Getting started with developing Sourcegraph

Have a look around, our code is on GitHub.

Outline

Environment

Sourcegraph server is a collection of smaller binaries. The development server, dev/start.sh, initializes the environment and starts a process manager that runs all of the binaries. See the Architecture doc for a full description of what each of these services does. The sections below describe the dependencies you need to run dev/start.sh.

Step 1: Install dependencies

Sourcegraph has the following dependencies:

The following are two recommendations for installing these dependencies:

macOS

  1. Install Homebrew.

  2. Install Docker for Mac.

    optionally via brew

    brew cask install docker
    
    1. Install Go, Node Version Manager, PostgreSQL, Redis, Git, NGINX, golang-migrate, Comby, and SQLite tools with the following command: bash brew install go yarn redis postgresql git gnu-sed nginx golang-migrate comby sqlite pcre FiloSottile/musl-cross/musl-cross
  3. Install the Node Version Manager (nvm) using:

    NVM_VERSION="$(curl https://api.github.com/repos/nvm-sh/nvm/releases/latest | jq -r .name)"
    curl -L https://raw.githubusercontent.com/nvm-sh/nvm/"$NVM_VERSION"/install.sh -o install-nvm.sh
    sh install-nvm.sh
    

    After the install script is finished, re-source your shell profile (e.g., source ~/.zshrc) or restart your terminal session to pick up the nvm definitions. Re-running the install script will update the installation. Note: nvm is implemented as a shell function, so it may not show up in the output of which nvm. Use type nvm to verify whether it is set up. There is also a Homebrew package for nvm, but it is unsupported by the nvm maintainers. 5. Install the current recommended version of Node JS by running the following from the working directory of a sourcegraph repository clone:

    nvm install
    nvm use --delete-prefix
    

    After doing this, node -v should show the same version mentioned in .nvmrc at the root of the sourcegraph repository.

    Note: Although there is a Homebrew package for Node, we advise using nvm instead, to ensure you get a Node version compatible with the current state of the sourcegraph repository.

  4. Configure PostgreSQL and Redis to start automatically

    brew services start postgresql
    brew services start redis
    

    (You can stop them later by calling stop instead of start above.) 7. Ensure psql, the PostgreSQL command line client, is on your $PATH. Homebrew does not put it there by default. Homebrew gives you the command to run to insert psql in your path in the “Caveats” section of brew info postgresql. Alternatively, you can use the command below. It might need to be adjusted depending on your Homebrew prefix (/usr/local below) and shell (bash below).

    hash psql || { echo 'export PATH="/usr/local/opt/postgresql/bin:$PATH"' >> ~/.bash_profile }
    source ~/.bash_profile
    
  5. Open a new Terminal window to ensure psql is now on your $PATH.

Ubuntu

  1. Add package repositories:

    # Go
    sudo add-apt-repository ppa:longsleep/golang-backports
    
    # Docker
    curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
    sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
    
    # Yarn
    curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
    echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
    
    1. Update repositories: bash sudo apt-get update
  2. Install dependencies:

    sudo apt install -y make git-all postgresql postgresql-contrib redis-server nginx libpcre3-dev libsqlite3-dev pkg-config golang-go musl-tools docker-ce docker-ce-cli containerd.io yarn
    
    # install golang-migrate (you must move the extracted binary into your $PATH)
    curl -L https://github.com/golang-migrate/migrate/releases/download/v4.7.0/migrate.linux-amd64.tar.gz | tar xvz
    
    # install comby (you must move the extracted binary into your $PATH)
    curl -L https://github.com/comby-tools/comby/releases/download/0.11.3/comby-0.11.3-x86_64-linux.tar.gz | tar xvz
    
    # nvm (to manage Node.js)
    curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.2/install.sh | bash
    
    # in repo dir: install current recommendend version of Node JS
    nvm install
    
    1. Configure startup services bash sudo systemctl enable postgresql sudo systemctl enable redis-server.service
  3. (optional) You can also run Redis using Docker

    In this case you should not enable the redis-server.service from the previous step.

    dockerd # if docker isn't already running
    docker run -p 6379:6379 -v $REDIS_DATA_DIR redis
    # $REDIS_DATA_DIR should be an absolute path to a folder where you intend to store Redis data
    

    You need to have Redis running when you start the dev server later on. If you have issues running Docker, try adding your user to the docker group, and/or updating the socket file persimissions, or try running these commands under sudo.

    (optional) asdf

    asdf is a CLI tool that manages runtime versions for a number of different languages and tools. It can be likened to a language-agnostic version of nvm or pyenv. We use asdf in buildkite to lock the versions of the tools that we use on a per-commit basis.

    Install

    asdf binary

    See the installation instructions on the official asdf documentation.

    Plugins

    sourcegraph/sourcegraph uses the following plugins: - Go

    asdf plugin add golang
    
asdf plugin add nodejs

# Import the Node.js release team's OpenPGP keys to main keyring
bash ~/.asdf/plugins/nodejs/bin/import-release-team-keyring

# Have asdf read .nvmrc for auto-switching between node version
## Add the following to $HOME/.asdfrc:
legacy_version_file = yes
asdf plugin add yarn

Usage instructions

asdf uses versions specified in .tool-versions whenever a command is run from one of sourcegraph/sourcegraph’s subdirectories.

You can install the all the versions specified in .tool-versions by running asdf install.

Step 2: Initialize your database

You need a fresh Postgres database and a database user that has full ownership of that database.

  1. Create a database for the current Unix user

    # For Linux users, first access the postgres user shell
    sudo su - postgres
    
    createdb
    
  2. Create the Sourcegraph user and password

    createuser --superuser sourcegraph
    psql -c "ALTER USER sourcegraph WITH PASSWORD 'sourcegraph';"
    
    1. Create the Sourcegraph database bash createdb --owner=sourcegraph --encoding=UTF8 --template=template0 sourcegraph
  3. Configure database settings in your environment

    The Sourcegraph server reads PostgreSQL connection configuration from the PG* environment variables.

    Add these, for example, in your ~/.bashrc:

    export PGPORT=5432
    export PGHOST=localhost
    export PGUSER=sourcegraph
    export PGPASSWORD=sourcegraph
    export PGDATABASE=sourcegraph
    export PGSSLMODE=disable
    

    You can also use a tool like envdir or a .dotenv file to source these env vars on demand when you start the server.

    More info

    For more information about data storage, read our full PostgreSQL Guide page. Migrations are applied automatically.

    Step 3: (macOS) Start Docker

    Option A: Docker for Mac

    This is the easy way - just launch Docker.app and wait for it to finish loading.

    Option B: docker-machine

    The Docker daemon should be running in the background, which you can test by running docker ps. If you’re on OS X and using docker-machine instead of Docker for Mac, you may have to run:

    docker-machine start default
    eval $(docker-machine env)
    

Step 4: Get the code

git clone https://github.com/sourcegraph/sourcegraph.git

Step 5: Configure HTTPS reverse proxy

Sourcegraph’s development environment ships with a Caddy 2 HTTPS reverse proxy that allows you to access your local sourcegraph instance via https://sourcegraph.test:3443 (a fake domain with a self-signed certificate that’s added to /etc/hosts).

Prerequisites

In order to configure the HTTPS reverse-proxy, you’ll need to edit /etc/hosts and initialize Caddy 2.

Add sourcegraph.test to /etc/hosts

sourcegraph.test needs to be added to /etc/hosts as an alias to 127.0.0.1. There are two main ways of accomplishing this:

  1. Manually append 127.0.0.1 sourcegraph.test to /etc/hosts
  2. Use the provided ./dev/add_https_domain_to_hosts.sh convenience script (sudo may be required).
> ./dev/add_https_domain_to_hosts.sh

--- adding sourcegraph.test to '/etc/hosts' (you may need to enter your password)
Password:
Adding host(s) "sourcegraph.test" to IP address 127.0.0.1
--- printing '/etc/hosts'
...
127.0.0.1        localhost sourcegraph.test
...

Initialize Caddy 2

Caddy 2 automatically manages self-signed certificates and configures your system so that your web browser can properly recognize them. The first time that Caddy runs, it needs root/sudo permissions to add its keys to your system’s certificate store. You can get this out the way after installing Caddy 2 by running the following command and entering your password when prompted:

env SOURCEGRAPH_HTTPS_DOMAIN=sourcegraph.test SOURCEGRAPH_HTTPS_PORT=3443 ./dev/caddy.sh run --watch --config=dev/Caddyfile

...
2020/03/23 12:30:18 [INFO][cache:0xc0007879a0] Started certificate maintenance routine
2020/03/23 19:30:18.079	INFO	http	enabling automatic HTTP->HTTPS redirects{"server_name": "srv0"}
2020/03/23 19:30:18.192	WARN	pki.ca.local	trusting root certificate (you might be prompted for password)	{"path": "storage:pki/authorities/local/root.crt"}
...
Password:

CTRL+C out of this command when it prints that the certificates have been installed properly:

2020/03/23 12:30:51 certificate installed properly in macOS keychain

You might need to restart your web browsers in order for them to recognize the certificates.

Step 6: Start the server

cd sourcegraph
./dev/start.sh

This will continuously compile your code and live reload your locally running instance of Sourcegraph.

Navigate your browser to https://sourcegraph.test:3443 to see if everything worked.

Troubleshooting

Problems with node_modules or Javascript packages

Noticing problems with node_modules/ or package versions? Try running this command to clear the local package cache.

yarn cache clean
rm -rf node_modules web/node_modules
yarn
cd web
yarn

dial tcp 127.0.0.1:3090: connect: connection refused

This means the frontend server failed to start, for some reason. Look through the previous logs for possible explanations, such as failure to contact the redis server, or database migrations failing.

Database migration failures

While developing Sourcegraph, you may run into:

frontend | failed to migrate the DB. Please contact [email protected] for further assistance:Dirty database version 1514702776. Fix and force version.

You may have to run migrations manually. First, install the Go migrate CLI, then run dev/migrate.sh up

If you get something like error: Dirty database version 1514702776. Fix and force version., you need to roll things back and start from scratch.

dev/migrate.sh drop
dev/migrate.sh up

If you receive errors while migrating, try dropping the database

dev/drop-entire-local-database.sh
dev/migrate.sh up

Internal Server Error

If you see this error when opening the app:

500 Internal Server Error template: app.html:21:70: executing "app.html" at <version "styles/styl...>: error calling version: open ui/assets/styles/app.bundle.css: no such file or directory

that means Webpack hasn’t finished compiling the styles yet (it takes about 3 minutes). Simply wait a little while for a message from webpack like web | Time: 180000ms to appear in the terminal.

Increase maximum available file descriptors.

./dev/start.sh may ask you to run ulimit to increase the maximum number of available file descriptors for a process. You can make this setting permanent for every shell session by adding the following line to your .*rc file (usually .bashrc or .zshrc):

# increase max number of file descriptors for running a sourcegraph instance.
ulimit -n 10000

On Linux, it may also be necessary to increase sysctl -n fs.inotify.max_user_watches, which can be done by running one of the following:

echo 524288 | sudo tee -a /proc/sys/fs/inotify/max_user_watches

# If the above doesn't work, you can also try this:
sudo sysctl fs.inotify.max_user_watches=524288

If you ever need to wipe your local database and Redis, run the following command.

./dev/drop-entire-local-database-and-redis.sh

Caddy 2 certificate problems

We use Caddy 2 to setup HTTPS for local development. It creates self-signed certificates and uses that to serve the local Sourcegraph instance. If your browser complains about the certificate, check the following:

  1. The first time that Caddy 2 reverse-proxies your Sourcegraph instance, it needs to add its certificate authority to your local certificate store. This may require elevated permissions on your machine. If you haven’t done so already, try running caddy reverse-proxy --to localhost:3080 and enter your password if prompted. You may also need to run that command as the root user.

  2. If you have completed the previous step and your browser still complains about the certificate, try restarting your browser or your local machine.

How to Run Tests

See testing.md for details.

CPU/RAM/bandwidth/battery usage

On first install, the program will use quite a bit of bandwidth to concurrently download all of the Go and Node packages. After packages have been installed, the Javascript assets will be compiled into a single Javascript file, which can take up to 5 minutes, and can be heavy on the CPU at times.

After the initial install/compile is complete, the Docker for Mac binary uses about 1.5GB of RAM. The numerous different Go binaries don’t use that much RAM or CPU each, about 5MB of RAM each.

If you notice heavy battery and CPU usage running gulp --color watch, please first double check that Spotlight is not indexing your Sourcegraph repository, as this can lead to additional, unnecessary, poll events.

If you’re running macOS 10.15.x (Catalina) reinstalling the Xcode Command Line Tools may be necessary as follows:

  1. Uninstall the Command Line Tools with rm -rf /Library/Developer/CommandLineTools
  2. Reinstall it with xcode-select --install
  3. Go to sourcegraph/sourcegraph’s root directory and run rm -rf node_modules
  4. Re-run the launch script (./dev/start.sh)

How to debug live code

How to debug a program with Visual Studio Code:

Debug TypeScript code

Requires “Debugger for Chrome” extension.

  • Quit Chrome
  • Launch Chrome (Canary) from the command line with a remote debugging port:
    • Mac OS: /Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary --remote-debugging-port=9222
    • Windows: start chrome.exe –remote-debugging-port=9222
    • Linux: chromium-browser --remote-debugging-port=9222
  • Go to http://localhost:3080
  • Open the Debugger in VSCode: “View” > “Debug”
  • Launch the (ui) http://localhost:3080/* debug configuration
  • Set breakpoints, enjoy

Debug Go code

Install Delve:

xcode-select --install
go get -u github.com/go-delve/delve/cmd/dlv

Then install pgrep:

brew install proctools

Make sure to run env DELVE=true dev/start.sh to disable optimizations during compilation, otherwise Delve will have difficulty stepping through optimized functions (line numbers will be off, you won’t be able to print local variables, etc.).

Now you can attach a debugger to any Go process (e.g. frontend, searcher, go-langserver) in 1 command:

dlv attach $(pgrep frontend)

Delve will pause the process once it attaches the debugger. Most used commands:

  • b cmd/frontend/db/access_tokens.go:52 to set a breakpoint on a line (bp lists all, clearall deletes all)
  • c to continue execution of the program
  • Ctrl-C pause the program to bring back the command prompt
  • n to step over the next statement
  • s to step into the next function call
  • stepout to step out of the current function call
  • Ctrl-D to exit

Go dependency management

We use Go modules to manage Go dependencies in this repository.

Codegen

The Sourcegraph repository relies on code generation triggered by go generate. Code generation is used for a variety of tasks:

  • generating code for mocking interfaces
  • generate wrappers for interfaces (e.g., ./server/internal/middleware/* packages)
  • pack app templates and assets into binaries

To generate everything, just run:

./dev/generate.sh

Note: Sometimes, there are erroneous diffs. This occurs for a few reasons, none of which are legitimate (i.e., they are tech debt items we need to address):

  • The codegen tools might emit code that depends on system configuration, such as the system timezone or packages you have in your GOPATH. We need to submit PRs to the tools to eliminate these issues.
  • You might have existing but gitignored files that the codegen tools read on your disk that other developers don’t have. (This occurs for app assets especially.)

If you think a diff is erroneous, don’t commit it. Add a tech debt item to the issue tracker and assign the person who you think is responsible (or ask).

Windows support

Running Sourcegraph on Windows is not actively tested, but should be possible within the Windows Subsystem for Linux (WSL). Sourcegraph currently relies on Unix specifics in several places, which makes it currently not possible to run Sourcegraph directly inside Windows without WSL. We are happy to accept contributions here! :)

Other nice things

Offline development

Sometimes you will want to develop Sourcegraph but it just so happens you will be on a plane or a train or perhaps a beach, and you will have no WiFi. And you may raise your fist toward heaven and say something like, “Why, we can put a man on the moon, so why can’t we develop high-quality code search without an Internet connection?” But lower your hand back to your keyboard and fret no further, for the year is 2019, and you can develop Sourcegraph with no connectivity by setting the OFFLINE environment variable:

OFFLINE=true dev/start.sh