- [Troubleshooting ElasticSearch](troubleshooting/elasticsearch.md): Tips to troubleshoot ElasticSearch.
-- [Kubernetes troubleshooting](troubleshooting/kubernetes_cheat_sheet.md): Commands and tips useful
-  for troubleshooting Kubernetes-related issues.
-- Useful links from the Support Team:
-  - [GitLab Developer Docs](https://docs.gitlab.com/ee/development/README.html).
-  - [Repairing and recovering broken Git repositories](https://git.seveas.net/repairing-and-recovering-broken-git-repositories.html).
-  - [Testing with OpenSSL](https://www.feistyduck.com/library/openssl-cookbook/online/ch-testing-with-openssl.html).
-  - [Strace zine](https://wizardzines.com/zines/strace/).
+- [Troubleshooting ElasticSearch](troubleshooting/elasticsearch.md)
+
+### Support Team Docs
+
+The GitLab Support Team has collected a lot of information about troubleshooting GitLab
+instances. These documents are normally used by the Support Team itself, or by customers
+with direct guidance from a Support Team member. GitLab administrators may find the
+information useful for troubleshooting, but if you are experiencing trouble with your
+GitLab instance, you should check your [support options](https://about.gitlab.com/support/)
+before referring to these documents.
+
+CAUTION: **Warning:**
+Using the commands listed in the documentation below could result in data loss or
+other damage to a GitLab instance, and should only be used by experienced administrators
+who are aware of the risks.
+
+- [Useful diagnostics tools](troubleshooting/diagnostics_tools.md)
+- [Useful Linux commands](troubleshooting/linux_cheat_sheet.md)
+- [Troubleshooting Kubernetes](troubleshooting/kubernetes_cheat_sheet.md)
+- [Guide to test environments](troubleshooting/test_environments.md) (for Support Engineers)
+- [GitLab rails console commands](troubleshooting/gitlab_rails_cheat_sheet.md) (for Support Engineers)
+- Useful links:
+  - [GitLab Developer Docs](../development/README.md)
+  - [Repairing and recovering broken Git repositories](https://git.seveas.net/repairing-and-recovering-broken-git-repositories.html)
+  - [Testing with OpenSSL](https://www.feistyduck.com/library/openssl-cookbook/online/ch-testing-with-openssl.html)
+  - [Strace zine](https://wizardzines.com/zines/strace/)

doc/administration/troubleshooting/linux_cheat_sheet.md

+---
+type: reference
+---
+
+# Linux Cheat Sheet
+
+This is the GitLab Support Team's collection of information regarding Linux, that they
+sometimes use while troubleshooting. It is listed here for transparency,
+and it may be useful for users with experience with Linux. If you are currently
+having an issue with GitLab, you may want to check your [support options](https://about.gitlab.com/support/)
+first, before attempting to use this information.
+
+CAUTION: **CAUTION:**
+If you are administering GitLab you are expected to know these commands for your distribution
+of choice. If you are a GitLab Support Engineer, consider this a cross-reference to
+translate `yum` -> `apt-get` and the like.
+
+Note: **Note:**
+Most of the commands below have not been labeled as to which distribution they work
+on. Contributions are welcome to help add them.
+
+## System Commands
+
+### Distro Information
+
+```bash
+# Debian/Ubuntu
+uname -a
+lsb_release -a
+
+# CentOS/RedHat
+cat /etc/centos-release
+cat /etc/redhat-release
+
+# This will provide a lot more information
+cat /etc/os-release
+```
+
+### Shut down or Reboot
+
+```bash
+shutdown -h now
+reboot
+```
+
+### Permissions
+
+```bash
+# change the user:group ownership of a file/dir
+chown root:git <file_or_dir>
+
+# make a file executable
+chmod u+x <file>
+```
+
+### Files & Dirs
+
+```bash
+# create a new directory and all subdirectories
+mkdir -p dir/dir2/dir3
+
+# Send a command's output to file.txt, no STDOUT
+ls > file.txt
+
+# Send a command's output to file.txt AND see it in STDOUT
+ls | tee /tmp/file.txt
+
+# Search and Replace within a file
+sed -i 's/original-text/new-text/g' <filename>
+```
+
+### See all set environment variables
+
+```bash
+env
+```
+
+## Searching
+
+### File names
+
+```bash
+# search for a file in a filesystem
+find . -name 'filename.rb' -print
+
+# locate a file
+locate <filename>
+
+# see command history
+history
+
+# search CLI history
+<ctrl>-R
+```
+
+### File contents
+
+```bash
+# -B/A = show 2 lines before/after search_term
+grep -B 2 -A 2 search_term <filename>
+
+# -<number> shows both before and after
+grep -2 search_term <filename>
+
+# Search on all files in directory (recursively)
+grep -r search_term <directory>
+
+# search through *.gz files is the same except with zgrep
+zgrep search_term <filename>
+
+# Fast grep printing lines containing a string pattern
+fgrep -R string_pattern <filename or directory>
+```
+
+### CLI
+
+```bash
+# View command history
+history
+
+# Run last command that started with 'his' (3 letters min)
+!his
+
+# Search through command history
+<ctrl>-R
+
+# Execute last command with sudo
+sudo !!
+```
+
+## Managing resources
+
+### Memory, Disk, & CPU usage
+
+```bash
+# disk space info.  The '-h' gives the data in human-readable values
+df -h
+
+# size of each file/dir and its contents in the current dir
+du -hd 1
+
+# or alternative
+du -h --max-depth=1
+
+# find files greater than certain size(k, M, G) and list them in order
+# get rid of the + for exact, - for less than
+find / -type f -size +100M -print0 | xargs -0 du -hs | sort -h
+
+# Find free memory on a system
+free -m
+
+# Find what processes are using memory/CPU and organize by it
+# Load average is 1/CPU for 1, 5, and 15 minutes
+top -o %MEM
+top -o %CPU
+```
+
+### Strace
+
+```bash
+# strace a process
+strace -tt -T -f -y -s 1024 -p <pid>
+
+# -tt   print timestamps with microsecond accuracy
+
+# -T    print the time spent in each syscall
+
+# -f    also trace any child processes that forked
+
+# -y    print the path associated with file handles
+
+# -s    max string length to print for an event
+
+# -o    output file
+
+# run strace on all unicorn processes
+ps auwx | grep unicorn | awk '{ print " -p " $2}' | xargs strace -tt -T -f -y -s 1024 -o /tmp/unicorn.txt
+```
+
+See the [strace zine](https://wizardzines.com/zines/strace/) for a quick walkthrough.
+
+Brendan Gregg has a more detailed explanation of [how to use strace](http://www.brendangregg.com/blog/2014-05-11/strace-wow-much-syscall.html).
+
+Be aware that strace can have major impacts to system performance when it is running.
+
+### The Strace Parser tool
+
+Our [strace-parser tool](https://gitlab.com/wchandler/strace-parser) can be used to
+provide a high level summary of the `strace` output.  It is similar to `strace -C`,
+but provides much more detailed statistics.
+
+MacOS and Linux binaries [are available](https://gitlab.com/gitlab-com/support/toolbox/strace-parser/-/tags),
+or you can build it from source if you have the Rust compiler.
+
+#### How to use the tool
+
+First run the tool with no arguments other than the strace output file name to get
+a summary of the top processes sorted by time spent actively performing tasks. You
+can also sort based on total time, # of syscalls made, PID #, and # of child processes
+using the `-S` or `--sort` flag. The number of results defaults to 25 processes, but
+can be changed using the `-c`/`--count` option.  See `--help` for full details.
+
+```sh
+$ ./strace-parser strace.txt
+
+Top 25 PIDs
+-----------
+
+  pid           active (ms)  wait (ms)  total (ms)   % active    syscalls
+  ----------    ----------  ---------   ---------   ---------   ---------
+  8795             689.072   45773.832   46462.902     16.89%       23018
+  13408            679.432   55910.891   56590.320     16.65%       28593
+  6423             554.822   13175.485   13730.308     13.60%       13735
+...
+```
+
+Based on the summary, you can then view the details of syscalls made by one or more
+procsses using the `-p`/`--pid` for a specific process, or `-s`/`--stats` flags for
+a sorted list. `--stats` takes the same sorting and count options as summary.
+
+```sh
+$ ./strace-parse strace.text -p 6423
+
+PID 6423
+13735 syscalls, active time: 554.822ms, total time: 13730.308ms
+
+  syscall              count         total         max         avg         min  errors
+                                      (ms)        (ms)        (ms)        (ms)
+  ---------------   --------    ----------  ----------  ----------  ----------  --------
+  epoll_wait             628     13175.485      21.259      20.980       0.020
+  clock_gettime         7326       199.500       0.249       0.027       0.013
+  stat                  2101       110.768      19.056       0.053       0.017  ENOENT: 2076
+  ...
+  ---------------
+
+  Parent PID: 495
+  Child PIDs:  8383, 8418, 8419, 8420, 8421
+
+  Slowest file access times for PID 6423:
+
+     open (ms)        timestamp              error     file name
+  -----------   ---------------    ---------------     ----------
+      29.818    10:53:11.528954                        /srv/gitlab-data/builds/2018_08/6174/954448.log
+      12.309    10:53:46.708274                        /srv/gitlab-data/builds/2018_08/5342/954186.log
+      0.039     10:53:49.222110                        /opt/gitlab/embedded/service/gitlab-rails/app/views/events/event/_note.html.haml
+      0.035     10:53:49.125115                        /opt/gitlab/embedded/service/gitlab-rails/app/views/events/event/_push.html.haml
+  ...
+```
+
+In the example above, we can see that file opening times on `/srv/gitlab-data` are
+extremely slow, about 100X slower than `/opt/gitlab`.
+
+When nothing stands out in the results, a good way to get more context is to run `strace`
+on your own GitLab instance while performing the action performed by the customer,
+then compare summaries of both results and dive into the differences.
+
+#### Stats for the open syscall
+
+Rough numbers for calls to `open` and `openat` (used to access files) on various configurations.
+Slow storage can cause the dreaded `DeadlineExceeded` error in Gitaly.
+
+Also [see this entry](https://docs.gitlab.com/ee/administration/operations/filesystem_benchmarking.html)
+in the handbook for quick tests customers can perform to check their filesystem performance.
+
+Keep in mind that timing information from `strace` is often somewhat inaccurate, so
+small differences should not be considered significant.
+
+|Setup          | access times  |
+|:--------------|:--------------|
+| EFS           | 10 - 30ms     |
+| Local Storage | 0.01 - 1ms    |
+
+## Networking
+
+### Ports
+
+```bash
+# Find the programs that are listening on ports
+netstat -plnt
+ss -plnt
+lsof -i -P | grep <port>
+```
+
+### Internet/DNS
+
+```bash
+# Show domain IP address
+dig +short example.com
+nslookup example.com
+
+# Check DNS using specific nameserver
+# 8.8.8.8 = google, 1.1.1.1 = cloudflare, 208.67.222.222 = opendns
+dig @8.8.8.8 example.com
+nslookup example.com 1.1.1.1
+
+# Find host provider
+whois <ip_address> | grep -i "orgname\|netname"
+
+# Curl headers with redirect
+curl --head --location https://example.com
+```
+
+## Package Management
+
+```bash
+# Debian/Ubuntu
+
+# List packages
+dpkg -l
+apt list --installed
+
+# Find an installed package
+dpkg -l | grep <package>
+apt list --installed | grep <package>
+
+# Install a package
+dpkg -i <package_name>.deb
+apt-get install <package>
+apt install <package>
+
+# CentOS/RedHat
+
+# Install a package
+yum install <package>
+dnf install <package> # RHEL/CentOS 8+
+
+rpm -ivh <package_name>.rpm
+
+# Find an installed package
+rpm -qa | grep <package>
+```
+
+## Logs
+
+```bash
+# Print last lines in log file where 'n'
+# is the number of lines to print
+tail -n /path/to/log/file
+```

doc/administration/troubleshooting/test_environments.md

+---
+type: reference
+---
+
+# Apps for a Testing Environment
+
+This is the GitLab Support Team's collection of information regarding testing environments,
+for use while troubleshooting. It is listed here for transparency, and it may be useful
+for users with experience with these tools. If you are currently having an issue with
+GitLab, you may want to check your [support options](https://about.gitlab.com/support/)
+first, before attempting to use this information.
+
+NOTE: **Note:**
+This page was initially written for Support Engineers, so some of the links
+are only available internally at GitLab.
+
+## Docker
+
+The following were tested on docker containers running in the cloud. Support Engineers,
+please see [these docs](https://gitlab.com/gitlab-com/dev-resources/tree/master/dev-resources#running-docker-containers)
+on how to run Docker containers on `dev-resources`. Other setups haven't been tested,
+but contributions are welcome.
+
+### GitLab
+
+Please see [our Docker test environment docs](https://docs.gitlab.com/ee/install/digitaloceandocker.html#create-new-gitlab-container)
+for how to run GitLab on Docker. When spinning this up with `docker-machine`, ensure
+you change a few things:
+
+1. Update the name of the `docker-machine` host. You can see a list of hosts
+   with `docker-machine ls`.
+1. Expose the necessary ports using the `-p` flag. Docker normally doesn't
+   allow access to any ports it uses outside of the container, so they must be
+   explicitly exposed.
+1. Add any necessary `gitlab.rb` configuration to the
+   `GITLAB_OMNIBUS_CONFIG` variable.
+
+For example, when the `docker-machine` host we want to use is `do-docker`:
+
+```sh
+docker run --detach --name gitlab \
+--env GITLAB_OMNIBUS_CONFIG="external_url 'http://$(docker-machine ip do-docker)'; gitlab_rails['gitlab_shell_ssh_port'] = 2222;" \
+--hostname $(docker-machine ip do-docker) \
+-p 80:80 -p 2222:22 \
+gitlab/gitlab-ee:11.5.3-ee.0
+```
+
+### SAML
+
+#### SAML for Authentication
+
+We can use the [test-saml-idp Docker image](https://hub.docker.com/r/jamedjo/test-saml-idp)
+to do the work for us:
+
+```sh
+docker run --name gitlab_saml -p 8080:8080 -p 8443:8443 \
+-e SIMPLESAMLPHP_SP_ENTITY_ID=<GITLAB_IP_OR_DOMAIN> \
+-e SIMPLESAMLPHP_SP_ASSERTION_CONSUMER_SERVICE=<GITLAB_IP_OR_DOMAIN>/users/auth/saml/callback \
+-d jamedjo/test-saml-idp
+```
+
+The following will also need to go in your `/etc/gitlab/gitlab.rb`. See [our SAML docs](https://docs.gitlab.com/ee/integration/saml.html)
+for more, as well as the list of [default usernames, passwords, and emails](https://hub.docker.com/r/jamedjo/test-saml-idp/#usage).
+
+```ruby
+gitlab_rails['omniauth_enabled'] = true
+gitlab_rails['omniauth_allow_single_sign_on'] = ['saml']
+gitlab_rails['omniauth_sync_email_from_provider'] = 'saml'
+gitlab_rails['omniauth_sync_profile_from_provider'] = ['saml']
+gitlab_rails['omniauth_sync_profile_attributes'] = ['email']
+gitlab_rails['omniauth_auto_sign_in_with_provider'] = 'saml'
+gitlab_rails['omniauth_block_auto_created_users'] = false
+gitlab_rails['omniauth_auto_link_ldap_user'] = false
+gitlab_rails['omniauth_auto_link_saml_user'] = true
+gitlab_rails['omniauth_providers'] = [
+  {
+    "name" => "saml",
+    "label" => "SAML",
+    "args" => {
+      assertion_consumer_service_url: '<GITLAB_IP_OR_DOMAIN>/users/auth/saml/callback',
+      idp_cert_fingerprint: '119b9e027959cdb7c662cfd075d9e2ef384e445f',
+      idp_sso_target_url: '<SAML_IP_OR_DOMAIN>:8080/simplesaml/saml2/idp/SSOService.php',
+      issuer: '<GITLAB_IP_OR_DOMAIN>',
+      name_identifier_format: 'urn:oasis:names:tc:SAML:2.0:nameid-format:persistent'
+    }
+  }
+]
+```
+
+#### GroupSAML for GitLab.com
+
+See [the GDK SAML documentation](https://gitlab.com/gitlab-org/gitlab-development-kit/blob/master/doc/howto/saml.md).
+
+### ElasticSearch
+
+```sh
+docker run -d --name elasticsearch \
+-p 9200:9200 -p 9300:9300 \
+-e "discovery.type=single-node" \
+docker.elastic.co/elasticsearch/elasticsearch:5.5.1
+```
+
+Then confirm it works in the browser at `curl http://<IP_ADDRESS>:9200/_cat/health`.
+ElasticSearch's default username is `elastic` and password is `changeme`.
+
+### PlantUML
+
+See [our PlantUML docs](../integration/plantuml.md#docker)
+on running PlantUML in Docker.
+
+### Jira
+
+```sh
+docker run -d -p 8081:8080 cptactionhank/atlassian-jira:latest
+```
+
+Then go to `<IP_ADDRESS>:8081` in the browser to set it up. This requires a
+Jira license.
+
+### Grafana
+
+```sh
+docker run -d --name grafana -e "GF_SECURITY_ADMIN_PASSWORD=gitlab" -p 3000:3000 grafana/grafana
+```
+
+Access it at `<IP_ADDRESS>:3000`.