[![Githbu actions build status](https://img.shields.io/github/workflow/status/snoyberg/keter/Stack)](https://github.com/snoyberg/keter/actions) Deployment system for web applications, originally intended for hosting Yesod applications. Keter does the following actions for your application: * Binds to the main port (usually port 80) and reverse proxies requests to your application based on virtual hostnames. * Provides SSL support if requested. * Automatically launches applications, monitors processes, and relaunches any processes which die. * Provides graceful redeployment support, by launching a second copy of your application, performing a health check[1], and then switching reverse proxying to the new process. * Management of log files. Keter provides many more advanced features and extension points. It allows configuration of static hosts, redirect rules, management of PostgreSQL databases, and more. It supports a simple bundle format for applications which allows for easy management of your web apps. [1]: The health check happens trough checking if a port is opened. If your app doesn't open a port after 30 seconds it's presumed not healthy and gets a term signal. ## Quick Start To get Keter up-and-running quickly for development purposes, on an Ubuntu system (not on your production server), run: wget -O - https://raw.githubusercontent.com/snoyberg/keter/master/setup-keter.sh | bash (Note: This assumes you already have keter installed via cabal.) (Note: you may need to run the above command twice, if the shell exits after `apt-get` but before running the rest of its instructions.) This will download and build Keter from source and get it running with a default configuration. By default Keter will be set up to support HTTPS and will require you to provide a key and certificate in `/opt/keter/etc`. You can disable HTTPS in `/opt/keter/etc/keter-config.yaml` by commenting the certificate and key lines. _This approach is not recommended for a production system_. We do not recommend installing a full GHC toolchain on a production server, nor running such ad-hoc scripts. This is intended to provide a quick way to play with Keter, especially for temporary virtual machines. For a production system, we recommend building the `keter` binary on a separate system, and tracking it via a package manager or similar strategy. ## Bundling your app for Keter 1. Modify your web app to check for the `PORT` environment variable, and have it listen for incoming HTTP requests on that port. Keter automatically assigns arbitrary ports to each web app it manages. When building an app based on the Yesod Scaffold, it may be necessary to change the `port` variable in `config/settings.yaml` from `YESOD_PORT` to `PORT` for compatibility with Keter. 2. Create a file `config/keter.yaml`. The minimal file just has two settings: ```yaml exec: ../path/to/executable host: mydomainname.example.com ``` See the bundles section below for more available settings. 3. Create a gzipped tarball with the `config/keter.yaml` file, your executable, and any other static resources you would like available to your application. This file should be given a `.keter` file extension, e.g. `myapp.keter`. 4. Copy the `.keter` file to `/opt/keter/incoming`. Keter will monitor this directory for file updates, and automatically redeploy new versions of your bundle. Examples are available in the [incoming](https://github.com/snoyberg/keter/tree/master/incoming) directory. ## Setup ### Building keter for Debian, Ubuntu and derivatives Eventually, I hope to provide a PPA for this (please contact me if you would like to assist with this). For now, the following steps should be sufficient: First, install PostgreSQL: sudo apt-get install postgresql Second, build the `keter` binary and place it at `/opt/keter/bin`. To do so, you'll need to install the Haskell Platform, and can then build with `cabal`. This would look something like: sudo apt-get install haskell-platform cabal update cabal install keter sudo mkdir -p /opt/keter/bin sudo cp ~/.cabal/bin/keter /opt/keter/bin Third, create a Keter config file. You can view a sample at https://github.com/snoyberg/keter/blob/master/etc/keter-config.yaml. Optionally, you may wish to change the owner on the `/opt/keter/incoming` folder to your user account, so that you can deploy without `sudo`ing. sudo mkdir -p /opt/keter/incoming sudo chown $USER /opt/keter/incoming ### Building keter for Redhat and derivatives (Centos, Fedora, etc) First, install PostgreSQL: sudo dnf install postgresql Second, build the `keter` binary and place it at `/opt/keter/bin`. To do so, you'll need to install the Haskell Platform, and can then build with `cabal`. This would look something like: sudo dnf install haskell-platform cabal update cabal install keter sudo mkdir -p /opt/keter/bin sudo cp ~/.cabal/bin/keter /opt/keter/bin Third, create a Keter config file. You can view a sample at https://github.com/snoyberg/keter/blob/master/etc/keter-config.yaml. ### Configuring startup For versions of Ubuntu and derivatives 15.04 or greater and Redhat and derivatives (Centos, Fedora, etc) use systemd ``` # /etc/systemd/system/keter.service [Unit] Description=Keter After=network.service [Service] Type=simple ExecStart=/opt/keter/bin/keter /opt/keter/etc/keter-config.yaml [Install] WantedBy=multi-user.target ``` Finally, enable and start the unit (Note: You may need to disable SELinux): sudo systemctl enable keter sudo systemctl start keter Verify that it's actually running with: sudo systemctl status keter Optionally, you may wish to change the owner on the `/opt/keter/incoming` folder to your user account, so that you can deploy without `sudo`ing. sudo mkdir -p /opt/keter/incoming sudo chown $USER /opt/keter/incoming --- For versions of Ubuntu and derivatives less than 15.04, configure an Upstart job. ``` # /etc/init/keter.conf start on (net-device-up and local-filesystems and runlevel [2345]) stop on runlevel [016] respawn # NB: keter writes logs to /opt/keter/log, but some exceptions occasionally # escape to standard error. This ensures they show up in system logs. console output exec /opt/keter/bin/keter /opt/keter/etc/keter-config.yaml ``` Finally, start the job for the first time: sudo start keter ### NixOS Add a nix file `keter.nix` that fetches this repository and imports the module file: ```nix let owner = "snoyberg"; repo = "keter"; rev = "be4e3132e988519dacd0f9b40a47e23d33865b76"; src = builtins.fetchTarball { url = "https://github.com/${owner}/${repo}/archive/${rev}.tar.gz"; }; in import "${src}/nix/module.nix" ``` Make sure to update rev to the latest commit! Now you can import this as an ordinary module in your `configuration.nix`: ```nix imports = [ ./keter.nix ]; ``` Now you can configure keter in the same `configuration.nix`: ```nix services.keter = { enable = true; keterPackage = pkgs.keter; bundle = { domain = "example.com"; secretScript = env.secretScript; publicScript = env.publicScript; package = myWebAppDerivation; executable = "exe"; }; }; ``` secretScript is used to load environment varialbes, for example: ``` MY_AWS_KEY=$(cat /run/keys/AWS_ACCESS_KEY_ID) ``` Public script does the same but emits the loading to the logs. which isn't good for secrets. For the full option list available see `nix/module.nix`. This should load most webapps but PR's for improved support are welcome. Note that the default expects keter to be run behind nginx. ## Bundles An application needs to be set up as a keter bundle. This is a GZIPed tarball with a `.keter` filename extension and which has one special file: `config/keter.yaml`. A sample file is available at https://github.com/snoyberg/keter/blob/master/incoming/foo1_0/config/keter.yaml. Keter also supports wildcard subdomains and exceptions, as in this example configuration: ```yaml exec: ../com.example.app args: - Hello - World - 1 host: www.example.com extra-hosts: - "*.example.com" - foo.bar.example.com static-hosts: - host: static.example.com root: ../static redirects: - from: example.com to: www.example.com ``` Due to YAML parsing, wildcard hostnames will need to be quoted as above. Wildcard hostnames are not recursive, so `foo.bar.example.com` must be explicitly added as an extra hostname in the above example, or alternatively, `*.*.example.com` would cover all host names two levels deep. It would not cover host names only one level deep, such as `qux.example.com`. In this manner, wildcard hostnames correspond to the manner in which SSL certificates are handled per RFC2818. Wildcards may be used in only one level of a hostname, as in `foo.*.example.com`. Full RFC2818 compliance is not present - `f*.example.com` will not be handled as a wildcard with a prefix. A sample Bash script for producing a Keter bundle is: ```bash #!/bin/bash -ex cabal build strip dist/build/yesodweb/yesodweb rm -rf static/tmp tar czfv yesodweb.keter dist/build/yesodweb/yesodweb config static ``` For users of Yesod, The `yesod` executable provides a `keter` command for creating the bundle, and the scaffolded site provides a `keter.yaml` file. ## Deploying In order to deploy, you simply copy the keter bundle to `/opt/keter/incoming`. To update an app, copy in the new version. The old process will only be terminated after the new process has started answering requests. To stop an application, delete the file from incoming. ## PostgreSQL support Keter ships by default with a PostgreSQL plugin, which will handle management of PostgreSQL databases for your application. To use this, make the following changes: * Add the following lines to your `config/keter.yaml` file: ```yaml plugins: postgres: true ``` * Keter can be configured to connect to a remote postgres server using the following syntax: ```yaml plugins: postgres: - server: remoteServerNameOrIP port: 1234 ``` Different webapps can be configured to use different servers using the above syntax. It should be noted that keter will prioritize it's own postgres.yaml record for an app. So if moving an existing app from a local postgres server to a remote one (or switching remote servers), the postgres.yaml file will need to be updated manually. Keter will connect to the remote servers using the `postgres` account. This setup assumes the remote server's `pg_hba.conf` file has been configured to allow connections from the keter-server IP using the `trust` method. (Note: The `plugins` configuration option was added in v1.0 of the keter configuration syntax. If you are using v0.4 then use `postgres: true`. The remote-postgres server syntax was added in v1.4.2.) * Modify your application to get its database connection settings from the following environment variables: * `PGHOST` * `PGPORT` * `PGUSER` * `PGPASS` * `PGDATABASE` * The Yesod scaffold site is already equipped to read these environment variables when they are set. ## Known issues * There are reports of Keter not working behind an nginx reverse proxy. From the reports, this appears to be a limitation in nginx's implementation, not a problem with Keter. Keter works fine behind other reverse proxies, including Apache and Amazon ELB. One possible workaround is to add the following lines to your nginx configuration: proxy_set_header Connection ""; proxy_http_version 1.1; This has not yet been confirmed to work in production. If you use this, please report either its success or failure back to me. Additionally, to make sure that nginx does not reset the `Host` header (which keter uses to choose the right target), you will need to add: proxy_set_header Host $host; * Keter does not handle password-protected SSL key files well. When provided with such a key file, unlike Apache and Nginx, Keter will not pause to ask for the password. Instead, your https connections will merely stall. To get around this, you need to create a copy of the key without password and deploy this new key: openssl rsa -in original.key -out new.key (Back up the original key first, just in case.) ## Stanza-based config files Starting with Keter 1.0, there is an alternate format for application Keter config files, which allows much more flexibility in defining multiple functionality for a single bundle (e.g., more than one web app, multiple redirects, etc). This README will eventually be updated to reflect all various options. In the meanwhile, please see the following examples of how to use this file format: * https://github.com/yesodweb/yesod-scaffold/blob/postgres/config/keter.yml * https://github.com/snoyberg/keter/blob/master/incoming/foo1_0/config/keter.yaml ## Multiple SSL Certificates Keter is able to serve different certificates for different hosts, allowing for the deployment of distinct domains using the same server. An example `keter-config.yaml` would look like:: ``` root: .. listeners: - host: "*4" # Listen on all IPv4 hosts port: 80 - host: 127.0.0.1 key: key.pem certificate: certificate1.pem - host: 127.0.0.2 key: key.pem certificate: certificate2.pem ``` An alternative way to make this possible is adding the following `ssl:` argument to the `keter.yaml` file in your Yesod app's `config folder` as follows: ``` stanzas: - type: webapp exec: ../yourproject ssl: key: /opt/keter/etc/cert/yourproject.key certificate: /opt/keter/etc/cert/yourproject.crt chain-certificates: [] ``` If you don't have your certificates bundled in one `.crt` file, you should add the other certificates in the following order ``` ssl: [..] chain-certificates: - /opt/keter/etc/middle.crt - /opt/keter/etc/root.crt ``` This way you can designate certificates per Yesod App while still having one SSL certificate in your main `/opt/keter/etc/keter-config.yaml` for your other Yesod apps to default to if they don't have this `ssl:` argument in their `config/keter.yaml`. NOTE: If you get an error that a Bool was expected instead of an Object when adding the `ssl:` argument, then for this to work you might need to build Keter from Github, because at the time of writing the version of Keter on Hackage does not have this functionality. Just clone or download this repository and build it using stack. ## FAQ * Keter spawns multiple failing process when run with `sudo start keter`. * This may be due to Keter being unable to find the SSL certificate and key. Try to run `sudo /opt/keter/bin/keter /opt/keter/etc/keter-config.yaml`. If it fails with `keter: etc/certificate.pem: openBinaryFile: does not exist` or something like it, you may need to provide valid SSL certificates and keys or disable HTTPS, by commenting the key and certificate lines from `/opt/keter/etc/keter-config.yaml`. ## Debugging There is a debug port option available in the global keter config: ```yaml cli-port = 1234 ``` This allows you to attach netcat to that port, and introspect which processes are running within keter: ```bash nc localhost 1234 ``` Then type `--help` for options, currently it can only list the apps, but this approach is easily extensible if you need additional debug information. This option is disabled by default, but can be useful to figure out what keter is doing. ## Contributing If you are interested in contributing, see https://github.com/snoyberg/keter/blob/master/incoming/README.md for a complete testing workflow. If you have any questions, you can open an issue in the issue tracker, ask on the #yesod freenode irc channel, or send an email to yesodweb@googlegroups.com.